[Clang] Crash on CTAD for alias template involving lambda

```c++
template <class T, class F>
struct A {
    A(T, F f = {}) { f({}); }
};

template <class T>
using AA = A<T, decltype([] (T) {})>;

AA a{0};
```

See https://compiler-explorer.com/z/bffrq8j91.

Unreachable:
```console
non-canonical or dependent type in IR-generation
UNREACHABLE executed at /root/llvm-project/llvm/tools/clang/lib/CodeGen/CodeGenFunction.cpp:263!
```

<details>

<summary>Stack dump</summary>

```console
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++20 <source>
1.	<eof> parser at end of file
2.	Per-file LLVM IR generation
3.	<source>:3:5: Generating code for declaration 'A<int, (lambda at <source>:7:26)>::A'
4.	<source>:3:20: LLVM IR generation of compound statement ('{}')
 #0 0x0000000003ef1728 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3ef1728)
 #1 0x0000000003eef3b4 llvm::sys::CleanupOnSignal(unsigned long) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3eef3b4)
 #2 0x0000000003e33ef8 CrashRecoverySignalHandler(int) CrashRecoveryContext.cpp:0:0
 #3 0x00007b77a7a42520 (/lib/x86_64-linux-gnu/libc.so.6+0x42520)
 #4 0x00007b77a7a969fc pthread_kill (/lib/x86_64-linux-gnu/libc.so.6+0x969fc)
 #5 0x00007b77a7a42476 gsignal (/lib/x86_64-linux-gnu/libc.so.6+0x42476)
 #6 0x00007b77a7a287f3 abort (/lib/x86_64-linux-gnu/libc.so.6+0x287f3)
 #7 0x0000000003e3f47a (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3e3f47a)
 #8 0x0000000004433f12 clang::CodeGen::CodeGenFunction::getEvaluationKind(clang::QualType) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4433f12)
 #9 0x000000000471c62f clang::CodeGen::isAggregateTypeForABI(clang::QualType) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x471c62f)
#10 0x0000000004702d14 (anonymous namespace)::X86_64ABIInfo::getIndirectResult(clang::QualType, unsigned int) const X86.cpp:0:0
#11 0x000000000470b338 (anonymous namespace)::X86_64ABIInfo::classifyArgumentType(clang::QualType, unsigned int, unsigned int&, unsigned int&, bool, bool) const X86.cpp:0:0
#12 0x000000000470bda4 (anonymous namespace)::X86_64ABIInfo::computeInfo(clang::CodeGen::CGFunctionInfo&) const X86.cpp:0:0
#13 0x000000000478c031 clang::CodeGen::CodeGenTypes::arrangeLLVMFunctionInfo(clang::CanQual<clang::Type>, clang::CodeGen::FnInfoOpts, llvm::ArrayRef<clang::CanQual<clang::Type>>, clang::FunctionType::ExtInfo, llvm::ArrayRef<clang::FunctionType::ExtParameterInfo>, clang::CodeGen::RequiredArgs) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x478c031)
#14 0x000000000478e643 arrangeLLVMFunctionInfo(clang::CodeGen::CodeGenTypes&, bool, llvm::SmallVectorImpl<clang::CanQual<clang::Type>>&, clang::CanQual<clang::FunctionProtoType>) CGCall.cpp:0:0
#15 0x000000000479187c clang::CodeGen::CodeGenTypes::arrangeCXXMethodType(clang::CXXRecordDecl const*, clang::FunctionProtoType const*, clang::CXXMethodDecl const*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x479187c)
#16 0x0000000004791a7b clang::CodeGen::CodeGenTypes::arrangeCXXMethodDeclaration(clang::CXXMethodDecl const*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4791a7b)
#17 0x000000000427b279 clang::CodeGen::CodeGenFunction::EmitCXXMemberOrOperatorMemberCallExpr(clang::CallExpr const*, clang::CXXMethodDecl const*, clang::CodeGen::ReturnValueSlot, bool, clang::NestedNameSpecifier*, bool, clang::Expr const*, llvm::CallBase**) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x427b279)
#18 0x000000000427c383 clang::CodeGen::CodeGenFunction::EmitCXXOperatorMemberCallExpr(clang::CXXOperatorCallExpr const*, clang::CXXMethodDecl const*, clang::CodeGen::ReturnValueSlot, llvm::CallBase**) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x427c383)
#19 0x0000000004256fc6 clang::CodeGen::CodeGenFunction::EmitCallExpr(clang::CallExpr const*, clang::CodeGen::ReturnValueSlot, llvm::CallBase**) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4256fc6)
#20 0x00000000042c8c34 (anonymous namespace)::ScalarExprEmitter::VisitCallExpr(clang::CallExpr const*) CGExprScalar.cpp:0:0
#21 0x00000000042bbea0 clang::StmtVisitorBase<std::add_pointer, (anonymous namespace)::ScalarExprEmitter, llvm::Value*>::Visit(clang::Stmt*) CGExprScalar.cpp:0:0
#22 0x00000000042c1c2c clang::CodeGen::CodeGenFunction::EmitScalarExpr(clang::Expr const*, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x42c1c2c)
#23 0x000000000422dfde clang::CodeGen::CodeGenFunction::EmitAnyExpr(clang::Expr const*, clang::CodeGen::AggValueSlot, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x422dfde)
#24 0x0000000004254f5d clang::CodeGen::CodeGenFunction::EmitIgnoredExpr(clang::Expr const*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4254f5d)
#25 0x00000000043c777e clang::CodeGen::CodeGenFunction::EmitStmt(clang::Stmt const*, llvm::ArrayRef<clang::Attr const*>) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x43c777e)
#26 0x00000000043cf6ec clang::CodeGen::CodeGenFunction::EmitCompoundStmtWithoutScope(clang::CompoundStmt const&, bool, clang::CodeGen::AggValueSlot) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x43cf6ec)
#27 0x00000000043cfafd clang::CodeGen::CodeGenFunction::EmitCompoundStmt(clang::CompoundStmt const&, bool, clang::CodeGen::AggValueSlot) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x43cfafd)
#28 0x00000000043cfcc5 clang::CodeGen::CodeGenFunction::EmitSimpleStmt(clang::Stmt const*, llvm::ArrayRef<clang::Attr const*>) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x43cfcc5)
#29 0x00000000043c7705 clang::CodeGen::CodeGenFunction::EmitStmt(clang::Stmt const*, llvm::ArrayRef<clang::Attr const*>) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x43c7705)
#30 0x00000000047c670f clang::CodeGen::CodeGenFunction::EmitConstructorBody(clang::CodeGen::FunctionArgList&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x47c670f)
#31 0x000000000444912d clang::CodeGen::CodeGenFunction::GenerateCode(clang::GlobalDecl, llvm::Function*, clang::CodeGen::CGFunctionInfo const&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x444912d)
#32 0x000000000477b9af clang::CodeGen::CodeGenModule::codegenCXXStructor(clang::GlobalDecl) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x477b9af)
#33 0x0000000004527fcd (anonymous namespace)::ItaniumCXXABI::emitCXXStructor(clang::GlobalDecl) ItaniumCXXABI.cpp:0:0
#34 0x00000000044ad376 clang::CodeGen::CodeGenModule::EmitGlobalDefinition(clang::GlobalDecl, llvm::GlobalValue*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x44ad376)
#35 0x00000000044b9857 clang::CodeGen::CodeGenModule::EmitDeferred() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x44b9857)
#36 0x00000000044b9778 clang::CodeGen::CodeGenModule::EmitDeferred() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x44b9778)
#37 0x00000000044bbde3 clang::CodeGen::CodeGenModule::Release() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x44bbde3)
#38 0x00000000048925ce (anonymous namespace)::CodeGeneratorImpl::HandleTranslationUnit(clang::ASTContext&) ModuleBuilder.cpp:0:0
#39 0x000000000488ea35 clang::BackendConsumer::HandleTranslationUnit(clang::ASTContext&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x488ea35)
#40 0x0000000006541fac clang::ParseAST(clang::Sema&, bool, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6541fac)
#41 0x000000000488f1c8 clang::CodeGenAction::ExecuteAction() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x488f1c8)
#42 0x0000000004b81c05 clang::FrontendAction::Execute() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4b81c05)
#43 0x0000000004b00bde clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4b00bde)
#44 0x0000000004c70e6e clang::ExecuteCompilerInvocation(clang::CompilerInstance*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4c70e6e)
#45 0x0000000000d9decf cc1_main(llvm::ArrayRef<char const*>, char const*, void*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xd9decf)
#46 0x0000000000d955da ExecuteCC1Tool(llvm::SmallVectorImpl<char const*>&, llvm::ToolContext const&) driver.cpp:0:0
#47 0x00000000048f57c9 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
#48 0x0000000003e34394 llvm::CrashRecoveryContext::RunSafely(llvm::function_ref<void ()>) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3e34394)
#49 0x00000000048f5ddf 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
#50 0x00000000048b82fd clang::driver::Compilation::ExecuteCommand(clang::driver::Command const&, clang::driver::Command const*&, bool) const (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x48b82fd)
#51 0x00000000048b938e 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+++0x48b938e)
#52 0x00000000048c11b5 clang::driver::Driver::ExecuteCompilation(clang::driver::Compilation&, llvm::SmallVectorImpl<std::pair<int, clang::driver::Command const*>>&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x48c11b5)
#53 0x0000000000d9ac18 clang_main(int, char**, llvm::ToolContext const&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xd9ac18)
#54 0x0000000000c229f4 main (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xc229f4)
#55 0x00007b77a7a29d90 (/lib/x86_64-linux-gnu/libc.so.6+0x29d90)
#56 0x00007b77a7a29e40 __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x29e40)
#57 0x0000000000d95085 _start (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xd95085)
```

</details>

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[Clang] Crash on CTAD for alias template involving lambda #136504

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[Clang] Crash on CTAD for alias template involving lambda #136504

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llvmbot commented on Apr 21, 2025

shafik commented on Apr 21, 2025

shafik commented on Apr 21, 2025

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