[clang][bytecode] Fix a crash with covariant return types (#201354)

tbaederr · web-flow · commit a53507fb5c10 · 2026-06-04T05:45:34.000+02:00
`Context::collectBaseOffset()` will assert if the passed-in classes are
the same.
diff --git a/clang/lib/AST/ByteCode/Interp.cpp b/clang/lib/AST/ByteCode/Interp.cpp
@@ -2001,6 +2001,12 @@ bool CallVirt(InterpState &S, CodePtr OpPC, const Function *Func,
         Overrider->getReturnType()->getPointeeType();
     QualType InitialPointeeType =
         InitialFunction->getReturnType()->getPointeeType();
+
+    // Nothing to do if the types already match.
+    if (S.getASTContext().hasSimilarType(InitialPointeeType,
+                                         OverriderPointeeType))
+      return true;
+
     // We've called Overrider above, but calling code expects us to return what
     // InitialFunction returned. According to the rules for covariant return
     // types, what InitialFunction returns needs to be a base class of what
diff --git a/clang/lib/AST/ByteCode/Pointer.h b/clang/lib/AST/ByteCode/Pointer.h
@@ -931,6 +931,8 @@ inline llvm::raw_ostream &operator<<(llvm::raw_ostream &OS, const Pointer &P) {
     OS << " dummy";
   if (!P.isLive())
     OS << " dead";
+  if (P.isBaseClass())
+    OS << " base-class";
   return OS;
 }
 
diff --git a/clang/test/AST/ByteCode/cxx20.cpp b/clang/test/AST/ByteCode/cxx20.cpp
@@ -1365,7 +1365,22 @@ namespace IndirectFieldInitializer {
     constexpr A() {}
   };
   static_assert(A().x == 3, "");
+}
 
+namespace Covariant {
+  struct A {
+    int a;
+    constexpr virtual const A* getA() const = 0;
+  };
+  struct B { int b; };
+
+  struct C: A, B {
+    constexpr const C* getA() const override {
+      return this;
+    }
+  };
+  constexpr  C c{};
+  static_assert(c.getA() == &c);
 }
 
 namespace InvalidOMPRequiredSimdAlign {

Original file line number	Diff line number	Diff line change
`@@ -931,6 +931,8 @@ inline llvm::raw_ostream &operator<<(llvm::raw_ostream &OS, const Pointer &P) {`
`931`	`931`	`OS << " dummy";`
`932`	`932`	`if (!P.isLive())`
`933`	`933`	`OS << " dead";`
	`934`	`+ if (P.isBaseClass())`
	`935`	`+ OS << " base-class";`
`934`	`936`	`return OS;`
`935`	`937`	`}`
`936`	`938`