[clang] Crash when calling object of type obtained from lambda in unevaluated context

[MagentaTreehouse]

The following C++20 code causes a crash on clang 17:

template <class>
struct A {
    template <class U>
    using Func = decltype([] {return U{};});
};

A<int>::Func<int> f{};
int i{f()};

Compiler Explorer: https://godbolt.org/z/74q87Kfjf

Compiler output:

clang++: /root/llvm-project/clang/lib/AST/Decl.cpp:2503: clang::APValue* clang::VarDecl::evaluateValueImpl(llvm::SmallVectorImpl<std::pair<clang::SourceLocation, clang::PartialDiagnostic> >&, bool) const: Assertion `!Init->isValueDependent()' failed.
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-17.0.1/bin/clang++ -gdwarf-4 -g -o /app/output.s -mllvm --x86-asm-syntax=intel -S --gcc-toolchain=/opt/compiler-explorer/gcc-13.2.0 -fcolor-diagnostics -fno-crash-diagnostics -std=c++20 -emit-llvm -Xclang -disable-llvm-passes <source>
1.	<eof> parser at end of file
2.	<source>:8:5: LLVM IR generation of declaration 'i'
3.	<source>:8:5: Generating code for declaration 'i'
 #0 0x00000000036e7558 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/opt/compiler-explorer/clang-assertions-17.0.1/bin/clang+++0x36e7558)
 #1 0x00000000036e53dc llvm::sys::CleanupOnSignal(unsigned long) (/opt/compiler-explorer/clang-assertions-17.0.1/bin/clang+++0x36e53dc)
 #2 0x0000000003632918 CrashRecoverySignalHandler(int) CrashRecoveryContext.cpp:0:0
 #3 0x00007f729cc42520 (/lib/x86_64-linux-gnu/libc.so.6+0x42520)
 #4 0x00007f729cc969fc pthread_kill (/lib/x86_64-linux-gnu/libc.so.6+0x969fc)
 #5 0x00007f729cc42476 gsignal (/lib/x86_64-linux-gnu/libc.so.6+0x42476)
 #6 0x00007f729cc287f3 abort (/lib/x86_64-linux-gnu/libc.so.6+0x287f3)
 #7 0x00007f729cc2871b (/lib/x86_64-linux-gnu/libc.so.6+0x2871b)
 #8 0x00007f729cc39e96 (/lib/x86_64-linux-gnu/libc.so.6+0x39e96)
 #9 0x0000000006e29bd3 (/opt/compiler-explorer/clang-assertions-17.0.1/bin/clang+++0x6e29bd3)
#10 0x0000000006e29c25 clang::VarDecl::evaluateValue() const (/opt/compiler-explorer/clang-assertions-17.0.1/bin/clang+++0x6e29c25)
#11 0x00000000039de21b clang::CodeGen::ConstantEmitter::tryEmitPrivateForVarInit(clang::VarDecl const&) (/opt/compiler-explorer/clang-assertions-17.0.1/bin/clang+++0x39de21b)
#12 0x00000000039de5d1 clang::CodeGen::ConstantEmitter::tryEmitForInitializer(clang::VarDecl const&) (/opt/compiler-explorer/clang-assertions-17.0.1/bin/clang+++0x39de5d1)
#13 0x0000000003ab0867 clang::CodeGen::CodeGenModule::EmitGlobalVarDefinition(clang::VarDecl const*, bool) (/opt/compiler-explorer/clang-assertions-17.0.1/bin/clang+++0x3ab0867)
#14 0x0000000003ad2831 clang::CodeGen::CodeGenModule::EmitGlobalDefinition(clang::GlobalDecl, llvm::GlobalValue*) (/opt/compiler-explorer/clang-assertions-17.0.1/bin/clang+++0x3ad2831)
#15 0x0000000003ad2e8b clang::CodeGen::CodeGenModule::EmitGlobal(clang::GlobalDecl) (/opt/compiler-explorer/clang-assertions-17.0.1/bin/clang+++0x3ad2e8b)
#16 0x0000000003adc05b clang::CodeGen::CodeGenModule::EmitTopLevelDecl(clang::Decl*) (.part.0) CodeGenModule.cpp:0:0
#17 0x000000000493c1e6 (anonymous namespace)::CodeGeneratorImpl::HandleTopLevelDecl(clang::DeclGroupRef) ModuleBuilder.cpp:0:0
#18 0x000000000492e988 clang::BackendConsumer::HandleTopLevelDecl(clang::DeclGroupRef) (/opt/compiler-explorer/clang-assertions-17.0.1/bin/clang+++0x492e988)
#19 0x0000000005deb754 clang::ParseAST(clang::Sema&, bool, bool) (/opt/compiler-explorer/clang-assertions-17.0.1/bin/clang+++0x5deb754)
#20 0x0000000004939258 clang::CodeGenAction::ExecuteAction() (/opt/compiler-explorer/clang-assertions-17.0.1/bin/clang+++0x4939258)
#21 0x00000000041a1c09 clang::FrontendAction::Execute() (/opt/compiler-explorer/clang-assertions-17.0.1/bin/clang+++0x41a1c09)
#22 0x00000000041278ce clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) (/opt/compiler-explorer/clang-assertions-17.0.1/bin/clang+++0x41278ce)
#23 0x0000000004281de6 clang::ExecuteCompilerInvocation(clang::CompilerInstance*) (/opt/compiler-explorer/clang-assertions-17.0.1/bin/clang+++0x4281de6)
#24 0x0000000000bc67eb cc1_main(llvm::ArrayRef<char const*>, char const*, void*) (/opt/compiler-explorer/clang-assertions-17.0.1/bin/clang+++0xbc67eb)
#25 0x0000000000bbefaa ExecuteCC1Tool(llvm::SmallVectorImpl<char const*>&, llvm::ToolContext const&) driver.cpp:0:0
#26 0x0000000003f83419 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
#27 0x0000000003632dc4 llvm::CrashRecoveryContext::RunSafely(llvm::function_ref<void ()>) (/opt/compiler-explorer/clang-assertions-17.0.1/bin/clang+++0x3632dc4)
#28 0x0000000003f83a0f 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
#29 0x0000000003f4b275 clang::driver::Compilation::ExecuteCommand(clang::driver::Command const&, clang::driver::Command const*&, bool) const (/opt/compiler-explorer/clang-assertions-17.0.1/bin/clang+++0x3f4b275)
#30 0x0000000003f4bcdd clang::driver::Compilation::ExecuteJobs(clang::driver::JobList const&, llvm::SmallVectorImpl<std::pair<int, clang::driver::Command const*>>&, bool) const (/opt/compiler-explorer/clang-assertions-17.0.1/bin/clang+++0x3f4bcdd)
#31 0x0000000003f5385d clang::driver::Driver::ExecuteCompilation(clang::driver::Compilation&, llvm::SmallVectorImpl<std::pair<int, clang::driver::Command const*>>&) (/opt/compiler-explorer/clang-assertions-17.0.1/bin/clang+++0x3f5385d)
#32 0x0000000000bc4a87 clang_main(int, char**, llvm::ToolContext const&) (/opt/compiler-explorer/clang-assertions-17.0.1/bin/clang+++0xbc4a87)
#33 0x0000000000abef61 main (/opt/compiler-explorer/clang-assertions-17.0.1/bin/clang+++0xabef61)
#34 0x00007f729cc29d90 (/lib/x86_64-linux-gnu/libc.so.6+0x29d90)
#35 0x00007f729cc29e40 __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x29e40)
#36 0x0000000000bbea8e _start (/opt/compiler-explorer/clang-assertions-17.0.1/bin/clang+++0xbbea8e)
clang++: error: clang frontend command failed with exit code 134 (use -v to see invocation)
Compiler returned: 134

[llvmbot]

@llvm/issue-subscribers-clang-codegen

Author: None (MagentaTreehouse)

The following C++20 code causes a crash on clang 17: ```cpp template <class> struct A { template <class U> using Func = decltype([] {return U{};}); };

A<int>::Func<int> f{};
int i{f()};

Compiler Explorer: [https://godbolt.org/z/74q87Kfjf](https://godbolt.org/z/74q87Kfjf)

Compiler output:

clang++: /root/llvm-project/clang/lib/AST/Decl.cpp:2503: clang::APValue* clang::VarDecl::evaluateValueImpl(llvm::SmallVectorImpl<std::pair<clang::SourceLocation, clang::PartialDiagnostic> >&, bool) const: Assertion `!Init->isValueDependent()' failed.
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-17.0.1/bin/clang++ -gdwarf-4 -g -o /app/output.s -mllvm --x86-asm-syntax=intel -S --gcc-toolchain=/opt/compiler-explorer/gcc-13.2.0 -fcolor-diagnostics -fno-crash-diagnostics -std=c++20 -emit-llvm -Xclang -disable-llvm-passes <source>

1. <eof> parser at end of file
2. <source>:8:5: LLVM IR generation of declaration 'i'
3. <source>:8:5: Generating code for declaration 'i'
   #0 0x00000000036e7558 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/opt/compiler-explorer/clang-assertions-17.0.1/bin/clang+++0x36e7558)
   #1 0x00000000036e53dc llvm::sys::CleanupOnSignal(unsigned long) (/opt/compiler-explorer/clang-assertions-17.0.1/bin/clang+++0x36e53dc)
   #2 0x0000000003632918 CrashRecoverySignalHandler(int) CrashRecoveryContext.cpp:0:0
   #3 0x00007f729cc42520 (/lib/x86_64-linux-gnu/libc.so.6+0x42520)
   #4 0x00007f729cc969fc pthread_kill (/lib/x86_64-linux-gnu/libc.so.6+0x969fc)
   #5 0x00007f729cc42476 gsignal (/lib/x86_64-linux-gnu/libc.so.6+0x42476)
   #6 0x00007f729cc287f3 abort (/lib/x86_64-linux-gnu/libc.so.6+0x287f3)
   #7 0x00007f729cc2871b (/lib/x86_64-linux-gnu/libc.so.6+0x2871b)
   #8 0x00007f729cc39e96 (/lib/x86_64-linux-gnu/libc.so.6+0x39e96)
   #9 0x0000000006e29bd3 (/opt/compiler-explorer/clang-assertions-17.0.1/bin/clang+++0x6e29bd3)
   #10 0x0000000006e29c25 clang::VarDecl::evaluateValue() const (/opt/compiler-explorer/clang-assertions-17.0.1/bin/clang+++0x6e29c25)
   #11 0x00000000039de21b clang::CodeGen::ConstantEmitter::tryEmitPrivateForVarInit(clang::VarDecl const&) (/opt/compiler-explorer/clang-assertions-17.0.1/bin/clang+++0x39de21b)
   #12 0x00000000039de5d1 clang::CodeGen::ConstantEmitter::tryEmitForInitializer(clang::VarDecl const&) (/opt/compiler-explorer/clang-assertions-17.0.1/bin/clang+++0x39de5d1)
   #13 0x0000000003ab0867 clang::CodeGen::CodeGenModule::EmitGlobalVarDefinition(clang::VarDecl const*, bool) (/opt/compiler-explorer/clang-assertions-17.0.1/bin/clang+++0x3ab0867)
   #14 0x0000000003ad2831 clang::CodeGen::CodeGenModule::EmitGlobalDefinition(clang::GlobalDecl, llvm::GlobalValue*) (/opt/compiler-explorer/clang-assertions-17.0.1/bin/clang+++0x3ad2831)
   #15 0x0000000003ad2e8b clang::CodeGen::CodeGenModule::EmitGlobal(clang::GlobalDecl) (/opt/compiler-explorer/clang-assertions-17.0.1/bin/clang+++0x3ad2e8b)
   #16 0x0000000003adc05b clang::CodeGen::CodeGenModule::EmitTopLevelDecl(clang::Decl*) (.part.0) CodeGenModule.cpp:0:0
   #17 0x000000000493c1e6 (anonymous namespace)::CodeGeneratorImpl::HandleTopLevelDecl(clang::DeclGroupRef) ModuleBuilder.cpp:0:0
   #18 0x000000000492e988 clang::BackendConsumer::HandleTopLevelDecl(clang::DeclGroupRef) (/opt/compiler-explorer/clang-assertions-17.0.1/bin/clang+++0x492e988)
   #19 0x0000000005deb754 clang::ParseAST(clang::Sema&, bool, bool) (/opt/compiler-explorer/clang-assertions-17.0.1/bin/clang+++0x5deb754)
   #20 0x0000000004939258 clang::CodeGenAction::ExecuteAction() (/opt/compiler-explorer/clang-assertions-17.0.1/bin/clang+++0x4939258)
   #21 0x00000000041a1c09 clang::FrontendAction::Execute() (/opt/compiler-explorer/clang-assertions-17.0.1/bin/clang+++0x41a1c09)
   #22 0x00000000041278ce clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) (/opt/compiler-explorer/clang-assertions-17.0.1/bin/clang+++0x41278ce)
   #23 0x0000000004281de6 clang::ExecuteCompilerInvocation(clang::CompilerInstance*) (/opt/compiler-explorer/clang-assertions-17.0.1/bin/clang+++0x4281de6)
   #24 0x0000000000bc67eb cc1_main(llvm::ArrayRef<char const*>, char const*, void*) (/opt/compiler-explorer/clang-assertions-17.0.1/bin/clang+++0xbc67eb)
   #25 0x0000000000bbefaa ExecuteCC1Tool(llvm::SmallVectorImpl<char const*>&, llvm::ToolContext const&) driver.cpp:0:0
   #26 0x0000000003f83419 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
   #27 0x0000000003632dc4 llvm::CrashRecoveryContext::RunSafely(llvm::function_ref<void ()>) (/opt/compiler-explorer/clang-assertions-17.0.1/bin/clang+++0x3632dc4)
   #28 0x0000000003f83a0f 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
   #29 0x0000000003f4b275 clang::driver::Compilation::ExecuteCommand(clang::driver::Command const&, clang::driver::Command const*&, bool) const (/opt/compiler-explorer/clang-assertions-17.0.1/bin/clang+++0x3f4b275)
   #30 0x0000000003f4bcdd clang::driver::Compilation::ExecuteJobs(clang::driver::JobList const&, llvm::SmallVectorImpl<std::pair<int, clang::driver::Command const*>>&, bool) const (/opt/compiler-explorer/clang-assertions-17.0.1/bin/clang+++0x3f4bcdd)
   #31 0x0000000003f5385d clang::driver::Driver::ExecuteCompilation(clang::driver::Compilation&, llvm::SmallVectorImpl<std::pair<int, clang::driver::Command const*>>&) (/opt/compiler-explorer/clang-assertions-17.0.1/bin/clang+++0x3f5385d)
   #32 0x0000000000bc4a87 clang_main(int, char**, llvm::ToolContext const&) (/opt/compiler-explorer/clang-assertions-17.0.1/bin/clang+++0xbc4a87)
   #33 0x0000000000abef61 main (/opt/compiler-explorer/clang-assertions-17.0.1/bin/clang+++0xabef61)
   #34 0x00007f729cc29d90 (/lib/x86_64-linux-gnu/libc.so.6+0x29d90)
   #35 0x00007f729cc29e40 __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x29e40)
   #36 0x0000000000bbea8e _start (/opt/compiler-explorer/clang-assertions-17.0.1/bin/clang+++0xbbea8e)
   clang++: error: clang frontend command failed with exit code 134 (use -v to see invocation)
   Compiler returned: 134

</details>

[shafik]

Looks like a similar to: #23317 but in the later case the code is ill-formed. In this case it looks well-formed. So the underlying problem may be the same but potentially we could fix the later without fixing this one.

[shafik]

This looks closer to a duplicate: #60432

CC @cor3ntin @erichkeane

[cor3ntin]

It looks like we are not substituting the dependent lambda in the initialization of the variable.
https://godbolt.org/z/3oq11dona

the equivalent code with the outer class template works fine

@erichkeane