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Co-authored-by: Corentin Jabot <[email protected]>

Author: shashforge

clang/docs/ReleaseNotes.rst

@@ -923,7 +923,7 @@ Bug Fixes to C++ Support
 - Improved handling of variables with ``consteval`` constructors, to
   consistently treat the initializer as manifestly constant-evaluated.
   (#GH135281)
-- Switch `ParseBaseClause` to use `BaseResult::isUsable()` instead of `isInvalid()`, fixing dropped or mis-parsed base specifiers in C++ classes. (#GH147186)
+- Fix a crash in the presence of invalid base classes. (#GH147186)
 
 Bug Fixes to AST Handling
 ^^^^^^^^^^^^^^^^^^^^^^^^^

clang/lib/Parse/ParseDeclCXX.cpp

@@ -2252,9 +2252,6 @@ void Parser::ParseBaseClause(Decl *ClassDecl) {
   while (true) {
     // Parse a base-specifier.
     BaseResult Result = ParseBaseSpecifier(ClassDecl);
-    // Skip any base-specifier we couldn’t actually build into a usable
-    // CXXBaseSpecifier (covers both syntactic invalidity and
-    // other un-usable cases).
     if (!Result.isUsable()) {
       // Skip the rest of this base specifier, up until the comma or
       // opening brace.

clang/test/SemaCXX/invalid-base-inheritance.cpp

@@ -1,6 +1,8 @@
 // Tests that invalid base-specifiers no longer crash the compiler.
 // RUN: %clang_cc1 -std=c++20 -fsyntax-only -verify %s
 
+namespace GH147186 {
+
 class X; // expected-note {{forward declaration of 'X'}} expected-note {{forward declaration of 'X'}}
 
 class A : X { // expected-error {{base class has incomplete type}}
@@ -11,3 +13,4 @@ class Y : int { // expected-error {{expected class name}}
 
 class Z : X*, virtual int { // expected-error {{base class has incomplete type}} expected-error {{expected class name}}
 };
+}