[clang][bytecode] Classify varible initializer, not the decl

I'm not attaching a test case because I wasn't able to reproduce.
The backtrace looks as follows:

    frame #10: 0x00007fffdedf0b0d libclang-cpp.so.21.0git`clang::interp::Context::evaluateAsInitializer(this=0x00007c6f839f62f0, Parent=0x00007bff7f3820e0, VD=0x00007bff77ce24b0, Result=0x00007bff7165cd78) at Context.cpp:123:16
    frame #11: 0x00007fffde7bcc2f libclang-cpp.so.21.0git`clang::Expr::EvaluateAsInitializer(this=0x00007bff77ce3078, Value=0x00007bff7165cd78, Ctx=0x00007e9f839f8200, VD=0x00007bff77ce24b0, Notes=0x00007bff7f0d1620, IsConstantInitialization=false) const at ExprConstant.cpp:17096:20
    frame #12: 0x00007fffdde7ca84 libclang-cpp.so.21.0git`clang::VarDecl::evaluateValueImpl(this=0x00007bff77ce24b0, Notes=0x00007bff7f0d1620, IsConstantInitialization=false) const at Decl.cpp:2607:23
    frame #13: 0x00007fffdde7a4a2 libclang-cpp.so.21.0git`clang::VarDecl::evaluateValue(this=0x00007bff77ce24b0) const at Decl.cpp:2583:10
    frame #14: 0x00007fffdde7a0d7 libclang-cpp.so.21.0git`clang::VarDecl::hasInitWithSideEffects(this=0x00007bff77ce24b0) const at Decl.cpp:2458:39
    frame #15: 0x00007fffe8c2e77b libclang-cpp.so.21.0git`clang::ASTDeclWriter::VisitVarDecl(this=0x00007bff7f381b50, D=0x00007bff77ce24b0) at ASTWriterDecl.cpp:1308:27
    frame #16: 0x00007fffe8c58bf8 libclang-cpp.so.21.0git`clang::declvisitor::Base<std::add_pointer, clang::ASTDeclWriter, void>::Visit(this=0x00007bff7f381b50, D=0x00007bff77ce24b0) at DeclNodes.inc:296:1
    frame #17: 0x00007fffe8c1ad7e libclang-cpp.so.21.0git`clang::ASTDeclWriter::Visit(this=0x00007bff7f381b50, D=0x00007bff77ce24b0) at ASTWriterDecl.cpp:460:31
    frame #18: 0x00007fffe8c4f5ae libclang-cpp.so.21.0git`clang::ASTWriter::WriteDecl(this=0x00007e0f83dd8608, Context=0x00007e9f839f8200, D=0x00007bff77ce24b0) at ASTWriterDecl.cpp:3060:5
    frame #19: 0x00007fffe8a908a7 libclang-cpp.so.21.0git`clang::ASTWriter::WriteDeclAndTypes(this=0x00007e0f83dd8608, Context=0x00007e9f839f8200) at ASTWriter.cpp:6243:9
    frame #20: 0x00007fffe8a805f5 libclang-cpp.so.21.0git`clang::ASTWriter::WriteASTCore(this=0x00007e0f83dd8608, SemaPtr=0x00007e8f83cd3200, isysroot=(Data = "", Length = 0), WritingModule=0x00007e0f83d5bc18) at ASTWriter.cpp:6083:5
    frame #21: 0x00007fffe8a7cfa2 libclang-cpp.so.21.0git`clang::ASTWriter::WriteAST(this=0x00007e0f83dd8608, Subject=PointerUnion<clang::Sema *, clang::Preprocessor *> @ 0x00007bff7f18e640, OutputFile=(Data = "/home/tbaeder/code/llvm-project/build/runtimes/runtimes-bins/libcxx/test/libcxx/clang_modules_include.gen.py/Output/complex.h.compile.pass.cpp.dir/t.tmp/1WNKSCAH8NSAM/std-PE20VSNDCJ1A.pcm", Length = 187), WritingModule=0x00007e0f83d5bc18, isysroot=(Data = "", Length = 0), ShouldCacheASTInMemory=true) at ASTWriter.cpp:5434:32
    frame #22: 0x00007fffe8cd2168 libclang-cpp.so.21.0git`clang::PCHGenerator::HandleTranslationUnit(this=0x00007e0f83dd8500, Ctx=0x00007e9f839f8200) at GeneratePCH.cpp:86:30
    frame #23: 0x00007fffe9595e11 libclang-cpp.so.21.0git`clang::MultiplexConsumer::HandleTranslationUnit(this=0x00007c5f83a00300, Ctx=0x00007e9f839f8200) at MultiplexConsumer.cpp:339:15
    frame #24: 0x00007fffdc94121d libclang-cpp.so.21.0git`clang::ParseAST(S=0x00007e8f83cd3200, PrintStats=false, SkipFunctionBodies=false) at ParseAST.cpp:183:13
    frame #25: 0x00007fffe9480085 libclang-cpp.so.21.0git`clang::ASTFrontendAction::ExecuteAction(this=0x00007bff7efb9020) at FrontendAction.cpp:1339:3
    frame #26: 0x00007fffe947e650 libclang-cpp.so.21.0git`clang::FrontendAction::Execute(this=0x00007bff7efb9020) at FrontendAction.cpp:1221:3
    frame #27: 0x00007fffe915a163 libclang-cpp.so.21.0git`clang::CompilerInstance::ExecuteAction(this=0x00007d2f839ef000, Act=0x00007bff7efb9020) at CompilerInstance.cpp:1055:33
    frame #28: 0x00007fffe9175bbf libclang-cpp.so.21.0git`clang::CompilerInstance::compileModule(clang::SourceLocation, llvm::StringRef, llvm::StringRef, clang::CompilerInstance&)::$_0::operator()(this=0x00007bff805225e0) const at CompilerInstance.cpp:1291:18
[...]
    frame #39: 0x00007fffa3ab2a35 libLLVM.so.21.0git`void* llvm::thread::ThreadProxy<std::tuple<void (*)(void*), (anonymous namespace)::RunSafelyOnThreadInfo*>>(Ptr=0x00007c1f839e4330) at thread.h:58:5
    frame #40: 0x000000000039933b clang++`asan_thread_start(void*) + 155
    frame #41: 0x00007fff84a7dfa8 libc.so.6`start_thread + 952
    frame #42: 0x00007fff84b01fcc libc.so.6`__clone3 + 44

where we encounter this declaration:
VarDecl 0x7bff790764b0 </[...]test-suite-install/include/c++/v1/__condition_variable/condition_variable.h:49:3, col:53> col:8 in std.condition_variable.condition_variable hidden referenced __result_max '_Rep' cinit
`-CallExpr 0x7bff79077078 <col:23, col:53> 'type':'long long'
  `-ImplicitCastExpr 0x7bff79077058 <col:23, col:49> 'type (*)() noexcept' <FunctionToPointerDecay>
    `-DeclRefExpr 0x7bff79076670 <col:23, col:49> 'type () noexcept' lvalue CXXMethod 0x7bff791df1f8 'max' 'type () noexcept'
      `-NestedNameSpecifier TypeSpec 'numeric_limits<__ns_rep>':'std::numeric_limits<long long>'

which looks fine at first, but the declaration type does not:

TemplateTypeParmType 0x7bff79074dd0 '_Rep' dependent depth 0 index 0
`-TemplateTypeParm 0x7bff79074d70 '_Rep'

we cannot classify this, so we later run into an assertion because we
assume PT_Ptr while the value on the stack is of type
classify(long long).

Work around this by only looking at the initializer type in that case.

For the record, the command line that crashed could be extractred from
ninja check-cxx and was:

/home/tbaeder/code/llvm-project/build/bin/clang++ /home/tbaeder/code/llvm-project/build/runtimes/runtimes-bins/libcxx/test/libcxx/clang_modules_include.gen.py/complex.h.compile.pass.cpp -pthread --target=x86_64-redhat-linux -nostdinc++ -I /home/tbaeder/code/llvm-project/build/runtimes/runtimes-bins/libcxx/test-suite-install/include/x86_64-redhat-linux/c++/v1 -I /home/tbaeder/code/llvm-project/build/runtimes/runtimes-bins/libcxx/test-suite-install/include/c++/v1 -I /home/tbaeder/code/llvm-project/libcxx/test/support -std=c++26 -Werror -Wall -Wctad-maybe-unsupported -Wextra -Wshadow -Wundef -Wunused-template -Wno-unused-command-line-argument -Wno-attributes -Wno-pessimizing-move -Wno-noexcept-type -Wno-atomic-alignment -Wno-reserved-module-identifier -Wdeprecated-copy -Wdeprecated-copy-dtor -Wshift-negative-value -Wno-user-defined-literals -Wno-tautological-compare -Wsign-compare -Wunused-variable -Wunused-parameter
 -Wunreachable-code -Wno-unused-local-typedef -Wno-local-type-template-args -Wno-c++11-extensions -Wno-unknown-pragmas -Wno-pass-failed -Wno-mismatched-new-delete -Wno-redundant-move -Wno-self-move -Wno-nullability-completeness -D_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER -D_LIBCPP_ENABLE_EXPERIMENTAL -D_LIBCPP_HARDENING_MODE=_LIBCPP_HARDENING_MODE_EXTENSIVE -Werror=thread-safety -Wuser-defined-warnings -fmodules -fcxx-modules -fmodules-cache-path=/home/tbaeder/code/llvm-project/build/runtimes/runtimes-bins/libcxx/test/libcxx/clang_modules_include.gen.py/Output/complex.h.compile.pass.cpp.dir/t.tmp -fsyntax-only

Author: tbaederr

clang/lib/AST/ByteCode/Compiler.cpp

@@ -4574,22 +4574,23 @@ VarCreationState Compiler<Emitter>::visitDecl(const VarDecl *VD,
 template <class Emitter>
 bool Compiler<Emitter>::visitDeclAndReturn(const VarDecl *VD,
                                            bool ConstantContext) {
-  std::optional<PrimType> VarT = classify(VD->getType());
 
   // We only create variables if we're evaluating in a constant context.
   // Otherwise, just evaluate the initializer and return it.
   if (!ConstantContext) {
     DeclScope<Emitter> LS(this, VD);
-    if (!this->visit(VD->getAnyInitializer()))
+    const Expr *Init = VD->getInit();
+    if (!this->visit(Init))
       return false;
-    return this->emitRet(VarT.value_or(PT_Ptr), VD) && LS.destroyLocals() &&
-           this->emitCheckAllocations(VD);
+    return this->emitRet(classify(Init).value_or(PT_Ptr), VD) &&
+           LS.destroyLocals() && this->emitCheckAllocations(VD);
   }
 
   LocalScope<Emitter> VDScope(this, VD);
   if (!this->visitVarDecl(VD, /*Toplevel=*/true))
     return false;
 
+  std::optional<PrimType> VarT = classify(VD->getType());
   if (Context::shouldBeGloballyIndexed(VD)) {
     auto GlobalIndex = P.getGlobal(VD);
     assert(GlobalIndex); // visitVarDecl() didn't return false.