From 327e91681765e1928d1d5dcc3bb8e2762e389cdc Mon Sep 17 00:00:00 2001
From: Denis Feklushkin <feklushkin.denis@gmail.com>
Date: Fri, 31 Jul 2026 12:42:18 +0300
Subject: [PATCH 01/29] core.system.Mem.reallocate alias added and used in
 registerGCFactory()

---
 druntime/src/core/gc/registry.d |  4 ++--
 druntime/src/core/system.d      | 11 +++++++++++
 2 files changed, 13 insertions(+), 2 deletions(-)
 create mode 100644 druntime/src/core/system.d

diff --git a/druntime/src/core/gc/registry.d b/druntime/src/core/gc/registry.d
index 2e6edf09c3e7..83e732c5f58f 100644
--- a/druntime/src/core/gc/registry.d
+++ b/druntime/src/core/gc/registry.d
@@ -60,9 +60,9 @@ alias GCThreadInitFunction = void function(ThreadBase base) nothrow @nogc;
 void registerGCFactory(string name, GCFactory factory,
         GCThreadInitFunction threadInit = null) nothrow @nogc
 {
-    import core.stdc.stdlib : realloc;
+    import core.system : Mem;
 
-    auto ptr = cast(Entry*)realloc(entries.ptr, (entries.length + 1) * Entry.sizeof);
+    auto ptr = cast(Entry*) Mem.reallocate(entries.ptr, (entries.length + 1) * Entry.sizeof);
     entries = ptr[0 .. entries.length + 1];
     entries[$ - 1] = Entry(name, factory, threadInit);
 }
diff --git a/druntime/src/core/system.d b/druntime/src/core/system.d
new file mode 100644
index 000000000000..994dd7efb18f
--- /dev/null
+++ b/druntime/src/core/system.d
@@ -0,0 +1,11 @@
+///
+module core.system;
+
+package:
+
+static struct Mem
+{
+    import core.stdc.stdlib;
+
+    alias reallocate = realloc;
+}

From 2cb303cb913fd3d78eb5f69e104d8243464390c2 Mon Sep 17 00:00:00 2001
From: Denis Feklushkin <feklushkin.denis@gmail.com>
Date: Fri, 31 Jul 2026 12:51:48 +0300
Subject: [PATCH 02/29] core.system.Mem: allocate and free aliases added and
 used in Runtime.loadLibrary()

---
 druntime/src/core/runtime.d | 10 +++++-----
 druntime/src/core/system.d  |  2 ++
 2 files changed, 7 insertions(+), 5 deletions(-)

diff --git a/druntime/src/core/runtime.d b/druntime/src/core/runtime.d
index 8cdb999c92fd..524cc3ca9ad7 100644
--- a/druntime/src/core/runtime.d
+++ b/druntime/src/core/runtime.d
@@ -209,7 +209,7 @@ struct Runtime
      */
     static void* loadLibrary()(const scope char[] name)
     {
-        import core.stdc.stdlib : free, malloc;
+        import core.system : Mem;
         version (Windows)
         {
             import core.sys.windows.winnls : CP_UTF8, MultiByteToWideChar;
@@ -222,9 +222,9 @@ struct Runtime
             if (len == 0)
                 return null;
 
-            auto buf = cast(WCHAR*)malloc((len+1) * WCHAR.sizeof);
+            auto buf = cast(WCHAR*) Mem.allocate((len+1) * WCHAR.sizeof);
             if (buf is null) return null;
-            scope (exit) free(buf);
+            scope (exit) Mem.free(buf);
 
             len = MultiByteToWideChar(
                 CP_UTF8, 0, name.ptr, cast(int)name.length, buf, len);
@@ -240,9 +240,9 @@ struct Runtime
             /* Need a 0-terminated C string for the dll name
              */
             immutable len = name.length;
-            auto buf = cast(char*)malloc(len + 1);
+            auto buf = cast(char*) Mem.allocate(len + 1);
             if (!buf) return null;
-            scope (exit) free(buf);
+            scope (exit) Mem.free(buf);
 
             buf[0 .. len] = name[];
             buf[len] = 0;
diff --git a/druntime/src/core/system.d b/druntime/src/core/system.d
index 994dd7efb18f..f21d3bcb0fb4 100644
--- a/druntime/src/core/system.d
+++ b/druntime/src/core/system.d
@@ -7,5 +7,7 @@ static struct Mem
 {
     import core.stdc.stdlib;
 
+    alias allocate = malloc;
     alias reallocate = realloc;
+    alias free = core.stdc.stdlib.free;
 }

From 90237dccf9588c9d7e8917fb3089124ceea7203d Mon Sep 17 00:00:00 2001
From: Denis Feklushkin <feklushkin.denis@gmail.com>
Date: Fri, 31 Jul 2026 13:14:58 +0300
Subject: [PATCH 03/29] Mem.allocateBlank() added

---
 druntime/mak/COPY          | 1 +
 druntime/mak/SRCS          | 1 +
 druntime/src/core/system.d | 9 ++++++++-
 3 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/druntime/mak/COPY b/druntime/mak/COPY
index 90dc5e23f599..3ed916ff8cd3 100644
--- a/druntime/mak/COPY
+++ b/druntime/mak/COPY
@@ -23,6 +23,7 @@ COPY=\
 	$(IMPDIR)\core\memory.d \
 	$(IMPDIR)\core\runtime.d \
 	$(IMPDIR)\core\simd.d \
+	$(IMPDIR)\core\system.d \
 	$(IMPDIR)\core\time.d \
 	$(IMPDIR)\core\vararg.d \
 	$(IMPDIR)\core\volatile.d \
diff --git a/druntime/mak/SRCS b/druntime/mak/SRCS
index eff0ab33b62c..b345ad10a842 100644
--- a/druntime/mak/SRCS
+++ b/druntime/mak/SRCS
@@ -17,6 +17,7 @@ SRCS=\
 	src\core\memory.d \
 	src\core\runtime.d \
 	src\core\simd.d \
+	src\core\system.d \
 	src\core\time.d \
 	src\core\vararg.d \
 	src\core\volatile.d \
diff --git a/druntime/src/core/system.d b/druntime/src/core/system.d
index f21d3bcb0fb4..81fdfc4eeb01 100644
--- a/druntime/src/core/system.d
+++ b/druntime/src/core/system.d
@@ -3,11 +3,18 @@ module core.system;
 
 package:
 
-static struct Mem
+struct Mem
 {
     import core.stdc.stdlib;
 
     alias allocate = malloc;
     alias reallocate = realloc;
     alias free = core.stdc.stdlib.free;
+
+    static void* allocateBlank(size_t size) nothrow @nogc
+    {
+        ubyte* p = cast(ubyte*) allocate(size);
+        p[0 .. size] = 0;
+        return cast(void*) p;
+    }
 }

From c8e5b4e18349eb95da6a26af321f6223ff7624f5 Mon Sep 17 00:00:00 2001
From: Denis Feklushkin <feklushkin.denis@gmail.com>
Date: Fri, 31 Jul 2026 13:15:30 +0300
Subject: [PATCH 04/29] calloc() and free() replaced by Mem in
 core.internal.gc.os module

---
 druntime/src/core/internal/gc/bits.d | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/druntime/src/core/internal/gc/bits.d b/druntime/src/core/internal/gc/bits.d
index 8aabf9e393d7..d9607967cad5 100644
--- a/druntime/src/core/internal/gc/bits.d
+++ b/druntime/src/core/internal/gc/bits.d
@@ -11,7 +11,7 @@ import core.internal.gc.os;
 
 import core.bitop;
 import core.exception : onOutOfMemoryError;
-import core.stdc.stdlib : calloc, free;
+import core.system : Mem;
 import core.stdc.string : memcpy, memset;
 
 // use version gcbitsSingleBitOperation to disable optimizations that use
@@ -38,7 +38,7 @@ struct GCBits
         if (data)
         {
             if (!AllocSupportsShared || !share)
-                free(data);
+                Mem.free(data);
             else static if (AllocSupportsShared)
                 os_mem_unmap_shared(data, nwords * data[0].sizeof);
             else
@@ -51,7 +51,7 @@ struct GCBits
     {
         this.nbits = nbits;
         if (!AllocSupportsShared || !share)
-            data = cast(typeof(data[0])*)calloc(nwords, data[0].sizeof);
+            data = cast(typeof(data[0])*) Mem.allocateBlank(nwords * data[0].sizeof);
         else static if (AllocSupportsShared)
             data = cast(typeof(data[0])*)os_mem_map_shared(nwords * data[0].sizeof); // Allocate as MAP_SHARED
         else

From f17cea962ea0504604260ab00f0d6ccae3d77396 Mon Sep 17 00:00:00 2001
From: Denis Feklushkin <feklushkin.denis@gmail.com>
Date: Fri, 31 Jul 2026 14:44:55 +0300
Subject: [PATCH 05/29] Mem.allocateBlank() on Posix uses calloc()

---
 druntime/src/core/system.d | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/druntime/src/core/system.d b/druntime/src/core/system.d
index 81fdfc4eeb01..4c6fb42d80f5 100644
--- a/druntime/src/core/system.d
+++ b/druntime/src/core/system.d
@@ -11,10 +11,14 @@ struct Mem
     alias reallocate = realloc;
     alias free = core.stdc.stdlib.free;
 
+    static void* allocateBlank(size_t size) nothrow @nogc => calloc(1, size);
+
+    /+
     static void* allocateBlank(size_t size) nothrow @nogc
     {
         ubyte* p = cast(ubyte*) allocate(size);
         p[0 .. size] = 0;
         return cast(void*) p;
     }
+    +/
 }

From 6c6908364beea9f9c9a870cec61137baadea243c Mon Sep 17 00:00:00 2001
From: Denis Feklushkin <feklushkin.denis@gmail.com>
Date: Fri, 31 Jul 2026 15:09:22 +0300
Subject: [PATCH 06/29] module rt.minfo now uses core.system.Mem

---
 druntime/src/core/system.d |  3 +-
 druntime/src/rt/minfo.d    | 58 +++++++++++++++++++-------------------
 2 files changed, 31 insertions(+), 30 deletions(-)

diff --git a/druntime/src/core/system.d b/druntime/src/core/system.d
index 4c6fb42d80f5..67d9fab93b84 100644
--- a/druntime/src/core/system.d
+++ b/druntime/src/core/system.d
@@ -1,7 +1,8 @@
 ///
 module core.system;
 
-package:
+//TODO: package
+//package:
 
 struct Mem
 {
diff --git a/druntime/src/rt/minfo.d b/druntime/src/rt/minfo.d
index a70aabbeb648..cc72831f5fd6 100644
--- a/druntime/src/rt/minfo.d
+++ b/druntime/src/rt/minfo.d
@@ -13,7 +13,7 @@
 module rt.minfo;
 
 import core.stdc.stdio : fprintf, stderr;
-import core.stdc.stdlib : free, malloc, realloc;
+import core.system : Mem;
 import core.stdc.string : memcpy, memset;
 import rt.sections;
 
@@ -66,11 +66,11 @@ struct ModuleGroup
         import core.bitop : bt, btc, bts;
 
         // set up all the arrays.
-        size_t[] cyclePath = (cast(size_t*)malloc(size_t.sizeof * _modules.length * 2))[0 .. _modules.length * 2];
+        size_t[] cyclePath = (cast(size_t*) Mem.allocate(size_t.sizeof * _modules.length * 2))[0 .. _modules.length * 2];
         size_t totalMods;
-        int[] distance = (cast(int*)malloc(int.sizeof * _modules.length))[0 .. _modules.length];
+        int[] distance = (cast(int*) Mem.allocate(int.sizeof * _modules.length))[0 .. _modules.length];
         scope(exit)
-            .free(distance.ptr);
+            Mem.free(distance.ptr);
 
         // determine the shortest path between two modules. Uses dijkstra
         // without a priority queue. (we can be a bit slow here, in order to
@@ -221,14 +221,14 @@ struct ModuleGroup
         // allocate some stack arrays that will be used throughout the process.
         immutable nwords = (len + 8 * size_t.sizeof - 1) / (8 * size_t.sizeof);
         immutable flagbytes = nwords * size_t.sizeof;
-        auto ctorstart = cast(size_t*) malloc(flagbytes); // ctor/dtor seen
-        auto ctordone = cast(size_t*) malloc(flagbytes); // ctor/dtor processed
-        auto relevant = cast(size_t*) malloc(flagbytes); // has ctors/dtors
+        auto ctorstart = cast(size_t*) Mem.allocate(flagbytes); // ctor/dtor seen
+        auto ctordone = cast(size_t*) Mem.allocate(flagbytes); // ctor/dtor processed
+        auto relevant = cast(size_t*) Mem.allocate(flagbytes); // has ctors/dtors
         scope (exit)
         {
-            .free(ctorstart);
-            .free(ctordone);
-            .free(relevant);
+            Mem.free(ctorstart);
+            Mem.free(ctordone);
+            Mem.free(relevant);
         }
 
         void clearFlags(size_t* flags)
@@ -239,15 +239,15 @@ struct ModuleGroup
 
         // build the edges between each module. We may need this for printing,
         // and also allows avoiding keeping a hash around for module lookups.
-        int[][] edges = (cast(int[]*)malloc((int[]).sizeof * _modules.length))[0 .. _modules.length];
+        int[][] edges = (cast(int[]*) Mem.allocate((int[]).sizeof * _modules.length))[0 .. _modules.length];
         {
             HashTab!(immutable(ModuleInfo)*, int) modIndexes;
             foreach (i, m; _modules)
                 modIndexes[m] = cast(int) i;
 
-            auto reachable = cast(size_t*) malloc(flagbytes);
+            auto reachable = cast(size_t*) Mem.allocate(flagbytes);
             scope(exit)
-                .free(reachable);
+                Mem.free(reachable);
 
             foreach (i, m; _modules)
             {
@@ -255,7 +255,7 @@ struct ModuleGroup
                 // https://issues.dlang.org/show_bug.cgi?id=16208
                 clearFlags(reachable);
                 // preallocate enough space to store all the indexes
-                int *edge = cast(int*)malloc(int.sizeof * _modules.length);
+                int *edge = cast(int*) Mem.allocate(int.sizeof * _modules.length);
                 size_t nEdges = 0;
                 foreach (imp; m.importedModules)
                 {
@@ -270,12 +270,12 @@ struct ModuleGroup
                 if (nEdges > 0)
                 {
                     // trim space to what is needed
-                    edges[i] = (cast(int*)realloc(edge, int.sizeof * nEdges))[0 .. nEdges];
+                    edges[i] = (cast(int*) Mem.reallocate(edge, int.sizeof * nEdges))[0 .. nEdges];
                 }
                 else
                 {
                     edges[i] = null;
-                    .free(edge);
+                    Mem.free(edge);
                 }
             }
         }
@@ -285,8 +285,8 @@ struct ModuleGroup
         {
             foreach (e; edges)
                 if (e.ptr)
-                    .free(e.ptr);
-            .free(edges.ptr);
+                    Mem.free(e.ptr);
+            Mem.free(edges.ptr);
         }
 
         void buildCycleMessage(size_t sourceIdx, size_t cycleIdx, scope void delegate(string) nothrow sink)
@@ -302,7 +302,7 @@ struct ModuleGroup
             sink(_modules[cycleIdx].name);
             sink(EOL);
             auto cyclePath = genCyclePath(sourceIdx, cycleIdx, edges);
-            scope(exit) .free(cyclePath.ptr);
+            scope(exit) Mem.free(cyclePath.ptr);
 
             sink(_modules[sourceIdx].name);
             sink("* ->" ~ EOL);
@@ -330,9 +330,9 @@ struct ModuleGroup
             }
 
             // initialize "stack"
-            auto stack = cast(stackFrame*) malloc(stackFrame.sizeof * len);
+            auto stack = cast(stackFrame*) Mem.allocate(stackFrame.sizeof * len);
             scope (exit)
-                .free(stack);
+                Mem.free(stack);
             auto stacktop = stack + len;
             auto sp = stack;
             sp.curMod = cast(int) idx;
@@ -423,9 +423,9 @@ struct ModuleGroup
             immutable ModuleInfo* current = _modules[curidx];
 
             // First, determine what modules are reachable.
-            auto reachable = cast(size_t*) malloc(flagbytes);
+            auto reachable = cast(size_t*) Mem.allocate(flagbytes);
             scope (exit)
-                .free(reachable);
+                Mem.free(reachable);
             if (!findDeps(curidx, reachable))
                 return false;   // deprecated cycle error
 
@@ -468,7 +468,7 @@ struct ModuleGroup
             clearFlags(ctordone);
 
             // pre-allocate enough space to hold all modules.
-            ctors = (cast(immutable(ModuleInfo)**).malloc(len * (void*).sizeof));
+            ctors = cast(immutable(ModuleInfo)**) Mem.allocate(len * (void*).sizeof);
             ctoridx = 0;
             foreach (idx, m; _modules)
             {
@@ -493,7 +493,7 @@ struct ModuleGroup
                 {
                     if (!processMod(idx))
                     {
-                        .free(ctors);
+                        Mem.free(ctors);
                         return false;
                     }
                 }
@@ -502,11 +502,11 @@ struct ModuleGroup
             if (ctoridx == 0)
             {
                 // no ctors in the list.
-                .free(ctors);
+                Mem.free(ctors);
             }
             else
             {
-                ctors = cast(immutable(ModuleInfo)**).realloc(ctors, ctoridx * (void*).sizeof);
+                ctors = cast(immutable(ModuleInfo)**) Mem.reallocate(ctors, ctoridx * (void*).sizeof);
                 if (ctors is null)
                     assert(0);
                 result = ctors[0 .. ctoridx];
@@ -561,10 +561,10 @@ struct ModuleGroup
     void free()
     {
         if (_ctors.ptr)
-            .free(_ctors.ptr);
+            Mem.free(_ctors.ptr);
         _ctors = null;
         if (_tlsctors.ptr)
-            .free(_tlsctors.ptr);
+            Mem.free(_tlsctors.ptr);
         _tlsctors = null;
         // _modules = null; // let the owner free it
     }

From afb47cc2ca223a7a2cac521697e3fc07986734c2 Mon Sep 17 00:00:00 2001
From: Denis Feklushkin <feklushkin.denis@gmail.com>
Date: Fri, 31 Jul 2026 15:23:46 +0300
Subject: [PATCH 07/29] core.internal.gc.impl.manual.gc uses core.system.Mem

---
 druntime/src/core/internal/gc/impl/manual/gc.d | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/druntime/src/core/internal/gc/impl/manual/gc.d b/druntime/src/core/internal/gc/impl/manual/gc.d
index 5f9c04187ed9..48e0fbdca764 100644
--- a/druntime/src/core/internal/gc/impl/manual/gc.d
+++ b/druntime/src/core/internal/gc/impl/manual/gc.d
@@ -25,7 +25,7 @@ import core.internal.container.array;
 
 import core.thread.threadbase : ThreadBase;
 
-import cstdlib = core.stdc.stdlib : calloc, free, malloc, realloc;
+import core.system: Mem;
 static import core.memory;
 
 extern (C) noreturn onOutOfMemoryError(void* pretend_sideffect = null, string file = __FILE__, size_t line = __LINE__) @trusted pure nothrow @nogc; /* dmd @@@BUG11461@@@ */
@@ -46,7 +46,7 @@ private GC initialize()
 {
     import core.lifetime : emplace;
 
-    auto gc = cast(ManualGC) cstdlib.malloc(__traits(classInstanceSize, ManualGC));
+    auto gc = cast(ManualGC) Mem.allocate(__traits(classInstanceSize, ManualGC));
     if (!gc)
         onOutOfMemoryError();
 
@@ -102,7 +102,7 @@ class ManualGC : GC
 
     void* malloc(size_t size, uint bits, const TypeInfo ti) nothrow
     {
-        void* p = cstdlib.malloc(size);
+        void* p = Mem.allocate(size);
 
         if (size && p is null)
             onOutOfMemoryError();
@@ -120,7 +120,7 @@ class ManualGC : GC
 
     void* calloc(size_t size, uint bits, const TypeInfo ti) nothrow
     {
-        void* p = cstdlib.calloc(1, size);
+        void* p = Mem.allocateBlank(size);
 
         if (size && p is null)
             onOutOfMemoryError();
@@ -129,7 +129,7 @@ class ManualGC : GC
 
     void* realloc(void* p, size_t size, uint bits, const TypeInfo ti) nothrow
     {
-        p = cstdlib.realloc(p, size);
+        p = Mem.reallocate(p, size);
 
         if (size && p is null)
             onOutOfMemoryError();
@@ -148,7 +148,7 @@ class ManualGC : GC
 
     void free(void* p) nothrow @nogc
     {
-        cstdlib.free(p);
+        Mem.free(p);
     }
 
     /**

From 80eff15656c5d1efbc155b252820b3197fd0c5f6 Mon Sep 17 00:00:00 2001
From: Denis Feklushkin <feklushkin.denis@gmail.com>
Date: Fri, 31 Jul 2026 15:29:30 +0300
Subject: [PATCH 08/29] module core.runtime uses core.system.Mem

---
 druntime/src/core/runtime.d | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/druntime/src/core/runtime.d b/druntime/src/core/runtime.d
index 524cc3ca9ad7..0269b6501b97 100644
--- a/druntime/src/core/runtime.d
+++ b/druntime/src/core/runtime.d
@@ -10,6 +10,8 @@
 
 module core.runtime;
 
+import core.system : Mem;
+
 version (OSX)
     version = Darwin;
 else version (iOS)
@@ -743,8 +745,7 @@ Throwable.TraceInfo defaultTraceHandler( void* ptr = null ) // @nogc
     static T allocate(T, Args...)(auto ref Args args) @nogc
     {
         import core.lifetime : emplace;
-        import core.stdc.stdlib : malloc;
-        auto result = cast(T)malloc(__traits(classInstanceSize, T));
+        auto result = cast(T) Mem.allocate(__traits(classInstanceSize, T));
         return emplace(result, args);
     }
     version (Windows)
@@ -803,8 +804,7 @@ void defaultTraceDeallocator(Throwable.TraceInfo info) nothrow
         return;
     auto obj = cast(Object)info;
     destroy(obj);
-    import core.stdc.stdlib : free;
-    free(cast(void *)obj);
+    Mem.free(cast(void *)obj);
 }
 
 /// Default implementation for most POSIX systems
@@ -812,7 +812,6 @@ version (WASI) {}
 else version (Posix) private class DefaultTraceInfo : Throwable.TraceInfo
 {
     import core.demangle;
-    import core.stdc.stdlib : free;
     import core.stdc.string : strlen, memchr, memmove;
 
     this() @nogc
@@ -879,7 +878,7 @@ else version (Posix) private class DefaultTraceInfo : Throwable.TraceInfo
         static if (hasExecinfo)
         {
             const framelist = backtrace_symbols( callstack.ptr, numframes );
-            scope(exit) free(cast(void*) framelist);
+            scope(exit) Mem.free(cast(void*) framelist);
 
             static if (enableDwarf)
             {

From 95a13a7a42d8dcf972c47e863b460c9a82a9a593 Mon Sep 17 00:00:00 2001
From: Denis Feklushkin <feklushkin.denis@gmail.com>
Date: Fri, 31 Jul 2026 15:31:52 +0300
Subject: [PATCH 09/29] core.gc.registry uses core.system.Mem

---
 druntime/src/core/gc/registry.d | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/druntime/src/core/gc/registry.d b/druntime/src/core/gc/registry.d
index 83e732c5f58f..ff4c20fbf4ba 100644
--- a/druntime/src/core/gc/registry.d
+++ b/druntime/src/core/gc/registry.d
@@ -77,7 +77,7 @@ void registerGCFactory(string name, GCFactory factory,
  */
 GC createGCInstance(string name)
 {
-    import core.stdc.stdlib : free;
+    import core.system : Mem;
 
     foreach (entry; entries)
     {
@@ -85,7 +85,7 @@ GC createGCInstance(string name)
             continue;
         auto instance = entry.factory();
         // only one GC at a time for now, so free the registry to not leak
-        free(entries.ptr);
+        Mem.free(entries.ptr);
         entries = null;
         return instance;
     }

From f121ab970d6c61fddd1ec1fbb55d5221c716745b Mon Sep 17 00:00:00 2001
From: Denis Feklushkin <feklushkin.denis@gmail.com>
Date: Fri, 31 Jul 2026 22:22:19 +0300
Subject: [PATCH 10/29] rt.dmain2: core.stdc.stdlib.alloca() replaced by
 Mem.allocateOnStack

---
 druntime/src/core/system.d |  2 ++
 druntime/src/rt/dmain2.d   | 21 +++++++++++----------
 2 files changed, 13 insertions(+), 10 deletions(-)

diff --git a/druntime/src/core/system.d b/druntime/src/core/system.d
index 67d9fab93b84..4583a2e42f73 100644
--- a/druntime/src/core/system.d
+++ b/druntime/src/core/system.d
@@ -22,4 +22,6 @@ struct Mem
         return cast(void*) p;
     }
     +/
+
+    alias allocateOnStack = alloca;
 }
diff --git a/druntime/src/rt/dmain2.d b/druntime/src/rt/dmain2.d
index 2a4d9beb80af..464539cd5803 100644
--- a/druntime/src/rt/dmain2.d
+++ b/druntime/src/rt/dmain2.d
@@ -15,11 +15,12 @@ import core.atomic;
 import core.internal.parseoptions : rt_parseOption;
 import core.stdc.errno : errno;
 import core.stdc.stdio : fflush, fprintf, fwrite, stderr, stdout;
-import core.stdc.stdlib : alloca, EXIT_FAILURE, EXIT_SUCCESS, free, malloc, realloc;
+import core.stdc.stdlib : EXIT_FAILURE, EXIT_SUCCESS, free, malloc, realloc;
 import core.stdc.string : strerror;
 import rt.config : rt_cmdline_enabled, rt_configOption;
 import rt.memory;
 import rt.sections;
+import core.system : Mem;
 
 version (Windows)
 {
@@ -49,7 +50,7 @@ else version (WASI)
 }
 
 version (DigitalMars) version (AArch64)
-    version = UseMalloc;   // cuz alloca() is not implemented yet
+    version = UseMalloc;   // cuz Mem.allocateOnStack is not implemented yet
 
 // not sure why we can't define this in one place, but this is to keep this
 // module from importing core.runtime.
@@ -294,7 +295,7 @@ extern (C) int _d_run_main(int argc, char** argv, MainFunc mainFunc)
             scope (exit) free(args.ptr);
         }
         else
-            char[][] args = (cast(char[]*) alloca(wargc * (char[]).sizeof))[0 .. wargc];
+            char[][] args = (cast(char[]*) Mem.allocateOnStack(wargc * (char[]).sizeof))[0 .. wargc];
 
         // This is required because WideCharToMultiByte requires int as input.
         assert(wCommandLineLength <= cast(size_t) int.max, "Wide char command line length must not exceed int.max");
@@ -309,7 +310,7 @@ extern (C) int _d_run_main(int argc, char** argv, MainFunc mainFunc)
                 scope (exit) free(totalArgsBuff);
             }
             else
-                char* totalArgsBuff = cast(char*) alloca(totalArgsLength);
+                char* totalArgsBuff = cast(char*) Mem.allocateOnStack(totalArgsLength);
             size_t j = 0;
             foreach (i; 0 .. wargc)
             {
@@ -339,7 +340,7 @@ extern (C) int _d_run_main(int argc, char** argv, MainFunc mainFunc)
             scope (exit) free(args.ptr);
         }
         else
-            char[][] args = (cast(char[]*) alloca(argc * (char[]).sizeof))[0 .. argc];
+            char[][] args = (cast(char[]*) Mem.allocateOnStack(argc * (char[]).sizeof))[0 .. argc];
 
         size_t totalArgsLength = 0;
         foreach (i, ref arg; args)
@@ -351,7 +352,7 @@ extern (C) int _d_run_main(int argc, char** argv, MainFunc mainFunc)
     else version (WASI)
     {
         // Allocate args[] on the stack
-        char[][] args = (cast(char[]*) alloca(argc * (char[]).sizeof))[0 .. argc];
+        char[][] args = (cast(char[]*) Mem.allocateOnStack(argc * (char[]).sizeof))[0 .. argc];
 
         size_t totalArgsLength = 0;
         foreach (i, ref arg; args)
@@ -376,7 +377,7 @@ version (Windows)
 extern (C) int _d_wrun_main(int argc, wchar** wargv, MainFunc mainFunc)
 {
      // Allocate args[] on the stack
-    char[][] args = (cast(char[]*) alloca(argc * (char[]).sizeof))[0 .. argc];
+    char[][] args = (cast(char[]*) Mem.allocateOnStack(argc * (char[]).sizeof))[0 .. argc];
 
     // 1st pass: compute each argument's length as UTF-16 and UTF-8
     size_t totalArgsLength = 0;
@@ -391,7 +392,7 @@ extern (C) int _d_wrun_main(int argc, wchar** wargv, MainFunc mainFunc)
     }
 
     // Allocate a single buffer for all (null-terminated) argument strings in UTF-8 on the stack
-    char* utf8Buffer = cast(char*) alloca(totalArgsLength);
+    char* utf8Buffer = cast(char*) Mem.allocateOnStack(totalArgsLength);
 
     // 2nd pass: convert to UTF-8 and finalize `args`
     char* utf8 = utf8Buffer;
@@ -405,7 +406,7 @@ extern (C) int _d_wrun_main(int argc, wchar** wargv, MainFunc mainFunc)
     }
 
     // Set C argc/argv; argv is a new stack-allocated array of UTF-8 C strings
-    char*[] argv = (cast(char**) alloca(argc * (char*).sizeof))[0 .. argc];
+    char*[] argv = (cast(char**) Mem.allocateOnStack(argc * (char*).sizeof))[0 .. argc];
     foreach (i, ref arg; argv)
         arg = args[i].ptr;
     _cArgs.argc = argc;
@@ -487,7 +488,7 @@ private extern (C) int _d_run_main2(char[][] args, size_t totalArgsLength, MainF
             //scope (exit) buff;
         }
         else
-            auto buff = cast(char[]*) alloca(length);
+            auto buff = cast(char[]*) Mem.allocateOnStack(length);
 
         char[][] argsCopy = buff[0 .. args.length];
         auto argBuff = cast(char*) (buff + args.length);

From 6f8d22b1a6070bb0341a446cbb44d296e1960476 Mon Sep 17 00:00:00 2001
From: Denis Feklushkin <feklushkin.denis@gmail.com>
Date: Fri, 31 Jul 2026 22:26:01 +0300
Subject: [PATCH 11/29] rt.dmain2: free, malloc, realloc replaced by Mem.*
 calls

---
 druntime/src/rt/dmain2.d | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/druntime/src/rt/dmain2.d b/druntime/src/rt/dmain2.d
index 464539cd5803..303944a34b70 100644
--- a/druntime/src/rt/dmain2.d
+++ b/druntime/src/rt/dmain2.d
@@ -15,7 +15,7 @@ import core.atomic;
 import core.internal.parseoptions : rt_parseOption;
 import core.stdc.errno : errno;
 import core.stdc.stdio : fflush, fprintf, fwrite, stderr, stdout;
-import core.stdc.stdlib : EXIT_FAILURE, EXIT_SUCCESS, free, malloc, realloc;
+import core.stdc.stdlib : EXIT_FAILURE, EXIT_SUCCESS;
 import core.stdc.string : strerror;
 import rt.config : rt_cmdline_enabled, rt_configOption;
 import rt.memory;
@@ -289,7 +289,7 @@ extern (C) int _d_run_main(int argc, char** argv, MainFunc mainFunc)
         // Allocate args[] on the stack - use wargc
         version (UseMalloc)
         {
-            char[][] args = (cast(char[]*) malloc(wargc * (char[]).sizeof))[0 .. wargc];
+            char[][] args = (cast(char[]*) Mem.allocate(wargc * (char[]).sizeof))[0 .. wargc];
             if (wargc)
                 assert(args.ptr);
             scope (exit) free(args.ptr);
@@ -304,7 +304,7 @@ extern (C) int _d_run_main(int argc, char** argv, MainFunc mainFunc)
         {
             version (UseMalloc)
             {
-                char* totalArgsBuff = cast(char*) malloc(totalArgsLength);
+                char* totalArgsBuff = cast(char*) Mem.allocate(totalArgsLength);
                 if (totalArgsLength)
                     assert(totalArgsBuff);
                 scope (exit) free(totalArgsBuff);
@@ -334,7 +334,7 @@ extern (C) int _d_run_main(int argc, char** argv, MainFunc mainFunc)
         // Allocate args[] on the stack
         version (UseMalloc)
         {
-            char[][] args = (cast(char[]*) malloc(argc * (char[]).sizeof))[0 .. argc];
+            char[][] args = (cast(char[]*) Mem.allocate(argc * (char[]).sizeof))[0 .. argc];
             if (argc)
                 assert(args.ptr);
             scope (exit) free(args.ptr);
@@ -482,7 +482,7 @@ private extern (C) int _d_run_main2(char[][] args, size_t totalArgsLength, MainF
         auto length = args.length * (char[]).sizeof + totalArgsLength;
         version (UseMalloc)
         {
-            auto buff = cast(char[]*) malloc(length);
+            auto buff = cast(char[]*) Mem.allocate(length);
             if (length)
                 assert(buff);
             //scope (exit) buff;
@@ -661,7 +661,7 @@ extern (C) void _d_print_throwable(Throwable t)
                         CP_UTF8, 0, s.ptr, cast(int)s.length, null, 0);
                 if (!swlen) return;
 
-                auto newPtr = cast(WCHAR*)realloc(ptr,
+                auto newPtr = cast(WCHAR*) Mem.reallocate(ptr,
                         (this.len + swlen + 1) * WCHAR.sizeof);
                 if (!newPtr) return;
                 ptr = newPtr;
@@ -672,7 +672,7 @@ extern (C) void _d_print_throwable(Throwable t)
 
             typeof(ptr) get() { if (ptr) ptr[len] = 0; return ptr; }
 
-            void free() { .free(ptr); }
+            void free() { Mem.free(ptr); }
         }
 
         HANDLE windowsHandle(int fd)
@@ -721,12 +721,12 @@ extern (C) void _d_print_throwable(Throwable t)
                 uint codepage = GetConsoleOutputCP();
                 const slen = WideCharToMultiByte(codepage, 0,
                         buf.ptr, cast(int)buf.len, null, 0, null, null);
-                if (auto sptr = cast(char*)malloc(slen * char.sizeof))
+                if (auto sptr = cast(char*) Mem.allocate(slen * char.sizeof))
                 {
                     WideCharToMultiByte(codepage, 0,
                         buf.ptr, cast(int)buf.len, sptr, slen, null, null);
                     WriteFile(hStdErr, sptr, slen, null, null);
-                    free(sptr);
+                    Mem.free(sptr);
                 }
                 buf.free();
             }

From 8ae2a8f879f93b7c9a0ca31e0d3c36ea6c349f11 Mon Sep 17 00:00:00 2001
From: Denis Feklushkin <feklushkin.denis@gmail.com>
Date: Sat, 1 Aug 2026 12:08:31 +0300
Subject: [PATCH 12/29] allocateBlank() commented-out code removed

---
 druntime/src/core/system.d | 10 ----------
 1 file changed, 10 deletions(-)

diff --git a/druntime/src/core/system.d b/druntime/src/core/system.d
index 4583a2e42f73..8fff44810b1c 100644
--- a/druntime/src/core/system.d
+++ b/druntime/src/core/system.d
@@ -11,17 +11,7 @@ struct Mem
     alias allocate = malloc;
     alias reallocate = realloc;
     alias free = core.stdc.stdlib.free;
-
     static void* allocateBlank(size_t size) nothrow @nogc => calloc(1, size);
 
-    /+
-    static void* allocateBlank(size_t size) nothrow @nogc
-    {
-        ubyte* p = cast(ubyte*) allocate(size);
-        p[0 .. size] = 0;
-        return cast(void*) p;
-    }
-    +/
-
     alias allocateOnStack = alloca;
 }

From 01dc1040dae4b9bf01777b04614d6d0d154f6b79 Mon Sep 17 00:00:00 2001
From: Denis Feklushkin <feklushkin.denis@gmail.com>
Date: Sat, 1 Aug 2026 12:14:53 +0300
Subject: [PATCH 13/29] Mem.allocate -> Mem.allocateOne

---
 .../src/core/internal/gc/impl/manual/gc.d     |  4 ++--
 druntime/src/core/runtime.d                   |  6 ++---
 druntime/src/core/system.d                    |  2 +-
 druntime/src/rt/dmain2.d                      | 10 ++++-----
 druntime/src/rt/minfo.d                       | 22 +++++++++----------
 5 files changed, 22 insertions(+), 22 deletions(-)

diff --git a/druntime/src/core/internal/gc/impl/manual/gc.d b/druntime/src/core/internal/gc/impl/manual/gc.d
index 48e0fbdca764..2d31b5121d56 100644
--- a/druntime/src/core/internal/gc/impl/manual/gc.d
+++ b/druntime/src/core/internal/gc/impl/manual/gc.d
@@ -46,7 +46,7 @@ private GC initialize()
 {
     import core.lifetime : emplace;
 
-    auto gc = cast(ManualGC) Mem.allocate(__traits(classInstanceSize, ManualGC));
+    auto gc = cast(ManualGC) Mem.allocateOne(__traits(classInstanceSize, ManualGC));
     if (!gc)
         onOutOfMemoryError();
 
@@ -102,7 +102,7 @@ class ManualGC : GC
 
     void* malloc(size_t size, uint bits, const TypeInfo ti) nothrow
     {
-        void* p = Mem.allocate(size);
+        void* p = Mem.allocateOne(size);
 
         if (size && p is null)
             onOutOfMemoryError();
diff --git a/druntime/src/core/runtime.d b/druntime/src/core/runtime.d
index 0269b6501b97..234af8444958 100644
--- a/druntime/src/core/runtime.d
+++ b/druntime/src/core/runtime.d
@@ -224,7 +224,7 @@ struct Runtime
             if (len == 0)
                 return null;
 
-            auto buf = cast(WCHAR*) Mem.allocate((len+1) * WCHAR.sizeof);
+            auto buf = cast(WCHAR*) Mem.allocateOne((len+1) * WCHAR.sizeof);
             if (buf is null) return null;
             scope (exit) Mem.free(buf);
 
@@ -242,7 +242,7 @@ struct Runtime
             /* Need a 0-terminated C string for the dll name
              */
             immutable len = name.length;
-            auto buf = cast(char*) Mem.allocate(len + 1);
+            auto buf = cast(char*) Mem.allocateOne(len + 1);
             if (!buf) return null;
             scope (exit) Mem.free(buf);
 
@@ -745,7 +745,7 @@ Throwable.TraceInfo defaultTraceHandler( void* ptr = null ) // @nogc
     static T allocate(T, Args...)(auto ref Args args) @nogc
     {
         import core.lifetime : emplace;
-        auto result = cast(T) Mem.allocate(__traits(classInstanceSize, T));
+        auto result = cast(T) Mem.allocateOne(__traits(classInstanceSize, T));
         return emplace(result, args);
     }
     version (Windows)
diff --git a/druntime/src/core/system.d b/druntime/src/core/system.d
index 8fff44810b1c..c595a140b257 100644
--- a/druntime/src/core/system.d
+++ b/druntime/src/core/system.d
@@ -8,7 +8,7 @@ struct Mem
 {
     import core.stdc.stdlib;
 
-    alias allocate = malloc;
+    alias allocateOne = malloc;
     alias reallocate = realloc;
     alias free = core.stdc.stdlib.free;
     static void* allocateBlank(size_t size) nothrow @nogc => calloc(1, size);
diff --git a/druntime/src/rt/dmain2.d b/druntime/src/rt/dmain2.d
index 303944a34b70..2efe24fc3e90 100644
--- a/druntime/src/rt/dmain2.d
+++ b/druntime/src/rt/dmain2.d
@@ -289,7 +289,7 @@ extern (C) int _d_run_main(int argc, char** argv, MainFunc mainFunc)
         // Allocate args[] on the stack - use wargc
         version (UseMalloc)
         {
-            char[][] args = (cast(char[]*) Mem.allocate(wargc * (char[]).sizeof))[0 .. wargc];
+            char[][] args = (cast(char[]*) Mem.allocateOne(wargc * (char[]).sizeof))[0 .. wargc];
             if (wargc)
                 assert(args.ptr);
             scope (exit) free(args.ptr);
@@ -304,7 +304,7 @@ extern (C) int _d_run_main(int argc, char** argv, MainFunc mainFunc)
         {
             version (UseMalloc)
             {
-                char* totalArgsBuff = cast(char*) Mem.allocate(totalArgsLength);
+                char* totalArgsBuff = cast(char*) Mem.allocateOne(totalArgsLength);
                 if (totalArgsLength)
                     assert(totalArgsBuff);
                 scope (exit) free(totalArgsBuff);
@@ -334,7 +334,7 @@ extern (C) int _d_run_main(int argc, char** argv, MainFunc mainFunc)
         // Allocate args[] on the stack
         version (UseMalloc)
         {
-            char[][] args = (cast(char[]*) Mem.allocate(argc * (char[]).sizeof))[0 .. argc];
+            char[][] args = (cast(char[]*) Mem.allocateOne(argc * (char[]).sizeof))[0 .. argc];
             if (argc)
                 assert(args.ptr);
             scope (exit) free(args.ptr);
@@ -482,7 +482,7 @@ private extern (C) int _d_run_main2(char[][] args, size_t totalArgsLength, MainF
         auto length = args.length * (char[]).sizeof + totalArgsLength;
         version (UseMalloc)
         {
-            auto buff = cast(char[]*) Mem.allocate(length);
+            auto buff = cast(char[]*) Mem.allocateOne(length);
             if (length)
                 assert(buff);
             //scope (exit) buff;
@@ -721,7 +721,7 @@ extern (C) void _d_print_throwable(Throwable t)
                 uint codepage = GetConsoleOutputCP();
                 const slen = WideCharToMultiByte(codepage, 0,
                         buf.ptr, cast(int)buf.len, null, 0, null, null);
-                if (auto sptr = cast(char*) Mem.allocate(slen * char.sizeof))
+                if (auto sptr = cast(char*) Mem.allocateOne(slen * char.sizeof))
                 {
                     WideCharToMultiByte(codepage, 0,
                         buf.ptr, cast(int)buf.len, sptr, slen, null, null);
diff --git a/druntime/src/rt/minfo.d b/druntime/src/rt/minfo.d
index cc72831f5fd6..0002e62bbd13 100644
--- a/druntime/src/rt/minfo.d
+++ b/druntime/src/rt/minfo.d
@@ -66,9 +66,9 @@ struct ModuleGroup
         import core.bitop : bt, btc, bts;
 
         // set up all the arrays.
-        size_t[] cyclePath = (cast(size_t*) Mem.allocate(size_t.sizeof * _modules.length * 2))[0 .. _modules.length * 2];
+        size_t[] cyclePath = (cast(size_t*) Mem.allocateOne(size_t.sizeof * _modules.length * 2))[0 .. _modules.length * 2];
         size_t totalMods;
-        int[] distance = (cast(int*) Mem.allocate(int.sizeof * _modules.length))[0 .. _modules.length];
+        int[] distance = (cast(int*) Mem.allocateOne(int.sizeof * _modules.length))[0 .. _modules.length];
         scope(exit)
             Mem.free(distance.ptr);
 
@@ -221,9 +221,9 @@ struct ModuleGroup
         // allocate some stack arrays that will be used throughout the process.
         immutable nwords = (len + 8 * size_t.sizeof - 1) / (8 * size_t.sizeof);
         immutable flagbytes = nwords * size_t.sizeof;
-        auto ctorstart = cast(size_t*) Mem.allocate(flagbytes); // ctor/dtor seen
-        auto ctordone = cast(size_t*) Mem.allocate(flagbytes); // ctor/dtor processed
-        auto relevant = cast(size_t*) Mem.allocate(flagbytes); // has ctors/dtors
+        auto ctorstart = cast(size_t*) Mem.allocateOne(flagbytes); // ctor/dtor seen
+        auto ctordone = cast(size_t*) Mem.allocateOne(flagbytes); // ctor/dtor processed
+        auto relevant = cast(size_t*) Mem.allocateOne(flagbytes); // has ctors/dtors
         scope (exit)
         {
             Mem.free(ctorstart);
@@ -239,13 +239,13 @@ struct ModuleGroup
 
         // build the edges between each module. We may need this for printing,
         // and also allows avoiding keeping a hash around for module lookups.
-        int[][] edges = (cast(int[]*) Mem.allocate((int[]).sizeof * _modules.length))[0 .. _modules.length];
+        int[][] edges = (cast(int[]*) Mem.allocateOne((int[]).sizeof * _modules.length))[0 .. _modules.length];
         {
             HashTab!(immutable(ModuleInfo)*, int) modIndexes;
             foreach (i, m; _modules)
                 modIndexes[m] = cast(int) i;
 
-            auto reachable = cast(size_t*) Mem.allocate(flagbytes);
+            auto reachable = cast(size_t*) Mem.allocateOne(flagbytes);
             scope(exit)
                 Mem.free(reachable);
 
@@ -255,7 +255,7 @@ struct ModuleGroup
                 // https://issues.dlang.org/show_bug.cgi?id=16208
                 clearFlags(reachable);
                 // preallocate enough space to store all the indexes
-                int *edge = cast(int*) Mem.allocate(int.sizeof * _modules.length);
+                int *edge = cast(int*) Mem.allocateOne(int.sizeof * _modules.length);
                 size_t nEdges = 0;
                 foreach (imp; m.importedModules)
                 {
@@ -330,7 +330,7 @@ struct ModuleGroup
             }
 
             // initialize "stack"
-            auto stack = cast(stackFrame*) Mem.allocate(stackFrame.sizeof * len);
+            auto stack = cast(stackFrame*) Mem.allocateOne(stackFrame.sizeof * len);
             scope (exit)
                 Mem.free(stack);
             auto stacktop = stack + len;
@@ -423,7 +423,7 @@ struct ModuleGroup
             immutable ModuleInfo* current = _modules[curidx];
 
             // First, determine what modules are reachable.
-            auto reachable = cast(size_t*) Mem.allocate(flagbytes);
+            auto reachable = cast(size_t*) Mem.allocateOne(flagbytes);
             scope (exit)
                 Mem.free(reachable);
             if (!findDeps(curidx, reachable))
@@ -468,7 +468,7 @@ struct ModuleGroup
             clearFlags(ctordone);
 
             // pre-allocate enough space to hold all modules.
-            ctors = cast(immutable(ModuleInfo)**) Mem.allocate(len * (void*).sizeof);
+            ctors = cast(immutable(ModuleInfo)**) Mem.allocateOne(len * (void*).sizeof);
             ctoridx = 0;
             foreach (idx, m; _modules)
             {

From 417361aa85e6880a4428c0da8d3803d205ab55f9 Mon Sep 17 00:00:00 2001
From: Denis Feklushkin <feklushkin.denis@gmail.com>
Date: Sat, 1 Aug 2026 12:17:16 +0300
Subject: [PATCH 14/29] allocateBlank() -> allocateOneBlank()

---
 druntime/src/core/internal/gc/bits.d           | 2 +-
 druntime/src/core/internal/gc/impl/manual/gc.d | 2 +-
 druntime/src/core/system.d                     | 2 +-
 3 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/druntime/src/core/internal/gc/bits.d b/druntime/src/core/internal/gc/bits.d
index d9607967cad5..1b0b1f8e043b 100644
--- a/druntime/src/core/internal/gc/bits.d
+++ b/druntime/src/core/internal/gc/bits.d
@@ -51,7 +51,7 @@ struct GCBits
     {
         this.nbits = nbits;
         if (!AllocSupportsShared || !share)
-            data = cast(typeof(data[0])*) Mem.allocateBlank(nwords * data[0].sizeof);
+            data = cast(typeof(data[0])*) Mem.allocateOneBlank(nwords * data[0].sizeof);
         else static if (AllocSupportsShared)
             data = cast(typeof(data[0])*)os_mem_map_shared(nwords * data[0].sizeof); // Allocate as MAP_SHARED
         else
diff --git a/druntime/src/core/internal/gc/impl/manual/gc.d b/druntime/src/core/internal/gc/impl/manual/gc.d
index 2d31b5121d56..ee7eeae97f78 100644
--- a/druntime/src/core/internal/gc/impl/manual/gc.d
+++ b/druntime/src/core/internal/gc/impl/manual/gc.d
@@ -120,7 +120,7 @@ class ManualGC : GC
 
     void* calloc(size_t size, uint bits, const TypeInfo ti) nothrow
     {
-        void* p = Mem.allocateBlank(size);
+        void* p = Mem.allocateOneBlank(size);
 
         if (size && p is null)
             onOutOfMemoryError();
diff --git a/druntime/src/core/system.d b/druntime/src/core/system.d
index c595a140b257..05ddc3f040ef 100644
--- a/druntime/src/core/system.d
+++ b/druntime/src/core/system.d
@@ -11,7 +11,7 @@ struct Mem
     alias allocateOne = malloc;
     alias reallocate = realloc;
     alias free = core.stdc.stdlib.free;
-    static void* allocateBlank(size_t size) nothrow @nogc => calloc(1, size);
+    static void* allocateOneBlank(size_t size) nothrow @nogc => calloc(1, size);
 
     alias allocateOnStack = alloca;
 }

From 85de307380045005e59b49e2875a7dfb747486c9 Mon Sep 17 00:00:00 2001
From: Denis Feklushkin <feklushkin.denis@gmail.com>
Date: Sat, 1 Aug 2026 12:29:34 +0300
Subject: [PATCH 15/29] allocateFew() and allocateFewBlank() added

---
 druntime/src/core/system.d | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/druntime/src/core/system.d b/druntime/src/core/system.d
index 05ddc3f040ef..ef933dee4f7d 100644
--- a/druntime/src/core/system.d
+++ b/druntime/src/core/system.d
@@ -9,9 +9,11 @@ struct Mem
     import core.stdc.stdlib;
 
     alias allocateOne = malloc;
+    alias allocateFew = (size_t num, size_t size) => allocateOne(num * size);
+    static void* allocateOneBlank(size_t size) nothrow @nogc => allocateFewBlank(1, size);
+    alias allocateFewBlank = calloc;
     alias reallocate = realloc;
     alias free = core.stdc.stdlib.free;
-    static void* allocateOneBlank(size_t size) nothrow @nogc => calloc(1, size);
 
     alias allocateOnStack = alloca;
 }

From 76191c4d9e115ee14558f1ccb03d96ca802024d9 Mon Sep 17 00:00:00 2001
From: Denis Feklushkin <feklushkin.denis@gmail.com>
Date: Sat, 1 Aug 2026 13:21:59 +0300
Subject: [PATCH 16/29] GC Config: initialization method does not need access
 to the outer scope

---
 druntime/src/core/gc/config.d | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/druntime/src/core/gc/config.d b/druntime/src/core/gc/config.d
index c3b79e0926b5..d386165beb2a 100644
--- a/druntime/src/core/gc/config.d
+++ b/druntime/src/core/gc/config.d
@@ -14,6 +14,14 @@ __gshared Config config;
 
 private __gshared bool _initialized;
 
+package(core) bool initialize(ref Config cfg) nothrow @nogc
+{
+    if (!_initialized)
+        _initialized = cfg.tryToInitialize();
+
+    return _initialized;
+}
+
 struct Config
 {
     bool disable;            // start disabled
@@ -37,11 +45,9 @@ struct Config
 
 @nogc nothrow:
 
-    bool initialize()
+    private bool tryToInitialize()
     {
-        if (!_initialized)
-            _initialized = initConfigOptions(this, "gcopt");
-        return _initialized;
+        return initConfigOptions(this, "gcopt");
     }
 
     void help() @nogc nothrow

From f20ede31a32b2f4de13d80e1ba4d2ab5cba2d937 Mon Sep 17 00:00:00 2001
From: Denis Feklushkin <feklushkin.denis@gmail.com>
Date: Sat, 1 Aug 2026 13:37:40 +0300
Subject: [PATCH 17/29] GC Config defined in core.system.Opt

---
 druntime/src/core/gc/config.d | 5 ++++-
 druntime/src/core/system.d    | 7 +++++++
 2 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/druntime/src/core/gc/config.d b/druntime/src/core/gc/config.d
index d386165beb2a..479e78d4d716 100644
--- a/druntime/src/core/gc/config.d
+++ b/druntime/src/core/gc/config.d
@@ -9,6 +9,9 @@ module core.gc.config;
 
 import core.internal.parseoptions;
 import core.stdc.stdio : printf;
+import core.system : Opt;
+
+alias Config = Opt.Config;
 
 __gshared Config config;
 
@@ -22,7 +25,7 @@ package(core) bool initialize(ref Config cfg) nothrow @nogc
     return _initialized;
 }
 
-struct Config
+struct ConfigT()
 {
     bool disable;            // start disabled
     bool fork = false;       // optional concurrent behaviour
diff --git a/druntime/src/core/system.d b/druntime/src/core/system.d
index ef933dee4f7d..c8c03de4e593 100644
--- a/druntime/src/core/system.d
+++ b/druntime/src/core/system.d
@@ -17,3 +17,10 @@ struct Mem
 
     alias allocateOnStack = alloca;
 }
+
+struct Opt
+{
+    import core.gc.config: ConfigT;
+
+    alias Config = ConfigT!();
+}

From 7075d9f4676bbd7d4eab850cc359611b9f7df43e Mon Sep 17 00:00:00 2001
From: Denis Feklushkin <feklushkin.denis@gmail.com>
Date: Sat, 1 Aug 2026 13:53:14 +0300
Subject: [PATCH 18/29] Opt.Config -> Opt.GcConfig

---
 druntime/src/core/gc/config.d | 2 +-
 druntime/src/core/system.d    | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/druntime/src/core/gc/config.d b/druntime/src/core/gc/config.d
index 479e78d4d716..3e640cdd2d8b 100644
--- a/druntime/src/core/gc/config.d
+++ b/druntime/src/core/gc/config.d
@@ -11,7 +11,7 @@ import core.internal.parseoptions;
 import core.stdc.stdio : printf;
 import core.system : Opt;
 
-alias Config = Opt.Config;
+alias Config = Opt.GcConfig;
 
 __gshared Config config;
 
diff --git a/druntime/src/core/system.d b/druntime/src/core/system.d
index c8c03de4e593..8c8c0ed75117 100644
--- a/druntime/src/core/system.d
+++ b/druntime/src/core/system.d
@@ -22,5 +22,5 @@ struct Opt
 {
     import core.gc.config: ConfigT;
 
-    alias Config = ConfigT!();
+    alias GcConfig = ConfigT!();
 }

From 21fb5a17c4aab1ee043f45b3ab28c3b8b4b1d4f8 Mon Sep 17 00:00:00 2001
From: Denis Feklushkin <feklushkin.denis@gmail.com>
Date: Sat, 1 Aug 2026 14:14:40 +0300
Subject: [PATCH 19/29] Attempt to fix build fo Windows by adding module
 core.system.opt

---
 druntime/mak/COPY                                |  3 ++-
 druntime/mak/SRCS                                |  3 ++-
 druntime/src/core/gc/config.d                    |  2 +-
 druntime/src/core/system/opt.d                   | 11 +++++++++++
 druntime/src/core/{system.d => system/package.d} |  7 -------
 5 files changed, 16 insertions(+), 10 deletions(-)
 create mode 100644 druntime/src/core/system/opt.d
 rename druntime/src/core/{system.d => system/package.d} (83%)

diff --git a/druntime/mak/COPY b/druntime/mak/COPY
index 3ed916ff8cd3..f2e790da5632 100644
--- a/druntime/mak/COPY
+++ b/druntime/mak/COPY
@@ -23,7 +23,8 @@ COPY=\
 	$(IMPDIR)\core\memory.d \
 	$(IMPDIR)\core\runtime.d \
 	$(IMPDIR)\core\simd.d \
-	$(IMPDIR)\core\system.d \
+	$(IMPDIR)\core\system\opt.d \
+	$(IMPDIR)\core\system\package.d \
 	$(IMPDIR)\core\time.d \
 	$(IMPDIR)\core\vararg.d \
 	$(IMPDIR)\core\volatile.d \
diff --git a/druntime/mak/SRCS b/druntime/mak/SRCS
index b345ad10a842..5fb674c196bd 100644
--- a/druntime/mak/SRCS
+++ b/druntime/mak/SRCS
@@ -17,7 +17,8 @@ SRCS=\
 	src\core\memory.d \
 	src\core\runtime.d \
 	src\core\simd.d \
-	src\core\system.d \
+	src\core\system\opt.d \
+	src\core\system\package.d \
 	src\core\time.d \
 	src\core\vararg.d \
 	src\core\volatile.d \
diff --git a/druntime/src/core/gc/config.d b/druntime/src/core/gc/config.d
index 3e640cdd2d8b..daeebec0f5d0 100644
--- a/druntime/src/core/gc/config.d
+++ b/druntime/src/core/gc/config.d
@@ -9,7 +9,7 @@ module core.gc.config;
 
 import core.internal.parseoptions;
 import core.stdc.stdio : printf;
-import core.system : Opt;
+import core.system.opt : Opt;
 
 alias Config = Opt.GcConfig;
 
diff --git a/druntime/src/core/system/opt.d b/druntime/src/core/system/opt.d
new file mode 100644
index 000000000000..38dd2e2a6a5c
--- /dev/null
+++ b/druntime/src/core/system/opt.d
@@ -0,0 +1,11 @@
+///
+module core.system.opt;
+
+package(core):
+
+struct Opt
+{
+    import core.gc.config: ConfigT;
+
+    alias GcConfig = ConfigT!();
+}
diff --git a/druntime/src/core/system.d b/druntime/src/core/system/package.d
similarity index 83%
rename from druntime/src/core/system.d
rename to druntime/src/core/system/package.d
index 8c8c0ed75117..ef933dee4f7d 100644
--- a/druntime/src/core/system.d
+++ b/druntime/src/core/system/package.d
@@ -17,10 +17,3 @@ struct Mem
 
     alias allocateOnStack = alloca;
 }
-
-struct Opt
-{
-    import core.gc.config: ConfigT;
-
-    alias GcConfig = ConfigT!();
-}

From 4b9b386b69909ac9b33365aa6b6687082067145a Mon Sep 17 00:00:00 2001
From: Denis Feklushkin <feklushkin.denis@gmail.com>
Date: Sun, 2 Aug 2026 12:31:35 +0300
Subject: [PATCH 20/29] druntime: -debug=PRINTF compilation fix

---
 druntime/src/core/internal/array/utils.d | 1 +
 1 file changed, 1 insertion(+)

diff --git a/druntime/src/core/internal/array/utils.d b/druntime/src/core/internal/array/utils.d
index 103a87bcd278..1020f3984373 100644
--- a/druntime/src/core/internal/array/utils.d
+++ b/druntime/src/core/internal/array/utils.d
@@ -11,6 +11,7 @@ module core.internal.array.utils;
 
 import core.internal.traits : Parameters;
 import core.memory : GC;
+debug(PRINTF) import core.stdc.stdio : printf;
 
 alias BlkAttr = GC.BlkAttr;
 

From b426febbde03c6d9895a0e940f6a715d8fd99b08 Mon Sep 17 00:00:00 2001
From: Denis Feklushkin <feklushkin.denis@gmail.com>
Date: Sun, 2 Aug 2026 12:44:01 +0300
Subject: [PATCH 21/29] core.system: Sys.abort() and printf() added

---
 druntime/src/core/system/package.d | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/druntime/src/core/system/package.d b/druntime/src/core/system/package.d
index ef933dee4f7d..a7d852662ba9 100644
--- a/druntime/src/core/system/package.d
+++ b/druntime/src/core/system/package.d
@@ -17,3 +17,23 @@ struct Mem
 
     alias allocateOnStack = alloca;
 }
+
+struct Sys
+{
+    static import core.stdc.stdlib;
+
+    alias abort = core.stdc.stdlib.abort;
+}
+
+debug(PRINTF)
+{
+    static import core.stdc.stdio;
+
+    void printf(T...)(scope const(char*) fmt, T vals) nothrow @nogc
+    {
+        int r = core.stdc.stdio.printf(fmt, vals);
+
+        if(r < 0)
+            Sys.abort();
+    }
+}

From 43eb8f8f47bd83488808b7a5056e4b83b2d1b835 Mon Sep 17 00:00:00 2001
From: Denis Feklushkin <feklushkin.denis@gmail.com>
Date: Sun, 2 Aug 2026 13:19:23 +0300
Subject: [PATCH 22/29] core.system comment about debugging added, aliases
 added

---
 druntime/src/core/system/package.d | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/druntime/src/core/system/package.d b/druntime/src/core/system/package.d
index a7d852662ba9..f56b88c05e8c 100644
--- a/druntime/src/core/system/package.d
+++ b/druntime/src/core/system/package.d
@@ -25,10 +25,15 @@ struct Sys
     alias abort = core.stdc.stdlib.abort;
 }
 
-debug(PRINTF)
+// Special case: we don't have resources to implement formatting functionality
+// for now just for the sake of using it at debugging
+debug
 {
     static import core.stdc.stdio;
 
+    alias sprintf = core.stdc.stdio.sprintf;
+    alias snprintf = core.stdc.stdio.snprintf;
+
     void printf(T...)(scope const(char*) fmt, T vals) nothrow @nogc
     {
         int r = core.stdc.stdio.printf(fmt, vals);

From ec6e2ecbb7323d72dab65d8e9009c7848a867412 Mon Sep 17 00:00:00 2001
From: Denis Feklushkin <feklushkin.denis@gmail.com>
Date: Sun, 2 Aug 2026 17:50:30 +0300
Subject: [PATCH 23/29] more correct printf result value check

---
 druntime/src/core/system/package.d | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/druntime/src/core/system/package.d b/druntime/src/core/system/package.d
index f56b88c05e8c..a84faf6c6093 100644
--- a/druntime/src/core/system/package.d
+++ b/druntime/src/core/system/package.d
@@ -38,7 +38,7 @@ debug
     {
         int r = core.stdc.stdio.printf(fmt, vals);
 
-        if(r < 0)
+        if(r < fmt.length)
             Sys.abort();
     }
 }

From e79d4d26d0c03cbfa41ddba3c37da62ea889eff2 Mon Sep 17 00:00:00 2001
From: Denis Feklushkin <feklushkin.denis@gmail.com>
Date: Sun, 2 Aug 2026 18:28:29 +0300
Subject: [PATCH 24/29] Sys.print() added

---
 druntime/src/core/system/package.d | 23 +++++++++++++++++++++--
 1 file changed, 21 insertions(+), 2 deletions(-)

diff --git a/druntime/src/core/system/package.d b/druntime/src/core/system/package.d
index a84faf6c6093..334d7fae991d 100644
--- a/druntime/src/core/system/package.d
+++ b/druntime/src/core/system/package.d
@@ -21,12 +21,31 @@ struct Mem
 struct Sys
 {
     static import core.stdc.stdlib;
+    import core.stdc.stdio;
 
     alias abort = core.stdc.stdlib.abort;
+
+    // Assumes str is null-terminated string
+    static void print(scope const char[] str) nothrow @nogc
+    {
+        auto r = fputs(str.ptr, stdout);
+        if(r < 0)
+            Sys.abort();
+    }
+
+    //~ void print(T)(scope const char[] str, T vals) nothrow @nogc
+    //~ {
+        //~ // Assume str is null-terminated string
+        //~ auto r = fputs(str.ptr, stdout);
+        //~ if(r < 0)
+            //~ Sys.abort();
+    //~ }
+
+    //~ alias format = snprintf
 }
 
-// Special case: we don't have resources to implement formatting functionality
-// for now just for the sake of using it at debugging
+// Special case: we don't have resources to implement mature formatting
+// functionality for now just for the sake of using it at debugging
 debug
 {
     static import core.stdc.stdio;

From f82da6f36827e0184637ba5b2fc760253b5e7424 Mon Sep 17 00:00:00 2001
From: Denis Feklushkin <feklushkin.denis@gmail.com>
Date: Sun, 2 Aug 2026 18:58:16 +0300
Subject: [PATCH 25/29] core.system.Sys.printf() implemented (depends on libc
 version) and used

---
 druntime/src/core/gc/config.d      | 13 +++++++------
 druntime/src/core/system/package.d | 26 ++++----------------------
 2 files changed, 11 insertions(+), 28 deletions(-)

diff --git a/druntime/src/core/gc/config.d b/druntime/src/core/gc/config.d
index daeebec0f5d0..b2d86a8890b9 100644
--- a/druntime/src/core/gc/config.d
+++ b/druntime/src/core/gc/config.d
@@ -9,6 +9,7 @@ module core.gc.config;
 
 import core.internal.parseoptions;
 import core.stdc.stdio : printf;
+import core.system : Sys;
 import core.system.opt : Opt;
 
 alias Config = Opt.GcConfig;
@@ -57,21 +58,21 @@ struct ConfigT()
     {
         import core.gc.registry : registeredGCFactories;
 
-        printf("GC options are specified as white space separated assignments:
+        Sys.printf("GC options are specified as white space separated assignments:
     disable:0|1    - start disabled (%d)
     fork:0|1       - set fork behaviour (%d)
     profile:0|1|2  - enable profiling with summary when terminating program (%d)
-    gc:".ptr, disable, fork, profile);
+    gc:", disable, fork, profile);
         foreach (i, entry; registeredGCFactories)
         {
-            if (i) printf("|");
-            printf("%.*s", cast(int) entry.name.length, entry.name.ptr);
+            if (i) Sys.print("|");
+            Sys.printf("%.*s", cast(int) entry.name.length, entry.name.ptr);
         }
         auto _initReserve = initReserve.bytes2prettyStruct;
         auto _minPoolSize = minPoolSize.bytes2prettyStruct;
         auto _maxPoolSize = maxPoolSize.bytes2prettyStruct;
         auto _incPoolSize = incPoolSize.bytes2prettyStruct;
-        printf(" - select gc implementation (default = conservative)
+        Sys.printf(" - select gc implementation (default = conservative)
 
     initReserve:N  - initial memory to reserve in MB (%lld%c)
     minPoolSize:N  - initial and minimum pool size in MB (%lld%c)
@@ -82,7 +83,7 @@ struct ConfigT()
     cleanup:none|collect|finalize - how to treat live objects when terminating (collect)
 
     Memory-related values can use B, K, M or G suffixes.
-".ptr,
+",
                _initReserve.v, _initReserve.u,
                _minPoolSize.v, _minPoolSize.u,
                _maxPoolSize.v, _maxPoolSize.u,
diff --git a/druntime/src/core/system/package.d b/druntime/src/core/system/package.d
index 334d7fae991d..bc941d5ec1d9 100644
--- a/druntime/src/core/system/package.d
+++ b/druntime/src/core/system/package.d
@@ -33,30 +33,12 @@ struct Sys
             Sys.abort();
     }
 
-    //~ void print(T)(scope const char[] str, T vals) nothrow @nogc
-    //~ {
-        //~ // Assume str is null-terminated string
-        //~ auto r = fputs(str.ptr, stdout);
-        //~ if(r < 0)
-            //~ Sys.abort();
-    //~ }
-
-    //~ alias format = snprintf
-}
-
-// Special case: we don't have resources to implement mature formatting
-// functionality for now just for the sake of using it at debugging
-debug
-{
-    static import core.stdc.stdio;
-
-    alias sprintf = core.stdc.stdio.sprintf;
-    alias snprintf = core.stdc.stdio.snprintf;
-
-    void printf(T...)(scope const(char*) fmt, T vals) nothrow @nogc
+    /// C-formatted print
+    static void printf(T...)(scope const char[] fmt, T vals) nothrow @nogc
     {
-        int r = core.stdc.stdio.printf(fmt, vals);
+        static assert(T.length > 0);
 
+        int r = core.stdc.stdio.printf(fmt.ptr, vals);
         if(r < fmt.length)
             Sys.abort();
     }

From b8d39b906191eba3ea9c5aeb410ba5fb272ef50f Mon Sep 17 00:00:00 2001
From: Denis Feklushkin <feklushkin.denis@gmail.com>
Date: Sun, 2 Aug 2026 23:23:15 +0300
Subject: [PATCH 26/29] Sys.print() can print non-null-terminated strings

---
 druntime/src/core/system/package.d | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/druntime/src/core/system/package.d b/druntime/src/core/system/package.d
index bc941d5ec1d9..8ddec160afb6 100644
--- a/druntime/src/core/system/package.d
+++ b/druntime/src/core/system/package.d
@@ -25,12 +25,16 @@ struct Sys
 
     alias abort = core.stdc.stdlib.abort;
 
-    // Assumes str is null-terminated string
     static void print(scope const char[] str) nothrow @nogc
     {
-        auto r = fputs(str.ptr, stdout);
-        if(r < 0)
-            Sys.abort();
+        // This is a silly approach, but it's a simple way to print non-null-terminated strings
+        // TODO: implement using write() or so
+        foreach(c; str)
+        {
+            auto r = fputc(c, stdout);
+            if(r == EOF)
+                Sys.abort();
+        }
     }
 
     /// C-formatted print

From c188f6ca849de14765fdd2b8b9e4b7b28485b859 Mon Sep 17 00:00:00 2001
From: Denis Feklushkin <feklushkin.denis@gmail.com>
Date: Mon, 3 Aug 2026 10:27:14 +0300
Subject: [PATCH 27/29] free() -> freeMem()

---
 druntime/src/core/gc/registry.d               |  2 +-
 druntime/src/core/internal/gc/bits.d          |  2 +-
 .../src/core/internal/gc/impl/manual/gc.d     |  2 +-
 druntime/src/core/runtime.d                   |  8 ++---
 druntime/src/core/system/package.d            |  2 +-
 druntime/src/rt/dmain2.d                      |  4 +--
 druntime/src/rt/minfo.d                       | 30 +++++++++----------
 7 files changed, 25 insertions(+), 25 deletions(-)

diff --git a/druntime/src/core/gc/registry.d b/druntime/src/core/gc/registry.d
index ff4c20fbf4ba..fde461ae2982 100644
--- a/druntime/src/core/gc/registry.d
+++ b/druntime/src/core/gc/registry.d
@@ -85,7 +85,7 @@ GC createGCInstance(string name)
             continue;
         auto instance = entry.factory();
         // only one GC at a time for now, so free the registry to not leak
-        Mem.free(entries.ptr);
+        Mem.freeMem(entries.ptr);
         entries = null;
         return instance;
     }
diff --git a/druntime/src/core/internal/gc/bits.d b/druntime/src/core/internal/gc/bits.d
index 1b0b1f8e043b..47d8f0a6621a 100644
--- a/druntime/src/core/internal/gc/bits.d
+++ b/druntime/src/core/internal/gc/bits.d
@@ -38,7 +38,7 @@ struct GCBits
         if (data)
         {
             if (!AllocSupportsShared || !share)
-                Mem.free(data);
+                Mem.freeMem(data);
             else static if (AllocSupportsShared)
                 os_mem_unmap_shared(data, nwords * data[0].sizeof);
             else
diff --git a/druntime/src/core/internal/gc/impl/manual/gc.d b/druntime/src/core/internal/gc/impl/manual/gc.d
index ee7eeae97f78..cd0accf765d9 100644
--- a/druntime/src/core/internal/gc/impl/manual/gc.d
+++ b/druntime/src/core/internal/gc/impl/manual/gc.d
@@ -148,7 +148,7 @@ class ManualGC : GC
 
     void free(void* p) nothrow @nogc
     {
-        Mem.free(p);
+        Mem.freeMem(p);
     }
 
     /**
diff --git a/druntime/src/core/runtime.d b/druntime/src/core/runtime.d
index 234af8444958..fa6155734a0b 100644
--- a/druntime/src/core/runtime.d
+++ b/druntime/src/core/runtime.d
@@ -226,7 +226,7 @@ struct Runtime
 
             auto buf = cast(WCHAR*) Mem.allocateOne((len+1) * WCHAR.sizeof);
             if (buf is null) return null;
-            scope (exit) Mem.free(buf);
+            scope (exit) Mem.freeMem(buf);
 
             len = MultiByteToWideChar(
                 CP_UTF8, 0, name.ptr, cast(int)name.length, buf, len);
@@ -244,7 +244,7 @@ struct Runtime
             immutable len = name.length;
             auto buf = cast(char*) Mem.allocateOne(len + 1);
             if (!buf) return null;
-            scope (exit) Mem.free(buf);
+            scope (exit) Mem.freeMem(buf);
 
             buf[0 .. len] = name[];
             buf[len] = 0;
@@ -804,7 +804,7 @@ void defaultTraceDeallocator(Throwable.TraceInfo info) nothrow
         return;
     auto obj = cast(Object)info;
     destroy(obj);
-    Mem.free(cast(void *)obj);
+    Mem.freeMem(cast(void *)obj);
 }
 
 /// Default implementation for most POSIX systems
@@ -878,7 +878,7 @@ else version (Posix) private class DefaultTraceInfo : Throwable.TraceInfo
         static if (hasExecinfo)
         {
             const framelist = backtrace_symbols( callstack.ptr, numframes );
-            scope(exit) Mem.free(cast(void*) framelist);
+            scope(exit) Mem.freeMem(cast(void*) framelist);
 
             static if (enableDwarf)
             {
diff --git a/druntime/src/core/system/package.d b/druntime/src/core/system/package.d
index 8ddec160afb6..b6d683ddbeb3 100644
--- a/druntime/src/core/system/package.d
+++ b/druntime/src/core/system/package.d
@@ -13,7 +13,7 @@ struct Mem
     static void* allocateOneBlank(size_t size) nothrow @nogc => allocateFewBlank(1, size);
     alias allocateFewBlank = calloc;
     alias reallocate = realloc;
-    alias free = core.stdc.stdlib.free;
+    alias freeMem = core.stdc.stdlib.free;
 
     alias allocateOnStack = alloca;
 }
diff --git a/druntime/src/rt/dmain2.d b/druntime/src/rt/dmain2.d
index 2efe24fc3e90..89c2a64e0981 100644
--- a/druntime/src/rt/dmain2.d
+++ b/druntime/src/rt/dmain2.d
@@ -672,7 +672,7 @@ extern (C) void _d_print_throwable(Throwable t)
 
             typeof(ptr) get() { if (ptr) ptr[len] = 0; return ptr; }
 
-            void free() { Mem.free(ptr); }
+            void free() { Mem.freeMem(ptr); }
         }
 
         HANDLE windowsHandle(int fd)
@@ -726,7 +726,7 @@ extern (C) void _d_print_throwable(Throwable t)
                     WideCharToMultiByte(codepage, 0,
                         buf.ptr, cast(int)buf.len, sptr, slen, null, null);
                     WriteFile(hStdErr, sptr, slen, null, null);
-                    Mem.free(sptr);
+                    Mem.freeMem(sptr);
                 }
                 buf.free();
             }
diff --git a/druntime/src/rt/minfo.d b/druntime/src/rt/minfo.d
index 0002e62bbd13..164a924c0c49 100644
--- a/druntime/src/rt/minfo.d
+++ b/druntime/src/rt/minfo.d
@@ -70,7 +70,7 @@ struct ModuleGroup
         size_t totalMods;
         int[] distance = (cast(int*) Mem.allocateOne(int.sizeof * _modules.length))[0 .. _modules.length];
         scope(exit)
-            Mem.free(distance.ptr);
+            Mem.freeMem(distance.ptr);
 
         // determine the shortest path between two modules. Uses dijkstra
         // without a priority queue. (we can be a bit slow here, in order to
@@ -226,9 +226,9 @@ struct ModuleGroup
         auto relevant = cast(size_t*) Mem.allocateOne(flagbytes); // has ctors/dtors
         scope (exit)
         {
-            Mem.free(ctorstart);
-            Mem.free(ctordone);
-            Mem.free(relevant);
+            Mem.freeMem(ctorstart);
+            Mem.freeMem(ctordone);
+            Mem.freeMem(relevant);
         }
 
         void clearFlags(size_t* flags)
@@ -247,7 +247,7 @@ struct ModuleGroup
 
             auto reachable = cast(size_t*) Mem.allocateOne(flagbytes);
             scope(exit)
-                Mem.free(reachable);
+                Mem.freeMem(reachable);
 
             foreach (i, m; _modules)
             {
@@ -275,7 +275,7 @@ struct ModuleGroup
                 else
                 {
                     edges[i] = null;
-                    Mem.free(edge);
+                    Mem.freeMem(edge);
                 }
             }
         }
@@ -285,8 +285,8 @@ struct ModuleGroup
         {
             foreach (e; edges)
                 if (e.ptr)
-                    Mem.free(e.ptr);
-            Mem.free(edges.ptr);
+                    Mem.freeMem(e.ptr);
+            Mem.freeMem(edges.ptr);
         }
 
         void buildCycleMessage(size_t sourceIdx, size_t cycleIdx, scope void delegate(string) nothrow sink)
@@ -302,7 +302,7 @@ struct ModuleGroup
             sink(_modules[cycleIdx].name);
             sink(EOL);
             auto cyclePath = genCyclePath(sourceIdx, cycleIdx, edges);
-            scope(exit) Mem.free(cyclePath.ptr);
+            scope(exit) Mem.freeMem(cyclePath.ptr);
 
             sink(_modules[sourceIdx].name);
             sink("* ->" ~ EOL);
@@ -332,7 +332,7 @@ struct ModuleGroup
             // initialize "stack"
             auto stack = cast(stackFrame*) Mem.allocateOne(stackFrame.sizeof * len);
             scope (exit)
-                Mem.free(stack);
+                Mem.freeMem(stack);
             auto stacktop = stack + len;
             auto sp = stack;
             sp.curMod = cast(int) idx;
@@ -425,7 +425,7 @@ struct ModuleGroup
             // First, determine what modules are reachable.
             auto reachable = cast(size_t*) Mem.allocateOne(flagbytes);
             scope (exit)
-                Mem.free(reachable);
+                Mem.freeMem(reachable);
             if (!findDeps(curidx, reachable))
                 return false;   // deprecated cycle error
 
@@ -493,7 +493,7 @@ struct ModuleGroup
                 {
                     if (!processMod(idx))
                     {
-                        Mem.free(ctors);
+                        Mem.freeMem(ctors);
                         return false;
                     }
                 }
@@ -502,7 +502,7 @@ struct ModuleGroup
             if (ctoridx == 0)
             {
                 // no ctors in the list.
-                Mem.free(ctors);
+                Mem.freeMem(ctors);
             }
             else
             {
@@ -561,10 +561,10 @@ struct ModuleGroup
     void free()
     {
         if (_ctors.ptr)
-            Mem.free(_ctors.ptr);
+            Mem.freeMem(_ctors.ptr);
         _ctors = null;
         if (_tlsctors.ptr)
-            Mem.free(_tlsctors.ptr);
+            Mem.freeMem(_tlsctors.ptr);
         _tlsctors = null;
         // _modules = null; // let the owner free it
     }

From 3755f544d1734a7f94caeb38888cd5c5b5a2776c Mon Sep 17 00:00:00 2001
From: Denis Feklushkin <feklushkin.denis@gmail.com>
Date: Mon, 3 Aug 2026 10:46:27 +0300
Subject: [PATCH 28/29] core.system.Mem code moved to new core.system.memory
 module It turned out that it was convenient to be able to import only certain
 functions, so I had to get rid of Mem structure

---
 druntime/mak/COPY                             |  1 +
 druntime/mak/SRCS                             |  1 +
 druntime/src/core/gc/registry.d               |  8 +--
 druntime/src/core/internal/gc/bits.d          |  6 +-
 .../src/core/internal/gc/impl/manual/gc.d     | 12 ++--
 druntime/src/core/runtime.d                   | 17 +++---
 druntime/src/core/system/memory.d             | 17 ++++++
 druntime/src/core/system/package.d            | 17 ------
 druntime/src/rt/dmain2.d                      | 36 ++++++------
 druntime/src/rt/minfo.d                       | 58 +++++++++----------
 10 files changed, 87 insertions(+), 86 deletions(-)
 create mode 100644 druntime/src/core/system/memory.d

diff --git a/druntime/mak/COPY b/druntime/mak/COPY
index f2e790da5632..b0c9a4df353e 100644
--- a/druntime/mak/COPY
+++ b/druntime/mak/COPY
@@ -23,6 +23,7 @@ COPY=\
 	$(IMPDIR)\core\memory.d \
 	$(IMPDIR)\core\runtime.d \
 	$(IMPDIR)\core\simd.d \
+	$(IMPDIR)\core\system\memory.d \
 	$(IMPDIR)\core\system\opt.d \
 	$(IMPDIR)\core\system\package.d \
 	$(IMPDIR)\core\time.d \
diff --git a/druntime/mak/SRCS b/druntime/mak/SRCS
index 5fb674c196bd..7559e93c09f0 100644
--- a/druntime/mak/SRCS
+++ b/druntime/mak/SRCS
@@ -17,6 +17,7 @@ SRCS=\
 	src\core\memory.d \
 	src\core\runtime.d \
 	src\core\simd.d \
+	src\core\system\memory.d \
 	src\core\system\opt.d \
 	src\core\system\package.d \
 	src\core\time.d \
diff --git a/druntime/src/core/gc/registry.d b/druntime/src/core/gc/registry.d
index fde461ae2982..7b5e28e01a8c 100644
--- a/druntime/src/core/gc/registry.d
+++ b/druntime/src/core/gc/registry.d
@@ -60,9 +60,9 @@ alias GCThreadInitFunction = void function(ThreadBase base) nothrow @nogc;
 void registerGCFactory(string name, GCFactory factory,
         GCThreadInitFunction threadInit = null) nothrow @nogc
 {
-    import core.system : Mem;
+    import core.system.memory : reallocate;
 
-    auto ptr = cast(Entry*) Mem.reallocate(entries.ptr, (entries.length + 1) * Entry.sizeof);
+    auto ptr = cast(Entry*) reallocate(entries.ptr, (entries.length + 1) * Entry.sizeof);
     entries = ptr[0 .. entries.length + 1];
     entries[$ - 1] = Entry(name, factory, threadInit);
 }
@@ -77,7 +77,7 @@ void registerGCFactory(string name, GCFactory factory,
  */
 GC createGCInstance(string name)
 {
-    import core.system : Mem;
+    import core.system.memory : freeMem;
 
     foreach (entry; entries)
     {
@@ -85,7 +85,7 @@ GC createGCInstance(string name)
             continue;
         auto instance = entry.factory();
         // only one GC at a time for now, so free the registry to not leak
-        Mem.freeMem(entries.ptr);
+        freeMem(entries.ptr);
         entries = null;
         return instance;
     }
diff --git a/druntime/src/core/internal/gc/bits.d b/druntime/src/core/internal/gc/bits.d
index 47d8f0a6621a..a6f47d384e1e 100644
--- a/druntime/src/core/internal/gc/bits.d
+++ b/druntime/src/core/internal/gc/bits.d
@@ -11,7 +11,7 @@ import core.internal.gc.os;
 
 import core.bitop;
 import core.exception : onOutOfMemoryError;
-import core.system : Mem;
+import core.system.memory : allocateOneBlank, freeMem;
 import core.stdc.string : memcpy, memset;
 
 // use version gcbitsSingleBitOperation to disable optimizations that use
@@ -38,7 +38,7 @@ struct GCBits
         if (data)
         {
             if (!AllocSupportsShared || !share)
-                Mem.freeMem(data);
+                freeMem(data);
             else static if (AllocSupportsShared)
                 os_mem_unmap_shared(data, nwords * data[0].sizeof);
             else
@@ -51,7 +51,7 @@ struct GCBits
     {
         this.nbits = nbits;
         if (!AllocSupportsShared || !share)
-            data = cast(typeof(data[0])*) Mem.allocateOneBlank(nwords * data[0].sizeof);
+            data = cast(typeof(data[0])*) allocateOneBlank(nwords * data[0].sizeof);
         else static if (AllocSupportsShared)
             data = cast(typeof(data[0])*)os_mem_map_shared(nwords * data[0].sizeof); // Allocate as MAP_SHARED
         else
diff --git a/druntime/src/core/internal/gc/impl/manual/gc.d b/druntime/src/core/internal/gc/impl/manual/gc.d
index cd0accf765d9..1541a2a0bdcd 100644
--- a/druntime/src/core/internal/gc/impl/manual/gc.d
+++ b/druntime/src/core/internal/gc/impl/manual/gc.d
@@ -25,7 +25,7 @@ import core.internal.container.array;
 
 import core.thread.threadbase : ThreadBase;
 
-import core.system: Mem;
+import core.system.memory;
 static import core.memory;
 
 extern (C) noreturn onOutOfMemoryError(void* pretend_sideffect = null, string file = __FILE__, size_t line = __LINE__) @trusted pure nothrow @nogc; /* dmd @@@BUG11461@@@ */
@@ -46,7 +46,7 @@ private GC initialize()
 {
     import core.lifetime : emplace;
 
-    auto gc = cast(ManualGC) Mem.allocateOne(__traits(classInstanceSize, ManualGC));
+    auto gc = cast(ManualGC) allocateOne(__traits(classInstanceSize, ManualGC));
     if (!gc)
         onOutOfMemoryError();
 
@@ -102,7 +102,7 @@ class ManualGC : GC
 
     void* malloc(size_t size, uint bits, const TypeInfo ti) nothrow
     {
-        void* p = Mem.allocateOne(size);
+        void* p = allocateOne(size);
 
         if (size && p is null)
             onOutOfMemoryError();
@@ -120,7 +120,7 @@ class ManualGC : GC
 
     void* calloc(size_t size, uint bits, const TypeInfo ti) nothrow
     {
-        void* p = Mem.allocateOneBlank(size);
+        void* p = allocateOneBlank(size);
 
         if (size && p is null)
             onOutOfMemoryError();
@@ -129,7 +129,7 @@ class ManualGC : GC
 
     void* realloc(void* p, size_t size, uint bits, const TypeInfo ti) nothrow
     {
-        p = Mem.reallocate(p, size);
+        p = reallocate(p, size);
 
         if (size && p is null)
             onOutOfMemoryError();
@@ -148,7 +148,7 @@ class ManualGC : GC
 
     void free(void* p) nothrow @nogc
     {
-        Mem.freeMem(p);
+        freeMem(p);
     }
 
     /**
diff --git a/druntime/src/core/runtime.d b/druntime/src/core/runtime.d
index fa6155734a0b..ade1e03910a3 100644
--- a/druntime/src/core/runtime.d
+++ b/druntime/src/core/runtime.d
@@ -10,7 +10,7 @@
 
 module core.runtime;
 
-import core.system : Mem;
+import core.system.memory : allocateOne, freeMem;
 
 version (OSX)
     version = Darwin;
@@ -211,7 +211,6 @@ struct Runtime
      */
     static void* loadLibrary()(const scope char[] name)
     {
-        import core.system : Mem;
         version (Windows)
         {
             import core.sys.windows.winnls : CP_UTF8, MultiByteToWideChar;
@@ -224,9 +223,9 @@ struct Runtime
             if (len == 0)
                 return null;
 
-            auto buf = cast(WCHAR*) Mem.allocateOne((len+1) * WCHAR.sizeof);
+            auto buf = cast(WCHAR*) allocateOne((len+1) * WCHAR.sizeof);
             if (buf is null) return null;
-            scope (exit) Mem.freeMem(buf);
+            scope (exit) freeMem(buf);
 
             len = MultiByteToWideChar(
                 CP_UTF8, 0, name.ptr, cast(int)name.length, buf, len);
@@ -242,9 +241,9 @@ struct Runtime
             /* Need a 0-terminated C string for the dll name
              */
             immutable len = name.length;
-            auto buf = cast(char*) Mem.allocateOne(len + 1);
+            auto buf = cast(char*) allocateOne(len + 1);
             if (!buf) return null;
-            scope (exit) Mem.freeMem(buf);
+            scope (exit) freeMem(buf);
 
             buf[0 .. len] = name[];
             buf[len] = 0;
@@ -745,7 +744,7 @@ Throwable.TraceInfo defaultTraceHandler( void* ptr = null ) // @nogc
     static T allocate(T, Args...)(auto ref Args args) @nogc
     {
         import core.lifetime : emplace;
-        auto result = cast(T) Mem.allocateOne(__traits(classInstanceSize, T));
+        auto result = cast(T) allocateOne(__traits(classInstanceSize, T));
         return emplace(result, args);
     }
     version (Windows)
@@ -804,7 +803,7 @@ void defaultTraceDeallocator(Throwable.TraceInfo info) nothrow
         return;
     auto obj = cast(Object)info;
     destroy(obj);
-    Mem.freeMem(cast(void *)obj);
+    freeMem(cast(void *)obj);
 }
 
 /// Default implementation for most POSIX systems
@@ -878,7 +877,7 @@ else version (Posix) private class DefaultTraceInfo : Throwable.TraceInfo
         static if (hasExecinfo)
         {
             const framelist = backtrace_symbols( callstack.ptr, numframes );
-            scope(exit) Mem.freeMem(cast(void*) framelist);
+            scope(exit) freeMem(cast(void*) framelist);
 
             static if (enableDwarf)
             {
diff --git a/druntime/src/core/system/memory.d b/druntime/src/core/system/memory.d
new file mode 100644
index 000000000000..385a440bd411
--- /dev/null
+++ b/druntime/src/core/system/memory.d
@@ -0,0 +1,17 @@
+///
+module core.system.memory;
+
+// libc version
+version (all)
+{
+    import core.stdc.stdlib;
+
+    alias allocateOne = malloc;
+    alias allocateFew = (size_t num, size_t size) nothrow @nogc => allocateOne(num * size);
+    void* allocateOneBlank(size_t size) nothrow @nogc => allocateFewBlank(1, size);
+    alias allocateFewBlank = calloc;
+    alias reallocate = realloc;
+    alias freeMem = core.stdc.stdlib.free;
+
+    alias allocateOnStack = alloca;
+}
diff --git a/druntime/src/core/system/package.d b/druntime/src/core/system/package.d
index b6d683ddbeb3..53096b1704c6 100644
--- a/druntime/src/core/system/package.d
+++ b/druntime/src/core/system/package.d
@@ -1,23 +1,6 @@
 ///
 module core.system;
 
-//TODO: package
-//package:
-
-struct Mem
-{
-    import core.stdc.stdlib;
-
-    alias allocateOne = malloc;
-    alias allocateFew = (size_t num, size_t size) => allocateOne(num * size);
-    static void* allocateOneBlank(size_t size) nothrow @nogc => allocateFewBlank(1, size);
-    alias allocateFewBlank = calloc;
-    alias reallocate = realloc;
-    alias freeMem = core.stdc.stdlib.free;
-
-    alias allocateOnStack = alloca;
-}
-
 struct Sys
 {
     static import core.stdc.stdlib;
diff --git a/druntime/src/rt/dmain2.d b/druntime/src/rt/dmain2.d
index 89c2a64e0981..9e15b821707b 100644
--- a/druntime/src/rt/dmain2.d
+++ b/druntime/src/rt/dmain2.d
@@ -20,7 +20,7 @@ import core.stdc.string : strerror;
 import rt.config : rt_cmdline_enabled, rt_configOption;
 import rt.memory;
 import rt.sections;
-import core.system : Mem;
+import core.system.memory;
 
 version (Windows)
 {
@@ -50,7 +50,7 @@ else version (WASI)
 }
 
 version (DigitalMars) version (AArch64)
-    version = UseMalloc;   // cuz Mem.allocateOnStack is not implemented yet
+    version = UseMalloc;   // cuz allocateOnStack is not implemented yet
 
 // not sure why we can't define this in one place, but this is to keep this
 // module from importing core.runtime.
@@ -289,13 +289,13 @@ extern (C) int _d_run_main(int argc, char** argv, MainFunc mainFunc)
         // Allocate args[] on the stack - use wargc
         version (UseMalloc)
         {
-            char[][] args = (cast(char[]*) Mem.allocateOne(wargc * (char[]).sizeof))[0 .. wargc];
+            char[][] args = (cast(char[]*) allocateOne(wargc * (char[]).sizeof))[0 .. wargc];
             if (wargc)
                 assert(args.ptr);
             scope (exit) free(args.ptr);
         }
         else
-            char[][] args = (cast(char[]*) Mem.allocateOnStack(wargc * (char[]).sizeof))[0 .. wargc];
+            char[][] args = (cast(char[]*) allocateOnStack(wargc * (char[]).sizeof))[0 .. wargc];
 
         // This is required because WideCharToMultiByte requires int as input.
         assert(wCommandLineLength <= cast(size_t) int.max, "Wide char command line length must not exceed int.max");
@@ -304,13 +304,13 @@ extern (C) int _d_run_main(int argc, char** argv, MainFunc mainFunc)
         {
             version (UseMalloc)
             {
-                char* totalArgsBuff = cast(char*) Mem.allocateOne(totalArgsLength);
+                char* totalArgsBuff = cast(char*) allocateOne(totalArgsLength);
                 if (totalArgsLength)
                     assert(totalArgsBuff);
                 scope (exit) free(totalArgsBuff);
             }
             else
-                char* totalArgsBuff = cast(char*) Mem.allocateOnStack(totalArgsLength);
+                char* totalArgsBuff = cast(char*) allocateOnStack(totalArgsLength);
             size_t j = 0;
             foreach (i; 0 .. wargc)
             {
@@ -334,13 +334,13 @@ extern (C) int _d_run_main(int argc, char** argv, MainFunc mainFunc)
         // Allocate args[] on the stack
         version (UseMalloc)
         {
-            char[][] args = (cast(char[]*) Mem.allocateOne(argc * (char[]).sizeof))[0 .. argc];
+            char[][] args = (cast(char[]*) allocateOne(argc * (char[]).sizeof))[0 .. argc];
             if (argc)
                 assert(args.ptr);
             scope (exit) free(args.ptr);
         }
         else
-            char[][] args = (cast(char[]*) Mem.allocateOnStack(argc * (char[]).sizeof))[0 .. argc];
+            char[][] args = (cast(char[]*) allocateOnStack(argc * (char[]).sizeof))[0 .. argc];
 
         size_t totalArgsLength = 0;
         foreach (i, ref arg; args)
@@ -352,7 +352,7 @@ extern (C) int _d_run_main(int argc, char** argv, MainFunc mainFunc)
     else version (WASI)
     {
         // Allocate args[] on the stack
-        char[][] args = (cast(char[]*) Mem.allocateOnStack(argc * (char[]).sizeof))[0 .. argc];
+        char[][] args = (cast(char[]*) allocateOnStack(argc * (char[]).sizeof))[0 .. argc];
 
         size_t totalArgsLength = 0;
         foreach (i, ref arg; args)
@@ -377,7 +377,7 @@ version (Windows)
 extern (C) int _d_wrun_main(int argc, wchar** wargv, MainFunc mainFunc)
 {
      // Allocate args[] on the stack
-    char[][] args = (cast(char[]*) Mem.allocateOnStack(argc * (char[]).sizeof))[0 .. argc];
+    char[][] args = (cast(char[]*) allocateOnStack(argc * (char[]).sizeof))[0 .. argc];
 
     // 1st pass: compute each argument's length as UTF-16 and UTF-8
     size_t totalArgsLength = 0;
@@ -392,7 +392,7 @@ extern (C) int _d_wrun_main(int argc, wchar** wargv, MainFunc mainFunc)
     }
 
     // Allocate a single buffer for all (null-terminated) argument strings in UTF-8 on the stack
-    char* utf8Buffer = cast(char*) Mem.allocateOnStack(totalArgsLength);
+    char* utf8Buffer = cast(char*) allocateOnStack(totalArgsLength);
 
     // 2nd pass: convert to UTF-8 and finalize `args`
     char* utf8 = utf8Buffer;
@@ -406,7 +406,7 @@ extern (C) int _d_wrun_main(int argc, wchar** wargv, MainFunc mainFunc)
     }
 
     // Set C argc/argv; argv is a new stack-allocated array of UTF-8 C strings
-    char*[] argv = (cast(char**) Mem.allocateOnStack(argc * (char*).sizeof))[0 .. argc];
+    char*[] argv = (cast(char**) allocateOnStack(argc * (char*).sizeof))[0 .. argc];
     foreach (i, ref arg; argv)
         arg = args[i].ptr;
     _cArgs.argc = argc;
@@ -482,13 +482,13 @@ private extern (C) int _d_run_main2(char[][] args, size_t totalArgsLength, MainF
         auto length = args.length * (char[]).sizeof + totalArgsLength;
         version (UseMalloc)
         {
-            auto buff = cast(char[]*) Mem.allocateOne(length);
+            auto buff = cast(char[]*) allocateOne(length);
             if (length)
                 assert(buff);
             //scope (exit) buff;
         }
         else
-            auto buff = cast(char[]*) Mem.allocateOnStack(length);
+            auto buff = cast(char[]*) allocateOnStack(length);
 
         char[][] argsCopy = buff[0 .. args.length];
         auto argBuff = cast(char*) (buff + args.length);
@@ -661,7 +661,7 @@ extern (C) void _d_print_throwable(Throwable t)
                         CP_UTF8, 0, s.ptr, cast(int)s.length, null, 0);
                 if (!swlen) return;
 
-                auto newPtr = cast(WCHAR*) Mem.reallocate(ptr,
+                auto newPtr = cast(WCHAR*) reallocate(ptr,
                         (this.len + swlen + 1) * WCHAR.sizeof);
                 if (!newPtr) return;
                 ptr = newPtr;
@@ -672,7 +672,7 @@ extern (C) void _d_print_throwable(Throwable t)
 
             typeof(ptr) get() { if (ptr) ptr[len] = 0; return ptr; }
 
-            void free() { Mem.freeMem(ptr); }
+            void free() { freeMem(ptr); }
         }
 
         HANDLE windowsHandle(int fd)
@@ -721,12 +721,12 @@ extern (C) void _d_print_throwable(Throwable t)
                 uint codepage = GetConsoleOutputCP();
                 const slen = WideCharToMultiByte(codepage, 0,
                         buf.ptr, cast(int)buf.len, null, 0, null, null);
-                if (auto sptr = cast(char*) Mem.allocateOne(slen * char.sizeof))
+                if (auto sptr = cast(char*) allocateOne(slen * char.sizeof))
                 {
                     WideCharToMultiByte(codepage, 0,
                         buf.ptr, cast(int)buf.len, sptr, slen, null, null);
                     WriteFile(hStdErr, sptr, slen, null, null);
-                    Mem.freeMem(sptr);
+                    freeMem(sptr);
                 }
                 buf.free();
             }
diff --git a/druntime/src/rt/minfo.d b/druntime/src/rt/minfo.d
index 164a924c0c49..8b4998350be7 100644
--- a/druntime/src/rt/minfo.d
+++ b/druntime/src/rt/minfo.d
@@ -13,7 +13,7 @@
 module rt.minfo;
 
 import core.stdc.stdio : fprintf, stderr;
-import core.system : Mem;
+import core.system.memory : freeMem, allocateOne, reallocate;
 import core.stdc.string : memcpy, memset;
 import rt.sections;
 
@@ -66,11 +66,11 @@ struct ModuleGroup
         import core.bitop : bt, btc, bts;
 
         // set up all the arrays.
-        size_t[] cyclePath = (cast(size_t*) Mem.allocateOne(size_t.sizeof * _modules.length * 2))[0 .. _modules.length * 2];
+        size_t[] cyclePath = (cast(size_t*) allocateOne(size_t.sizeof * _modules.length * 2))[0 .. _modules.length * 2];
         size_t totalMods;
-        int[] distance = (cast(int*) Mem.allocateOne(int.sizeof * _modules.length))[0 .. _modules.length];
+        int[] distance = (cast(int*) allocateOne(int.sizeof * _modules.length))[0 .. _modules.length];
         scope(exit)
-            Mem.freeMem(distance.ptr);
+            freeMem(distance.ptr);
 
         // determine the shortest path between two modules. Uses dijkstra
         // without a priority queue. (we can be a bit slow here, in order to
@@ -221,14 +221,14 @@ struct ModuleGroup
         // allocate some stack arrays that will be used throughout the process.
         immutable nwords = (len + 8 * size_t.sizeof - 1) / (8 * size_t.sizeof);
         immutable flagbytes = nwords * size_t.sizeof;
-        auto ctorstart = cast(size_t*) Mem.allocateOne(flagbytes); // ctor/dtor seen
-        auto ctordone = cast(size_t*) Mem.allocateOne(flagbytes); // ctor/dtor processed
-        auto relevant = cast(size_t*) Mem.allocateOne(flagbytes); // has ctors/dtors
+        auto ctorstart = cast(size_t*) allocateOne(flagbytes); // ctor/dtor seen
+        auto ctordone = cast(size_t*) allocateOne(flagbytes); // ctor/dtor processed
+        auto relevant = cast(size_t*) allocateOne(flagbytes); // has ctors/dtors
         scope (exit)
         {
-            Mem.freeMem(ctorstart);
-            Mem.freeMem(ctordone);
-            Mem.freeMem(relevant);
+            freeMem(ctorstart);
+            freeMem(ctordone);
+            freeMem(relevant);
         }
 
         void clearFlags(size_t* flags)
@@ -239,15 +239,15 @@ struct ModuleGroup
 
         // build the edges between each module. We may need this for printing,
         // and also allows avoiding keeping a hash around for module lookups.
-        int[][] edges = (cast(int[]*) Mem.allocateOne((int[]).sizeof * _modules.length))[0 .. _modules.length];
+        int[][] edges = (cast(int[]*) allocateOne((int[]).sizeof * _modules.length))[0 .. _modules.length];
         {
             HashTab!(immutable(ModuleInfo)*, int) modIndexes;
             foreach (i, m; _modules)
                 modIndexes[m] = cast(int) i;
 
-            auto reachable = cast(size_t*) Mem.allocateOne(flagbytes);
+            auto reachable = cast(size_t*) allocateOne(flagbytes);
             scope(exit)
-                Mem.freeMem(reachable);
+                freeMem(reachable);
 
             foreach (i, m; _modules)
             {
@@ -255,7 +255,7 @@ struct ModuleGroup
                 // https://issues.dlang.org/show_bug.cgi?id=16208
                 clearFlags(reachable);
                 // preallocate enough space to store all the indexes
-                int *edge = cast(int*) Mem.allocateOne(int.sizeof * _modules.length);
+                int *edge = cast(int*) allocateOne(int.sizeof * _modules.length);
                 size_t nEdges = 0;
                 foreach (imp; m.importedModules)
                 {
@@ -270,12 +270,12 @@ struct ModuleGroup
                 if (nEdges > 0)
                 {
                     // trim space to what is needed
-                    edges[i] = (cast(int*) Mem.reallocate(edge, int.sizeof * nEdges))[0 .. nEdges];
+                    edges[i] = (cast(int*) reallocate(edge, int.sizeof * nEdges))[0 .. nEdges];
                 }
                 else
                 {
                     edges[i] = null;
-                    Mem.freeMem(edge);
+                    freeMem(edge);
                 }
             }
         }
@@ -285,8 +285,8 @@ struct ModuleGroup
         {
             foreach (e; edges)
                 if (e.ptr)
-                    Mem.freeMem(e.ptr);
-            Mem.freeMem(edges.ptr);
+                    freeMem(e.ptr);
+            freeMem(edges.ptr);
         }
 
         void buildCycleMessage(size_t sourceIdx, size_t cycleIdx, scope void delegate(string) nothrow sink)
@@ -302,7 +302,7 @@ struct ModuleGroup
             sink(_modules[cycleIdx].name);
             sink(EOL);
             auto cyclePath = genCyclePath(sourceIdx, cycleIdx, edges);
-            scope(exit) Mem.freeMem(cyclePath.ptr);
+            scope(exit) freeMem(cyclePath.ptr);
 
             sink(_modules[sourceIdx].name);
             sink("* ->" ~ EOL);
@@ -330,9 +330,9 @@ struct ModuleGroup
             }
 
             // initialize "stack"
-            auto stack = cast(stackFrame*) Mem.allocateOne(stackFrame.sizeof * len);
+            auto stack = cast(stackFrame*) allocateOne(stackFrame.sizeof * len);
             scope (exit)
-                Mem.freeMem(stack);
+                freeMem(stack);
             auto stacktop = stack + len;
             auto sp = stack;
             sp.curMod = cast(int) idx;
@@ -423,9 +423,9 @@ struct ModuleGroup
             immutable ModuleInfo* current = _modules[curidx];
 
             // First, determine what modules are reachable.
-            auto reachable = cast(size_t*) Mem.allocateOne(flagbytes);
+            auto reachable = cast(size_t*) allocateOne(flagbytes);
             scope (exit)
-                Mem.freeMem(reachable);
+                freeMem(reachable);
             if (!findDeps(curidx, reachable))
                 return false;   // deprecated cycle error
 
@@ -468,7 +468,7 @@ struct ModuleGroup
             clearFlags(ctordone);
 
             // pre-allocate enough space to hold all modules.
-            ctors = cast(immutable(ModuleInfo)**) Mem.allocateOne(len * (void*).sizeof);
+            ctors = cast(immutable(ModuleInfo)**) allocateOne(len * (void*).sizeof);
             ctoridx = 0;
             foreach (idx, m; _modules)
             {
@@ -493,7 +493,7 @@ struct ModuleGroup
                 {
                     if (!processMod(idx))
                     {
-                        Mem.freeMem(ctors);
+                        freeMem(ctors);
                         return false;
                     }
                 }
@@ -502,11 +502,11 @@ struct ModuleGroup
             if (ctoridx == 0)
             {
                 // no ctors in the list.
-                Mem.freeMem(ctors);
+                freeMem(ctors);
             }
             else
             {
-                ctors = cast(immutable(ModuleInfo)**) Mem.reallocate(ctors, ctoridx * (void*).sizeof);
+                ctors = cast(immutable(ModuleInfo)**) reallocate(ctors, ctoridx * (void*).sizeof);
                 if (ctors is null)
                     assert(0);
                 result = ctors[0 .. ctoridx];
@@ -561,10 +561,10 @@ struct ModuleGroup
     void free()
     {
         if (_ctors.ptr)
-            Mem.freeMem(_ctors.ptr);
+            freeMem(_ctors.ptr);
         _ctors = null;
         if (_tlsctors.ptr)
-            Mem.freeMem(_tlsctors.ptr);
+            freeMem(_tlsctors.ptr);
         _tlsctors = null;
         // _modules = null; // let the owner free it
     }

From 5de3953b1359bb75f50dd21ee1624b2db7fc8f5a Mon Sep 17 00:00:00 2001
From: Denis Feklushkin <feklushkin.denis@gmail.com>
Date: Wed, 5 Aug 2026 15:59:26 +0300
Subject: [PATCH 29/29] modules renamed: core.system.* ->
 core.internal.config.*

---
 druntime/mak/COPY                                       | 6 +++---
 druntime/mak/SRCS                                       | 6 +++---
 druntime/src/core/gc/config.d                           | 4 ++--
 druntime/src/core/gc/registry.d                         | 4 ++--
 druntime/src/core/{system => internal/config}/memory.d  | 2 +-
 druntime/src/core/{system => internal/config}/opt.d     | 4 +---
 druntime/src/core/{system => internal/config}/package.d | 2 +-
 druntime/src/core/internal/gc/bits.d                    | 2 +-
 druntime/src/core/internal/gc/impl/manual/gc.d          | 2 +-
 druntime/src/core/runtime.d                             | 2 +-
 druntime/src/rt/dmain2.d                                | 2 +-
 druntime/src/rt/minfo.d                                 | 2 +-
 12 files changed, 18 insertions(+), 20 deletions(-)
 rename druntime/src/core/{system => internal/config}/memory.d (92%)
 rename druntime/src/core/{system => internal/config}/opt.d (69%)
 rename druntime/src/core/{system => internal/config}/package.d (96%)

diff --git a/druntime/mak/COPY b/druntime/mak/COPY
index a6f93a9c69c9..29846cbffe5a 100644
--- a/druntime/mak/COPY
+++ b/druntime/mak/COPY
@@ -25,9 +25,6 @@ COPY=\
 	$(IMPDIR)\core\memory.d \
 	$(IMPDIR)\core\runtime.d \
 	$(IMPDIR)\core\simd.d \
-	$(IMPDIR)\core\system\memory.d \
-	$(IMPDIR)\core\system\opt.d \
-	$(IMPDIR)\core\system\package.d \
 	$(IMPDIR)\core\time.d \
 	$(IMPDIR)\core\vararg.d \
 	$(IMPDIR)\core\volatile.d \
@@ -36,6 +33,9 @@ COPY=\
 	$(IMPDIR)\core\internal\atomic.d \
 	$(IMPDIR)\core\internal\attributes.d \
 	$(IMPDIR)\core\internal\cast_.d \
+	$(IMPDIR)\core\internal\config\memory.d \
+	$(IMPDIR)\core\internal\config\opt.d \
+	$(IMPDIR)\core\internal\config\package.d \
 	$(IMPDIR)\core\internal\convert.d \
 	$(IMPDIR)\core\internal\dassert.d \
 	$(IMPDIR)\core\internal\destruction.d \
diff --git a/druntime/mak/SRCS b/druntime/mak/SRCS
index 971e187725c1..6b6604058150 100644
--- a/druntime/mak/SRCS
+++ b/druntime/mak/SRCS
@@ -18,9 +18,6 @@ SRCS=\
 	src\core\memory.d \
 	src\core\runtime.d \
 	src\core\simd.d \
-	src\core\system\memory.d \
-	src\core\system\opt.d \
-	src\core\system\package.d \
 	src\core\time.d \
 	src\core\vararg.d \
 	src\core\volatile.d \
@@ -33,6 +30,9 @@ SRCS=\
 	src\core\internal\atomic.d \
 	src\core\internal\attributes.d \
 	src\core\internal\cast_.d \
+	src\core\internal\config\memory.d \
+	src\core\internal\config\opt.d \
+	src\core\internal\config\package.d \
 	src\core\internal\convert.d \
 	src\core\internal\dassert.d \
 	src\core\internal\destruction.d \
diff --git a/druntime/src/core/gc/config.d b/druntime/src/core/gc/config.d
index b2d86a8890b9..b0b9e54c8090 100644
--- a/druntime/src/core/gc/config.d
+++ b/druntime/src/core/gc/config.d
@@ -9,8 +9,8 @@ module core.gc.config;
 
 import core.internal.parseoptions;
 import core.stdc.stdio : printf;
-import core.system : Sys;
-import core.system.opt : Opt;
+import core.internal.config : Sys;
+import core.internal.config.opt : Opt;
 
 alias Config = Opt.GcConfig;
 
diff --git a/druntime/src/core/gc/registry.d b/druntime/src/core/gc/registry.d
index 7b5e28e01a8c..64c7f89869ea 100644
--- a/druntime/src/core/gc/registry.d
+++ b/druntime/src/core/gc/registry.d
@@ -60,7 +60,7 @@ alias GCThreadInitFunction = void function(ThreadBase base) nothrow @nogc;
 void registerGCFactory(string name, GCFactory factory,
         GCThreadInitFunction threadInit = null) nothrow @nogc
 {
-    import core.system.memory : reallocate;
+    import core.internal.config.memory : reallocate;
 
     auto ptr = cast(Entry*) reallocate(entries.ptr, (entries.length + 1) * Entry.sizeof);
     entries = ptr[0 .. entries.length + 1];
@@ -77,7 +77,7 @@ void registerGCFactory(string name, GCFactory factory,
  */
 GC createGCInstance(string name)
 {
-    import core.system.memory : freeMem;
+    import core.internal.config.memory : freeMem;
 
     foreach (entry; entries)
     {
diff --git a/druntime/src/core/system/memory.d b/druntime/src/core/internal/config/memory.d
similarity index 92%
rename from druntime/src/core/system/memory.d
rename to druntime/src/core/internal/config/memory.d
index 385a440bd411..0c3d107cbf1a 100644
--- a/druntime/src/core/system/memory.d
+++ b/druntime/src/core/internal/config/memory.d
@@ -1,5 +1,5 @@
 ///
-module core.system.memory;
+module core.internal.config.memory;
 
 // libc version
 version (all)
diff --git a/druntime/src/core/system/opt.d b/druntime/src/core/internal/config/opt.d
similarity index 69%
rename from druntime/src/core/system/opt.d
rename to druntime/src/core/internal/config/opt.d
index 38dd2e2a6a5c..16f6db1041b2 100644
--- a/druntime/src/core/system/opt.d
+++ b/druntime/src/core/internal/config/opt.d
@@ -1,7 +1,5 @@
 ///
-module core.system.opt;
-
-package(core):
+module core.internal.config.opt;
 
 struct Opt
 {
diff --git a/druntime/src/core/system/package.d b/druntime/src/core/internal/config/package.d
similarity index 96%
rename from druntime/src/core/system/package.d
rename to druntime/src/core/internal/config/package.d
index 53096b1704c6..0b004bd907f0 100644
--- a/druntime/src/core/system/package.d
+++ b/druntime/src/core/internal/config/package.d
@@ -1,5 +1,5 @@
 ///
-module core.system;
+module core.internal.config;
 
 struct Sys
 {
diff --git a/druntime/src/core/internal/gc/bits.d b/druntime/src/core/internal/gc/bits.d
index a6f47d384e1e..82f1c1660ff4 100644
--- a/druntime/src/core/internal/gc/bits.d
+++ b/druntime/src/core/internal/gc/bits.d
@@ -11,7 +11,7 @@ import core.internal.gc.os;
 
 import core.bitop;
 import core.exception : onOutOfMemoryError;
-import core.system.memory : allocateOneBlank, freeMem;
+import core.internal.config.memory : allocateOneBlank, freeMem;
 import core.stdc.string : memcpy, memset;
 
 // use version gcbitsSingleBitOperation to disable optimizations that use
diff --git a/druntime/src/core/internal/gc/impl/manual/gc.d b/druntime/src/core/internal/gc/impl/manual/gc.d
index 1541a2a0bdcd..0a8ba42bf4a6 100644
--- a/druntime/src/core/internal/gc/impl/manual/gc.d
+++ b/druntime/src/core/internal/gc/impl/manual/gc.d
@@ -25,7 +25,7 @@ import core.internal.container.array;
 
 import core.thread.threadbase : ThreadBase;
 
-import core.system.memory;
+import core.internal.config.memory;
 static import core.memory;
 
 extern (C) noreturn onOutOfMemoryError(void* pretend_sideffect = null, string file = __FILE__, size_t line = __LINE__) @trusted pure nothrow @nogc; /* dmd @@@BUG11461@@@ */
diff --git a/druntime/src/core/runtime.d b/druntime/src/core/runtime.d
index ade1e03910a3..5ff94fd7fd38 100644
--- a/druntime/src/core/runtime.d
+++ b/druntime/src/core/runtime.d
@@ -10,7 +10,7 @@
 
 module core.runtime;
 
-import core.system.memory : allocateOne, freeMem;
+import core.internal.config.memory : allocateOne, freeMem;
 
 version (OSX)
     version = Darwin;
diff --git a/druntime/src/rt/dmain2.d b/druntime/src/rt/dmain2.d
index 9e15b821707b..d895b51598a4 100644
--- a/druntime/src/rt/dmain2.d
+++ b/druntime/src/rt/dmain2.d
@@ -20,7 +20,7 @@ import core.stdc.string : strerror;
 import rt.config : rt_cmdline_enabled, rt_configOption;
 import rt.memory;
 import rt.sections;
-import core.system.memory;
+import core.internal.config.memory;
 
 version (Windows)
 {
diff --git a/druntime/src/rt/minfo.d b/druntime/src/rt/minfo.d
index 8b4998350be7..b7f12e50936a 100644
--- a/druntime/src/rt/minfo.d
+++ b/druntime/src/rt/minfo.d
@@ -13,7 +13,7 @@
 module rt.minfo;
 
 import core.stdc.stdio : fprintf, stderr;
-import core.system.memory : freeMem, allocateOne, reallocate;
+import core.internal.config.memory : freeMem, allocateOne, reallocate;
 import core.stdc.string : memcpy, memset;
 import rt.sections;