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[Clang] ICE because of decltype(args)... in the requires of a template friend #114685

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Link1J opened this issue Nov 2, 2024 · 1 comment · Fixed by #114749
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[Clang] ICE because of decltype(args)... in the requires of a template friend #114685

Link1J opened this issue Nov 2, 2024 · 1 comment · Fixed by #114749
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clang:frontend Language frontend issues, e.g. anything involving "Sema" concepts C++20 concepts crash Prefer [crash-on-valid] or [crash-on-invalid]

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@Link1J
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Link1J commented Nov 2, 2024

The following code (which is simplify to contain what is needed for the error) compiles fine on Clang 18, but crashes Clang 19. (godbolt)

template <typename T>
struct ptr {
    template <typename U>
    friend ptr<U> make_item(auto&&... args) noexcept
        requires(__is_constructible(U, decltype(args)...));
};

template <typename U>
ptr<U> make_item(auto&&... args) noexcept
    requires(__is_constructible(U, decltype(args)...));
    
ptr<char> target;

With an assert compiler, it outputs this.

clang++: /root/llvm-project/clang/lib/Sema/SemaTemplateInstantiate.cpp:4404: 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-19.1.0/bin/clang++ -gdwarf-4 -g -o /app/output.s -mllvm --x86-asm-syntax=intel -fno-verbose-asm -S --gcc-toolchain=/opt/compiler-explorer/gcc-14.2.0 -fcolor-diagnostics -fno-crash-diagnostics -std=c++20 <source>
1.	<source>:12:17: current parser token ';'
2.	<source>:2:8: instantiating class definition 'ptr<char>'
 #0 0x0000000003ae9978 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/opt/compiler-explorer/clang-assertions-19.1.0/bin/clang+++0x3ae9978)
 #1 0x0000000003ae766c llvm::sys::CleanupOnSignal(unsigned long) (/opt/compiler-explorer/clang-assertions-19.1.0/bin/clang+++0x3ae766c)
 #2 0x0000000003a308f8 CrashRecoverySignalHandler(int) CrashRecoveryContext.cpp:0:0
 #3 0x000072d738a42520 (/lib/x86_64-linux-gnu/libc.so.6+0x42520)
 #4 0x000072d738a969fc pthread_kill (/lib/x86_64-linux-gnu/libc.so.6+0x969fc)
 #5 0x000072d738a42476 gsignal (/lib/x86_64-linux-gnu/libc.so.6+0x42476)
 #6 0x000072d738a287f3 abort (/lib/x86_64-linux-gnu/libc.so.6+0x287f3)
 #7 0x000072d738a2871b (/lib/x86_64-linux-gnu/libc.so.6+0x2871b)
 #8 0x000072d738a39e96 (/lib/x86_64-linux-gnu/libc.so.6+0x39e96)
 #9 0x000000000714e9ec clang::LocalInstantiationScope::findInstantiationOf(clang::Decl const*) (/opt/compiler-explorer/clang-assertions-19.1.0/bin/clang+++0x714e9ec)
#10 0x0000000007232609 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-19.1.0/bin/clang+++0x7232609)
#11 0x000000000716de68 clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformTypeTraitExpr(clang::TypeTraitExpr*) SemaTemplateInstantiate.cpp:0:0
#12 0x000000000715c0e6 clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformExpr(clang::Expr*) SemaTemplateInstantiate.cpp:0:0
#13 0x00000000071647f8 clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformParenExpr(clang::ParenExpr*) SemaTemplateInstantiate.cpp:0:0
#14 0x000000000715c025 clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformExpr(clang::Expr*) SemaTemplateInstantiate.cpp:0:0
#15 0x000000000716b0a8 clang::Sema::SubstConstraintExprWithoutSatisfaction(clang::Expr*, clang::MultiLevelTemplateArgumentList const&) (/opt/compiler-explorer/clang-assertions-19.1.0/bin/clang+++0x716b0a8)
#16 0x00000000067a11ee SubstituteConstraintExpressionWithoutSatisfaction(clang::Sema&, clang::Sema::TemplateCompareNewDeclInfo const&, clang::Expr const*) SemaConcept.cpp:0:0
#17 0x00000000067abeb0 clang::Sema::AreConstraintExpressionsEqual(clang::NamedDecl const*, clang::Expr const*, clang::Sema::TemplateCompareNewDeclInfo const&, clang::Expr const*) (/opt/compiler-explorer/clang-assertions-19.1.0/bin/clang+++0x67abeb0)
#18 0x0000000006e99229 IsOverloadOrOverrideImpl(clang::Sema&, clang::FunctionDecl*, clang::FunctionDecl*, bool, bool, bool) SemaOverload.cpp:0:0
#19 0x0000000006e99681 clang::Sema::CheckOverload(clang::Scope*, clang::FunctionDecl*, clang::LookupResult const&, clang::NamedDecl*&, bool) (/opt/compiler-explorer/clang-assertions-19.1.0/bin/clang+++0x6e99681)
#20 0x0000000006885090 clang::Sema::CheckFunctionDeclaration(clang::Scope*, clang::FunctionDecl*, clang::LookupResult&, bool, bool) (/opt/compiler-explorer/clang-assertions-19.1.0/bin/clang+++0x6885090)
#21 0x0000000007223dd2 clang::TemplateDeclInstantiator::VisitFunctionDecl(clang::FunctionDecl*, clang::TemplateParameterList*, clang::TemplateDeclInstantiator::RewriteKind) (/opt/compiler-explorer/clang-assertions-19.1.0/bin/clang+++0x7223dd2)
#22 0x0000000007229ced clang::TemplateDeclInstantiator::VisitFunctionTemplateDecl(clang::FunctionTemplateDecl*) (/opt/compiler-explorer/clang-assertions-19.1.0/bin/clang+++0x7229ced)
#23 0x000000000722729b clang::TemplateDeclInstantiator::VisitFriendDecl(clang::FriendDecl*) (/opt/compiler-explorer/clang-assertions-19.1.0/bin/clang+++0x722729b)
#24 0x00000000071820bb clang::Sema::InstantiateClass(clang::SourceLocation, clang::CXXRecordDecl*, clang::CXXRecordDecl*, clang::MultiLevelTemplateArgumentList const&, clang::TemplateSpecializationKind, bool) (/opt/compiler-explorer/clang-assertions-19.1.0/bin/clang+++0x71820bb)
#25 0x00000000071a6c12 clang::Sema::InstantiateClassTemplateSpecialization(clang::SourceLocation, clang::ClassTemplateSpecializationDecl*, clang::TemplateSpecializationKind, bool) (/opt/compiler-explorer/clang-assertions-19.1.0/bin/clang+++0x71a6c12)
#26 0x0000000007257ccf void llvm::function_ref<void ()>::callback_fn<clang::Sema::RequireCompleteTypeImpl(clang::SourceLocation, clang::QualType, clang::Sema::CompleteTypeKind, clang::Sema::TypeDiagnoser*)::'lambda'()>(long) SemaType.cpp:0:0
#27 0x000000000663df41 clang::Sema::runWithSufficientStackSpace(clang::SourceLocation, llvm::function_ref<void ()>) (/opt/compiler-explorer/clang-assertions-19.1.0/bin/clang+++0x663df41)
#28 0x0000000007261217 clang::Sema::RequireCompleteTypeImpl(clang::SourceLocation, clang::QualType, clang::Sema::CompleteTypeKind, clang::Sema::TypeDiagnoser*) (/opt/compiler-explorer/clang-assertions-19.1.0/bin/clang+++0x7261217)
#29 0x0000000007261565 clang::Sema::RequireCompleteType(clang::SourceLocation, clang::QualType, clang::Sema::CompleteTypeKind, clang::Sema::TypeDiagnoser&) (/opt/compiler-explorer/clang-assertions-19.1.0/bin/clang+++0x7261565)
#30 0x00000000072616e5 clang::Sema::RequireCompleteType(clang::SourceLocation, clang::QualType, clang::Sema::CompleteTypeKind, unsigned int) (/opt/compiler-explorer/clang-assertions-19.1.0/bin/clang+++0x72616e5)
#31 0x000000000686bd31 clang::Sema::ActOnUninitializedDecl(clang::Decl*) (.part.0) SemaDecl.cpp:0:0
#32 0x0000000006503014 clang::Parser::ParseDeclarationAfterDeclaratorAndAttributes(clang::Declarator&, clang::Parser::ParsedTemplateInfo const&, clang::Parser::ForRangeInit*) (/opt/compiler-explorer/clang-assertions-19.1.0/bin/clang+++0x6503014)
#33 0x0000000006511a1a clang::Parser::ParseDeclGroup(clang::ParsingDeclSpec&, clang::DeclaratorContext, clang::ParsedAttributes&, clang::Parser::ParsedTemplateInfo&, clang::SourceLocation*, clang::Parser::ForRangeInit*) (/opt/compiler-explorer/clang-assertions-19.1.0/bin/clang+++0x6511a1a)
#34 0x00000000064d115e clang::Parser::ParseDeclOrFunctionDefInternal(clang::ParsedAttributes&, clang::ParsedAttributes&, clang::ParsingDeclSpec&, clang::AccessSpecifier) (/opt/compiler-explorer/clang-assertions-19.1.0/bin/clang+++0x64d115e)
#35 0x00000000064d190e clang::Parser::ParseDeclarationOrFunctionDefinition(clang::ParsedAttributes&, clang::ParsedAttributes&, clang::ParsingDeclSpec*, clang::AccessSpecifier) (/opt/compiler-explorer/clang-assertions-19.1.0/bin/clang+++0x64d190e)
#36 0x00000000064d8077 clang::Parser::ParseExternalDeclaration(clang::ParsedAttributes&, clang::ParsedAttributes&, clang::ParsingDeclSpec*) (/opt/compiler-explorer/clang-assertions-19.1.0/bin/clang+++0x64d8077)
#37 0x00000000064d8f6f clang::Parser::ParseTopLevelDecl(clang::OpaquePtr<clang::DeclGroupRef>&, clang::Sema::ModuleImportState&) (/opt/compiler-explorer/clang-assertions-19.1.0/bin/clang+++0x64d8f6f)
#38 0x00000000064cc33a clang::ParseAST(clang::Sema&, bool, bool) (/opt/compiler-explorer/clang-assertions-19.1.0/bin/clang+++0x64cc33a)
#39 0x00000000043f9448 clang::CodeGenAction::ExecuteAction() (/opt/compiler-explorer/clang-assertions-19.1.0/bin/clang+++0x43f9448)
#40 0x0000000004684f59 clang::FrontendAction::Execute() (/opt/compiler-explorer/clang-assertions-19.1.0/bin/clang+++0x4684f59)
#41 0x0000000004609f8e clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) (/opt/compiler-explorer/clang-assertions-19.1.0/bin/clang+++0x4609f8e)
#42 0x000000000476e2be clang::ExecuteCompilerInvocation(clang::CompilerInstance*) (/opt/compiler-explorer/clang-assertions-19.1.0/bin/clang+++0x476e2be)
#43 0x0000000000c82b7f cc1_main(llvm::ArrayRef<char const*>, char const*, void*) (/opt/compiler-explorer/clang-assertions-19.1.0/bin/clang+++0xc82b7f)
#44 0x0000000000c7bcda ExecuteCC1Tool(llvm::SmallVectorImpl<char const*>&, llvm::ToolContext const&) driver.cpp:0:0
#45 0x000000000443cba9 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
#46 0x0000000003a30da4 llvm::CrashRecoveryContext::RunSafely(llvm::function_ref<void ()>) (/opt/compiler-explorer/clang-assertions-19.1.0/bin/clang+++0x3a30da4)
#47 0x000000000443d19f 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
#48 0x0000000004402c05 clang::driver::Compilation::ExecuteCommand(clang::driver::Command const&, clang::driver::Command const*&, bool) const (/opt/compiler-explorer/clang-assertions-19.1.0/bin/clang+++0x4402c05)
#49 0x000000000440366d clang::driver::Compilation::ExecuteJobs(clang::driver::JobList const&, llvm::SmallVectorImpl<std::pair<int, clang::driver::Command const*>>&, bool) const (/opt/compiler-explorer/clang-assertions-19.1.0/bin/clang+++0x440366d)
#50 0x000000000440b075 clang::driver::Driver::ExecuteCompilation(clang::driver::Compilation&, llvm::SmallVectorImpl<std::pair<int, clang::driver::Command const*>>&) (/opt/compiler-explorer/clang-assertions-19.1.0/bin/clang+++0x440b075)
#51 0x0000000000c7fe95 clang_main(int, char**, llvm::ToolContext const&) (/opt/compiler-explorer/clang-assertions-19.1.0/bin/clang+++0xc7fe95)
#52 0x0000000000b547a4 main (/opt/compiler-explorer/clang-assertions-19.1.0/bin/clang+++0xb547a4)
#53 0x000072d738a29d90 (/lib/x86_64-linux-gnu/libc.so.6+0x29d90)
#54 0x000072d738a29e40 __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x29e40)
#55 0x0000000000c7b78e _start (/opt/compiler-explorer/clang-assertions-19.1.0/bin/clang+++0xc7b78e)
clang++: error: clang frontend command failed with exit code 134 (use -v to see invocation)

It seems to be related to decltype(args)... in the requires of a template friend that has a templated function, as removing the make_item is the global scope, or replacing decltype(args)... with A... makes the code compile.
@github-actions github-actions bot added the clang Clang issues not falling into any other category label Nov 2, 2024
@EugeneZelenko EugeneZelenko added clang:frontend Language frontend issues, e.g. anything involving "Sema" concepts C++20 concepts crash Prefer [crash-on-valid] or [crash-on-invalid] and removed clang Clang issues not falling into any other category labels Nov 3, 2024
@llvmbot
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llvmbot commented Nov 3, 2024

@llvm/issue-subscribers-clang-frontend

Author: Jared Irwin (Link1J)

The following code (which is simplify to contain what is needed for the error) compiles fine on Clang 18, but crashes Clang 19. ([godbolt](https://godbolt.org/#z:OYLghAFBqd5QCxAYwPYBMCmBRdBLAF1QCcAaPECAMzwBtMA7AQwFtMQByARg9KtQYEAysib0QXACx8BBAKoBnTAAUAHpwAMvAFYTStJg1DIApACYAQuYukl9ZATwDKjdAGFUtAK4sGEgBykrgAyeAyYAHI%2BAEaYxBJmpAAOqAqETgwe3r56KWmOAqHhUSyx8Vy2mPYFDEIETMQEWT5%2BXIF2mA4ZdQ0ERZExcQm29Y3NORUKo31hA6VDXACUtqhexMjsHASYLEkG2wDUJgDMbgQAnkmMrJgHACon2CYaAIJTxF4OB0kExEcA7FZXgcQQdtrt9rcTmdLtc2Ac5I9ni9QQcqMQ8K5vr9oYjjtgDiwmABrTAAfUIOwgTC8RHMADYGQA6FkHBrABSLA4MVCYVQbH7I1Go4iYACOXjwooUEDJFIUZLQDHen0c0XoEDkpAOWGQtAuV2pxA5ixZTMWixOQJeJn%2BABErcjkeC9kxDtCDXDbninq8fsRcY9CSTyZSWNTaagGczWezOdzefzMILgaDRRKpZgZXK8AqlSquurMJrtbr9bCjSazRbHa9kf7ocgEA0g6NgJgCFaOMtaJwAKy8PzcXioThuazWA4KVbrKFmY48UgETTd5bEkBmf5MrjHPtcDTHfwATkk9KP%2B8kiV7HEkg5XpFHHF4ChAGiXK%2BWcFgMEQKFQuzoOJyEoNAAPoeI9UMYA2i4JgFCURo%2BDobZiBfCBonvaIwgac5OEXLDmGIc4AHlom0Tpl2HUhQLYQRiIYWhcI4LRSCwaIvGANwxFoF8qKwIkjHEZjeHwUUugANyze8%2BU6WlNkXMJtmvFjaDwaJiBwjwsHvX48BYPDeEk4holSTA7R2KDVKMD8%2BAMDkADVMQAd2Iq4h0XfhBBEMR2CkGRBEUFR1GE0hdCvKCUAnSx9DUl9IGWVAfgyXiAFopnQE47VMSxrDMFjUCMjEsDiiBlg6LpnAgVxxlaIIGHQfoSjKXJUnSAQapa/IMkawZykqapummDrJiqCjBt6Hr5j6qZemGkYJtmJqFjKmcNgkHt%2BzvELHwOVR/HpFL6UkA5IKMA42m3JkNAOal4LiGp4wgXBCBII55yWXhKK0C1SHXY5jiZf6geBkH9E4W9SH0vs3yHfLOGfV932Ez8fwgJBVgIJJaWAiBQKSQDiAiG5OD2g6jpOgwzq4I9LpYzB8CIIq9E84RRHEPyWcCtR7zC0gnI0pIDI2jgB1IWGR04YjaSxggDlQKhdv2w7jtO4Bzv8WmbrghCHq5CAPDAuI3uOMxFk%2Bj9lgQTAmCweJSrBm9eChmH70fBG3y%2B1dfpAY4ab7Bc%2B3pTd/mp/5A%2BOekHeOLa4afJHvtIL8oFRpA8YJnG0/AlBKeg89tfupD9TiNCMJCgicIM0hy6I0jyIcSuaMYAh6MY%2B82I4rjaB4yv%2BMszYWNEsbJN4unVFk7ZK8Uqp71U9TNIwfvPoxfSqKMkylHMgTgCs0BkdspgHOc1zGErlnvPZ6ROaUbmQt0Coc8inLotnkqEqSgRUvSzLsqsSw8pHQqeBirwDKqNCqfgqr1TmiERavVOptUyJ4Fo8CaiTWaiNAaAgehjCQRMfqY0sHTDQQseaODsi1Rmo0Yh5QVprDWksB2otxYPk4IrMmKsc7nRplwK6Ws7qNGSnrZ6jNjYfXjl7P6AMQbSKBg7CGzsxau3hrYRGnsUbwDRiADGMsM7/nxuBImbASZK3JqrLhmtbo60EbwemL0mYVDPmzXyl9ZBc2CixO%2BfMBZC0YTHCWHApaY1pHLBWpNlYUyguYnh11LH3UETdA2%2BijbmAXGbcRP0rY2yGPba88iQDQ0UdtZRL4PYW29v9QGMjpFRz8SwuOajhZmFqW7dJywjJpGcJIIAA%3D%3D%3D)) ```c++ template <typename T> struct ptr { template <typename U> friend ptr<U> make_item(auto&&... args) noexcept requires(__is_constructible(U, decltype(args)...)); };

template <typename U>
ptr<U> make_item(auto&&... args) noexcept
requires(__is_constructible(U, decltype(args)...));

ptr<char> target;


With an assert compiler, it outputs this.

clang++: /root/llvm-project/clang/lib/Sema/SemaTemplateInstantiate.cpp:4404: 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-19.1.0/bin/clang++ -gdwarf-4 -g -o /app/output.s -mllvm --x86-asm-syntax=intel -fno-verbose-asm -S --gcc-toolchain=/opt/compiler-explorer/gcc-14.2.0 -fcolor-diagnostics -fno-crash-diagnostics -std=c++20 <source>

  1. <source>:12:17: current parser token ';'
  2. <source>:2:8: instantiating class definition 'ptr<char>'
    #0 0x0000000003ae9978 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/opt/compiler-explorer/clang-assertions-19.1.0/bin/clang+++0x3ae9978)
    #1 0x0000000003ae766c llvm::sys::CleanupOnSignal(unsigned long) (/opt/compiler-explorer/clang-assertions-19.1.0/bin/clang+++0x3ae766c)
    #2 0x0000000003a308f8 CrashRecoverySignalHandler(int) CrashRecoveryContext.cpp:0:0
    #3 0x000072d738a42520 (/lib/x86_64-linux-gnu/libc.so.6+0x42520)
    #4 0x000072d738a969fc pthread_kill (/lib/x86_64-linux-gnu/libc.so.6+0x969fc)
    #5 0x000072d738a42476 gsignal (/lib/x86_64-linux-gnu/libc.so.6+0x42476)
    #6 0x000072d738a287f3 abort (/lib/x86_64-linux-gnu/libc.so.6+0x287f3)
    #7 0x000072d738a2871b (/lib/x86_64-linux-gnu/libc.so.6+0x2871b)
    #8 0x000072d738a39e96 (/lib/x86_64-linux-gnu/libc.so.6+0x39e96)
    #9 0x000000000714e9ec clang::LocalInstantiationScope::findInstantiationOf(clang::Decl const*) (/opt/compiler-explorer/clang-assertions-19.1.0/bin/clang+++0x714e9ec)
    #10 0x0000000007232609 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-19.1.0/bin/clang+++0x7232609)
    #11 0x000000000716de68 clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformTypeTraitExpr(clang::TypeTraitExpr*) SemaTemplateInstantiate.cpp:0:0
    #12 0x000000000715c0e6 clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformExpr(clang::Expr*) SemaTemplateInstantiate.cpp:0:0
    #13 0x00000000071647f8 clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformParenExpr(clang::ParenExpr*) SemaTemplateInstantiate.cpp:0:0
    #14 0x000000000715c025 clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformExpr(clang::Expr*) SemaTemplateInstantiate.cpp:0:0
    #15 0x000000000716b0a8 clang::Sema::SubstConstraintExprWithoutSatisfaction(clang::Expr*, clang::MultiLevelTemplateArgumentList const&) (/opt/compiler-explorer/clang-assertions-19.1.0/bin/clang+++0x716b0a8)
    #16 0x00000000067a11ee SubstituteConstraintExpressionWithoutSatisfaction(clang::Sema&, clang::Sema::TemplateCompareNewDeclInfo const&, clang::Expr const*) SemaConcept.cpp:0:0
    #17 0x00000000067abeb0 clang::Sema::AreConstraintExpressionsEqual(clang::NamedDecl const*, clang::Expr const*, clang::Sema::TemplateCompareNewDeclInfo const&, clang::Expr const*) (/opt/compiler-explorer/clang-assertions-19.1.0/bin/clang+++0x67abeb0)
    #18 0x0000000006e99229 IsOverloadOrOverrideImpl(clang::Sema&, clang::FunctionDecl*, clang::FunctionDecl*, bool, bool, bool) SemaOverload.cpp:0:0
    #19 0x0000000006e99681 clang::Sema::CheckOverload(clang::Scope*, clang::FunctionDecl*, clang::LookupResult const&, clang::NamedDecl*&, bool) (/opt/compiler-explorer/clang-assertions-19.1.0/bin/clang+++0x6e99681)
    #20 0x0000000006885090 clang::Sema::CheckFunctionDeclaration(clang::Scope*, clang::FunctionDecl*, clang::LookupResult&, bool, bool) (/opt/compiler-explorer/clang-assertions-19.1.0/bin/clang+++0x6885090)
    #21 0x0000000007223dd2 clang::TemplateDeclInstantiator::VisitFunctionDecl(clang::FunctionDecl*, clang::TemplateParameterList*, clang::TemplateDeclInstantiator::RewriteKind) (/opt/compiler-explorer/clang-assertions-19.1.0/bin/clang+++0x7223dd2)
    #22 0x0000000007229ced clang::TemplateDeclInstantiator::VisitFunctionTemplateDecl(clang::FunctionTemplateDecl*) (/opt/compiler-explorer/clang-assertions-19.1.0/bin/clang+++0x7229ced)
    #23 0x000000000722729b clang::TemplateDeclInstantiator::VisitFriendDecl(clang::FriendDecl*) (/opt/compiler-explorer/clang-assertions-19.1.0/bin/clang+++0x722729b)
    #24 0x00000000071820bb clang::Sema::InstantiateClass(clang::SourceLocation, clang::CXXRecordDecl*, clang::CXXRecordDecl*, clang::MultiLevelTemplateArgumentList const&, clang::TemplateSpecializationKind, bool) (/opt/compiler-explorer/clang-assertions-19.1.0/bin/clang+++0x71820bb)
    #25 0x00000000071a6c12 clang::Sema::InstantiateClassTemplateSpecialization(clang::SourceLocation, clang::ClassTemplateSpecializationDecl*, clang::TemplateSpecializationKind, bool) (/opt/compiler-explorer/clang-assertions-19.1.0/bin/clang+++0x71a6c12)
    #26 0x0000000007257ccf void llvm::function_ref<void ()>::callback_fn<clang::Sema::RequireCompleteTypeImpl(clang::SourceLocation, clang::QualType, clang::Sema::CompleteTypeKind, clang::Sema::TypeDiagnoser*)::'lambda'()>(long) SemaType.cpp:0:0
    #27 0x000000000663df41 clang::Sema::runWithSufficientStackSpace(clang::SourceLocation, llvm::function_ref<void ()>) (/opt/compiler-explorer/clang-assertions-19.1.0/bin/clang+++0x663df41)
    #28 0x0000000007261217 clang::Sema::RequireCompleteTypeImpl(clang::SourceLocation, clang::QualType, clang::Sema::CompleteTypeKind, clang::Sema::TypeDiagnoser*) (/opt/compiler-explorer/clang-assertions-19.1.0/bin/clang+++0x7261217)
    #29 0x0000000007261565 clang::Sema::RequireCompleteType(clang::SourceLocation, clang::QualType, clang::Sema::CompleteTypeKind, clang::Sema::TypeDiagnoser&) (/opt/compiler-explorer/clang-assertions-19.1.0/bin/clang+++0x7261565)
    #30 0x00000000072616e5 clang::Sema::RequireCompleteType(clang::SourceLocation, clang::QualType, clang::Sema::CompleteTypeKind, unsigned int) (/opt/compiler-explorer/clang-assertions-19.1.0/bin/clang+++0x72616e5)
    #31 0x000000000686bd31 clang::Sema::ActOnUninitializedDecl(clang::Decl*) (.part.0) SemaDecl.cpp:0:0
    #32 0x0000000006503014 clang::Parser::ParseDeclarationAfterDeclaratorAndAttributes(clang::Declarator&, clang::Parser::ParsedTemplateInfo const&, clang::Parser::ForRangeInit*) (/opt/compiler-explorer/clang-assertions-19.1.0/bin/clang+++0x6503014)
    #33 0x0000000006511a1a clang::Parser::ParseDeclGroup(clang::ParsingDeclSpec&, clang::DeclaratorContext, clang::ParsedAttributes&, clang::Parser::ParsedTemplateInfo&, clang::SourceLocation*, clang::Parser::ForRangeInit*) (/opt/compiler-explorer/clang-assertions-19.1.0/bin/clang+++0x6511a1a)
    #34 0x00000000064d115e clang::Parser::ParseDeclOrFunctionDefInternal(clang::ParsedAttributes&, clang::ParsedAttributes&, clang::ParsingDeclSpec&, clang::AccessSpecifier) (/opt/compiler-explorer/clang-assertions-19.1.0/bin/clang+++0x64d115e)
    #35 0x00000000064d190e clang::Parser::ParseDeclarationOrFunctionDefinition(clang::ParsedAttributes&, clang::ParsedAttributes&, clang::ParsingDeclSpec*, clang::AccessSpecifier) (/opt/compiler-explorer/clang-assertions-19.1.0/bin/clang+++0x64d190e)
    #36 0x00000000064d8077 clang::Parser::ParseExternalDeclaration(clang::ParsedAttributes&, clang::ParsedAttributes&, clang::ParsingDeclSpec*) (/opt/compiler-explorer/clang-assertions-19.1.0/bin/clang+++0x64d8077)
    #37 0x00000000064d8f6f clang::Parser::ParseTopLevelDecl(clang::OpaquePtr<clang::DeclGroupRef>&, clang::Sema::ModuleImportState&) (/opt/compiler-explorer/clang-assertions-19.1.0/bin/clang+++0x64d8f6f)
    #38 0x00000000064cc33a clang::ParseAST(clang::Sema&, bool, bool) (/opt/compiler-explorer/clang-assertions-19.1.0/bin/clang+++0x64cc33a)
    #39 0x00000000043f9448 clang::CodeGenAction::ExecuteAction() (/opt/compiler-explorer/clang-assertions-19.1.0/bin/clang+++0x43f9448)
    #40 0x0000000004684f59 clang::FrontendAction::Execute() (/opt/compiler-explorer/clang-assertions-19.1.0/bin/clang+++0x4684f59)
    #41 0x0000000004609f8e clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) (/opt/compiler-explorer/clang-assertions-19.1.0/bin/clang+++0x4609f8e)
    #42 0x000000000476e2be clang::ExecuteCompilerInvocation(clang::CompilerInstance*) (/opt/compiler-explorer/clang-assertions-19.1.0/bin/clang+++0x476e2be)
    #43 0x0000000000c82b7f cc1_main(llvm::ArrayRef<char const*>, char const*, void*) (/opt/compiler-explorer/clang-assertions-19.1.0/bin/clang+++0xc82b7f)
    #44 0x0000000000c7bcda ExecuteCC1Tool(llvm::SmallVectorImpl<char const*>&, llvm::ToolContext const&) driver.cpp:0:0
    #45 0x000000000443cba9 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
    #46 0x0000000003a30da4 llvm::CrashRecoveryContext::RunSafely(llvm::function_ref<void ()>) (/opt/compiler-explorer/clang-assertions-19.1.0/bin/clang+++0x3a30da4)
    #47 0x000000000443d19f 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
    #48 0x0000000004402c05 clang::driver::Compilation::ExecuteCommand(clang::driver::Command const&, clang::driver::Command const*&, bool) const (/opt/compiler-explorer/clang-assertions-19.1.0/bin/clang+++0x4402c05)
    #49 0x000000000440366d clang::driver::Compilation::ExecuteJobs(clang::driver::JobList const&, llvm::SmallVectorImpl<std::pair<int, clang::driver::Command const*>>&, bool) const (/opt/compiler-explorer/clang-assertions-19.1.0/bin/clang+++0x440366d)
    #50 0x000000000440b075 clang::driver::Driver::ExecuteCompilation(clang::driver::Compilation&, llvm::SmallVectorImpl<std::pair<int, clang::driver::Command const*>>&) (/opt/compiler-explorer/clang-assertions-19.1.0/bin/clang+++0x440b075)
    #51 0x0000000000c7fe95 clang_main(int, char**, llvm::ToolContext const&) (/opt/compiler-explorer/clang-assertions-19.1.0/bin/clang+++0xc7fe95)
    #52 0x0000000000b547a4 main (/opt/compiler-explorer/clang-assertions-19.1.0/bin/clang+++0xb547a4)
    #53 0x000072d738a29d90 (/lib/x86_64-linux-gnu/libc.so.6+0x29d90)
    #54 0x000072d738a29e40 __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x29e40)
    #55 0x0000000000c7b78e _start (/opt/compiler-explorer/clang-assertions-19.1.0/bin/clang+++0xc7b78e)
    clang++: error: clang frontend command failed with exit code 134 (use -v to see invocation)

---

It seems to be related to `decltype(args)...` in the `requires` of a `template friend` that has a `template`d function, as removing the `make_item` is the global scope, or replacing `decltype(args)...` with `A...` makes the code compile.
</details>

@zyn0217 zyn0217 mentioned this issue Nov 4, 2024
Merged
zyn0217 added a commit that referenced this issue Nov 4, 2024
@zyn0217
[Clang] Consider outer instantiation scopes for constraint normalizat…
227afac 
…ion (#114749)

We need to compare constraint expressions when instantiating a friend
declaration that is lexically defined within a class template. Since the
evaluation is deferred, the expression might refer to untransformed
function parameters such that the substitution needs the mapping of
instantiation.

These mappings are maintained by the function declaration instantiation,
so we need to establish a "transparent" LocalInstantiationScope before
substituting into the constraint.

No release note as this fixes a regression in 19.

Fixes #114685
PhilippRados pushed a commit to PhilippRados/llvm-project that referenced this issue Nov 6, 2024
@zyn0217 @PhilippRados
[Clang] Consider outer instantiation scopes for constraint normalizat…
2d242d3 
…ion (llvm#114749)

We need to compare constraint expressions when instantiating a friend
declaration that is lexically defined within a class template. Since the
evaluation is deferred, the expression might refer to untransformed
function parameters such that the substitution needs the mapping of
instantiation.

These mappings are maintained by the function declaration instantiation,
so we need to establish a "transparent" LocalInstantiationScope before
substituting into the constraint.

No release note as this fixes a regression in 19.

Fixes llvm#114685
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[Clang] Consider outer instantiation scopes for constraint normalization zyn0217/llvm-project
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@EugeneZelenko @Link1J @llvmbot