ICE on valid(?) C++20 code

[ericniebler]

[build] Stack dump:
[build] 0.	Program arguments: /usr/bin/clang++-16 -I/home/eniebler/Code/stdexec/include -fsanitize=address -g -std=gnu++20 -Wall -ferror-limit=0 -fmacro-backtrace-limit=0 -ftemplate-backtrace-limit=0 -MD -MT examples/CMakeFiles/example.hello_world.dir/hello_world.cpp.o -MF examples/CMakeFiles/example.hello_world.dir/hello_world.cpp.o.d -o examples/CMakeFiles/example.hello_world.dir/hello_world.cpp.o -c /home/eniebler/Code/stdexec/examples/hello_world.cpp
[build] 1.	/home/eniebler/Code/stdexec/include/stdexec/execution.hpp:2366:50: current parser token ')'
[build] 2.	/home/eniebler/Code/stdexec/include/stdexec/execution.hpp:91:1: parsing namespace 'stdexec'
[build] 3.	/home/eniebler/Code/stdexec/include/stdexec/execution.hpp:2338:3: parsing namespace 'stdexec::__inln'
[build] 4.	/home/eniebler/Code/stdexec/include/stdexec/execution.hpp:2361:5: parsing struct/union/class body 'stdexec::__inln::__scheduler'
[build] 5.	/home/eniebler/Code/stdexec/include/stdexec/execution.hpp:2365:55: parsing function body 'stdexec::__inln::tag_invoke'
[build] 6.	/home/eniebler/Code/stdexec/include/stdexec/execution.hpp:2365:55: in compound statement ('{}')
[build] 7.	/home/eniebler/Code/stdexec/include/stdexec/__detail/__sender_utils.hpp:138:5: instantiating function definition 'stdexec::(anonymous class)::operator()<stdexec::__inln::__schedule_t, stdexec::__>'
[build] 8.	/home/eniebler/Code/stdexec/include/stdexec/__detail/__sender_utils.hpp:59:10: instantiating class definition 'stdexec::__basic_sender<(lambda at /home/eniebler/Code/stdexec/include/stdexec/__detail/__sender_utils.hpp:143:14)>'
[build] Stack dump without symbol names (ensure you have llvm-symbolizer in your PATH or set the environment var `LLVM_SYMBOLIZER_PATH` to point to it):
[build] 0  libLLVM-16.so.1    0x00007feedfdbe706 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) + 54
[build] 1  libLLVM-16.so.1    0x00007feedfdbc8a0 llvm::sys::RunSignalHandlers() + 80
[build] 2  libLLVM-16.so.1    0x00007feedfcfd0f0
[build] 3  libc.so.6          0x00007feede642520
[build] 4  libclang-cpp.so.16 0x00007feee80a225e clang::Sema::CheckParameterPacksForExpansion(clang::SourceLocation, clang::SourceRange, llvm::ArrayRef<std::pair<llvm::PointerUnion<clang::TemplateTypeParmType const*, clang::NamedDecl*>, clang::SourceLocation>>, clang::MultiLevelTemplateArgumentList const&, bool&, bool&, std::optional<unsigned int>&) + 382
[build] 5  libclang-cpp.so.16 0x00007feee8039371
[build] 6  libclang-cpp.so.16 0x00007feee803f3ab
[build] 7  libclang-cpp.so.16 0x00007feee804d551
[build] 8  libclang-cpp.so.16 0x00007feee8044c79
[build] 9  libclang-cpp.so.16 0x00007feee8038d82 clang::Sema::SubstConstraintExpr(clang::Expr*, clang::MultiLevelTemplateArgumentList const&) + 82
[build] 10 libclang-cpp.so.16 0x00007feee7a66e17
[build] 11 libclang-cpp.so.16 0x00007feee7a65d09
[build] 12 libclang-cpp.so.16 0x00007feee7a60f6f
[build] 13 libclang-cpp.so.16 0x00007feee7a6091c clang::Sema::CheckConstraintSatisfaction(clang::NamedDecl const*, llvm::ArrayRef<clang::Expr const*>, llvm::SmallVectorImpl<clang::Expr*>&, clang::MultiLevelTemplateArgumentList const&, clang::SourceRange, clang::ConstraintSatisfaction&) + 796
[build] 14 libclang-cpp.so.16 0x00007feee7a63215 clang::Sema::CheckInstantiatedFunctionTemplateConstraints(clang::SourceLocation, clang::FunctionDecl*, llvm::ArrayRef<clang::TemplateArgument>, clang::ConstraintSatisfaction&) + 837
[build] 15 libclang-cpp.so.16 0x00007feee7fd837f 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 ()>) + 3423
[build] 16 libclang-cpp.so.16 0x00007feee802b837
[build] 17 libclang-cpp.so.16 0x00007feee792e56d clang::Sema::runWithSufficientStackSpace(clang::SourceLocation, llvm::function_ref<void ()>) + 61
[build] 18 libclang-cpp.so.16 0x00007feee7fd9821 clang::Sema::DeduceTemplateArguments(clang::FunctionTemplateDecl*, clang::TemplateArgumentListInfo*, llvm::ArrayRef<clang::Expr*>, clang::FunctionDecl*&, clang::sema::TemplateDeductionInfo&, bool, llvm::function_ref<bool (llvm::ArrayRef<clang::QualType>)>) + 2353
[build] 19 libclang-cpp.so.16 0x00007feee7eb6670 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) + 640
[build] 20 libclang-cpp.so.16 0x00007feee7eb7043 clang::Sema::AddMethodCandidate(clang::DeclAccessPair, clang::QualType, clang::Expr::Classification, llvm::ArrayRef<clang::Expr*>, clang::OverloadCandidateSet&, bool, clang::OverloadCandidateParamOrder) + 211
[build] 21 libclang-cpp.so.16 0x00007feee7ecdee7 clang::Sema::BuildCallToObjectOfClassType(clang::Scope*, clang::Expr*, clang::SourceLocation, llvm::MutableArrayRef<clang::Expr*>, clang::SourceLocation) + 983
[build] 22 libclang-cpp.so.16 0x00007feee7be7c71 clang::Sema::BuildCallExpr(clang::Scope*, clang::Expr*, clang::SourceLocation, llvm::MutableArrayRef<clang::Expr*>, clang::SourceLocation, clang::Expr*, bool, bool) + 2337
[build] 23 libclang-cpp.so.16 0x00007feee7bffdad clang::Sema::ActOnCallExpr(clang::Scope*, clang::Expr*, clang::SourceLocation, llvm::MutableArrayRef<clang::Expr*>, clang::SourceLocation, clang::Expr*) + 77
[build] 24 libclang-cpp.so.16 0x00007feee803f4d1
[build] 25 libclang-cpp.so.16 0x00007feee8051bd7
[build] 26 libclang-cpp.so.16 0x00007feee8031590
[build] 27 libclang-cpp.so.16 0x00007feee8031f27 clang::Sema::SubstType(clang::QualType, clang::MultiLevelTemplateArgumentList const&, clang::SourceLocation, clang::DeclarationName) + 135
[build] 28 libclang-cpp.so.16 0x00007feee7f3123a clang::Sema::CheckTemplateIdType(clang::TemplateName, clang::SourceLocation, clang::TemplateArgumentListInfo&) + 858
[build] 29 libclang-cpp.so.16 0x00007feee8048158
[build] 30 libclang-cpp.so.16 0x00007feee80556b5
[build] 31 libclang-cpp.so.16 0x00007feee805361f
[build] 32 libclang-cpp.so.16 0x00007feee8031590
[build] 33 libclang-cpp.so.16 0x00007feee803124c clang::Sema::SubstType(clang::TypeSourceInfo*, clang::MultiLevelTemplateArgumentList const&, clang::SourceLocation, clang::DeclarationName, bool) + 108
[build] 34 libclang-cpp.so.16 0x00007feee806770b clang::TemplateDeclInstantiator::InstantiateTypedefNameDecl(clang::TypedefNameDecl*, bool) + 107
[build] 35 libclang-cpp.so.16 0x00007feee80687a1 clang::TemplateDeclInstantiator::VisitTypeAliasDecl(clang::TypeAliasDecl*) + 17
[build] 36 libclang-cpp.so.16 0x00007feee8035316 clang::Sema::InstantiateClass(clang::SourceLocation, clang::CXXRecordDecl*, clang::CXXRecordDecl*, clang::MultiLevelTemplateArgumentList const&, clang::TemplateSpecializationKind, bool) + 1590
[build] 37 libclang-cpp.so.16 0x00007feee80371a5 clang::Sema::InstantiateClassTemplateSpecialization(clang::SourceLocation, clang::ClassTemplateSpecializationDecl*, clang::TemplateSpecializationKind, bool) + 2213
[build] 38 libclang-cpp.so.16 0x00007feee80e002e
[build] 39 libclang-cpp.so.16 0x00007feee792e56d clang::Sema::runWithSufficientStackSpace(clang::SourceLocation, llvm::function_ref<void ()>) + 61
[build] 40 libclang-cpp.so.16 0x00007feee80d25fa clang::Sema::RequireCompleteTypeImpl(clang::SourceLocation, clang::QualType, clang::Sema::CompleteTypeKind, clang::Sema::TypeDiagnoser*) + 1786
[build] 41 libclang-cpp.so.16 0x00007feee80d1dd0 clang::Sema::RequireCompleteType(clang::SourceLocation, clang::QualType, clang::Sema::CompleteTypeKind, clang::Sema::TypeDiagnoser&) + 16
[build] 42 libclang-cpp.so.16 0x00007feee7cfd77f clang::Sema::BuildCXXTypeConstructExpr(clang::TypeSourceInfo*, clang::SourceLocation, llvm::MutableArrayRef<clang::Expr*>, clang::SourceLocation, bool) + 2271
[build] 43 libclang-cpp.so.16 0x00007feee803f12a
[build] 44 libclang-cpp.so.16 0x00007feee805c445
[build] 45 libclang-cpp.so.16 0x00007feee8050240
[build] 46 libclang-cpp.so.16 0x00007feee8037bb4 clang::Sema::SubstStmt(clang::Stmt*, clang::MultiLevelTemplateArgumentList const&) + 84
[build] 47 libclang-cpp.so.16 0x00007feee8077ee6 clang::Sema::InstantiateFunctionDefinition(clang::SourceLocation, clang::FunctionDecl*, bool, bool, bool) + 2662
[build] 48 libclang-cpp.so.16 0x00007feee792e56d clang::Sema::runWithSufficientStackSpace(clang::SourceLocation, llvm::function_ref<void ()>) + 61
[build] 49 libclang-cpp.so.16 0x00007feee7fdcfc5 clang::Sema::DeduceReturnType(clang::FunctionDecl*, clang::SourceLocation, bool) + 741
[build] 50 libclang-cpp.so.16 0x00007feee7be2fde clang::Sema::DiagnoseUseOfDecl(clang::NamedDecl*, llvm::ArrayRef<clang::SourceLocation>, clang::ObjCInterfaceDecl const*, bool, bool, clang::ObjCInterfaceDecl*, bool) + 1102
[build] 51 libclang-cpp.so.16 0x00007feee7ec84c4
[build] 52 libclang-cpp.so.16 0x00007feee7ece99f clang::Sema::BuildCallToObjectOfClassType(clang::Scope*, clang::Expr*, clang::SourceLocation, llvm::MutableArrayRef<clang::Expr*>, clang::SourceLocation) + 3727
[build] 53 libclang-cpp.so.16 0x00007feee7be7c71 clang::Sema::BuildCallExpr(clang::Scope*, clang::Expr*, clang::SourceLocation, llvm::MutableArrayRef<clang::Expr*>, clang::SourceLocation, clang::Expr*, bool, bool) + 2337
[build] 54 libclang-cpp.so.16 0x00007feee7bffdad clang::Sema::ActOnCallExpr(clang::Scope*, clang::Expr*, clang::SourceLocation, llvm::MutableArrayRef<clang::Expr*>, clang::SourceLocation, clang::Expr*) + 77
[build] 55 libclang-cpp.so.16 0x00007feee7213c0c clang::Parser::ParsePostfixExpressionSuffix(clang::ActionResult<clang::Expr*, true>) + 5196
[build] 56 libclang-cpp.so.16 0x00007feee7214b25 clang::Parser::ParseCastExpression(clang::Parser::CastParseKind, bool, bool&, clang::Parser::TypeCastState, bool, bool*) + 213
[build] 57 libclang-cpp.so.16 0x00007feee7210da1 clang::Parser::ParseAssignmentExpression(clang::Parser::TypeCastState) + 273
[build] 58 libclang-cpp.so.16 0x00007feee7210c79 clang::Parser::ParseExpression(clang::Parser::TypeCastState) + 9
[build] 59 libclang-cpp.so.16 0x00007feee7274634 clang::Parser::ParseReturnStatement() + 260
[build] 60 libclang-cpp.so.16 0x00007feee726eca9 clang::Parser::ParseStatementOrDeclarationAfterAttributes(llvm::SmallVector<clang::Stmt*, 32u>&, clang::Parser::ParsedStmtContext, clang::SourceLocation*, clang::ParsedAttributes&, clang::ParsedAttributes&) + 2649
[build] 61 libclang-cpp.so.16 0x00007feee726e01d clang::Parser::ParseStatementOrDeclaration(llvm::SmallVector<clang::Stmt*, 32u>&, clang::Parser::ParsedStmtContext, clang::SourceLocation*) + 349
[build] 62 libclang-cpp.so.16 0x00007feee72764b0 clang::Parser::ParseCompoundStatementBody(bool) + 1600
[build] 63 libclang-cpp.so.16 0x00007feee727756f clang::Parser::ParseFunctionStatementBody(clang::Decl*, clang::Parser::ParseScope&) + 175
[build] 64 libclang-cpp.so.16 0x00007feee71d2171 clang::Parser::ParseLexedMethodDef(clang::Parser::LexedMethod&) + 609
[build] 65 libclang-cpp.so.16 0x00007feee71d0e7a clang::Parser::ParseLexedMethodDefs(clang::Parser::ParsingClass&) + 74
[build] 66 libclang-cpp.so.16 0x00007feee7204b69 clang::Parser::ParseCXXMemberSpecification(clang::SourceLocation, clang::SourceLocation, clang::ParsedAttributes&, unsigned int, clang::Decl*) + 4457
[build] 67 libclang-cpp.so.16 0x00007feee7202416 clang::Parser::ParseClassSpecifier(clang::tok::TokenKind, clang::SourceLocation, clang::DeclSpec&, clang::Parser::ParsedTemplateInfo const&, clang::AccessSpecifier, bool, clang::Parser::DeclSpecContext, clang::ParsedAttributes&) + 7206
[build] 68 libclang-cpp.so.16 0x00007feee71e47e1 clang::Parser::ParseDeclarationSpecifiers(clang::DeclSpec&, clang::Parser::ParsedTemplateInfo const&, clang::AccessSpecifier, clang::Parser::DeclSpecContext, clang::Parser::LateParsedAttrList*, clang::ImplicitTypenameContext) + 1857
[build] 69 libclang-cpp.so.16 0x00007feee72904c0 clang::Parser::ParseDeclOrFunctionDefInternal(clang::ParsedAttributes&, clang::ParsedAttributes&, clang::ParsingDeclSpec&, clang::AccessSpecifier) + 192
[build] 70 libclang-cpp.so.16 0x00007feee7290229 clang::Parser::ParseDeclarationOrFunctionDefinition(clang::ParsedAttributes&, clang::ParsedAttributes&, clang::ParsingDeclSpec*, clang::AccessSpecifier) + 457
[build] 71 libclang-cpp.so.16 0x00007feee728f4c7 clang::Parser::ParseExternalDeclaration(clang::ParsedAttributes&, clang::ParsedAttributes&, clang::ParsingDeclSpec*) + 1943
[build] 72 libclang-cpp.so.16 0x00007feee71fae1d clang::Parser::ParseInnerNamespace(llvm::SmallVector<clang::Parser::InnerNamespaceInfo, 4u> const&, unsigned int, clang::SourceLocation&, clang::ParsedAttributes&, clang::BalancedDelimiterTracker&) + 301
[build] 73 libclang-cpp.so.16 0x00007feee71fa7be clang::Parser::ParseNamespace(clang::DeclaratorContext, clang::SourceLocation&, clang::SourceLocation) + 4766
[build] 74 libclang-cpp.so.16 0x00007feee71df8a1 clang::Parser::ParseDeclaration(clang::DeclaratorContext, clang::SourceLocation&, clang::ParsedAttributes&, clang::ParsedAttributes&, clang::SourceLocation*) + 1169
[build] 75 libclang-cpp.so.16 0x00007feee728ede5 clang::Parser::ParseExternalDeclaration(clang::ParsedAttributes&, clang::ParsedAttributes&, clang::ParsingDeclSpec*) + 181
[build] 76 libclang-cpp.so.16 0x00007feee71fae1d clang::Parser::ParseInnerNamespace(llvm::SmallVector<clang::Parser::InnerNamespaceInfo, 4u> const&, unsigned int, clang::SourceLocation&, clang::ParsedAttributes&, clang::BalancedDelimiterTracker&) + 301
[build] 77 libclang-cpp.so.16 0x00007feee71fa7be clang::Parser::ParseNamespace(clang::DeclaratorContext, clang::SourceLocation&, clang::SourceLocation) + 4766
[build] 78 libclang-cpp.so.16 0x00007feee71df8a1 clang::Parser::ParseDeclaration(clang::DeclaratorContext, clang::SourceLocation&, clang::ParsedAttributes&, clang::ParsedAttributes&, clang::SourceLocation*) + 1169
[build] 79 libclang-cpp.so.16 0x00007feee728ede5 clang::Parser::ParseExternalDeclaration(clang::ParsedAttributes&, clang::ParsedAttributes&, clang::ParsingDeclSpec*) + 181
[build] 80 libclang-cpp.so.16 0x00007feee728d86e clang::Parser::ParseTopLevelDecl(clang::OpaquePtr<clang::DeclGroupRef>&, clang::Sema::ModuleImportState&) + 1182
[build] 81 libclang-cpp.so.16 0x00007feee71cd51e clang::ParseAST(clang::Sema&, bool, bool) + 718
[build] 82 libclang-cpp.so.16 0x00007feee8de4bd5 clang::FrontendAction::Execute() + 85
[build] 83 libclang-cpp.so.16 0x00007feee8d61dc4 clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) + 724
[build] 84 libclang-cpp.so.16 0x00007feee8e5d654 clang::ExecuteCompilerInvocation(clang::CompilerInstance*) + 660
[build] 85 clang++-16         0x000055a4f63cff4c cc1_main(llvm::ArrayRef<char const*>, char const*, void*) + 2348
[build] 86 clang++-16         0x000055a4f63cd1f0
[build] 87 libclang-cpp.so.16 0x00007feee8a3e632
[build] 88 libLLVM-16.so.1    0x00007feedfcfce8c llvm::CrashRecoveryContext::RunSafely(llvm::function_ref<void ()>) + 140
[build] 89 libclang-cpp.so.16 0x00007feee8a3dd53 clang::driver::CC1Command::Execute(llvm::ArrayRef<std::optional<llvm::StringRef>>, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char>>*, bool*) const + 355
[build] 90 libclang-cpp.so.16 0x00007feee8a095d2 clang::driver::Compilation::ExecuteCommand(clang::driver::Command const&, clang::driver::Command const*&, bool) const + 866
[build] 91 libclang-cpp.so.16 0x00007feee8a0982e clang::driver::Compilation::ExecuteJobs(clang::driver::JobList const&, llvm::SmallVectorImpl<std::pair<int, clang::driver::Command const*>>&, bool) const + 142
[build] 92 libclang-cpp.so.16 0x00007feee8a23f8d clang::driver::Driver::ExecuteCompilation(clang::driver::Compilation&, llvm::SmallVectorImpl<std::pair<int, clang::driver::Command const*>>&) + 349
[build] 93 clang++-16         0x000055a4f63cc8b5 clang_main(int, char**) + 11541
[build] 94 libc.so.6          0x00007feede629d90
[build] 95 libc.so.6          0x00007feede629e40 __libc_start_main + 128
[build] 96 clang++-16         0x000055a4f63c9855 _start + 37
[build] clang: error: clang frontend command failed with exit code 139 (use -v to see invocation)
[build] Ubuntu clang version 16.0.6 (++20230710042027+7cbf1a259152-1~exp1~20230710162048.105)
[build] Target: x86_64-pc-linux-gnu
[build] Thread model: posix
[build] InstalledDir: /usr/bin
[build] clang: note: diagnostic msg: 
[build] ********************
[build] 
[build] PLEASE ATTACH THE FOLLOWING FILES TO THE BUG REPORT:
[build] Preprocessed source(s) and associated run script(s) are located at:
[build] clang: note: diagnostic msg: /tmp/hello_world-ef8864.cpp
[build] clang: note: diagnostic msg: /tmp/hello_world-ef8864.sh
[build] clang: note: diagnostic msg: 
[build] 
[build] ********************

hello_world.zip

[llvmbot]

@llvm/issue-subscribers-clang-frontend

[llvmbot]

@llvm/issue-subscribers-c-20

[Endilll]

One reduction of this crash has been fixed in post-18 trunk: https://godbolt.org/z/P1zad4cKP
Reduced by me and C-Reduce:

auto a = 
  [](auto... __captures) {
    return []() requires requires { 0(__captures...); } {};
  }()(); 

Clang 17 crash:

clang++: /root/llvm-project/clang/lib/Sema/SemaTemplateInstantiate.cpp:4181:
llvm::PointerUnion<clang::Decl*, llvm::SmallVector<clang::VarDecl*, 4>*>* clang::LocalInstantiationScope::findInstantiationOf(const clang::Decl*):
Assertion `isa<LabelDecl>(D) && "declaration not instantiated in this scope"' 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 <source>
1.	<source>:4:7: current parser token ')'
 #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 0x00007fc5d5642520 (/lib/x86_64-linux-gnu/libc.so.6+0x42520)
 #4 0x00007fc5d56969fc pthread_kill (/lib/x86_64-linux-gnu/libc.so.6+0x969fc)
 #5 0x00007fc5d5642476 gsignal (/lib/x86_64-linux-gnu/libc.so.6+0x42476)
 #6 0x00007fc5d56287f3 abort (/lib/x86_64-linux-gnu/libc.so.6+0x287f3)
 #7 0x00007fc5d562871b (/lib/x86_64-linux-gnu/libc.so.6+0x2871b)
 #8 0x00007fc5d5639e96 (/lib/x86_64-linux-gnu/libc.so.6+0x39e96)
 #9 0x00000000068e3b85 clang::LocalInstantiationScope::findInstantiationOf(clang::Decl const*) (/opt/compiler-explorer/clang-assertions-17.0.1/bin/clang+++0x68e3b85)
#10 0x0000000006989c59 clang::Sema::CheckParameterPacksForExpansion(clang::SourceLocation, clang::SourceRange, llvm::ArrayRef<std::pair<llvm::PointerUnion<clang::TemplateTypeParmType const*, clang::NamedDecl*>, clang::SourceLocation>>, clang::MultiLevelTemplateArgumentList const&, bool&, bool&, std::optional<unsigned int>&) (/opt/compiler-explorer/clang-assertions-17.0.1/bin/clang+++0x6989c59)
#11 0x00000000068ec04d clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformExprs(clang::Expr* const*, unsigned int, bool, llvm::SmallVectorImpl<clang::Expr*>&, bool*) SemaTemplateInstantiate.cpp:0:0
#12 0x00000000068f48e1 clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformCallExpr(clang::CallExpr*) SemaTemplateInstantiate.cpp:0:0
#13 0x00000000068eafe2 clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformExpr(clang::Expr*) SemaTemplateInstantiate.cpp:0:0
#14 0x0000000006913311 clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformRequiresExpr(clang::RequiresExpr*) SemaTemplateInstantiate.cpp:0:0
#15 0x0000000006914d1e (anonymous namespace)::TemplateInstantiator::TransformRequiresExpr(clang::RequiresExpr*) SemaTemplateInstantiate.cpp:0:0
#16 0x00000000068eab42 clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformExpr(clang::Expr*) SemaTemplateInstantiate.cpp:0:0
#17 0x0000000006925718 clang::Sema::SubstConstraintExpr(clang::Expr*, clang::MultiLevelTemplateArgumentList const&) (/opt/compiler-explorer/clang-assertions-17.0.1/bin/clang+++0x6925718)
#18 0x00000000060954e7 calculateConstraintSatisfaction(clang::Sema&, clang::NamedDecl const*, clang::SourceLocation, clang::MultiLevelTemplateArgumentList const&, clang::Expr const*, clang::ConstraintSatisfaction&)::'lambda'(clang::Expr const*)::operator()(clang::Expr const*) const SemaConcept.cpp:0:0
#19 0x0000000006096b3b 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
#20 0x0000000006097342 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
#21 0x000000000609797a 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-17.0.1/bin/clang+++0x609797a)
#22 0x00000000060993d3 clang::Sema::CheckFunctionConstraints(clang::FunctionDecl const*, clang::ConstraintSatisfaction&, clang::SourceLocation, bool) (/opt/compiler-explorer/clang-assertions-17.0.1/bin/clang+++0x60993d3)
#23 0x00000000066cbf54 clang::Sema::AddMethodCandidate(clang::CXXMethodDecl*, clang::DeclAccessPair, clang::CXXRecordDecl*, clang::QualType, clang::Expr::Classification, llvm::ArrayRef<clang::Expr*>, clang::OverloadCandidateSet&, bool, bool, llvm::MutableArrayRef<clang::ImplicitConversionSequence>, clang::OverloadCandidateParamOrder) (/opt/compiler-explorer/clang-assertions-17.0.1/bin/clang+++0x66cbf54)
#24 0x00000000066cd3eb clang::Sema::AddMethodCandidate(clang::DeclAccessPair, clang::QualType, clang::Expr::Classification, llvm::ArrayRef<clang::Expr*>, clang::OverloadCandidateSet&, bool, clang::OverloadCandidateParamOrder) (/opt/compiler-explorer/clang-assertions-17.0.1/bin/clang+++0x66cd3eb)
#25 0x00000000066e7d3b clang::Sema::BuildCallToObjectOfClassType(clang::Scope*, clang::Expr*, clang::SourceLocation, llvm::MutableArrayRef<clang::Expr*>, clang::SourceLocation) (/opt/compiler-explorer/clang-assertions-17.0.1/bin/clang+++0x66e7d3b)
#26 0x000000000638eed8 clang::Sema::BuildCallExpr(clang::Scope*, clang::Expr*, clang::SourceLocation, llvm::MutableArrayRef<clang::Expr*>, clang::SourceLocation, clang::Expr*, bool, bool) (/opt/compiler-explorer/clang-assertions-17.0.1/bin/clang+++0x638eed8)
#27 0x0000000006390d3c clang::Sema::ActOnCallExpr(clang::Scope*, clang::Expr*, clang::SourceLocation, llvm::MutableArrayRef<clang::Expr*>, clang::SourceLocation, clang::Expr*) (/opt/compiler-explorer/clang-assertions-17.0.1/bin/clang+++0x6390d3c)
#28 0x0000000005e585c0 clang::Parser::ParsePostfixExpressionSuffix(clang::ActionResult<clang::Expr*, true>) (/opt/compiler-explorer/clang-assertions-17.0.1/bin/clang+++0x5e585c0)
#29 0x0000000005e50751 clang::Parser::ParseCastExpression(clang::Parser::CastParseKind, bool, bool&, clang::Parser::TypeCastState, bool, bool*) (/opt/compiler-explorer/clang-assertions-17.0.1/bin/clang+++0x5e50751)
#30 0x0000000005e5389a clang::Parser::ParseCastExpression(clang::Parser::CastParseKind, bool, clang::Parser::TypeCastState, bool, bool*) (/opt/compiler-explorer/clang-assertions-17.0.1/bin/clang+++0x5e5389a)
#31 0x0000000005e53a39 clang::Parser::ParseAssignmentExpression(clang::Parser::TypeCastState) (/opt/compiler-explorer/clang-assertions-17.0.1/bin/clang+++0x5e53a39)
#32 0x0000000005e1502d clang::Parser::ParseDeclarationAfterDeclaratorAndAttributes(clang::Declarator&, clang::Parser::ParsedTemplateInfo const&, clang::Parser::ForRangeInit*) (/opt/compiler-explorer/clang-assertions-17.0.1/bin/clang+++0x5e1502d)
#33 0x0000000005e21f40 clang::Parser::ParseDeclGroup(clang::ParsingDeclSpec&, clang::DeclaratorContext, clang::ParsedAttributes&, clang::SourceLocation*, clang::Parser::ForRangeInit*) (/opt/compiler-explorer/clang-assertions-17.0.1/bin/clang+++0x5e21f40)
#34 0x0000000005defc4a clang::Parser::ParseDeclOrFunctionDefInternal(clang::ParsedAttributes&, clang::ParsedAttributes&, clang::ParsingDeclSpec&, clang::AccessSpecifier) (/opt/compiler-explorer/clang-assertions-17.0.1/bin/clang+++0x5defc4a)
#35 0x0000000005df04df clang::Parser::ParseDeclarationOrFunctionDefinition(clang::ParsedAttributes&, clang::ParsedAttributes&, clang::ParsingDeclSpec*, clang::AccessSpecifier) (.part.0) Parser.cpp:0:0
#36 0x0000000005df6b51 clang::Parser::ParseExternalDeclaration(clang::ParsedAttributes&, clang::ParsedAttributes&, clang::ParsingDeclSpec*) (/opt/compiler-explorer/clang-assertions-17.0.1/bin/clang+++0x5df6b51)
#37 0x0000000005df7452 clang::Parser::ParseTopLevelDecl(clang::OpaquePtr<clang::DeclGroupRef>&, clang::Sema::ModuleImportState&) (/opt/compiler-explorer/clang-assertions-17.0.1/bin/clang+++0x5df7452)
#38 0x0000000005df78a0 clang::Parser::ParseFirstTopLevelDecl(clang::OpaquePtr<clang::DeclGroupRef>&, clang::Sema::ModuleImportState&) (/opt/compiler-explorer/clang-assertions-17.0.1/bin/clang+++0x5df78a0)
#39 0x0000000005deb732 clang::ParseAST(clang::Sema&, bool, bool) (/opt/compiler-explorer/clang-assertions-17.0.1/bin/clang+++0x5deb732)
#40 0x0000000004939258 clang::CodeGenAction::ExecuteAction() (/opt/compiler-explorer/clang-assertions-17.0.1/bin/clang+++0x4939258)
#41 0x00000000041a1c09 clang::FrontendAction::Execute() (/opt/compiler-explorer/clang-assertions-17.0.1/bin/clang+++0x41a1c09)
#42 0x00000000041278ce clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) (/opt/compiler-explorer/clang-assertions-17.0.1/bin/clang+++0x41278ce)
#43 0x0000000004281de6 clang::ExecuteCompilerInvocation(clang::CompilerInstance*) (/opt/compiler-explorer/clang-assertions-17.0.1/bin/clang+++0x4281de6)
#44 0x0000000000bc67eb cc1_main(llvm::ArrayRef<char const*>, char const*, void*) (/opt/compiler-explorer/clang-assertions-17.0.1/bin/clang+++0xbc67eb)
#45 0x0000000000bbefaa ExecuteCC1Tool(llvm::SmallVectorImpl<char const*>&, llvm::ToolContext const&) driver.cpp:0:0
#46 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
#47 0x0000000003632dc4 llvm::CrashRecoveryContext::RunSafely(llvm::function_ref<void ()>) (/opt/compiler-explorer/clang-assertions-17.0.1/bin/clang+++0x3632dc4)
#48 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
#49 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)
#50 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)
#51 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)
#52 0x0000000000bc4a87 clang_main(int, char**, llvm::ToolContext const&) (/opt/compiler-explorer/clang-assertions-17.0.1/bin/clang+++0xbc4a87)
#53 0x0000000000abef61 main (/opt/compiler-explorer/clang-assertions-17.0.1/bin/clang+++0xabef61)
#54 0x00007fc5d5629d90 (/lib/x86_64-linux-gnu/libc.so.6+0x29d90)
#55 0x00007fc5d5629e40 __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x29e40)
#56 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

[Endilll]

However, a different reduction is still crashing in post-18 trunk: https://godbolt.org/z/MP45d35bj
Reduced by me and C-Reduce:

template <class _ImplFn>
struct __basic_sender {
   __basic_sender(_ImplFn);
};

auto a = 
  __basic_sender {
    [](auto... __captures) {
      return []() requires requires { 0(__captures...); } {};
    }()
  }

Backtrace:

clang++: /root/llvm-project/clang/lib/Sema/SemaTemplateInstantiate.cpp:4272: llvm::PointerUnion<clang::Decl*, llvm::SmallVector<clang::VarDecl*, 4>*>* clang::LocalInstantiationScope::findInstantiationOf(const clang::Decl*): Assertion `isa<LabelDecl>(D) && "declaration not instantiated in this scope"' 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 -mllvm --x86-asm-syntax=intel -S --gcc-toolchain=/opt/compiler-explorer/gcc-snapshot -fcolor-diagnostics -fno-crash-diagnostics -std=c++20 <source>
1.	<eof> parser at end of file
 #0 0x000000000388a128 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x388a128)
 #1 0x0000000003887e0c llvm::sys::CleanupOnSignal(unsigned long) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3887e0c)
 #2 0x00000000037d02e8 CrashRecoverySignalHandler(int) CrashRecoveryContext.cpp:0:0
 #3 0x00007f628b042520 (/lib/x86_64-linux-gnu/libc.so.6+0x42520)
 #4 0x00007f628b0969fc pthread_kill (/lib/x86_64-linux-gnu/libc.so.6+0x969fc)
 #5 0x00007f628b042476 gsignal (/lib/x86_64-linux-gnu/libc.so.6+0x42476)
 #6 0x00007f628b0287f3 abort (/lib/x86_64-linux-gnu/libc.so.6+0x287f3)
 #7 0x00007f628b02871b (/lib/x86_64-linux-gnu/libc.so.6+0x2871b)
 #8 0x00007f628b039e96 (/lib/x86_64-linux-gnu/libc.so.6+0x39e96)
 #9 0x0000000006bfc5ac clang::LocalInstantiationScope::findInstantiationOf(clang::Decl const*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6bfc5ac)
#10 0x0000000006ca93a9 clang::Sema::CheckParameterPacksForExpansion(clang::SourceLocation, clang::SourceRange, llvm::ArrayRef<std::pair<llvm::PointerUnion<clang::TemplateTypeParmType const*, clang::NamedDecl*>, clang::SourceLocation>>, clang::MultiLevelTemplateArgumentList const&, bool&, bool&, std::optional<unsigned int>&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6ca93a9)
#11 0x0000000006c054fd clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformExprs(clang::Expr* const*, unsigned int, bool, llvm::SmallVectorImpl<clang::Expr*>&, bool*) SemaTemplateInstantiate.cpp:0:0
#12 0x0000000006c0fa21 clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformCallExpr(clang::CallExpr*) SemaTemplateInstantiate.cpp:0:0
#13 0x0000000006c03d28 clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformExpr(clang::Expr*) SemaTemplateInstantiate.cpp:0:0
#14 0x0000000006c2f076 clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformRequiresExpr(clang::RequiresExpr*) SemaTemplateInstantiate.cpp:0:0
#15 0x0000000006c30c5e (anonymous namespace)::TemplateInstantiator::TransformRequiresExpr(clang::RequiresExpr*) SemaTemplateInstantiate.cpp:0:0
#16 0x0000000006c04201 clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformExpr(clang::Expr*) SemaTemplateInstantiate.cpp:0:0
#17 0x0000000006c39ac4 clang::Sema::SubstConstraintExpr(clang::Expr*, clang::MultiLevelTemplateArgumentList const&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6c39ac4)
#18 0x0000000006389670 calculateConstraintSatisfaction(clang::Sema&, clang::NamedDecl const*, clang::SourceLocation, clang::MultiLevelTemplateArgumentList const&, clang::Expr const*, clang::ConstraintSatisfaction&)::'lambda'(clang::Expr const*)::operator()(clang::Expr const*) const SemaConcept.cpp:0:0
#19 0x000000000638ad5b 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
#20 0x000000000638b572 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
#21 0x000000000638bbaa 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+++0x638bbaa)
#22 0x000000000638d6d0 clang::Sema::CheckFunctionConstraints(clang::FunctionDecl const*, clang::ConstraintSatisfaction&, clang::SourceLocation, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x638d6d0)
#23 0x000000000638d062 clang::Sema::CheckFunctionConstraints(clang::FunctionDecl const*, clang::ConstraintSatisfaction&, clang::SourceLocation, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x638d062)
#24 0x00000000069d5bfc clang::Sema::AddConversionCandidate(clang::CXXConversionDecl*, clang::DeclAccessPair, clang::CXXRecordDecl*, clang::Expr*, clang::QualType, clang::OverloadCandidateSet&, bool, bool, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x69d5bfc)
#25 0x00000000069dd61c IsUserDefinedConversion(clang::Sema&, clang::Expr*, clang::QualType, clang::UserDefinedConversionSequence&, clang::OverloadCandidateSet&, clang::Sema::AllowedExplicit, bool) SemaOverload.cpp:0:0
#26 0x00000000069de2a0 TryUserDefinedConversion(clang::Sema&, clang::Expr*, clang::QualType, bool, clang::Sema::AllowedExplicit, bool, bool, bool, bool) (.constprop.0) SemaOverload.cpp:0:0
#27 0x00000000069de854 TryImplicitConversion(clang::Sema&, clang::Expr*, clang::QualType, bool, clang::Sema::AllowedExplicit, bool, bool, bool, bool) SemaOverload.cpp:0:0
#28 0x00000000069d7ba7 TryReferenceInit(clang::Sema&, clang::Expr*, clang::QualType, clang::SourceLocation, bool, bool) SemaOverload.cpp:0:0
#29 0x00000000069d91bf TryCopyInitialization(clang::Sema&, clang::Expr*, clang::QualType, bool, bool, bool, bool) SemaOverload.cpp:0:0
#30 0x00000000069dbd46 clang::Sema::AddOverloadCandidate(clang::FunctionDecl*, clang::DeclAccessPair, llvm::ArrayRef<clang::Expr*>, clang::OverloadCandidateSet&, bool, bool, bool, bool, clang::CallExpr::ADLCallKind, llvm::MutableArrayRef<clang::ImplicitConversionSequence>, clang::OverloadCandidateParamOrder, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x69dbd46)
#31 0x0000000006825000 ResolveConstructorOverload(clang::Sema&, clang::SourceLocation, llvm::MutableArrayRef<clang::Expr*>, clang::OverloadCandidateSet&, clang::QualType, clang::DeclContextLookupResult, clang::OverloadCandidate*&, bool, bool, bool, bool, bool, bool) SemaInit.cpp:0:0
#32 0x00000000068366d2 TryConstructorInitialization(clang::Sema&, clang::InitializedEntity const&, clang::InitializationKind const&, llvm::MutableArrayRef<clang::Expr*>, clang::QualType, clang::QualType, clang::InitializationSequence&, bool, bool) SemaInit.cpp:0:0
#33 0x0000000006840843 TryListInitialization(clang::Sema&, clang::InitializedEntity const&, clang::InitializationKind const&, clang::InitListExpr*, clang::InitializationSequence&, bool) SemaInit.cpp:0:0
#34 0x000000000683de7b 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+++0x683de7b)
#35 0x0000000006755be1 clang::Sema::BuildCXXTypeConstructExpr(clang::TypeSourceInfo*, clang::SourceLocation, llvm::MutableArrayRef<clang::Expr*>, clang::SourceLocation, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6755be1)
#36 0x00000000067e22ed clang::Sema::ActOnCXXTypeConstructExpr(clang::OpaquePtr<clang::QualType>, clang::SourceLocation, llvm::MutableArrayRef<clang::Expr*>, clang::SourceLocation, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x67e22ed)
#37 0x0000000006158d06 clang::Parser::ParseCXXTypeConstructExpression(clang::DeclSpec const&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6158d06)
#38 0x000000000613b6b5 clang::Parser::ParseCastExpression(clang::Parser::CastParseKind, bool, bool&, clang::Parser::TypeCastState, bool, bool*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x613b6b5)
#39 0x000000000613a24a clang::Parser::ParseCastExpression(clang::Parser::CastParseKind, bool, bool&, clang::Parser::TypeCastState, bool, bool*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x613a24a)
#40 0x000000000613d28a clang::Parser::ParseCastExpression(clang::Parser::CastParseKind, bool, clang::Parser::TypeCastState, bool, bool*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x613d28a)
#41 0x000000000613d429 clang::Parser::ParseAssignmentExpression(clang::Parser::TypeCastState) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x613d429)
#42 0x00000000060faebd clang::Parser::ParseDeclarationAfterDeclaratorAndAttributes(clang::Declarator&, clang::Parser::ParsedTemplateInfo const&, clang::Parser::ForRangeInit*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x60faebd)
#43 0x0000000006109e7a clang::Parser::ParseDeclGroup(clang::ParsingDeclSpec&, clang::DeclaratorContext, clang::ParsedAttributes&, clang::Parser::ParsedTemplateInfo&, clang::SourceLocation*, clang::Parser::ForRangeInit*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6109e7a)
#44 0x00000000060c7c1e clang::Parser::ParseDeclOrFunctionDefInternal(clang::ParsedAttributes&, clang::ParsedAttributes&, clang::ParsingDeclSpec&, clang::AccessSpecifier) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x60c7c1e)
#45 0x00000000060c83f1 clang::Parser::ParseDeclarationOrFunctionDefinition(clang::ParsedAttributes&, clang::ParsedAttributes&, clang::ParsingDeclSpec*, clang::AccessSpecifier) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x60c83f1)
#46 0x00000000060cf6b6 clang::Parser::ParseExternalDeclaration(clang::ParsedAttributes&, clang::ParsedAttributes&, clang::ParsingDeclSpec*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x60cf6b6)
#47 0x00000000060d055d clang::Parser::ParseTopLevelDecl(clang::OpaquePtr<clang::DeclGroupRef>&, clang::Sema::ModuleImportState&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x60d055d)
#48 0x00000000060c341a clang::ParseAST(clang::Sema&, bool, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x60c341a)
#49 0x0000000004118c48 clang::CodeGenAction::ExecuteAction() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4118c48)
#50 0x0000000004389719 clang::FrontendAction::Execute() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4389719)
#51 0x00000000043081ee clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x43081ee)
#52 0x000000000446940e clang::ExecuteCompilerInvocation(clang::CompilerInstance*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x446940e)
#53 0x0000000000c126b6 cc1_main(llvm::ArrayRef<char const*>, char const*, void*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xc126b6)
#54 0x0000000000c09eca ExecuteCC1Tool(llvm::SmallVectorImpl<char const*>&, llvm::ToolContext const&) driver.cpp:0:0
#55 0x000000000415a1f9 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
#56 0x00000000037d0794 llvm::CrashRecoveryContext::RunSafely(llvm::function_ref<void ()>) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x37d0794)
#57 0x000000000415a7ef 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
#58 0x00000000041224e5 clang::driver::Compilation::ExecuteCommand(clang::driver::Command const&, clang::driver::Command const*&, bool) const (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x41224e5)
#59 0x0000000004122f4d 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+++0x4122f4d)
#60 0x000000000412ae85 clang::driver::Driver::ExecuteCompilation(clang::driver::Compilation&, llvm::SmallVectorImpl<std::pair<int, clang::driver::Command const*>>&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x412ae85)
#61 0x0000000000c0fa3c clang_main(int, char**, llvm::ToolContext const&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xc0fa3c)
#62 0x0000000000b06be4 main (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xb06be4)
#63 0x00007f628b029d90 (/lib/x86_64-linux-gnu/libc.so.6+0x29d90)
#64 0x00007f628b029e40 __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x29e40)
#65 0x0000000000c099ae _start (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xc099ae)
clang++: error: clang frontend command failed with exit code 134 (use -v to see invocation)
Compiler returned: 134