mgca: Don't ICE when evaluating ValTrees that contain error constants

compiler/rustc_middle/src/mir/consts.rs

@@ -320,6 +320,10 @@ impl<'tcx> Const<'tcx> {
     ) -> Result<ConstValue, ErrorHandled> {
         match self {
             Const::Ty(_, c) => {
+                if let Err(e) = c.error_reported() {
+                    return Err(ReportedErrorInfo::non_const_eval_error(e).into());
+                }
+
                 // FIXME(generic_const_exprs): We shouldn't encounter placeholders here
                 // and could change this to ICE when encountering them instead.
                 if c.has_non_region_param() || c.has_non_region_placeholders() {

tests/ui/const-generics/mgca/none-as-usize-const-arg.rs

@@ -0,0 +1,14 @@
+// Regression test for https://github.com/rust-lang/rust/issues/150969
+
+#![feature(generic_const_exprs)]
+#![feature(min_generic_const_args)]
+
+fn pass_enum<const N: usize, const M: usize = const { N }> {
+    //~^ ERROR: missing parameters for function definition
+    //~| ERROR: defaults for generic parameters are not allowed here
+    //~| ERROR: overly complex generic constant
+    pass_enum::<{ core::direct_const_arg!(None) }>
+    //~^ ERROR: missing generics for enum `Option` [E0107]
+}
+
+fn main() {}

tests/ui/const-generics/mgca/none-as-usize-const-arg.stderr

@@ -0,0 +1,40 @@
+error: missing parameters for function definition
+  --> $DIR/none-as-usize-const-arg.rs:6:59
+   |
+LL | fn pass_enum<const N: usize, const M: usize = const { N }> {
+   |                                                           ^
+   |
+help: add a parameter list
+   |
+LL | fn pass_enum<const N: usize, const M: usize = const { N }>() {
+   |                                                           ++
+
+error: defaults for generic parameters are not allowed here
+  --> $DIR/none-as-usize-const-arg.rs:6:30
+   |
+LL | fn pass_enum<const N: usize, const M: usize = const { N }> {
+   |                              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error[E0107]: missing generics for enum `Option`
+  --> $DIR/none-as-usize-const-arg.rs:10:43
+   |
+LL |     pass_enum::<{ core::direct_const_arg!(None) }>
+   |                                           ^^^^ expected 1 generic argument
+   |
+help: add missing generic argument
+   |
+LL |     pass_enum::<{ core::direct_const_arg!(None<T>) }>
+   |                                               +++
+
+error: overly complex generic constant
+  --> $DIR/none-as-usize-const-arg.rs:6:47
+   |
+LL | fn pass_enum<const N: usize, const M: usize = const { N }> {
+   |                                               ^^^^^^^^^^^ const blocks are not supported in generic constants
+   |
+   = help: consider moving this anonymous constant into a `const` function
+   = note: this operation may be supported in the future
+
+error: aborting due to 4 previous errors
+
+For more information about this error, try `rustc --explain E0107`.

tests/ui/const-generics/mgca/type_const-adt-expr-missing-field.rs

@@ -0,0 +1,14 @@
+// Regression test for https://github.com/rust-lang/rust/issues/154632
+
+#![feature(generic_const_exprs)]
+#![feature(min_generic_const_args)]
+#![feature(macroless_generic_const_args)]
+#![feature(generic_const_items)]
+
+type const ADD1<const N: usize>: usize = const { N + 1 };
+//~^ ERROR: unconstrained generic constant
+type const AliasFnUnused: ADD1 = ADD1::<{ Some::<usize> {} }>;
+//~^ ERROR: cannot find type `ADD1` in this scope [E0573]
+//~| ERROR: struct expression with missing field initialiser for `0`
+
+fn main() {}

tests/ui/const-generics/mgca/type_const-adt-expr-missing-field.stderr

@@ -0,0 +1,28 @@
+error[E0573]: cannot find type `ADD1` in this scope
+  --> $DIR/type_const-adt-expr-missing-field.rs:10:27
+   |
+LL | type const AliasFnUnused: ADD1 = ADD1::<{ Some::<usize> {} }>;
+   |                           ^^^^ not found in this scope
+   |
+   = note: a constant named `ADD1` exists in another namespace
+
+error: unconstrained generic constant
+  --> $DIR/type_const-adt-expr-missing-field.rs:8:1
+   |
+LL | type const ADD1<const N: usize>: usize = const { N + 1 };
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: try adding a `where` bound
+   |
+LL | type const ADD1<const N: usize>: usize where [(); const { N + 1 }]: = const { N + 1 };
+   |                                        ++++++++++++++++++++++++++++
+
+error: struct expression with missing field initialiser for `0`
+  --> $DIR/type_const-adt-expr-missing-field.rs:10:43
+   |
+LL | type const AliasFnUnused: ADD1 = ADD1::<{ Some::<usize> {} }>;
+   |                                           ^^^^^^^^^^^^^^^^
+
+error: aborting due to 3 previous errors
+
+For more information about this error, try `rustc --explain E0573`.

tests/ui/const-generics/mgca/type_const-tuple-call-expr-missing-field.rs

@@ -0,0 +1,18 @@
+#![feature(generic_const_exprs)]
+#![feature(min_generic_const_args)]
+#![feature(macroless_generic_const_args)]
+#![feature(adt_const_params)]
+#![feature(generic_const_items)]
+
+use std::marker::ConstParamTy;
+
+#[derive(Eq, PartialEq, ConstParamTy)]
+struct Wrap(usize);
+
+type const ADD1<const N: usize>: usize = const { N + 1 };
+//~^ ERROR: unconstrained generic constant
+type const AliasFnUnused: ADD1 = ADD1::<{ Wrap(Some::<usize> {}) }>;
+//~^ ERROR: cannot find type `ADD1` in this scope [E0573]
+//~| ERROR: struct expression with missing field initialiser for `0`
+
+fn main() {}

tests/ui/const-generics/mgca/type_const-tuple-call-expr-missing-field.stderr

@@ -0,0 +1,28 @@
+error[E0573]: cannot find type `ADD1` in this scope
+  --> $DIR/type_const-tuple-call-expr-missing-field.rs:14:27
+   |
+LL | type const AliasFnUnused: ADD1 = ADD1::<{ Wrap(Some::<usize> {}) }>;
+   |                           ^^^^ not found in this scope
+   |
+   = note: a constant named `ADD1` exists in another namespace
+
+error: unconstrained generic constant
+  --> $DIR/type_const-tuple-call-expr-missing-field.rs:12:1
+   |
+LL | type const ADD1<const N: usize>: usize = const { N + 1 };
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+help: try adding a `where` bound
+   |
+LL | type const ADD1<const N: usize>: usize where [(); const { N + 1 }]: = const { N + 1 };
+   |                                        ++++++++++++++++++++++++++++
+
+error: struct expression with missing field initialiser for `0`
+  --> $DIR/type_const-tuple-call-expr-missing-field.rs:14:48
+   |
+LL | type const AliasFnUnused: ADD1 = ADD1::<{ Wrap(Some::<usize> {}) }>;
+   |                                                ^^^^^^^^^^^^^^^^
+
+error: aborting due to 3 previous errors
+
+For more information about this error, try `rustc --explain E0573`.