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[Clang] Crash when lambda requires clause uses a parameter declared in an outer requires expression #126550

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MagentaTreehouse opened this issue Feb 10, 2025 · 6 comments
Open

[Clang] Crash when lambda requires clause uses a parameter declared in an outer requires expression #126550

MagentaTreehouse opened this issue Feb 10, 2025 · 6 comments
Labels
clang:frontend Language frontend issues, e.g. anything involving "Sema" concepts C++20 concepts confirmed Verified by a second party crash Prefer [crash-on-valid] or [crash-on-invalid] lambda C++11 lambda expressions regression:18 Regression in 18 release

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@MagentaTreehouse
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The following C++20 code causes a crash since Clang 18:

template <class T>
constexpr bool B = requires (T x) {
    [] () requires requires { x; } {}();
};

static_assert(B<int>);

See https://compiler-explorer.com/z/zsdnhrh5P.

Assertion:

clang++: /root/llvm-project/clang/lib/Sema/SemaTemplateInstantiate.cpp:4664:
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.
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>:6:21: current parser token ')'
2.	<source>:2:16: instantiating variable definition 'B<int>'
 #0 0x0000000003e722d8 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3e722d8)
 #1 0x0000000003e6ff94 llvm::sys::CleanupOnSignal(unsigned long) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3e6ff94)
 #2 0x0000000003dbc468 CrashRecoverySignalHandler(int) CrashRecoveryContext.cpp:0:0
 #3 0x00007bb56a842520 (/lib/x86_64-linux-gnu/libc.so.6+0x42520)
 #4 0x00007bb56a8969fc pthread_kill (/lib/x86_64-linux-gnu/libc.so.6+0x969fc)
 #5 0x00007bb56a842476 gsignal (/lib/x86_64-linux-gnu/libc.so.6+0x42476)
 #6 0x00007bb56a8287f3 abort (/lib/x86_64-linux-gnu/libc.so.6+0x287f3)
 #7 0x00007bb56a82871b (/lib/x86_64-linux-gnu/libc.so.6+0x2871b)
 #8 0x00007bb56a839e96 (/lib/x86_64-linux-gnu/libc.so.6+0x39e96)
 #9 0x0000000006f9ce25 clang::LocalInstantiationScope::findInstantiationOf(clang::Decl const*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6f9ce25)
#10 0x00000000070791b6 clang::Sema::FindInstantiatedDecl(clang::SourceLocation, clang::NamedDecl*, clang::MultiLevelTemplateArgumentList const&, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x70791b6)
#11 0x0000000006f94c8f (anonymous namespace)::TemplateInstantiator::TransformDecl(clang::SourceLocation, clang::Decl*) SemaTemplateInstantiate.cpp:0:0
#12 0x0000000006ff5820 clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformDeclRefExpr(clang::DeclRefExpr*) SemaTemplateInstantiate.cpp:0:0
#13 0x0000000006ffc31d (anonymous namespace)::TemplateInstantiator::TransformDeclRefExpr(clang::DeclRefExpr*) SemaTemplateInstantiate.cpp:0:0
#14 0x0000000006fd1a73 clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformExpr(clang::Expr*) SemaTemplateInstantiate.cpp:0:0
#15 0x0000000006fde805 clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformRequiresExpr(clang::RequiresExpr*) SemaTemplateInstantiate.cpp:0:0
#16 0x0000000006fd1dd8 clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformExpr(clang::Expr*) SemaTemplateInstantiate.cpp:0:0
#17 0x0000000006ffa392 clang::Sema::SubstConstraintExpr(clang::Expr*, clang::MultiLevelTemplateArgumentList const&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6ffa392)
#18 0x0000000006732690 clang::ActionResult<clang::Expr*, true> calculateConstraintSatisfaction<calculateConstraintSatisfaction(clang::Sema&, clang::NamedDecl const*, clang::SourceLocation, clang::MultiLevelTemplateArgumentList const&, clang::Expr const*, clang::ConstraintSatisfaction&)::ConstraintEvaluator>(clang::Sema&, clang::Expr const*, clang::ConstraintSatisfaction&, calculateConstraintSatisfaction(clang::Sema&, clang::NamedDecl const*, clang::SourceLocation, clang::MultiLevelTemplateArgumentList const&, clang::Expr const*, clang::ConstraintSatisfaction&)::ConstraintEvaluator const&) SemaConcept.cpp:0:0
#19 0x000000000673432e 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
#20 0x000000000673498d 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+++0x673498d)
#21 0x00000000067362cd clang::Sema::CheckFunctionConstraints(clang::FunctionDecl const*, clang::ConstraintSatisfaction&, clang::SourceLocation, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x67362cd)
#22 0x0000000006d4fee5 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, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6d4fee5)
#23 0x0000000006d5d7c2 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+++0x6d5d7c2)
#24 0x0000000006d6dc72 clang::Sema::BuildCallToObjectOfClassType(clang::Scope*, clang::Expr*, clang::SourceLocation, llvm::MutableArrayRef<clang::Expr*>, clang::SourceLocation) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6d6dc72)
#25 0x0000000006988623 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+++0x6988623)
#26 0x0000000006988f0c 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+++0x6988f0c)
#27 0x0000000006fe3968 clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformCallExpr(clang::CallExpr*) SemaTemplateInstantiate.cpp:0:0
#28 0x0000000006fd19ae clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformExpr(clang::Expr*) SemaTemplateInstantiate.cpp:0:0
#29 0x0000000006fde805 clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformRequiresExpr(clang::RequiresExpr*) SemaTemplateInstantiate.cpp:0:0
#30 0x0000000006fd1dd8 clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformExpr(clang::Expr*) SemaTemplateInstantiate.cpp:0:0
#31 0x0000000006fd4be5 clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformInitializer(clang::Expr*, bool) (.part.0) SemaTemplateInstantiate.cpp:0:0
#32 0x0000000006fd541b clang::Sema::SubstInitializer(clang::Expr*, clang::MultiLevelTemplateArgumentList const&, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6fd541b)
#33 0x000000000702fe66 clang::Sema::InstantiateVariableInitializer(clang::VarDecl*, clang::VarDecl*, clang::MultiLevelTemplateArgumentList const&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x702fe66)
#34 0x00000000070302de clang::Sema::CompleteVarTemplateSpecializationDecl(clang::VarTemplateSpecializationDecl*, clang::VarDecl*, clang::MultiLevelTemplateArgumentList const&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x70302de)
#35 0x000000000707e2bf clang::Sema::InstantiateVariableDefinition(clang::SourceLocation, clang::VarDecl*, bool, bool, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x707e2bf)
#36 0x0000000007cc59a1 clang::StackExhaustionHandler::runWithSufficientStackSpace(clang::SourceLocation, llvm::function_ref<void ()>) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x7cc59a1)
#37 0x0000000006952c53 DoMarkVarDeclReferenced(clang::Sema&, clang::SourceLocation, clang::VarDecl*, clang::Expr*, llvm::DenseMap<clang::VarDecl const*, int, llvm::DenseMapInfo<clang::VarDecl const*, void>, llvm::detail::DenseMapPair<clang::VarDecl const*, int>>&) SemaExpr.cpp:0:0
#38 0x000000000696356e MarkExprReferenced(clang::Sema&, clang::SourceLocation, clang::Decl*, clang::Expr*, bool, llvm::DenseMap<clang::VarDecl const*, int, llvm::DenseMapInfo<clang::VarDecl const*, void>, llvm::detail::DenseMapPair<clang::VarDecl const*, int>>&) SemaExpr.cpp:0:0
#39 0x0000000006953259 clang::Sema::BuildDeclRefExpr(clang::ValueDecl*, clang::QualType, clang::ExprValueKind, clang::DeclarationNameInfo const&, clang::NestedNameSpecifierLoc, clang::NamedDecl*, clang::SourceLocation, clang::TemplateArgumentListInfo const*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6953259)
#40 0x0000000006953a0f clang::Sema::BuildDeclRefExpr(clang::ValueDecl*, clang::QualType, clang::ExprValueKind, clang::DeclarationNameInfo const&, clang::CXXScopeSpec const*, clang::NamedDecl*, clang::SourceLocation, clang::TemplateArgumentListInfo const*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6953a0f)
#41 0x0000000006959843 clang::Sema::BuildDeclarationNameExpr(clang::CXXScopeSpec const&, clang::DeclarationNameInfo const&, clang::NamedDecl*, clang::NamedDecl*, clang::TemplateArgumentListInfo const*, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6959843)
#42 0x0000000006e5a0fb clang::Sema::BuildTemplateIdExpr(clang::CXXScopeSpec const&, clang::SourceLocation, clang::LookupResult&, bool, clang::TemplateArgumentListInfo const*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6e5a0fb)
#43 0x000000000695bb18 clang::Sema::ActOnIdExpression(clang::Scope*, clang::CXXScopeSpec&, clang::SourceLocation, clang::UnqualifiedId&, bool, bool, clang::CorrectionCandidateCallback*, bool, clang::Token*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x695bb18)
#44 0x00000000064e7ec6 clang::Parser::tryParseCXXIdExpression(clang::CXXScopeSpec&, bool, clang::Token&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x64e7ec6)
#45 0x00000000064e81ea clang::Parser::ParseCXXIdExpression(bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x64e81ea)
#46 0x00000000064cb89a clang::Parser::ParseCastExpression(clang::Parser::CastParseKind, bool, bool&, clang::Parser::TypeCastState, bool, bool*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x64cb89a)
#47 0x00000000064cb05e clang::Parser::ParseCastExpression(clang::Parser::CastParseKind, bool, bool&, clang::Parser::TypeCastState, bool, bool*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x64cb05e)
#48 0x00000000064d88ee clang::Parser::ParseConstantExpressionInExprEvalContext(clang::Parser::TypeCastState) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x64d88ee)
#49 0x00000000064afbfb clang::Parser::ParseStaticAssertDeclaration(clang::SourceLocation&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x64afbfb)
#50 0x000000000649dc79 clang::Parser::ParseDeclaration(clang::DeclaratorContext, clang::SourceLocation&, clang::ParsedAttributes&, clang::ParsedAttributes&, clang::SourceLocation*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x649dc79)
#51 0x000000000645c627 clang::Parser::ParseExternalDeclaration(clang::ParsedAttributes&, clang::ParsedAttributes&, clang::ParsingDeclSpec*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x645c627)
#52 0x000000000645d4dd clang::Parser::ParseTopLevelDecl(clang::OpaquePtr<clang::DeclGroupRef>&, clang::Sema::ModuleImportState&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x645d4dd)
#53 0x000000000644f97a clang::ParseAST(clang::Sema&, bool, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x644f97a)
#54 0x0000000004807f18 clang::CodeGenAction::ExecuteAction() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4807f18)
#55 0x0000000004ace965 clang::FrontendAction::Execute() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4ace965)
#56 0x0000000004a5232e clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4a5232e)
#57 0x0000000004bbd27e clang::ExecuteCompilerInvocation(clang::CompilerInstance*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4bbd27e)
#58 0x0000000000d4c60f cc1_main(llvm::ArrayRef<char const*>, char const*, void*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xd4c60f)
#59 0x0000000000d4408a ExecuteCC1Tool(llvm::SmallVectorImpl<char const*>&, llvm::ToolContext const&) driver.cpp:0:0
#60 0x000000000484e4f9 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
#61 0x0000000003dbc914 llvm::CrashRecoveryContext::RunSafely(llvm::function_ref<void ()>) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3dbc914)
#62 0x000000000484eaef 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
#63 0x0000000004811c6d clang::driver::Compilation::ExecuteCommand(clang::driver::Command const&, clang::driver::Command const*&, bool) const (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4811c6d)
#64 0x0000000004812cee 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+++0x4812cee)
#65 0x000000000481aca5 clang::driver::Driver::ExecuteCompilation(clang::driver::Compilation&, llvm::SmallVectorImpl<std::pair<int, clang::driver::Command const*>>&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x481aca5)
#66 0x0000000000d49403 clang_main(int, char**, llvm::ToolContext const&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xd49403)
#67 0x0000000000c11eb4 main (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xc11eb4)
#68 0x00007bb56a829d90 (/lib/x86_64-linux-gnu/libc.so.6+0x29d90)
#69 0x00007bb56a829e40 __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x29e40)
#70 0x0000000000d43b35 _start (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xd43b35)
@llvmbot llvmbot added the clang Clang issues not falling into any other category label Feb 10, 2025
@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] lambda C++11 lambda expressions and removed clang Clang issues not falling into any other category labels Feb 10, 2025
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llvmbot commented Feb 10, 2025

@llvm/issue-subscribers-clang-frontend

Author: None (MagentaTreehouse)

The following C++20 code causes a crash since Clang 18: ```c++ template <class T> constexpr bool B = requires (T x) { [] () requires requires { x; } {}(); };

static_assert(B<int>);


See https://compiler-explorer.com/z/zsdnhrh5P.

Assertion:
```console
clang++: /root/llvm-project/clang/lib/Sema/SemaTemplateInstantiate.cpp:4664:
llvm::PointerUnion&lt;clang::Decl*, llvm::SmallVector&lt;clang::VarDecl*, 4&gt;*&gt;* clang::LocalInstantiationScope::findInstantiationOf(const clang::Decl*):
Assertion `isa&lt;LabelDecl&gt;(D) &amp;&amp; "declaration not instantiated in this scope"' failed.

<details>

<summary>Stack dump</summary>

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 &lt;source&gt;
1.	&lt;source&gt;:6:21: current parser token ')'
2.	&lt;source&gt;:2:16: instantiating variable definition 'B&lt;int&gt;'
 #<!-- -->0 0x0000000003e722d8 llvm::sys::PrintStackTrace(llvm::raw_ostream&amp;, int) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3e722d8)
 #<!-- -->1 0x0000000003e6ff94 llvm::sys::CleanupOnSignal(unsigned long) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3e6ff94)
 #<!-- -->2 0x0000000003dbc468 CrashRecoverySignalHandler(int) CrashRecoveryContext.cpp:0:0
 #<!-- -->3 0x00007bb56a842520 (/lib/x86_64-linux-gnu/libc.so.6+0x42520)
 #<!-- -->4 0x00007bb56a8969fc pthread_kill (/lib/x86_64-linux-gnu/libc.so.6+0x969fc)
 #<!-- -->5 0x00007bb56a842476 gsignal (/lib/x86_64-linux-gnu/libc.so.6+0x42476)
 #<!-- -->6 0x00007bb56a8287f3 abort (/lib/x86_64-linux-gnu/libc.so.6+0x287f3)
 #<!-- -->7 0x00007bb56a82871b (/lib/x86_64-linux-gnu/libc.so.6+0x2871b)
 #<!-- -->8 0x00007bb56a839e96 (/lib/x86_64-linux-gnu/libc.so.6+0x39e96)
 #<!-- -->9 0x0000000006f9ce25 clang::LocalInstantiationScope::findInstantiationOf(clang::Decl const*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6f9ce25)
#<!-- -->10 0x00000000070791b6 clang::Sema::FindInstantiatedDecl(clang::SourceLocation, clang::NamedDecl*, clang::MultiLevelTemplateArgumentList const&amp;, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x70791b6)
#<!-- -->11 0x0000000006f94c8f (anonymous namespace)::TemplateInstantiator::TransformDecl(clang::SourceLocation, clang::Decl*) SemaTemplateInstantiate.cpp:0:0
#<!-- -->12 0x0000000006ff5820 clang::TreeTransform&lt;(anonymous namespace)::TemplateInstantiator&gt;::TransformDeclRefExpr(clang::DeclRefExpr*) SemaTemplateInstantiate.cpp:0:0
#<!-- -->13 0x0000000006ffc31d (anonymous namespace)::TemplateInstantiator::TransformDeclRefExpr(clang::DeclRefExpr*) SemaTemplateInstantiate.cpp:0:0
#<!-- -->14 0x0000000006fd1a73 clang::TreeTransform&lt;(anonymous namespace)::TemplateInstantiator&gt;::TransformExpr(clang::Expr*) SemaTemplateInstantiate.cpp:0:0
#<!-- -->15 0x0000000006fde805 clang::TreeTransform&lt;(anonymous namespace)::TemplateInstantiator&gt;::TransformRequiresExpr(clang::RequiresExpr*) SemaTemplateInstantiate.cpp:0:0
#<!-- -->16 0x0000000006fd1dd8 clang::TreeTransform&lt;(anonymous namespace)::TemplateInstantiator&gt;::TransformExpr(clang::Expr*) SemaTemplateInstantiate.cpp:0:0
#<!-- -->17 0x0000000006ffa392 clang::Sema::SubstConstraintExpr(clang::Expr*, clang::MultiLevelTemplateArgumentList const&amp;) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6ffa392)
#<!-- -->18 0x0000000006732690 clang::ActionResult&lt;clang::Expr*, true&gt; calculateConstraintSatisfaction&lt;calculateConstraintSatisfaction(clang::Sema&amp;, clang::NamedDecl const*, clang::SourceLocation, clang::MultiLevelTemplateArgumentList const&amp;, clang::Expr const*, clang::ConstraintSatisfaction&amp;)::ConstraintEvaluator&gt;(clang::Sema&amp;, clang::Expr const*, clang::ConstraintSatisfaction&amp;, calculateConstraintSatisfaction(clang::Sema&amp;, clang::NamedDecl const*, clang::SourceLocation, clang::MultiLevelTemplateArgumentList const&amp;, clang::Expr const*, clang::ConstraintSatisfaction&amp;)::ConstraintEvaluator const&amp;) SemaConcept.cpp:0:0
#<!-- -->19 0x000000000673432e CheckConstraintSatisfaction(clang::Sema&amp;, clang::NamedDecl const*, llvm::ArrayRef&lt;clang::Expr const*&gt;, llvm::SmallVectorImpl&lt;clang::Expr*&gt;&amp;, clang::MultiLevelTemplateArgumentList const&amp;, clang::SourceRange, clang::ConstraintSatisfaction&amp;) SemaConcept.cpp:0:0
#<!-- -->20 0x000000000673498d clang::Sema::CheckConstraintSatisfaction(clang::NamedDecl const*, llvm::ArrayRef&lt;clang::Expr const*&gt;, llvm::SmallVectorImpl&lt;clang::Expr*&gt;&amp;, clang::MultiLevelTemplateArgumentList const&amp;, clang::SourceRange, clang::ConstraintSatisfaction&amp;) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x673498d)
#<!-- -->21 0x00000000067362cd clang::Sema::CheckFunctionConstraints(clang::FunctionDecl const*, clang::ConstraintSatisfaction&amp;, clang::SourceLocation, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x67362cd)
#<!-- -->22 0x0000000006d4fee5 clang::Sema::AddMethodCandidate(clang::CXXMethodDecl*, clang::DeclAccessPair, clang::CXXRecordDecl*, clang::QualType, clang::Expr::Classification, llvm::ArrayRef&lt;clang::Expr*&gt;, clang::OverloadCandidateSet&amp;, bool, bool, llvm::MutableArrayRef&lt;clang::ImplicitConversionSequence&gt;, clang::OverloadCandidateParamOrder, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6d4fee5)
#<!-- -->23 0x0000000006d5d7c2 clang::Sema::AddMethodCandidate(clang::DeclAccessPair, clang::QualType, clang::Expr::Classification, llvm::ArrayRef&lt;clang::Expr*&gt;, clang::OverloadCandidateSet&amp;, bool, clang::OverloadCandidateParamOrder) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6d5d7c2)
#<!-- -->24 0x0000000006d6dc72 clang::Sema::BuildCallToObjectOfClassType(clang::Scope*, clang::Expr*, clang::SourceLocation, llvm::MutableArrayRef&lt;clang::Expr*&gt;, clang::SourceLocation) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6d6dc72)
#<!-- -->25 0x0000000006988623 clang::Sema::BuildCallExpr(clang::Scope*, clang::Expr*, clang::SourceLocation, llvm::MutableArrayRef&lt;clang::Expr*&gt;, clang::SourceLocation, clang::Expr*, bool, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6988623)
#<!-- -->26 0x0000000006988f0c clang::Sema::ActOnCallExpr(clang::Scope*, clang::Expr*, clang::SourceLocation, llvm::MutableArrayRef&lt;clang::Expr*&gt;, clang::SourceLocation, clang::Expr*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6988f0c)
#<!-- -->27 0x0000000006fe3968 clang::TreeTransform&lt;(anonymous namespace)::TemplateInstantiator&gt;::TransformCallExpr(clang::CallExpr*) SemaTemplateInstantiate.cpp:0:0
#<!-- -->28 0x0000000006fd19ae clang::TreeTransform&lt;(anonymous namespace)::TemplateInstantiator&gt;::TransformExpr(clang::Expr*) SemaTemplateInstantiate.cpp:0:0
#<!-- -->29 0x0000000006fde805 clang::TreeTransform&lt;(anonymous namespace)::TemplateInstantiator&gt;::TransformRequiresExpr(clang::RequiresExpr*) SemaTemplateInstantiate.cpp:0:0
#<!-- -->30 0x0000000006fd1dd8 clang::TreeTransform&lt;(anonymous namespace)::TemplateInstantiator&gt;::TransformExpr(clang::Expr*) SemaTemplateInstantiate.cpp:0:0
#<!-- -->31 0x0000000006fd4be5 clang::TreeTransform&lt;(anonymous namespace)::TemplateInstantiator&gt;::TransformInitializer(clang::Expr*, bool) (.part.0) SemaTemplateInstantiate.cpp:0:0
#<!-- -->32 0x0000000006fd541b clang::Sema::SubstInitializer(clang::Expr*, clang::MultiLevelTemplateArgumentList const&amp;, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6fd541b)
#<!-- -->33 0x000000000702fe66 clang::Sema::InstantiateVariableInitializer(clang::VarDecl*, clang::VarDecl*, clang::MultiLevelTemplateArgumentList const&amp;) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x702fe66)
#<!-- -->34 0x00000000070302de clang::Sema::CompleteVarTemplateSpecializationDecl(clang::VarTemplateSpecializationDecl*, clang::VarDecl*, clang::MultiLevelTemplateArgumentList const&amp;) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x70302de)
#<!-- -->35 0x000000000707e2bf clang::Sema::InstantiateVariableDefinition(clang::SourceLocation, clang::VarDecl*, bool, bool, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x707e2bf)
#<!-- -->36 0x0000000007cc59a1 clang::StackExhaustionHandler::runWithSufficientStackSpace(clang::SourceLocation, llvm::function_ref&lt;void ()&gt;) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x7cc59a1)
#<!-- -->37 0x0000000006952c53 DoMarkVarDeclReferenced(clang::Sema&amp;, clang::SourceLocation, clang::VarDecl*, clang::Expr*, llvm::DenseMap&lt;clang::VarDecl const*, int, llvm::DenseMapInfo&lt;clang::VarDecl const*, void&gt;, llvm::detail::DenseMapPair&lt;clang::VarDecl const*, int&gt;&gt;&amp;) SemaExpr.cpp:0:0
#<!-- -->38 0x000000000696356e MarkExprReferenced(clang::Sema&amp;, clang::SourceLocation, clang::Decl*, clang::Expr*, bool, llvm::DenseMap&lt;clang::VarDecl const*, int, llvm::DenseMapInfo&lt;clang::VarDecl const*, void&gt;, llvm::detail::DenseMapPair&lt;clang::VarDecl const*, int&gt;&gt;&amp;) SemaExpr.cpp:0:0
#<!-- -->39 0x0000000006953259 clang::Sema::BuildDeclRefExpr(clang::ValueDecl*, clang::QualType, clang::ExprValueKind, clang::DeclarationNameInfo const&amp;, clang::NestedNameSpecifierLoc, clang::NamedDecl*, clang::SourceLocation, clang::TemplateArgumentListInfo const*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6953259)
#<!-- -->40 0x0000000006953a0f clang::Sema::BuildDeclRefExpr(clang::ValueDecl*, clang::QualType, clang::ExprValueKind, clang::DeclarationNameInfo const&amp;, clang::CXXScopeSpec const*, clang::NamedDecl*, clang::SourceLocation, clang::TemplateArgumentListInfo const*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6953a0f)
#<!-- -->41 0x0000000006959843 clang::Sema::BuildDeclarationNameExpr(clang::CXXScopeSpec const&amp;, clang::DeclarationNameInfo const&amp;, clang::NamedDecl*, clang::NamedDecl*, clang::TemplateArgumentListInfo const*, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6959843)
#<!-- -->42 0x0000000006e5a0fb clang::Sema::BuildTemplateIdExpr(clang::CXXScopeSpec const&amp;, clang::SourceLocation, clang::LookupResult&amp;, bool, clang::TemplateArgumentListInfo const*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6e5a0fb)
#<!-- -->43 0x000000000695bb18 clang::Sema::ActOnIdExpression(clang::Scope*, clang::CXXScopeSpec&amp;, clang::SourceLocation, clang::UnqualifiedId&amp;, bool, bool, clang::CorrectionCandidateCallback*, bool, clang::Token*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x695bb18)
#<!-- -->44 0x00000000064e7ec6 clang::Parser::tryParseCXXIdExpression(clang::CXXScopeSpec&amp;, bool, clang::Token&amp;) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x64e7ec6)
#<!-- -->45 0x00000000064e81ea clang::Parser::ParseCXXIdExpression(bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x64e81ea)
#<!-- -->46 0x00000000064cb89a clang::Parser::ParseCastExpression(clang::Parser::CastParseKind, bool, bool&amp;, clang::Parser::TypeCastState, bool, bool*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x64cb89a)
#<!-- -->47 0x00000000064cb05e clang::Parser::ParseCastExpression(clang::Parser::CastParseKind, bool, bool&amp;, clang::Parser::TypeCastState, bool, bool*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x64cb05e)
#<!-- -->48 0x00000000064d88ee clang::Parser::ParseConstantExpressionInExprEvalContext(clang::Parser::TypeCastState) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x64d88ee)
#<!-- -->49 0x00000000064afbfb clang::Parser::ParseStaticAssertDeclaration(clang::SourceLocation&amp;) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x64afbfb)
#<!-- -->50 0x000000000649dc79 clang::Parser::ParseDeclaration(clang::DeclaratorContext, clang::SourceLocation&amp;, clang::ParsedAttributes&amp;, clang::ParsedAttributes&amp;, clang::SourceLocation*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x649dc79)
#<!-- -->51 0x000000000645c627 clang::Parser::ParseExternalDeclaration(clang::ParsedAttributes&amp;, clang::ParsedAttributes&amp;, clang::ParsingDeclSpec*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x645c627)
#<!-- -->52 0x000000000645d4dd clang::Parser::ParseTopLevelDecl(clang::OpaquePtr&lt;clang::DeclGroupRef&gt;&amp;, clang::Sema::ModuleImportState&amp;) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x645d4dd)
#<!-- -->53 0x000000000644f97a clang::ParseAST(clang::Sema&amp;, bool, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x644f97a)
#<!-- -->54 0x0000000004807f18 clang::CodeGenAction::ExecuteAction() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4807f18)
#<!-- -->55 0x0000000004ace965 clang::FrontendAction::Execute() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4ace965)
#<!-- -->56 0x0000000004a5232e clang::CompilerInstance::ExecuteAction(clang::FrontendAction&amp;) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4a5232e)
#<!-- -->57 0x0000000004bbd27e clang::ExecuteCompilerInvocation(clang::CompilerInstance*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4bbd27e)
#<!-- -->58 0x0000000000d4c60f cc1_main(llvm::ArrayRef&lt;char const*&gt;, char const*, void*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xd4c60f)
#<!-- -->59 0x0000000000d4408a ExecuteCC1Tool(llvm::SmallVectorImpl&lt;char const*&gt;&amp;, llvm::ToolContext const&amp;) driver.cpp:0:0
#<!-- -->60 0x000000000484e4f9 void llvm::function_ref&lt;void ()&gt;::callback_fn&lt;clang::driver::CC1Command::Execute(llvm::ArrayRef&lt;std::optional&lt;llvm::StringRef&gt;&gt;, std::__cxx11::basic_string&lt;char, std::char_traits&lt;char&gt;, std::allocator&lt;char&gt;&gt;*, bool*) const::'lambda'()&gt;(long) Job.cpp:0:0
#<!-- -->61 0x0000000003dbc914 llvm::CrashRecoveryContext::RunSafely(llvm::function_ref&lt;void ()&gt;) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3dbc914)
#<!-- -->62 0x000000000484eaef clang::driver::CC1Command::Execute(llvm::ArrayRef&lt;std::optional&lt;llvm::StringRef&gt;&gt;, std::__cxx11::basic_string&lt;char, std::char_traits&lt;char&gt;, std::allocator&lt;char&gt;&gt;*, bool*) const (.part.0) Job.cpp:0:0
#<!-- -->63 0x0000000004811c6d clang::driver::Compilation::ExecuteCommand(clang::driver::Command const&amp;, clang::driver::Command const*&amp;, bool) const (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4811c6d)
#<!-- -->64 0x0000000004812cee clang::driver::Compilation::ExecuteJobs(clang::driver::JobList const&amp;, llvm::SmallVectorImpl&lt;std::pair&lt;int, clang::driver::Command const*&gt;&gt;&amp;, bool) const (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4812cee)
#<!-- -->65 0x000000000481aca5 clang::driver::Driver::ExecuteCompilation(clang::driver::Compilation&amp;, llvm::SmallVectorImpl&lt;std::pair&lt;int, clang::driver::Command const*&gt;&gt;&amp;) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x481aca5)
#<!-- -->66 0x0000000000d49403 clang_main(int, char**, llvm::ToolContext const&amp;) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xd49403)
#<!-- -->67 0x0000000000c11eb4 main (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xc11eb4)
#<!-- -->68 0x00007bb56a829d90 (/lib/x86_64-linux-gnu/libc.so.6+0x29d90)
#<!-- -->69 0x00007bb56a829e40 __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x29e40)
#<!-- -->70 0x0000000000d43b35 _start (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xd43b35)

</details>

@shafik shafik added confirmed Verified by a second party regression:18 Regression in 18 release labels Feb 10, 2025
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shafik commented Feb 10, 2025

Confirmed, this does look like an 18 regression

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shafik commented Feb 11, 2025

@0x59616e git bisect points to 548d67a as being responsible for this regression

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zyn0217 commented Feb 12, 2025

@mizvekov

We need to find out the pattern/instantiation pair of x within the lambda expression's constraint, but this isn't currently possible because we don't track RequiresExprBodyDecl nor the RequiresExpr (that would otherwise act as the lambda's parent like a FunctionDecl).

I looked at #107942, but I couldn’t tell if you've started to treat RequiresExprBodyDecl as a context declaration for a lambda without a debugger. You might want to take a look too.

@shafik: I don't think 548d67a is the offending change, since the underlying issue relates to deferred concept evaluation with which we don't transform a function's associated constraint until its instantiation.

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A RequiresExprBodyDecl is already a declcontext.

The problem is that some times the RequiresExprBodyDecl can appear in a context which is not a declcontext as well, and my lambda patch does fix that.

I haven't tried this particular test case in that patch, and not be able to until the next week due to WG21 meeting.

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shafik commented Feb 12, 2025

@shafik: I don't think 548d67a is the offending change, since the underlying issue relates to deferred concept evaluation with which we don't transform a function's associated constraint until its instantiation.

I just did a git bisect, so perhaps that patch just uncovered an underlying bug and the real bug is deeper than that. I did not try a revert.

@zyn0217 zyn0217 mentioned this issue Mar 14, 2025
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@frederick-vs-ja frederick-vs-ja mentioned this issue Mar 25, 2025
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@shafik shafik mentioned this issue Mar 25, 2025
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clang:frontend Language frontend issues, e.g. anything involving "Sema" concepts C++20 concepts confirmed Verified by a second party crash Prefer [crash-on-valid] or [crash-on-invalid] lambda C++11 lambda expressions regression:18 Regression in 18 release
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