Variable template lambda with constrained call operator converted to function pointer causes Assertion `!isValueDependent() && "Expression evaluator can't be called on a dependent expression."'

[davidstone]

The following valid translation unit

template<typename>
concept any = true;

template<typename>
auto f = [](any auto) {
};

using function_ptr = void(*)(int);
function_ptr ptr = f<void>;

Causes clang to crash with an assertion failure

clang++: /root/llvm-project/clang/lib/AST/ExprConstant.cpp:15157: bool clang::Expr::EvaluateAsConstantExpr(clang::Expr::EvalResult&, const clang::ASTContext&, clang::Expr::ConstantExprKind) const: Assertion `!isValueDependent() && "Expression evaluator can't be called on a dependent expression."' 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-trunk/bin/clang++ -gdwarf-4 -g -o /app/output.s -S --gcc-toolchain=/opt/compiler-explorer/gcc-snapshot -fcolor-diagnostics -fno-crash-diagnostics -std=c++2b <source>
1.	<source>:9:27: current parser token ';'
 #0 0x000055d9bc75cce4 PrintStackTraceSignalHandler(void*) Signals.cpp:0:0
 #1 0x000055d9bc75aa8c llvm::sys::CleanupOnSignal(unsigned long) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3f6ea8c)
 #2 0x000055d9bc691a18 CrashRecoverySignalHandler(int) CrashRecoveryContext.cpp:0:0
 #3 0x00007f58eaa18420 __restore_rt (/lib/x86_64-linux-gnu/libpthread.so.0+0x14420)
 #4 0x00007f58ea4e500b raise (/lib/x86_64-linux-gnu/libc.so.6+0x4300b)
 #5 0x00007f58ea4c4859 abort (/lib/x86_64-linux-gnu/libc.so.6+0x22859)
 #6 0x00007f58ea4c4729 (/lib/x86_64-linux-gnu/libc.so.6+0x22729)
 #7 0x00007f58ea4d5fd6 (/lib/x86_64-linux-gnu/libc.so.6+0x33fd6)
 #8 0x000055d9bfd4fc4f (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x7563c4f)
 #9 0x000055d9bef69cc1 clang::ActionResult<clang::Expr*, true> calculateConstraintSatisfaction<calculateConstraintSatisfaction(clang::Sema&, clang::NamedDecl const*, clang::SourceLocation, clang::MultiLevelTemplateArgumentList const&, clang::Expr const*, clang::ConstraintSatisfaction&)::'lambda'(clang::Expr const*)>(clang::Sema&, clang::Expr const*, clang::ConstraintSatisfaction&, calculateConstraintSatisfaction(clang::Sema&, clang::NamedDecl const*, clang::SourceLocation, clang::MultiLevelTemplateArgumentList const&, clang::Expr const*, clang::ConstraintSatisfaction&)::'lambda'(clang::Expr const*)&&) SemaConcept.cpp:0:0
#10 0x000055d9bef6a362 CheckConstraintSatisfaction(clang::Sema&, clang::NamedDecl const*, llvm::ArrayRef<clang::Expr const*>, llvm::SmallVectorImpl<clang::Expr*>&, clang::MultiLevelTemplateArgumentList const&, clang::SourceRange, clang::ConstraintSatisfaction&) SemaConcept.cpp:0:0
#11 0x000055d9bef6a8ae clang::Sema::CheckConstraintSatisfaction(clang::NamedDecl const*, llvm::ArrayRef<clang::Expr const*>, llvm::SmallVectorImpl<clang::Expr*>&, clang::MultiLevelTemplateArgumentList const&, clang::SourceRange, clang::ConstraintSatisfaction&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x677e8ae)
#12 0x000055d9bef6aebb clang::Sema::CheckInstantiatedFunctionTemplateConstraints(clang::SourceLocation, clang::FunctionDecl*, llvm::ArrayRef<clang::TemplateArgument>, clang::ConstraintSatisfaction&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x677eebb)
#13 0x000055d9bf70c05f clang::Sema::FinishTemplateArgumentDeduction(clang::FunctionTemplateDecl*, llvm::SmallVectorImpl<clang::DeducedTemplateArgument>&, unsigned int, clang::FunctionDecl*&, clang::sema::TemplateDeductionInfo&, llvm::SmallVectorImpl<clang::Sema::OriginalCallArg> const*, bool, llvm::function_ref<bool ()>) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6f2005f)
#14 0x000055d9bf70ccc2 void llvm::function_ref<void ()>::callback_fn<clang::Sema::DeduceTemplateArguments(clang::FunctionTemplateDecl*, clang::QualType, clang::CXXConversionDecl*&, clang::sema::TemplateDeductionInfo&)::'lambda'()>(long) SemaTemplateDeduction.cpp:0:0
#15 0x000055d9bee19be5 clang::Sema::runWithSufficientStackSpace(clang::SourceLocation, llvm::function_ref<void ()>) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x662dbe5)
#16 0x000055d9bf70177e clang::Sema::DeduceTemplateArguments(clang::FunctionTemplateDecl*, clang::QualType, clang::CXXConversionDecl*&, clang::sema::TemplateDeductionInfo&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6f1577e)
#17 0x000055d9bf532c13 clang::Sema::AddTemplateConversionCandidate(clang::FunctionTemplateDecl*, clang::DeclAccessPair, clang::CXXRecordDecl*, clang::Expr*, clang::QualType, clang::OverloadCandidateSet&, bool, bool, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6d46c13)
#18 0x000055d9bf387fb0 TryUserDefinedConversion(clang::Sema&, clang::QualType, clang::InitializationKind const&, clang::Expr*, clang::InitializationSequence&, bool) SemaInit.cpp:0:0
#19 0x000055d9bf39acdf clang::InitializationSequence::InitializeFrom(clang::Sema&, clang::InitializedEntity const&, clang::InitializationKind const&, llvm::MutableArrayRef<clang::Expr*>, bool, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6baecdf)
#20 0x000055d9bf01e357 clang::Sema::AddInitializerToDecl(clang::Decl*, clang::Expr*, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6832357)
#21 0x000055d9becfa0d6 clang::Parser::ParseDeclarationAfterDeclaratorAndAttributes(clang::Declarator&, clang::Parser::ParsedTemplateInfo const&, clang::Parser::ForRangeInit*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x650e0d6)
#22 0x000055d9bed15880 clang::Parser::ParseDeclGroup(clang::ParsingDeclSpec&, clang::DeclaratorContext, clang::ParsedAttributes&, clang::SourceLocation*, clang::Parser::ForRangeInit*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6529880)
#23 0x000055d9becd6bb9 clang::Parser::ParseDeclOrFunctionDefInternal(clang::ParsedAttributes&, clang::ParsingDeclSpec&, clang::AccessSpecifier) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x64eabb9)
#24 0x000055d9becd7410 clang::Parser::ParseDeclarationOrFunctionDefinition(clang::ParsedAttributes&, clang::ParsingDeclSpec*, clang::AccessSpecifier) (.part.0) Parser.cpp:0:0
#25 0x000055d9becdcbcb clang::Parser::ParseExternalDeclaration(clang::ParsedAttributes&, clang::ParsingDeclSpec*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x64f0bcb)
#26 0x000055d9becdda5a clang::Parser::ParseTopLevelDecl(clang::OpaquePtr<clang::DeclGroupRef>&, clang::Sema::ModuleImportState&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x64f1a5a)
#27 0x000055d9becd1f0a clang::ParseAST(clang::Sema&, bool, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x64e5f0a)
#28 0x000055d9bda76058 clang::CodeGenAction::ExecuteAction() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x528a058)
#29 0x000055d9bd30fb99 clang::FrontendAction::Execute() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4b23b99)
#30 0x000055d9bd29735e clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4aab35e)
#31 0x000055d9bd3f5143 clang::ExecuteCompilerInvocation(clang::CompilerInstance*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4c09143)
#32 0x000055d9b9c10df4 cc1_main(llvm::ArrayRef<char const*>, char const*, void*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x1424df4)
#33 0x000055d9b9c09ed8 ExecuteCC1Tool(llvm::SmallVectorImpl<char const*>&) driver.cpp:0:0
#34 0x000055d9bd1064a9 void llvm::function_ref<void ()>::callback_fn<clang::driver::CC1Command::Execute(llvm::ArrayRef<llvm::Optional<llvm::StringRef>>, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char>>*, bool*) const::'lambda'()>(long) Job.cpp:0:0
#35 0x000055d9bc6921ba llvm::CrashRecoveryContext::RunSafely(llvm::function_ref<void ()>) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3ea61ba)
#36 0x000055d9bd106cff clang::driver::CC1Command::Execute(llvm::ArrayRef<llvm::Optional<llvm::StringRef>>, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char>>*, bool*) const (.part.0) Job.cpp:0:0
#37 0x000055d9bd0d0f69 clang::driver::Compilation::ExecuteCommand(clang::driver::Command const&, clang::driver::Command const*&, bool) const (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x48e4f69)
#38 0x000055d9bd0d19ed 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+++0x48e59ed)
#39 0x000055d9bd0db48c clang::driver::Driver::ExecuteCompilation(clang::driver::Compilation&, llvm::SmallVectorImpl<std::pair<int, clang::driver::Command const*>>&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x48ef48c)
#40 0x000055d9b9c0f1d3 clang_main(int, char**) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x14231d3)
#41 0x00007f58ea4c6083 __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x24083)
#42 0x000055d9b9c09ace _start (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x141dace)
clang-16: error: clang frontend command failed with exit code 134 (use -v to see invocation)
Compiler returned: 134

See it live: https://godbolt.org/z/8Tdsneahj

[llvmbot]

@llvm/issue-subscribers-clang-frontend

[llvmbot]

@llvm/issue-subscribers-c-2b

[yuanfang-chen]

@erichkeane might be related to deferred concept instantiation.

[erichkeane]

Yep, I suspect so. I think we have a couple of similar issues with instantiation of constraints on lambdas. I suspect there is 1 issue that all of these bugs are reproducing, but I have been on weekend and haven't had a chance to debug them yet to confirm.

[erichkeane]

I've confirmed for myself that this is a duplicate of #57958 . So I'm going to 'close as a duplicate'. I'll use the reproducer here as well for my testing, so thank you! The 2nd 1/2 of the bug report in #57945 is ALSO a duplicate, but I'm using that to track a slightly different issue.

The 'fact pattern' here is a generic lambda used in the initializer of a templated variable. It causes us to not properly set up the instantiation parameters. SO, closing as a duplicate.