[clang] Crash in `mangleUnqualifiedName`

[gbresearch]

The following code fails with code 139:

template<class Base, template<class...> class S>
inline auto create_unique(auto&&... args) -> std::unique_ptr<Base>
requires(std::derived_from<std::remove_cvref_t<decltype(S{std::forward<decltype(args)>(args)...})>, Base>)
{
    using Type = std::remove_cvref_t<decltype(S{std::forward<decltype(args)>(args)...})>;
    return std::make_unique<Type>(std::forward<decltype(args)>(args)...);
}

removing constraint, code compiles. Full demo in Code Explorer,

[DimitryAndric]

This regressed with llvmorg-19-init-14238-g2e1ad93 ("[clang] fix broken canonicalization of DeducedTemplateSpecializationType (#95202)") by @mizvekov (cc @ChuanqiXu9, @hokein, @chapuni ).

[llvmbot]

@llvm/issue-subscribers-clang-frontend

Author: Gene (gbresearch)

The following code fails with code 139: ``` template<class Base, template<class...> class S> inline auto create_unique(auto&&... args) -> std::unique_ptr<Base> requires(std::derived_from<std::remove_cvref_t<decltype(S{std::forward<decltype(args)>(args)...})>, Base>) { using Type = std::remove_cvref_t<decltype(S{std::forward<decltype(args)>(args)...})>; return std::make_unique<Type>(std::forward<decltype(args)>(args)...); } ``` removing constraint, code compiles. Full [demo](https://gcc.godbolt.org/z/5esrWsETT) in Code Explorer,

[shafik]

Assertion:

clang++: /root/llvm-project/llvm/include/llvm/Support/Casting.h:578:
decltype(auto) llvm::cast(From*) [with To = clang::TagDecl; From = const clang::NamedDecl]: 
Assertion `isa<To>(Val) && "cast<Ty>() argument of incompatible type!"' failed.

Backtrace:

PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace, preprocessed source, and associated run script.
Stack dump:
0.	Program arguments: /opt/compiler-explorer/clang-assertions-trunk/bin/clang++ -gdwarf-4 -g -o /app/output.s -mllvm --x86-asm-syntax=intel -fno-verbose-asm -S --gcc-toolchain=/opt/compiler-explorer/gcc-snapshot -fcolor-diagnostics -fno-crash-diagnostics -std=c++23 <source>
1.	<eof> parser at end of file
2.	<source>:26:5: LLVM IR generation of declaration 'main'
3.	<source>:26:5: Generating code for declaration 'main'
4.	<source>:6:13: Mangling declaration 'create_unique'
 #0 0x0000000003b123c8 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3b123c8)
 #1 0x0000000003b100bc llvm::sys::CleanupOnSignal(unsigned long) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3b100bc)
 #2 0x0000000003a58af8 CrashRecoverySignalHandler(int) CrashRecoveryContext.cpp:0:0
 #3 0x0000787027042520 (/lib/x86_64-linux-gnu/libc.so.6+0x42520)
 #4 0x00007870270969fc pthread_kill (/lib/x86_64-linux-gnu/libc.so.6+0x969fc)
 #5 0x0000787027042476 gsignal (/lib/x86_64-linux-gnu/libc.so.6+0x42476)
 #6 0x00007870270287f3 abort (/lib/x86_64-linux-gnu/libc.so.6+0x287f3)
 #7 0x000078702702871b (/lib/x86_64-linux-gnu/libc.so.6+0x2871b)
 #8 0x0000787027039e96 (/lib/x86_64-linux-gnu/libc.so.6+0x39e96)
 #9 0x0000000007b58439 (anonymous namespace)::CXXNameMangler::mangleUnqualifiedName(clang::GlobalDecl, clang::DeclarationName, clang::DeclContext const*, unsigned int, llvm::SmallVector<llvm::StringRef, 4u> const*) (.constprop.0) ItaniumMangle.cpp:0:0
#10 0x0000000007b5a8de (anonymous namespace)::CXXNameMangler::mangleNameWithAbiTags(clang::GlobalDecl, llvm::SmallVector<llvm::StringRef, 4u> const*) ItaniumMangle.cpp:0:0
#11 0x0000000007b5b4ca (anonymous namespace)::CXXNameMangler::mangleName(clang::GlobalDecl) ItaniumMangle.cpp:0:0
#12 0x0000000007b5dcd6 (anonymous namespace)::CXXNameMangler::mangleType(clang::QualType) ItaniumMangle.cpp:0:0
#13 0x0000000007b6c723 (anonymous namespace)::CXXNameMangler::mangleExpression(clang::Expr const*, unsigned int, bool) ItaniumMangle.cpp:0:0
#14 0x0000000007b5e50f (anonymous namespace)::CXXNameMangler::mangleType(clang::QualType) ItaniumMangle.cpp:0:0
#15 0x0000000007b7c3f8 (anonymous namespace)::CXXNameMangler::mangleTemplateArg(clang::TemplateArgument, bool) ItaniumMangle.cpp:0:0
#16 0x0000000007b7b193 (anonymous namespace)::CXXNameMangler::mangleTemplateArgs(clang::TemplateName, llvm::ArrayRef<clang::TemplateArgument>) ItaniumMangle.cpp:0:0
#17 0x0000000007b7d11f (anonymous namespace)::CXXNameMangler::manglePrefix(clang::NestedNameSpecifier*) ItaniumMangle.cpp:0:0
#18 0x0000000007b5e0d9 (anonymous namespace)::CXXNameMangler::mangleType(clang::QualType) ItaniumMangle.cpp:0:0
#19 0x0000000007b7c3f8 (anonymous namespace)::CXXNameMangler::mangleTemplateArg(clang::TemplateArgument, bool) ItaniumMangle.cpp:0:0
#20 0x0000000007b7e2e3 (anonymous namespace)::CXXNameMangler::mangleUnresolvedName(clang::NestedNameSpecifier*, clang::DeclarationName, clang::TemplateArgumentLoc const*, unsigned int, unsigned int) ItaniumMangle.cpp:0:0
#21 0x0000000007b6e112 (anonymous namespace)::CXXNameMangler::mangleExpression(clang::Expr const*, unsigned int, bool) ItaniumMangle.cpp:0:0
#22 0x0000000007b7127b (anonymous namespace)::CXXNameMangler::mangleBareFunctionType(clang::FunctionProtoType const*, bool, clang::FunctionDecl const*) ItaniumMangle.cpp:0:0
#23 0x0000000007b72751 (anonymous namespace)::CXXNameMangler::mangleFunctionEncoding(clang::GlobalDecl) ItaniumMangle.cpp:0:0
#24 0x0000000007b766ae (anonymous namespace)::ItaniumMangleContextImpl::mangleCXXName(clang::GlobalDecl, llvm::raw_ostream&) ItaniumMangle.cpp:0:0
#25 0x0000000007b9b1f3 clang::MangleContext::mangleName(clang::GlobalDecl, llvm::raw_ostream&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x7b9b1f3)
#26 0x0000000003f0fafc getMangledNameImpl(clang::CodeGen::CodeGenModule&, clang::GlobalDecl, clang::NamedDecl const*, bool) CodeGenModule.cpp:0:0
#27 0x0000000003f2173d clang::CodeGen::CodeGenModule::getMangledName(clang::GlobalDecl) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3f2173d)
#28 0x0000000003f57f61 clang::CodeGen::CodeGenModule::GetAddrOfFunction(clang::GlobalDecl, llvm::Type*, bool, bool, clang::CodeGen::ForDefinition_t) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3f57f61)
#29 0x000000000428580e clang::CodeGen::CodeGenModule::getRawFunctionPointer(clang::GlobalDecl, llvm::Type*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x428580e)
#30 0x0000000004290b74 EmitDirectCallee(clang::CodeGen::CodeGenFunction&, clang::GlobalDecl) CGExpr.cpp:0:0
#31 0x00000000042b17b9 clang::CodeGen::CodeGenFunction::EmitCallee(clang::Expr const*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x42b17b9)
#32 0x00000000042b1767 clang::CodeGen::CodeGenFunction::EmitCallee(clang::Expr const*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x42b1767)
#33 0x00000000042b1d85 clang::CodeGen::CodeGenFunction::EmitCallExpr(clang::CallExpr const*, clang::CodeGen::ReturnValueSlot) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x42b1d85)
#34 0x00000000042b3d95 clang::CodeGen::RValue llvm::function_ref<clang::CodeGen::RValue (clang::CodeGen::ReturnValueSlot)>::callback_fn<(anonymous namespace)::AggExprEmitter::VisitCallExpr(clang::CallExpr const*)::'lambda'(clang::CodeGen::ReturnValueSlot)>(long, clang::CodeGen::ReturnValueSlot) CGExprAgg.cpp:0:0
#35 0x00000000042b977a (anonymous namespace)::AggExprEmitter::withReturnValueSlot(clang::Expr const*, llvm::function_ref<clang::CodeGen::RValue (clang::CodeGen::ReturnValueSlot)>) CGExprAgg.cpp:0:0
#36 0x00000000042b9f55 (anonymous namespace)::AggExprEmitter::VisitCallExpr(clang::CallExpr const*) CGExprAgg.cpp:0:0
#37 0x00000000042bc2d1 (anonymous namespace)::AggExprEmitter::Visit(clang::Expr*) CGExprAgg.cpp:0:0
#38 0x00000000042c4868 (anonymous namespace)::AggExprEmitter::VisitCXXBindTemporaryExpr(clang::CXXBindTemporaryExpr*) CGExprAgg.cpp:0:0
#39 0x00000000042bc6f3 (anonymous namespace)::AggExprEmitter::Visit(clang::Expr*) CGExprAgg.cpp:0:0
#40 0x00000000042bc4af (anonymous namespace)::AggExprEmitter::Visit(clang::Expr*) CGExprAgg.cpp:0:0
#41 0x00000000042bcf5c clang::CodeGen::CodeGenFunction::EmitAggExpr(clang::Expr const*, clang::CodeGen::AggValueSlot) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x42bcf5c)
#42 0x0000000004288cc1 clang::CodeGen::CodeGenFunction::EmitAnyExpr(clang::Expr const*, clang::CodeGen::AggValueSlot, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4288cc1)
#43 0x00000000042adcdd clang::CodeGen::CodeGenFunction::EmitIgnoredExpr(clang::Expr const*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x42adcdd)
#44 0x0000000003e727c5 clang::CodeGen::CodeGenFunction::EmitStmt(clang::Stmt const*, llvm::ArrayRef<clang::Attr const*>) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3e727c5)
#45 0x0000000003e7a4e4 clang::CodeGen::CodeGenFunction::EmitCompoundStmtWithoutScope(clang::CompoundStmt const&, bool, clang::CodeGen::AggValueSlot) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3e7a4e4)
#46 0x0000000003ee1c74 clang::CodeGen::CodeGenFunction::EmitFunctionBody(clang::Stmt const*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3ee1c74)
#47 0x0000000003ef6b3f clang::CodeGen::CodeGenFunction::GenerateCode(clang::GlobalDecl, llvm::Function*, clang::CodeGen::CGFunctionInfo const&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3ef6b3f)
#48 0x0000000003f5843a clang::CodeGen::CodeGenModule::EmitGlobalFunctionDefinition(clang::GlobalDecl, llvm::GlobalValue*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3f5843a)
#49 0x0000000003f52f95 clang::CodeGen::CodeGenModule::EmitGlobalDefinition(clang::GlobalDecl, llvm::GlobalValue*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3f52f95)
#50 0x0000000003f5354b clang::CodeGen::CodeGenModule::EmitGlobal(clang::GlobalDecl) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3f5354b)
#51 0x0000000003f5d953 clang::CodeGen::CodeGenModule::EmitTopLevelDecl(clang::Decl*) (.part.0) CodeGenModule.cpp:0:0
#52 0x000000000442ca36 (anonymous namespace)::CodeGeneratorImpl::HandleTopLevelDecl(clang::DeclGroupRef) ModuleBuilder.cpp:0:0
#53 0x000000000441cbb8 clang::BackendConsumer::HandleTopLevelDecl(clang::DeclGroupRef) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x441cbb8)
#54 0x0000000006534ad4 clang::ParseAST(clang::Sema&, bool, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6534ad4)
#55 0x000000000442a558 clang::CodeGenAction::ExecuteAction() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x442a558)
#56 0x00000000046b9999 clang::FrontendAction::Execute() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x46b9999)
#57 0x000000000463cf8e clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x463cf8e)
#58 0x00000000047a31de clang::ExecuteCompilerInvocation(clang::CompilerInstance*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x47a31de)
#59 0x0000000000ca71af cc1_main(llvm::ArrayRef<char const*>, char const*, void*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xca71af)
#60 0x0000000000ca03fa ExecuteCC1Tool(llvm::SmallVectorImpl<char const*>&, llvm::ToolContext const&) driver.cpp:0:0
#61 0x000000000446d7f9 void llvm::function_ref<void ()>::callback_fn<clang::driver::CC1Command::Execute(llvm::ArrayRef<std::optional<llvm::StringRef>>, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char>>*, bool*) const::'lambda'()>(long) Job.cpp:0:0
#62 0x0000000003a58fa4 llvm::CrashRecoveryContext::RunSafely(llvm::function_ref<void ()>) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3a58fa4)
#63 0x000000000446ddef clang::driver::CC1Command::Execute(llvm::ArrayRef<std::optional<llvm::StringRef>>, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char>>*, bool*) const (.part.0) Job.cpp:0:0
#64 0x0000000004433da5 clang::driver::Compilation::ExecuteCommand(clang::driver::Command const&, clang::driver::Command const*&, bool) const (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4433da5)
#65 0x000000000443480d clang::driver::Compilation::ExecuteJobs(clang::driver::JobList const&, llvm::SmallVectorImpl<std::pair<int, clang::driver::Command const*>>&, bool) const (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x443480d)
#66 0x000000000443c445 clang::driver::Driver::ExecuteCompilation(clang::driver::Compilation&, llvm::SmallVectorImpl<std::pair<int, clang::driver::Command const*>>&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x443c445)
#67 0x0000000000ca45a5 clang_main(int, char**, llvm::ToolContext const&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xca45a5)
#68 0x0000000000b78974 main (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xb78974)
#69 0x0000787027029d90 (/lib/x86_64-linux-gnu/libc.so.6+0x29d90)
#70 0x0000787027029e40 __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x29e40)
#71 0x0000000000c9feae _start (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xc9feae)
clang++: error: clang frontend command failed with exit code 134 (use -v to see invocation)
Compiler returned: 134