repl: inline ghost-text suggestions for symbol autocomplete

src/jsc/bindings/bindings.cpp

@@ -6774,7 +6774,12 @@ extern "C" JSC::EncodedJSValue Bun__REPL__getCompletions(
     size_t prefixLen)
 {
     auto& vm = JSC::getVM(globalObject);
-    auto scope = DECLARE_THROW_SCOPE(vm);
+    // The Rust caller (repl.rs) has no exception scope, so nothing may escape.
+    auto scope = DECLARE_TOP_EXCEPTION_SCOPE(vm);
+    auto clearAndEncode = [&](JSC::JSValue v) {
+        scope.clearException();
+        return JSC::JSValue::encode(v);
+    };
 
     JSC::JSValue target = JSC::JSValue::decode(targetValue);
     if (!target || target.isUndefined() || target.isNull()) {
@@ -6783,54 +6788,67 @@ extern "C" JSC::EncodedJSValue Bun__REPL__getCompletions(
 
     if (!target.isObject()) {
         JSObject* boxed = target.toObject(globalObject);
-        RETURN_IF_EXCEPTION(scope, JSC::JSValue::encode(JSC::jsUndefined()));
+        if (scope.exception()) [[unlikely]]
+            return clearAndEncode(JSC::jsUndefined());
         target = boxed;
     }
 
     WTF::String prefix = prefixLen > 0
         ? WTF::String::fromUTF8(std::span { prefixPtr, prefixLen })
         : WTF::String();
 
+    // getPropertyNames already walks (and dedups) the prototype chain, throwing past maximumPrototypeChainDepth.
     JSC::JSObject* object = target.getObject();
     JSC::PropertyNameArrayBuilder propertyNames(vm, JSC::PropertyNameMode::Strings, JSC::PrivateSymbolMode::Exclude);
     object->getPropertyNames(globalObject, propertyNames, DontEnumPropertiesMode::Include);
-    RETURN_IF_EXCEPTION(scope, JSC::JSValue::encode(JSC::jsUndefined()));
+    if (scope.exception()) [[unlikely]]
+        return clearAndEncode(JSC::jsUndefined());
 
     JSC::JSArray* completions = JSC::constructEmptyArray(globalObject, nullptr, 0);
-    RETURN_IF_EXCEPTION(scope, JSC::JSValue::encode(JSC::jsUndefined()));
+    if (scope.exception()) [[unlikely]]
+        return clearAndEncode(JSC::jsUndefined());
 
     unsigned completionIndex = 0;
     for (const auto& propertyName : propertyNames) {
         WTF::String name = propertyName.string();
         if (prefix.isEmpty() || name.startsWith(prefix)) {
             completions->putDirectIndex(globalObject, completionIndex++, JSC::jsString(vm, name));
-            RETURN_IF_EXCEPTION(scope, JSC::JSValue::encode(JSC::jsUndefined()));
+            if (scope.exception()) [[unlikely]]
+                return clearAndEncode(JSC::jsUndefined());
         }
     }
 
-    // Also check the prototype chain
-    JSC::JSValue proto = object->getPrototype(globalObject);
-    RETURN_IF_EXCEPTION(scope, JSC::JSValue::encode(completions));
+    return JSC::JSValue::encode(completions);
+}
 
-    while (proto && proto.isObject()) {
-        JSC::JSObject* protoObj = proto.getObject();
-        JSC::PropertyNameArrayBuilder protoNames(vm, JSC::PropertyNameMode::Strings, JSC::PrivateSymbolMode::Exclude);
-        protoObj->getPropertyNames(globalObject, protoNames, DontEnumPropertiesMode::Include);
-        RETURN_IF_EXCEPTION(scope, JSC::JSValue::encode(completions));
+// One `base.name` step of a completion chain: ordinary property semantics (primitives boxed, prototype chain, getters run), UTF-8 name; a miss or a throwing getter yields undefined.
+extern "C" JSC::EncodedJSValue Bun__REPL__getProperty(
+    JSC::JSGlobalObject* globalObject,
+    JSC::EncodedJSValue baseValue,
+    const unsigned char* namePtr,
+    size_t nameLen)
+{
+    auto& vm = JSC::getVM(globalObject);
+    // As in Bun__REPL__getCompletions: the Rust caller has no exception scope.
+    auto scope = DECLARE_TOP_EXCEPTION_SCOPE(vm);
 
-        for (const auto& propertyName : protoNames) {
-            WTF::String name = propertyName.string();
-            if (prefix.isEmpty() || name.startsWith(prefix)) {
-                completions->putDirectIndex(globalObject, completionIndex++, JSC::jsString(vm, name));
-                RETURN_IF_EXCEPTION(scope, JSC::JSValue::encode(completions));
-            }
-        }
+    JSC::JSValue base = JSC::JSValue::decode(baseValue);
+    WTF::String name = WTF::String::fromUTF8(std::span { namePtr, nameLen });
+    if (!base || base.isUndefinedOrNull() || name.isNull())
+        return JSC::JSValue::encode(JSC::jsUndefined());
 
-        proto = protoObj->getPrototype(globalObject);
-        RETURN_IF_EXCEPTION(scope, JSC::JSValue::encode(completions));
+    JSC::JSObject* object = base.toObject(globalObject);
+    if (scope.exception()) [[unlikely]] {
+        scope.clearException();
+        return JSC::JSValue::encode(JSC::jsUndefined());
     }
 
-    return JSC::JSValue::encode(completions);
+    JSC::JSValue result = object->getIfPropertyExists(globalObject, JSC::Identifier::fromString(vm, name));
+    if (scope.exception()) [[unlikely]] {
+        scope.clearException();
+        return JSC::JSValue::encode(JSC::jsUndefined());
+    }
+    return JSC::JSValue::encode(result ? result : JSC::jsUndefined());
 }
 
 // Format a value for REPL output using util.inspect style