`FunctionDecl::getParamDecl`: Assertion `i < getNumParams() && "Illegal param #"` failed

[Endilll]

While reducing #77250, I stumbled upon the following assertion (https://godbolt.org/z/s77h5PEKv):

auto __make_tuple = []< class _Tag, class... _Captures >(_Tag, _Captures...) {
  return []< class _Fun >( _Fun) -> void
           requires requires { 0; }
  {};
};

template < class, class... _As >
using __call_result_t = decltype(__make_tuple(0)(_As{}...));

using T = __call_result_t< int, int >;

Clang 20.0 crash:

clang++: /root/llvm-project/clang/include/clang/AST/Decl.h:2674:
clang::ParmVarDecl* clang::FunctionDecl::getParamDecl(unsigned int):
Assertion `i < getNumParams() && "Illegal param #"' 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 -fno-verbose-asm -S --gcc-toolchain=/opt/compiler-explorer/gcc-snapshot -fcolor-diagnostics -fno-crash-diagnostics -std=c++20 <source>
1.	<source>:10:11: at annotation token
 #0 0x0000000003abe608 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3abe608)
 #1 0x0000000003abc2fc llvm::sys::CleanupOnSignal(unsigned long) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3abc2fc)
 #2 0x0000000003a052f8 CrashRecoverySignalHandler(int) CrashRecoveryContext.cpp:0:0
 #3 0x000075b56c842520 (/lib/x86_64-linux-gnu/libc.so.6+0x42520)
 #4 0x000075b56c8969fc pthread_kill (/lib/x86_64-linux-gnu/libc.so.6+0x969fc)
 #5 0x000075b56c842476 gsignal (/lib/x86_64-linux-gnu/libc.so.6+0x42476)
 #6 0x000075b56c8287f3 abort (/lib/x86_64-linux-gnu/libc.so.6+0x287f3)
 #7 0x000075b56c82871b (/lib/x86_64-linux-gnu/libc.so.6+0x2871b)
 #8 0x000075b56c839e96 (/lib/x86_64-linux-gnu/libc.so.6+0x39e96)
 #9 0x00000000071aeee9 clang::Sema::addInstantiatedParametersToScope(clang::FunctionDecl*, clang::FunctionDecl const*, clang::LocalInstantiationScope&, clang::MultiLevelTemplateArgumentList const&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x71aeee9)
#10 0x0000000006ce50b6 clang::Sema::LambdaScopeForCallOperatorInstantiationRAII::LambdaScopeForCallOperatorInstantiationRAII(clang::Sema&, clang::FunctionDecl*, clang::MultiLevelTemplateArgumentList, clang::LocalInstantiationScope&, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6ce50b6)
#11 0x00000000067bd4ae clang::Sema::CheckInstantiatedFunctionTemplateConstraints(clang::SourceLocation, clang::FunctionDecl*, llvm::ArrayRef<clang::TemplateArgument>, clang::ConstraintSatisfaction&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x67bd4ae)
#12 0x00000000070a6702 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 0x00000000070a710a 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 0x0000000006640431 clang::Sema::runWithSufficientStackSpace(clang::SourceLocation, llvm::function_ref<void ()>) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6640431)
#15 0x00000000070b2212 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-assertions-trunk/bin/clang+++0x70b2212)
#16 0x0000000006ec639d 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 0x0000000006ec6d21 clang::Sema::AddMethodCandidate(clang::DeclAccessPair, clang::QualType, clang::Expr::Classification, llvm::ArrayRef<clang::Expr*>, clang::OverloadCandidateSet&, bool, clang::OverloadCandidateParamOrder) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6ec6d21)
#18 0x0000000006ed72e2 clang::Sema::BuildCallToObjectOfClassType(clang::Scope*, clang::Expr*, clang::SourceLocation, llvm::MutableArrayRef<clang::Expr*>, clang::SourceLocation) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6ed72e2)
#19 0x0000000006ac4ccd clang::Sema::BuildCallExpr(clang::Scope*, clang::Expr*, clang::SourceLocation, llvm::MutableArrayRef<clang::Expr*>, clang::SourceLocation, clang::Expr*, bool, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6ac4ccd)
#20 0x0000000006ac6cec clang::Sema::ActOnCallExpr(clang::Scope*, clang::Expr*, clang::SourceLocation, llvm::MutableArrayRef<clang::Expr*>, clang::SourceLocation, clang::Expr*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6ac6cec)
#21 0x0000000007169920 clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformCallExpr(clang::CallExpr*) SemaTemplateInstantiate.cpp:0:0
#22 0x000000000715d445 clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformExpr(clang::Expr*) SemaTemplateInstantiate.cpp:0:0
#23 0x000000000716e047 clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformType(clang::TypeLocBuilder&, clang::TypeLoc) SemaTemplateInstantiate.cpp:0:0
#24 0x00000000071749fa clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformType(clang::TypeSourceInfo*) SemaTemplateInstantiate.cpp:0:0
#25 0x0000000007174b1c clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformType(clang::QualType) SemaTemplateInstantiate.cpp:0:0
#26 0x00000000071767db clang::Sema::SubstType(clang::QualType, clang::MultiLevelTemplateArgumentList const&, clang::SourceLocation, clang::DeclarationName) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x71767db)
#27 0x0000000006fad6e6 clang::Sema::CheckTemplateIdType(clang::TemplateName, clang::SourceLocation, clang::TemplateArgumentListInfo&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6fad6e6)
#28 0x0000000006fafaa7 clang::Sema::ActOnTemplateIdType(clang::Scope*, clang::CXXScopeSpec&, clang::SourceLocation, clang::OpaquePtr<clang::TemplateName>, clang::IdentifierInfo const*, clang::SourceLocation, clang::SourceLocation, llvm::MutableArrayRef<clang::ParsedTemplateArgument>, clang::SourceLocation, bool, bool, clang::ImplicitTypenameContext) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6fafaa7)
#29 0x00000000065d9e4b clang::Parser::AnnotateTemplateIdTokenAsType(clang::CXXScopeSpec&, clang::ImplicitTypenameContext, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x65d9e4b)
#30 0x0000000006515492 clang::Parser::ParseDeclarationSpecifiers(clang::DeclSpec&, clang::Parser::ParsedTemplateInfo&, clang::AccessSpecifier, clang::Parser::DeclSpecContext, clang::Parser::LateParsedAttrList*, clang::ImplicitTypenameContext) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6515492)
#31 0x0000000006518212 clang::Parser::ParseSpecifierQualifierList(clang::DeclSpec&, clang::ImplicitTypenameContext, clang::AccessSpecifier, clang::Parser::DeclSpecContext) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6518212)
#32 0x000000000651f1f0 clang::Parser::ParseTypeName(clang::SourceRange*, clang::DeclaratorContext, clang::AccessSpecifier, clang::Decl**, clang::ParsedAttributes*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x651f1f0)
#33 0x000000000652cb59 clang::Parser::ParseAliasDeclarationAfterDeclarator(clang::Parser::ParsedTemplateInfo const&, clang::SourceLocation, clang::Parser::UsingDeclarator&, clang::SourceLocation&, clang::AccessSpecifier, clang::ParsedAttributes&, clang::Decl**) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x652cb59)
#34 0x000000000653664e clang::Parser::ParseUsingDeclaration(clang::DeclaratorContext, clang::Parser::ParsedTemplateInfo const&, clang::SourceLocation, clang::SourceLocation&, clang::ParsedAttributes&, clang::AccessSpecifier) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x653664e)
#35 0x00000000065373a5 clang::Parser::ParseUsingDirectiveOrDeclaration(clang::DeclaratorContext, clang::Parser::ParsedTemplateInfo const&, clang::SourceLocation&, clang::ParsedAttributes&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x65373a5)
#36 0x000000000651bbdf clang::Parser::ParseDeclaration(clang::DeclaratorContext, clang::SourceLocation&, clang::ParsedAttributes&, clang::ParsedAttributes&, clang::SourceLocation*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x651bbdf)
#37 0x00000000064d89e1 clang::Parser::ParseExternalDeclaration(clang::ParsedAttributes&, clang::ParsedAttributes&, clang::ParsingDeclSpec*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x64d89e1)
#38 0x00000000064d986d clang::Parser::ParseTopLevelDecl(clang::OpaquePtr<clang::DeclGroupRef>&, clang::Sema::ModuleImportState&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x64d986d)
#39 0x00000000064ccd3a clang::ParseAST(clang::Sema&, bool, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x64ccd3a)
#40 0x00000000043d11d8 clang::CodeGenAction::ExecuteAction() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x43d11d8)
#41 0x000000000465d109 clang::FrontendAction::Execute() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x465d109)
#42 0x00000000045e170e clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x45e170e)
#43 0x00000000047465de clang::ExecuteCompilerInvocation(clang::CompilerInstance*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x47465de)
#44 0x0000000000c9299f cc1_main(llvm::ArrayRef<char const*>, char const*, void*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xc9299f)
#45 0x0000000000c8bb2a ExecuteCC1Tool(llvm::SmallVectorImpl<char const*>&, llvm::ToolContext const&) driver.cpp:0:0
#46 0x0000000004414819 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 0x0000000003a057a4 llvm::CrashRecoveryContext::RunSafely(llvm::function_ref<void ()>) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3a057a4)
#48 0x0000000004414e0f 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 0x00000000043da9d5 clang::driver::Compilation::ExecuteCommand(clang::driver::Command const&, clang::driver::Command const*&, bool) const (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x43da9d5)
#50 0x00000000043db43d 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+++0x43db43d)
#51 0x00000000043e3055 clang::driver::Driver::ExecuteCompilation(clang::driver::Compilation&, llvm::SmallVectorImpl<std::pair<int, clang::driver::Command const*>>&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x43e3055)
#52 0x0000000000c8fcd5 clang_main(int, char**, llvm::ToolContext const&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xc8fcd5)
#53 0x0000000000b63ba4 main (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xb63ba4)
#54 0x000075b56c829d90 (/lib/x86_64-linux-gnu/libc.so.6+0x29d90)
#55 0x000075b56c829e40 __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x29e40)
#56 0x0000000000c8b5de _start (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xc8b5de)
clang++: error: clang frontend command failed with exit code 134 (use -v to see invocation)
Compiler returned: 134

[llvmbot]

@llvm/issue-subscribers-clang-frontend

Author: Vlad Serebrennikov (Endilll)

While reducing #77250, I stumbled upon the following assertion (https://godbolt.org/z/s77h5PEKv): ```cpp auto __make_tuple = []< class _Tag, class... _Captures >(_Tag, _Captures...) { return []< class _Fun >( _Fun) -> void requires requires { 0; } {}; };

template < class, class... _As >
using __call_result_t = decltype(__make_tuple(0)(_As{}...));

using T = __call_result_t< int, int >;

Clang 20.0 crash:

clang++: /root/llvm-project/clang/include/clang/AST/Decl.h:2674: clang::ParmVarDecl* clang::FunctionDecl::getParamDecl(unsigned int): Assertion `i < getNumParams() && "Illegal param #"' 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 -fno-verbose-asm -S --gcc-toolchain=/opt/compiler-explorer/gcc-snapshot -fcolor-diagnostics -fno-crash-diagnostics -std=c++20 <source>

1. <source>:10:11: at annotation token
   #0 0x0000000003abe608 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3abe608)
   #1 0x0000000003abc2fc llvm::sys::CleanupOnSignal(unsigned long) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3abc2fc)
   #2 0x0000000003a052f8 CrashRecoverySignalHandler(int) CrashRecoveryContext.cpp:0:0
   #3 0x000075b56c842520 (/lib/x86_64-linux-gnu/libc.so.6+0x42520)
   #4 0x000075b56c8969fc pthread_kill (/lib/x86_64-linux-gnu/libc.so.6+0x969fc)
   #5 0x000075b56c842476 gsignal (/lib/x86_64-linux-gnu/libc.so.6+0x42476)
   #6 0x000075b56c8287f3 abort (/lib/x86_64-linux-gnu/libc.so.6+0x287f3)
   #7 0x000075b56c82871b (/lib/x86_64-linux-gnu/libc.so.6+0x2871b)
   #8 0x000075b56c839e96 (/lib/x86_64-linux-gnu/libc.so.6+0x39e96)
   #9 0x00000000071aeee9 clang::Sema::addInstantiatedParametersToScope(clang::FunctionDecl*, clang::FunctionDecl const*, clang::LocalInstantiationScope&, clang::MultiLevelTemplateArgumentList const&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x71aeee9)
   #10 0x0000000006ce50b6 clang::Sema::LambdaScopeForCallOperatorInstantiationRAII::LambdaScopeForCallOperatorInstantiationRAII(clang::Sema&, clang::FunctionDecl*, clang::MultiLevelTemplateArgumentList, clang::LocalInstantiationScope&, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6ce50b6)
   #11 0x00000000067bd4ae clang::Sema::CheckInstantiatedFunctionTemplateConstraints(clang::SourceLocation, clang::FunctionDecl*, llvm::ArrayRef<clang::TemplateArgument>, clang::ConstraintSatisfaction&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x67bd4ae)
   #12 0x00000000070a6702 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 0x00000000070a710a 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 0x0000000006640431 clang::Sema::runWithSufficientStackSpace(clang::SourceLocation, llvm::function_ref<void ()>) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6640431)
   #15 0x00000000070b2212 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-assertions-trunk/bin/clang+++0x70b2212)
   #16 0x0000000006ec639d 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 0x0000000006ec6d21 clang::Sema::AddMethodCandidate(clang::DeclAccessPair, clang::QualType, clang::Expr::Classification, llvm::ArrayRef<clang::Expr*>, clang::OverloadCandidateSet&, bool, clang::OverloadCandidateParamOrder) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6ec6d21)
   #18 0x0000000006ed72e2 clang::Sema::BuildCallToObjectOfClassType(clang::Scope*, clang::Expr*, clang::SourceLocation, llvm::MutableArrayRef<clang::Expr*>, clang::SourceLocation) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6ed72e2)
   #19 0x0000000006ac4ccd clang::Sema::BuildCallExpr(clang::Scope*, clang::Expr*, clang::SourceLocation, llvm::MutableArrayRef<clang::Expr*>, clang::SourceLocation, clang::Expr*, bool, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6ac4ccd)
   #20 0x0000000006ac6cec clang::Sema::ActOnCallExpr(clang::Scope*, clang::Expr*, clang::SourceLocation, llvm::MutableArrayRef<clang::Expr*>, clang::SourceLocation, clang::Expr*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6ac6cec)
   #21 0x0000000007169920 clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformCallExpr(clang::CallExpr*) SemaTemplateInstantiate.cpp:0:0
   #22 0x000000000715d445 clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformExpr(clang::Expr*) SemaTemplateInstantiate.cpp:0:0
   #23 0x000000000716e047 clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformType(clang::TypeLocBuilder&, clang::TypeLoc) SemaTemplateInstantiate.cpp:0:0
   #24 0x00000000071749fa clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformType(clang::TypeSourceInfo*) SemaTemplateInstantiate.cpp:0:0
   #25 0x0000000007174b1c clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformType(clang::QualType) SemaTemplateInstantiate.cpp:0:0
   #26 0x00000000071767db clang::Sema::SubstType(clang::QualType, clang::MultiLevelTemplateArgumentList const&, clang::SourceLocation, clang::DeclarationName) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x71767db)
   #27 0x0000000006fad6e6 clang::Sema::CheckTemplateIdType(clang::TemplateName, clang::SourceLocation, clang::TemplateArgumentListInfo&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6fad6e6)
   #28 0x0000000006fafaa7 clang::Sema::ActOnTemplateIdType(clang::Scope*, clang::CXXScopeSpec&, clang::SourceLocation, clang::OpaquePtr<clang::TemplateName>, clang::IdentifierInfo const*, clang::SourceLocation, clang::SourceLocation, llvm::MutableArrayRef<clang::ParsedTemplateArgument>, clang::SourceLocation, bool, bool, clang::ImplicitTypenameContext) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6fafaa7)
   #29 0x00000000065d9e4b clang::Parser::AnnotateTemplateIdTokenAsType(clang::CXXScopeSpec&, clang::ImplicitTypenameContext, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x65d9e4b)
   #30 0x0000000006515492 clang::Parser::ParseDeclarationSpecifiers(clang::DeclSpec&, clang::Parser::ParsedTemplateInfo&, clang::AccessSpecifier, clang::Parser::DeclSpecContext, clang::Parser::LateParsedAttrList*, clang::ImplicitTypenameContext) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6515492)
   #31 0x0000000006518212 clang::Parser::ParseSpecifierQualifierList(clang::DeclSpec&, clang::ImplicitTypenameContext, clang::AccessSpecifier, clang::Parser::DeclSpecContext) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6518212)
   #32 0x000000000651f1f0 clang::Parser::ParseTypeName(clang::SourceRange*, clang::DeclaratorContext, clang::AccessSpecifier, clang::Decl**, clang::ParsedAttributes*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x651f1f0)
   #33 0x000000000652cb59 clang::Parser::ParseAliasDeclarationAfterDeclarator(clang::Parser::ParsedTemplateInfo const&, clang::SourceLocation, clang::Parser::UsingDeclarator&, clang::SourceLocation&, clang::AccessSpecifier, clang::ParsedAttributes&, clang::Decl**) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x652cb59)
   #34 0x000000000653664e clang::Parser::ParseUsingDeclaration(clang::DeclaratorContext, clang::Parser::ParsedTemplateInfo const&, clang::SourceLocation, clang::SourceLocation&, clang::ParsedAttributes&, clang::AccessSpecifier) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x653664e)
   #35 0x00000000065373a5 clang::Parser::ParseUsingDirectiveOrDeclaration(clang::DeclaratorContext, clang::Parser::ParsedTemplateInfo const&, clang::SourceLocation&, clang::ParsedAttributes&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x65373a5)
   #36 0x000000000651bbdf clang::Parser::ParseDeclaration(clang::DeclaratorContext, clang::SourceLocation&, clang::ParsedAttributes&, clang::ParsedAttributes&, clang::SourceLocation*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x651bbdf)
   #37 0x00000000064d89e1 clang::Parser::ParseExternalDeclaration(clang::ParsedAttributes&, clang::ParsedAttributes&, clang::ParsingDeclSpec*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x64d89e1)
   #38 0x00000000064d986d clang::Parser::ParseTopLevelDecl(clang::OpaquePtr<clang::DeclGroupRef>&, clang::Sema::ModuleImportState&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x64d986d)
   #39 0x00000000064ccd3a clang::ParseAST(clang::Sema&, bool, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x64ccd3a)
   #40 0x00000000043d11d8 clang::CodeGenAction::ExecuteAction() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x43d11d8)
   #41 0x000000000465d109 clang::FrontendAction::Execute() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x465d109)
   #42 0x00000000045e170e clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x45e170e)
   #43 0x00000000047465de clang::ExecuteCompilerInvocation(clang::CompilerInstance*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x47465de)
   #44 0x0000000000c9299f cc1_main(llvm::ArrayRef<char const*>, char const*, void*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xc9299f)
   #45 0x0000000000c8bb2a ExecuteCC1Tool(llvm::SmallVectorImpl<char const*>&, llvm::ToolContext const&) driver.cpp:0:0
   #46 0x0000000004414819 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 0x0000000003a057a4 llvm::CrashRecoveryContext::RunSafely(llvm::function_ref<void ()>) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3a057a4)
   #48 0x0000000004414e0f 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 0x00000000043da9d5 clang::driver::Compilation::ExecuteCommand(clang::driver::Command const&, clang::driver::Command const*&, bool) const (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x43da9d5)
   #50 0x00000000043db43d 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+++0x43db43d)
   #51 0x00000000043e3055 clang::driver::Driver::ExecuteCompilation(clang::driver::Compilation&, llvm::SmallVectorImpl<std::pair<int, clang::driver::Command const*>>&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x43e3055)
   #52 0x0000000000c8fcd5 clang_main(int, char**, llvm::ToolContext const&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xc8fcd5)
   #53 0x0000000000b63ba4 main (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xb63ba4)
   #54 0x000075b56c829d90 (/lib/x86_64-linux-gnu/libc.so.6+0x29d90)
   #55 0x000075b56c829e40 __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x29e40)
   #56 0x0000000000c8b5de _start (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xc8b5de)
   clang++: error: clang frontend command failed with exit code 134 (use -v to see invocation)
   Compiler returned: 134

</details>

[llvmbot]

@llvm/issue-subscribers-c-20

Author: Vlad Serebrennikov (Endilll)

While reducing #77250, I stumbled upon the following assertion (https://godbolt.org/z/s77h5PEKv): ```cpp auto __make_tuple = []< class _Tag, class... _Captures >(_Tag, _Captures...) { return []< class _Fun >( _Fun) -> void requires requires { 0; } {}; };

template < class, class... _As >
using __call_result_t = decltype(__make_tuple(0)(_As{}...));

using T = __call_result_t< int, int >;

Clang 20.0 crash:

clang++: /root/llvm-project/clang/include/clang/AST/Decl.h:2674: clang::ParmVarDecl* clang::FunctionDecl::getParamDecl(unsigned int): Assertion `i < getNumParams() && "Illegal param #"' 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 -fno-verbose-asm -S --gcc-toolchain=/opt/compiler-explorer/gcc-snapshot -fcolor-diagnostics -fno-crash-diagnostics -std=c++20 <source>

1. <source>:10:11: at annotation token
   #0 0x0000000003abe608 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3abe608)
   #1 0x0000000003abc2fc llvm::sys::CleanupOnSignal(unsigned long) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3abc2fc)
   #2 0x0000000003a052f8 CrashRecoverySignalHandler(int) CrashRecoveryContext.cpp:0:0
   #3 0x000075b56c842520 (/lib/x86_64-linux-gnu/libc.so.6+0x42520)
   #4 0x000075b56c8969fc pthread_kill (/lib/x86_64-linux-gnu/libc.so.6+0x969fc)
   #5 0x000075b56c842476 gsignal (/lib/x86_64-linux-gnu/libc.so.6+0x42476)
   #6 0x000075b56c8287f3 abort (/lib/x86_64-linux-gnu/libc.so.6+0x287f3)
   #7 0x000075b56c82871b (/lib/x86_64-linux-gnu/libc.so.6+0x2871b)
   #8 0x000075b56c839e96 (/lib/x86_64-linux-gnu/libc.so.6+0x39e96)
   #9 0x00000000071aeee9 clang::Sema::addInstantiatedParametersToScope(clang::FunctionDecl*, clang::FunctionDecl const*, clang::LocalInstantiationScope&, clang::MultiLevelTemplateArgumentList const&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x71aeee9)
   #10 0x0000000006ce50b6 clang::Sema::LambdaScopeForCallOperatorInstantiationRAII::LambdaScopeForCallOperatorInstantiationRAII(clang::Sema&, clang::FunctionDecl*, clang::MultiLevelTemplateArgumentList, clang::LocalInstantiationScope&, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6ce50b6)
   #11 0x00000000067bd4ae clang::Sema::CheckInstantiatedFunctionTemplateConstraints(clang::SourceLocation, clang::FunctionDecl*, llvm::ArrayRef<clang::TemplateArgument>, clang::ConstraintSatisfaction&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x67bd4ae)
   #12 0x00000000070a6702 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 0x00000000070a710a 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 0x0000000006640431 clang::Sema::runWithSufficientStackSpace(clang::SourceLocation, llvm::function_ref<void ()>) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6640431)
   #15 0x00000000070b2212 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-assertions-trunk/bin/clang+++0x70b2212)
   #16 0x0000000006ec639d 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 0x0000000006ec6d21 clang::Sema::AddMethodCandidate(clang::DeclAccessPair, clang::QualType, clang::Expr::Classification, llvm::ArrayRef<clang::Expr*>, clang::OverloadCandidateSet&, bool, clang::OverloadCandidateParamOrder) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6ec6d21)
   #18 0x0000000006ed72e2 clang::Sema::BuildCallToObjectOfClassType(clang::Scope*, clang::Expr*, clang::SourceLocation, llvm::MutableArrayRef<clang::Expr*>, clang::SourceLocation) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6ed72e2)
   #19 0x0000000006ac4ccd clang::Sema::BuildCallExpr(clang::Scope*, clang::Expr*, clang::SourceLocation, llvm::MutableArrayRef<clang::Expr*>, clang::SourceLocation, clang::Expr*, bool, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6ac4ccd)
   #20 0x0000000006ac6cec clang::Sema::ActOnCallExpr(clang::Scope*, clang::Expr*, clang::SourceLocation, llvm::MutableArrayRef<clang::Expr*>, clang::SourceLocation, clang::Expr*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6ac6cec)
   #21 0x0000000007169920 clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformCallExpr(clang::CallExpr*) SemaTemplateInstantiate.cpp:0:0
   #22 0x000000000715d445 clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformExpr(clang::Expr*) SemaTemplateInstantiate.cpp:0:0
   #23 0x000000000716e047 clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformType(clang::TypeLocBuilder&, clang::TypeLoc) SemaTemplateInstantiate.cpp:0:0
   #24 0x00000000071749fa clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformType(clang::TypeSourceInfo*) SemaTemplateInstantiate.cpp:0:0
   #25 0x0000000007174b1c clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformType(clang::QualType) SemaTemplateInstantiate.cpp:0:0
   #26 0x00000000071767db clang::Sema::SubstType(clang::QualType, clang::MultiLevelTemplateArgumentList const&, clang::SourceLocation, clang::DeclarationName) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x71767db)
   #27 0x0000000006fad6e6 clang::Sema::CheckTemplateIdType(clang::TemplateName, clang::SourceLocation, clang::TemplateArgumentListInfo&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6fad6e6)
   #28 0x0000000006fafaa7 clang::Sema::ActOnTemplateIdType(clang::Scope*, clang::CXXScopeSpec&, clang::SourceLocation, clang::OpaquePtr<clang::TemplateName>, clang::IdentifierInfo const*, clang::SourceLocation, clang::SourceLocation, llvm::MutableArrayRef<clang::ParsedTemplateArgument>, clang::SourceLocation, bool, bool, clang::ImplicitTypenameContext) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6fafaa7)
   #29 0x00000000065d9e4b clang::Parser::AnnotateTemplateIdTokenAsType(clang::CXXScopeSpec&, clang::ImplicitTypenameContext, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x65d9e4b)
   #30 0x0000000006515492 clang::Parser::ParseDeclarationSpecifiers(clang::DeclSpec&, clang::Parser::ParsedTemplateInfo&, clang::AccessSpecifier, clang::Parser::DeclSpecContext, clang::Parser::LateParsedAttrList*, clang::ImplicitTypenameContext) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6515492)
   #31 0x0000000006518212 clang::Parser::ParseSpecifierQualifierList(clang::DeclSpec&, clang::ImplicitTypenameContext, clang::AccessSpecifier, clang::Parser::DeclSpecContext) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6518212)
   #32 0x000000000651f1f0 clang::Parser::ParseTypeName(clang::SourceRange*, clang::DeclaratorContext, clang::AccessSpecifier, clang::Decl**, clang::ParsedAttributes*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x651f1f0)
   #33 0x000000000652cb59 clang::Parser::ParseAliasDeclarationAfterDeclarator(clang::Parser::ParsedTemplateInfo const&, clang::SourceLocation, clang::Parser::UsingDeclarator&, clang::SourceLocation&, clang::AccessSpecifier, clang::ParsedAttributes&, clang::Decl**) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x652cb59)
   #34 0x000000000653664e clang::Parser::ParseUsingDeclaration(clang::DeclaratorContext, clang::Parser::ParsedTemplateInfo const&, clang::SourceLocation, clang::SourceLocation&, clang::ParsedAttributes&, clang::AccessSpecifier) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x653664e)
   #35 0x00000000065373a5 clang::Parser::ParseUsingDirectiveOrDeclaration(clang::DeclaratorContext, clang::Parser::ParsedTemplateInfo const&, clang::SourceLocation&, clang::ParsedAttributes&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x65373a5)
   #36 0x000000000651bbdf clang::Parser::ParseDeclaration(clang::DeclaratorContext, clang::SourceLocation&, clang::ParsedAttributes&, clang::ParsedAttributes&, clang::SourceLocation*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x651bbdf)
   #37 0x00000000064d89e1 clang::Parser::ParseExternalDeclaration(clang::ParsedAttributes&, clang::ParsedAttributes&, clang::ParsingDeclSpec*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x64d89e1)
   #38 0x00000000064d986d clang::Parser::ParseTopLevelDecl(clang::OpaquePtr<clang::DeclGroupRef>&, clang::Sema::ModuleImportState&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x64d986d)
   #39 0x00000000064ccd3a clang::ParseAST(clang::Sema&, bool, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x64ccd3a)
   #40 0x00000000043d11d8 clang::CodeGenAction::ExecuteAction() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x43d11d8)
   #41 0x000000000465d109 clang::FrontendAction::Execute() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x465d109)
   #42 0x00000000045e170e clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x45e170e)
   #43 0x00000000047465de clang::ExecuteCompilerInvocation(clang::CompilerInstance*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x47465de)
   #44 0x0000000000c9299f cc1_main(llvm::ArrayRef<char const*>, char const*, void*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xc9299f)
   #45 0x0000000000c8bb2a ExecuteCC1Tool(llvm::SmallVectorImpl<char const*>&, llvm::ToolContext const&) driver.cpp:0:0
   #46 0x0000000004414819 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 0x0000000003a057a4 llvm::CrashRecoveryContext::RunSafely(llvm::function_ref<void ()>) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3a057a4)
   #48 0x0000000004414e0f 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 0x00000000043da9d5 clang::driver::Compilation::ExecuteCommand(clang::driver::Command const&, clang::driver::Command const*&, bool) const (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x43da9d5)
   #50 0x00000000043db43d 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+++0x43db43d)
   #51 0x00000000043e3055 clang::driver::Driver::ExecuteCompilation(clang::driver::Compilation&, llvm::SmallVectorImpl<std::pair<int, clang::driver::Command const*>>&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x43e3055)
   #52 0x0000000000c8fcd5 clang_main(int, char**, llvm::ToolContext const&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xc8fcd5)
   #53 0x0000000000b63ba4 main (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xb63ba4)
   #54 0x000075b56c829d90 (/lib/x86_64-linux-gnu/libc.so.6+0x29d90)
   #55 0x000075b56c829e40 __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x29e40)
   #56 0x0000000000c8b5de _start (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xc8b5de)
   clang++: error: clang frontend command failed with exit code 134 (use -v to see invocation)
   Compiler returned: 134

</details>

[shafik]

Looks like a regression from clang-18: https://godbolt.org/z/TWhdfzvc3

[Endilll]

Bisected to 843cc47 (#82310)
CC @zyn0217 as the author.

[cor3ntin]

@AaronBallman if there is an rc4, we should keep an eyes on this one

[zyn0217]

Sorry for replying late.
As I have explained on Discord, I have a follow-up patch #89934 for that flaw fix, and just now I tested locally and found it fixed this bug. However, since @mizvekov said he is going to have an ultimate solution for lambda context declarations that could supersede these two patches as well as the lambda dependencies, I'm not sure if we should proceed with #89934 and backport it so we ensure we don't regress in the first release of Clang 19.

EDIT: I mean, 19.

[cor3ntin]

#89934 might be small enough to backport - major refactor of lambdas is strictly for clang 20+