https://github.com/shashi1687 created https://github.com/llvm/llvm-project/pull/147213
### Summary Briefly what this PR does, in one or two sentences. > Filters out invalid (null) base-specifiers in `ActOnBaseSpecifiers()`, > preventing ICEs on incomplete or non-class bases. ### Motivation Why this change is needed. > When you inherit from a forward‐declared class or non-class type, Sema used > to emit an error _and_ still hand the bad pointer to later code, causing an > internal compiler error. We now drop those invalid entries immediately. ### Root Cause Analysis A very short bulleted “root cause.” - `ActOnBaseSpecifier` returns `nullptr` for invalid bases. - `ActOnBaseSpecifiers` passed **all** pointers (including null) to `AttachBaseSpecifiers`. - Later layout or special‐member lookup on null caused the ICE. ### Changes in this PR List the key files and rough diff summary. - **clang/lib/Sema/SemaDeclCXX.cpp** - In `ActOnBaseSpecifiers()`, gather `Bases` into a `SmallVector`, skipping null entries. - **clang/test/SemaCXX/invalid-base-inheritance.cpp** - New regression test checking for the proper diagnostics and that no ICE occurs. ### Test Plan How you verified the change. 1. **Local build/test** ```bash mkdir build && cd build cmake -G Ninja ../llvm \ -DLLVM_ENABLE_PROJECTS="clang" \ -DCMAKE_BUILD_TYPE=Release ninja clang ninja check-clang >From 36559cab1bce1bbd8b501521c6c252d6d3fa00ce Mon Sep 17 00:00:00 2001 From: Shashi Shankar <shashishankar1...@gmail.com> Date: Sun, 6 Jul 2025 22:25:48 +0200 Subject: [PATCH] Sema: filter out invalid base-specifiers before attaching ActOnBaseSpecifiers now skips nullptr entries returned for invalid bases, avoiding ICE on invalid inheritance. Added regression test in SemaCXX/invalid-inheritance.cpp. Signed-off-by: Shashi Shankar <shashishankar1...@gmail.com> --- clang/lib/Sema/SemaDeclCXX.cpp | 17 ++++++++++++++++- clang/test/SemaCXX/invalid-base-inheritance.cpp | 17 +++++++++++++++++ 2 files changed, 33 insertions(+), 1 deletion(-) create mode 100644 clang/test/SemaCXX/invalid-base-inheritance.cpp diff --git a/clang/lib/Sema/SemaDeclCXX.cpp b/clang/lib/Sema/SemaDeclCXX.cpp index f0247f865ba40..231610241d8ee 100644 --- a/clang/lib/Sema/SemaDeclCXX.cpp +++ b/clang/lib/Sema/SemaDeclCXX.cpp @@ -3031,8 +3031,23 @@ void Sema::ActOnBaseSpecifiers(Decl *ClassDecl, if (!ClassDecl || Bases.empty()) return; + // --- drop any bases already diagnosed invalid --- + SmallVector<CXXBaseSpecifier *, 4> ValidBases; + ValidBases.reserve(Bases.size()); + for (auto *BS : Bases) + if (BS) + ValidBases.push_back(BS); + if (ValidBases.empty()) + return; + + if (ValidBases.empty()) + return; // nothing valid to attach + AdjustDeclIfTemplate(ClassDecl); - AttachBaseSpecifiers(cast<CXXRecordDecl>(ClassDecl), Bases); + // Attach only the valid bases so downstream never ICEs + AttachBaseSpecifiers(cast<CXXRecordDecl>(ClassDecl), + llvm::MutableArrayRef<CXXBaseSpecifier *>( + ValidBases.data(), ValidBases.size())); } bool Sema::IsDerivedFrom(SourceLocation Loc, CXXRecordDecl *Derived, diff --git a/clang/test/SemaCXX/invalid-base-inheritance.cpp b/clang/test/SemaCXX/invalid-base-inheritance.cpp new file mode 100644 index 0000000000000..e37b77bcd3fea --- /dev/null +++ b/clang/test/SemaCXX/invalid-base-inheritance.cpp @@ -0,0 +1,17 @@ +// Tests that invalid base-specifiers no longer crash the compiler. +// RUN: %clang_cc1 -fsyntax-only -verify %s + +class X; // forward declaration + +class A : X { // incomplete base → error, but no ICE + // expected-error@-1 {{base class has incomplete type}} +}; + +class Y : int { // base not a class → error, but no ICE + // expected-error@-1 {{expected class name}} +}; + +class Z : X*, virtual int { // mixed invalid specifiers + // expected-error@-2 {{base class has incomplete type}} + // expected-error@-1 {{expected class name}} +}; _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits