https://github.com/tbaederr created https://github.com/llvm/llvm-project/pull/213592
This can happen via virtual bases. Fixes https://github.com/llvm/llvm-project/issues/213569 >From cdca5701b716fef94eb1d214038fde09a5b22ede Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Timm=20B=C3=A4der?= <[email protected]> Date: Mon, 3 Aug 2026 06:55:18 +0200 Subject: [PATCH] [clang][bytecode] Handle multiple base paths in dynamic_cast This can happen via virtual bases. --- clang/lib/AST/ByteCode/Interp.cpp | 8 ++++++-- clang/test/AST/ByteCode/dynamic-cast.cpp | 14 ++++++++++++++ 2 files changed, 20 insertions(+), 2 deletions(-) diff --git a/clang/lib/AST/ByteCode/Interp.cpp b/clang/lib/AST/ByteCode/Interp.cpp index 475d206356de8..2da4e4e764971 100644 --- a/clang/lib/AST/ByteCode/Interp.cpp +++ b/clang/lib/AST/ByteCode/Interp.cpp @@ -2166,9 +2166,13 @@ bool DynamicCast(InterpState &S, CodePtr OpPC, const Type *DestTypePtr, CXXBasePaths Paths; getRecord(P.getBase())->isDerivedFrom(getRecord(P), Paths); - assert(std::distance(Paths.begin(), Paths.end()) == 1); - return Paths.front().Access == AS_private; + // Through virtual bases, they might be more than one "direct" base. They + // can have different access specifiers. They must all be private for the + // base to be private. + return llvm::all_of(Paths, [](const CXXBasePath &P) -> bool { + return P.Access == AS_private; + }); }; enum { diff --git a/clang/test/AST/ByteCode/dynamic-cast.cpp b/clang/test/AST/ByteCode/dynamic-cast.cpp index a81bab400a50a..83a745e271a28 100644 --- a/clang/test/AST/ByteCode/dynamic-cast.cpp +++ b/clang/test/AST/ByteCode/dynamic-cast.cpp @@ -338,3 +338,17 @@ namespace UnrelatedInitializingPtr { constexpr auto p = dynamic_cast<C &>(a); // both-error {{must be initialized by a constant expression}} \ // both-note {{reference dynamic_cast failed: dynamic type 'UnrelatedInitializingPtr::D' of operand does not have a base class of type 'C'}} } + +namespace VirtualBase { + struct A { virtual constexpr ~A() = default; }; + struct B : public virtual A {}; + struct C : private virtual A {}; + struct D : B, C {}; + + constexpr bool test() { + D d; + A *a = static_cast<B *>(&d); + return dynamic_cast<C *>(a) == static_cast<C *>(&d); + } + static_assert(test()); +} _______________________________________________ cfe-commits mailing list [email protected] https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
