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ICE on lambda with explicit return type of another lambda #97953

Open Fedr opened 1 month ago

Fedr commented 1 month ago

This program

template<typename T>
concept C = true;

static_assert(
    []<int I=0>() -> decltype([]<C auto = 0>{ return true; })
    { return {}; }()());

is accepted by GCC and MSVC, but Clang crashes:

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-18.1.0/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 -Wall -Wextra -pedantic-errors -stdlib=libc++ <source>
1.  <source>:6:22: current parser token ')'
 #0 0x000000000351ae38 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/opt/compiler-explorer/clang-18.1.0/bin/clang+++0x351ae38)
 #1 0x0000000003518f84 llvm::sys::CleanupOnSignal(unsigned long) (/opt/compiler-explorer/clang-18.1.0/bin/clang+++0x3518f84)
 #2 0x0000000003467018 CrashRecoverySignalHandler(int) CrashRecoveryContext.cpp:0:0
 #3 0x0000739ccde42520 (/lib/x86_64-linux-gnu/libc.so.6+0x42520)
 #4 0x0000000006ce1f98 clang::StmtVisitorBase<llvm::make_const_ptr, (anonymous namespace)::IntExprEvaluator, bool>::Visit(clang::Stmt const*) ExprConstant.cpp:0:0
 #5 0x0000000006ccee3e Evaluate(clang::APValue&, (anonymous namespace)::EvalInfo&, clang::Expr const*) ExprConstant.cpp:0:0
 #6 0x0000000006cee7f2 EvaluateInPlace(clang::APValue&, (anonymous namespace)::EvalInfo&, (anonymous namespace)::LValue const&, clang::Expr const*, bool) (.constprop.0) ExprConstant.cpp:0:0
 #7 0x0000000006cfbcfa clang::Expr::EvaluateAsConstantExpr(clang::Expr::EvalResult&, clang::ASTContext const&, clang::Expr::ConstantExprKind) const (/opt/compiler-explorer/clang-18.1.0/bin/clang+++0x6cfbcfa)
 #8 0x0000000005e6641b 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
 #9 0x0000000005e66d08 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
#10 0x0000000005e672a8 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-18.1.0/bin/clang+++0x5e672a8)
#11 0x0000000005e67f1f clang::Sema::CheckInstantiatedFunctionTemplateConstraints(clang::SourceLocation, clang::FunctionDecl*, llvm::ArrayRef<clang::TemplateArgument>, clang::ConstraintSatisfaction&) (/opt/compiler-explorer/clang-18.1.0/bin/clang+++0x5e67f1f)
#12 0x000000000666f1ea 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 ()>) (.constprop.0) SemaTemplateDeduction.cpp:0:0
#13 0x000000000666fd0a void llvm::function_ref<void ()>::callback_fn<clang::Sema::DeduceTemplateArguments(clang::FunctionTemplateDecl*, clang::TemplateArgumentListInfo*, llvm::ArrayRef<clang::Expr*>, clang::FunctionDecl*&, clang::sema::TemplateDeductionInfo&, bool, bool, clang::QualType, clang::Expr::Classification, llvm::function_ref<bool (llvm::ArrayRef<clang::QualType>)>)::'lambda1'()>(long) SemaTemplateDeduction.cpp:0:0
#14 0x0000000005cff961 clang::Sema::runWithSufficientStackSpace(clang::SourceLocation, llvm::function_ref<void ()>) (/opt/compiler-explorer/clang-18.1.0/bin/clang+++0x5cff961)
#15 0x000000000668554a clang::Sema::DeduceTemplateArguments(clang::FunctionTemplateDecl*, clang::TemplateArgumentListInfo*, llvm::ArrayRef<clang::Expr*>, clang::FunctionDecl*&, clang::sema::TemplateDeductionInfo&, bool, bool, clang::QualType, clang::Expr::Classification, llvm::function_ref<bool (llvm::ArrayRef<clang::QualType>)>) (/opt/compiler-explorer/clang-18.1.0/bin/clang+++0x668554a)
#16 0x00000000064a2d4f clang::Sema::AddMethodTemplateCandidate(clang::FunctionTemplateDecl*, clang::DeclAccessPair, clang::CXXRecordDecl*, clang::TemplateArgumentListInfo*, clang::QualType, clang::Expr::Classification, llvm::ArrayRef<clang::Expr*>, clang::OverloadCandidateSet&, bool, bool, clang::OverloadCandidateParamOrder) (.constprop.0) SemaOverload.cpp:0:0
#17 0x00000000064a350d clang::Sema::AddMethodCandidate(clang::DeclAccessPair, clang::QualType, clang::Expr::Classification, llvm::ArrayRef<clang::Expr*>, clang::OverloadCandidateSet&, bool, clang::OverloadCandidateParamOrder) (/opt/compiler-explorer/clang-18.1.0/bin/clang+++0x64a350d)
#18 0x00000000064b4a50 clang::Sema::BuildCallToObjectOfClassType(clang::Scope*, clang::Expr*, clang::SourceLocation, llvm::MutableArrayRef<clang::Expr*>, clang::SourceLocation) (/opt/compiler-explorer/clang-18.1.0/bin/clang+++0x64b4a50)
#19 0x000000000615ffce clang::Sema::BuildCallExpr(clang::Scope*, clang::Expr*, clang::SourceLocation, llvm::MutableArrayRef<clang::Expr*>, clang::SourceLocation, clang::Expr*, bool, bool) (/opt/compiler-explorer/clang-18.1.0/bin/clang+++0x615ffce)
#20 0x0000000006165a4c clang::Sema::ActOnCallExpr(clang::Scope*, clang::Expr*, clang::SourceLocation, llvm::MutableArrayRef<clang::Expr*>, clang::SourceLocation, clang::Expr*) (/opt/compiler-explorer/clang-18.1.0/bin/clang+++0x6165a4c)
#21 0x0000000005c17df3 clang::Parser::ParsePostfixExpressionSuffix(clang::ActionResult<clang::Expr*, true>) (/opt/compiler-explorer/clang-18.1.0/bin/clang+++0x5c17df3)
#22 0x0000000005c0e671 clang::Parser::ParseCastExpression(clang::Parser::CastParseKind, bool, bool&, clang::Parser::TypeCastState, bool, bool*) (/opt/compiler-explorer/clang-18.1.0/bin/clang+++0x5c0e671)
#23 0x0000000005c1e259 clang::Parser::ParseConstantExpressionInExprEvalContext(clang::Parser::TypeCastState) (/opt/compiler-explorer/clang-18.1.0/bin/clang+++0x5c1e259)
#24 0x0000000005bf50a1 clang::Parser::ParseStaticAssertDeclaration(clang::SourceLocation&) (/opt/compiler-explorer/clang-18.1.0/bin/clang+++0x5bf50a1)
#25 0x0000000005be4b60 clang::Parser::ParseDeclaration(clang::DeclaratorContext, clang::SourceLocation&, clang::ParsedAttributes&, clang::ParsedAttributes&, clang::SourceLocation*) (/opt/compiler-explorer/clang-18.1.0/bin/clang+++0x5be4b60)
#26 0x0000000005ba53d7 clang::Parser::ParseExternalDeclaration(clang::ParsedAttributes&, clang::ParsedAttributes&, clang::ParsingDeclSpec*) (/opt/compiler-explorer/clang-18.1.0/bin/clang+++0x5ba53d7)
#27 0x0000000005ba6f27 clang::Parser::ParseTopLevelDecl(clang::OpaquePtr<clang::DeclGroupRef>&, clang::Sema::ModuleImportState&) (/opt/compiler-explorer/clang-18.1.0/bin/clang+++0x5ba6f27)
#28 0x0000000005b963ba clang::ParseAST(clang::Sema&, bool, bool) (/opt/compiler-explorer/clang-18.1.0/bin/clang+++0x5b963ba)
#29 0x0000000003d5a725 clang::CodeGenAction::ExecuteAction() (/opt/compiler-explorer/clang-18.1.0/bin/clang+++0x3d5a725)
#30 0x0000000003fe2aa1 clang::FrontendAction::Execute() (/opt/compiler-explorer/clang-18.1.0/bin/clang+++0x3fe2aa1)
#31 0x0000000003f6010b clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) (/opt/compiler-explorer/clang-18.1.0/bin/clang+++0x3f6010b)
#32 0x00000000040c2473 clang::ExecuteCompilerInvocation(clang::CompilerInstance*) (/opt/compiler-explorer/clang-18.1.0/bin/clang+++0x40c2473)
#33 0x0000000000c19746 cc1_main(llvm::ArrayRef<char const*>, char const*, void*) (/opt/compiler-explorer/clang-18.1.0/bin/clang+++0xc19746)
#34 0x0000000000c1211d ExecuteCC1Tool(llvm::SmallVectorImpl<char const*>&, llvm::ToolContext const&) driver.cpp:0:0
#35 0x0000000003da1979 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
#36 0x0000000003467443 llvm::CrashRecoveryContext::RunSafely(llvm::function_ref<void ()>) (/opt/compiler-explorer/clang-18.1.0/bin/clang+++0x3467443)
#37 0x0000000003da1b99 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
#38 0x0000000003d69d17 clang::driver::Compilation::ExecuteCommand(clang::driver::Command const&, clang::driver::Command const*&, bool) const (/opt/compiler-explorer/clang-18.1.0/bin/clang+++0x3d69d17)
#39 0x0000000003d6a6cd clang::driver::Compilation::ExecuteJobs(clang::driver::JobList const&, llvm::SmallVectorImpl<std::pair<int, clang::driver::Command const*>>&, bool) const (/opt/compiler-explorer/clang-18.1.0/bin/clang+++0x3d6a6cd)
#40 0x0000000003d7445c clang::driver::Driver::ExecuteCompilation(clang::driver::Compilation&, llvm::SmallVectorImpl<std::pair<int, clang::driver::Command const*>>&) (/opt/compiler-explorer/clang-18.1.0/bin/clang+++0x3d7445c)
#41 0x0000000000c16a21 clang_main(int, char**, llvm::ToolContext const&) (/opt/compiler-explorer/clang-18.1.0/bin/clang+++0xc16a21)
#42 0x0000000000b0fa84 main (/opt/compiler-explorer/clang-18.1.0/bin/clang+++0xb0fa84)
#43 0x0000739ccde29d90 (/lib/x86_64-linux-gnu/libc.so.6+0x29d90)
#44 0x0000739ccde29e40 __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x29e40)
#45 0x0000000000c1191e _start (/opt/compiler-explorer/clang-18.1.0/bin/clang+++0xc1191e)
clang++: error: clang frontend command failed with exit code 139 (use -v to see invocation)
Compiler returned: 139

Online demo: https://gcc.godbolt.org/z/z39Gfs5fd

It is a modified example from https://stackoverflow.com/q/77431308/7325599

EugeneZelenko commented 1 month ago

Still crashes in main: https://gcc.godbolt.org/z/ceexbPaar.

llvmbot commented 1 month ago

@llvm/issue-subscribers-clang-frontend

Author: Fedor Chelnokov (Fedr)

This program ``` template<typename T> concept C = true; static_assert( []<int I=0>() -> decltype([]<C auto = 0>{ return true; }) { return {}; }()()); ``` is accepted by GCC and MSVC, but Clang crashes: ``` 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-18.1.0/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 -Wall -Wextra -pedantic-errors -stdlib=libc++ <source> 1. <source>:6:22: current parser token ')' #0 0x000000000351ae38 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/opt/compiler-explorer/clang-18.1.0/bin/clang+++0x351ae38) #1 0x0000000003518f84 llvm::sys::CleanupOnSignal(unsigned long) (/opt/compiler-explorer/clang-18.1.0/bin/clang+++0x3518f84) #2 0x0000000003467018 CrashRecoverySignalHandler(int) CrashRecoveryContext.cpp:0:0 #3 0x0000739ccde42520 (/lib/x86_64-linux-gnu/libc.so.6+0x42520) #4 0x0000000006ce1f98 clang::StmtVisitorBase<llvm::make_const_ptr, (anonymous namespace)::IntExprEvaluator, bool>::Visit(clang::Stmt const*) ExprConstant.cpp:0:0 #5 0x0000000006ccee3e Evaluate(clang::APValue&, (anonymous namespace)::EvalInfo&, clang::Expr const*) ExprConstant.cpp:0:0 #6 0x0000000006cee7f2 EvaluateInPlace(clang::APValue&, (anonymous namespace)::EvalInfo&, (anonymous namespace)::LValue const&, clang::Expr const*, bool) (.constprop.0) ExprConstant.cpp:0:0 #7 0x0000000006cfbcfa clang::Expr::EvaluateAsConstantExpr(clang::Expr::EvalResult&, clang::ASTContext const&, clang::Expr::ConstantExprKind) const (/opt/compiler-explorer/clang-18.1.0/bin/clang+++0x6cfbcfa) #8 0x0000000005e6641b 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 #9 0x0000000005e66d08 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 #10 0x0000000005e672a8 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-18.1.0/bin/clang+++0x5e672a8) #11 0x0000000005e67f1f clang::Sema::CheckInstantiatedFunctionTemplateConstraints(clang::SourceLocation, clang::FunctionDecl*, llvm::ArrayRef<clang::TemplateArgument>, clang::ConstraintSatisfaction&) (/opt/compiler-explorer/clang-18.1.0/bin/clang+++0x5e67f1f) #12 0x000000000666f1ea 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 ()>) (.constprop.0) SemaTemplateDeduction.cpp:0:0 #13 0x000000000666fd0a void llvm::function_ref<void ()>::callback_fn<clang::Sema::DeduceTemplateArguments(clang::FunctionTemplateDecl*, clang::TemplateArgumentListInfo*, llvm::ArrayRef<clang::Expr*>, clang::FunctionDecl*&, clang::sema::TemplateDeductionInfo&, bool, bool, clang::QualType, clang::Expr::Classification, llvm::function_ref<bool (llvm::ArrayRef<clang::QualType>)>)::'lambda1'()>(long) SemaTemplateDeduction.cpp:0:0 #14 0x0000000005cff961 clang::Sema::runWithSufficientStackSpace(clang::SourceLocation, llvm::function_ref<void ()>) (/opt/compiler-explorer/clang-18.1.0/bin/clang+++0x5cff961) #15 0x000000000668554a clang::Sema::DeduceTemplateArguments(clang::FunctionTemplateDecl*, clang::TemplateArgumentListInfo*, llvm::ArrayRef<clang::Expr*>, clang::FunctionDecl*&, clang::sema::TemplateDeductionInfo&, bool, bool, clang::QualType, clang::Expr::Classification, llvm::function_ref<bool (llvm::ArrayRef<clang::QualType>)>) (/opt/compiler-explorer/clang-18.1.0/bin/clang+++0x668554a) #16 0x00000000064a2d4f clang::Sema::AddMethodTemplateCandidate(clang::FunctionTemplateDecl*, clang::DeclAccessPair, clang::CXXRecordDecl*, clang::TemplateArgumentListInfo*, clang::QualType, clang::Expr::Classification, llvm::ArrayRef<clang::Expr*>, clang::OverloadCandidateSet&, bool, bool, clang::OverloadCandidateParamOrder) (.constprop.0) SemaOverload.cpp:0:0 #17 0x00000000064a350d clang::Sema::AddMethodCandidate(clang::DeclAccessPair, clang::QualType, clang::Expr::Classification, llvm::ArrayRef<clang::Expr*>, clang::OverloadCandidateSet&, bool, clang::OverloadCandidateParamOrder) (/opt/compiler-explorer/clang-18.1.0/bin/clang+++0x64a350d) #18 0x00000000064b4a50 clang::Sema::BuildCallToObjectOfClassType(clang::Scope*, clang::Expr*, clang::SourceLocation, llvm::MutableArrayRef<clang::Expr*>, clang::SourceLocation) (/opt/compiler-explorer/clang-18.1.0/bin/clang+++0x64b4a50) #19 0x000000000615ffce clang::Sema::BuildCallExpr(clang::Scope*, clang::Expr*, clang::SourceLocation, llvm::MutableArrayRef<clang::Expr*>, clang::SourceLocation, clang::Expr*, bool, bool) (/opt/compiler-explorer/clang-18.1.0/bin/clang+++0x615ffce) #20 0x0000000006165a4c clang::Sema::ActOnCallExpr(clang::Scope*, clang::Expr*, clang::SourceLocation, llvm::MutableArrayRef<clang::Expr*>, clang::SourceLocation, clang::Expr*) (/opt/compiler-explorer/clang-18.1.0/bin/clang+++0x6165a4c) #21 0x0000000005c17df3 clang::Parser::ParsePostfixExpressionSuffix(clang::ActionResult<clang::Expr*, true>) (/opt/compiler-explorer/clang-18.1.0/bin/clang+++0x5c17df3) #22 0x0000000005c0e671 clang::Parser::ParseCastExpression(clang::Parser::CastParseKind, bool, bool&, clang::Parser::TypeCastState, bool, bool*) (/opt/compiler-explorer/clang-18.1.0/bin/clang+++0x5c0e671) #23 0x0000000005c1e259 clang::Parser::ParseConstantExpressionInExprEvalContext(clang::Parser::TypeCastState) (/opt/compiler-explorer/clang-18.1.0/bin/clang+++0x5c1e259) #24 0x0000000005bf50a1 clang::Parser::ParseStaticAssertDeclaration(clang::SourceLocation&) (/opt/compiler-explorer/clang-18.1.0/bin/clang+++0x5bf50a1) #25 0x0000000005be4b60 clang::Parser::ParseDeclaration(clang::DeclaratorContext, clang::SourceLocation&, clang::ParsedAttributes&, clang::ParsedAttributes&, clang::SourceLocation*) (/opt/compiler-explorer/clang-18.1.0/bin/clang+++0x5be4b60) #26 0x0000000005ba53d7 clang::Parser::ParseExternalDeclaration(clang::ParsedAttributes&, clang::ParsedAttributes&, clang::ParsingDeclSpec*) (/opt/compiler-explorer/clang-18.1.0/bin/clang+++0x5ba53d7) #27 0x0000000005ba6f27 clang::Parser::ParseTopLevelDecl(clang::OpaquePtr<clang::DeclGroupRef>&, clang::Sema::ModuleImportState&) (/opt/compiler-explorer/clang-18.1.0/bin/clang+++0x5ba6f27) #28 0x0000000005b963ba clang::ParseAST(clang::Sema&, bool, bool) (/opt/compiler-explorer/clang-18.1.0/bin/clang+++0x5b963ba) #29 0x0000000003d5a725 clang::CodeGenAction::ExecuteAction() (/opt/compiler-explorer/clang-18.1.0/bin/clang+++0x3d5a725) #30 0x0000000003fe2aa1 clang::FrontendAction::Execute() (/opt/compiler-explorer/clang-18.1.0/bin/clang+++0x3fe2aa1) #31 0x0000000003f6010b clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) (/opt/compiler-explorer/clang-18.1.0/bin/clang+++0x3f6010b) #32 0x00000000040c2473 clang::ExecuteCompilerInvocation(clang::CompilerInstance*) (/opt/compiler-explorer/clang-18.1.0/bin/clang+++0x40c2473) #33 0x0000000000c19746 cc1_main(llvm::ArrayRef<char const*>, char const*, void*) (/opt/compiler-explorer/clang-18.1.0/bin/clang+++0xc19746) #34 0x0000000000c1211d ExecuteCC1Tool(llvm::SmallVectorImpl<char const*>&, llvm::ToolContext const&) driver.cpp:0:0 #35 0x0000000003da1979 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 #36 0x0000000003467443 llvm::CrashRecoveryContext::RunSafely(llvm::function_ref<void ()>) (/opt/compiler-explorer/clang-18.1.0/bin/clang+++0x3467443) #37 0x0000000003da1b99 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 #38 0x0000000003d69d17 clang::driver::Compilation::ExecuteCommand(clang::driver::Command const&, clang::driver::Command const*&, bool) const (/opt/compiler-explorer/clang-18.1.0/bin/clang+++0x3d69d17) #39 0x0000000003d6a6cd clang::driver::Compilation::ExecuteJobs(clang::driver::JobList const&, llvm::SmallVectorImpl<std::pair<int, clang::driver::Command const*>>&, bool) const (/opt/compiler-explorer/clang-18.1.0/bin/clang+++0x3d6a6cd) #40 0x0000000003d7445c clang::driver::Driver::ExecuteCompilation(clang::driver::Compilation&, llvm::SmallVectorImpl<std::pair<int, clang::driver::Command const*>>&) (/opt/compiler-explorer/clang-18.1.0/bin/clang+++0x3d7445c) #41 0x0000000000c16a21 clang_main(int, char**, llvm::ToolContext const&) (/opt/compiler-explorer/clang-18.1.0/bin/clang+++0xc16a21) #42 0x0000000000b0fa84 main (/opt/compiler-explorer/clang-18.1.0/bin/clang+++0xb0fa84) #43 0x0000739ccde29d90 (/lib/x86_64-linux-gnu/libc.so.6+0x29d90) #44 0x0000739ccde29e40 __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x29e40) #45 0x0000000000c1191e _start (/opt/compiler-explorer/clang-18.1.0/bin/clang+++0xc1191e) clang++: error: clang frontend command failed with exit code 139 (use -v to see invocation) Compiler returned: 139 ``` Online demo: https://gcc.godbolt.org/z/z39Gfs5fd It is a modified example from https://stackoverflow.com/q/77431308/7325599
shafik commented 1 month ago

Confirmed, we should always test w/ clang assertions trunk: https://gcc.godbolt.org/z/Wcc4va3ae

Assertions are more useful when we have them and it is good to know if it is fixed in trunk or not.

Assertion:

clang++: /root/llvm-project/clang/lib/AST/ExprConstant.cpp:16048:
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.
zyn0217 commented 1 month ago

This is a consequence of having the inner lambda (defined in decltype) live in an old uninstantiated lambda context, regardless of whether the outer lambda is an instantiation. Therefore, getTemplateInstantiationArgs() would fail to recover the complete template argument lists while evaluating the type constraint, hence the assert.

Actually, if we managed to give the inner lambda an instantiated parent, we would also fix https://github.com/llvm/llvm-project/issues/97958, where the implicit constexpr-ness would be properly computed because the inner lambda's parent is no longer dependent.