[Clang][Regression:20] Crash on constraint for lambda in lambda with init-capture #133719
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clang:frontend
Language frontend issues, e.g. anything involving "Sema"
confirmed
Verified by a second party
constexpr
Anything related to constant evaluation
crash
Prefer [crash-on-valid] or [crash-on-invalid]
lambda
C++11 lambda expressions
regression:20
Regression in 20 release
Comments
EugeneZelenko
added
clang:frontend
|
@llvm/issue-subscribers-clang-frontend Author: None (MagentaTreehouse)
The following C++20 code causes a crash since Clang 20:
template <class T>
constexpr auto f{[] (auto arg) {
return [a{arg}] {
[] () requires true {}();
};
}};
int main() {
f<int>(0);
}See https://compiler-explorer.com/z/Gh6soKaEE. See also #128175. Assertion: clang++: /root/llvm-project/clang/lib/Sema/SemaConcept.cpp:733:
bool clang::Sema::addInstantiatedCapturesToScope(clang::FunctionDecl*, const clang::FunctionDecl*, clang::LocalInstantiationScope&, const clang::MultiLevelTemplateArgumentList&):
Assertion `InstantiatingScope' 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 <source>
1. <source>:9:13: current parser token ')'
2. <source>:8:12: parsing function body 'main'
3. <source>:8:12: in compound statement ('{}')
4. <source>:2:18: instantiating function definition '(anonymous class)::operator()<int>'
#<!-- -->0 0x0000000003ea56b8 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3ea56b8)
#<!-- -->1 0x0000000003ea3344 llvm::sys::CleanupOnSignal(unsigned long) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3ea3344)
#<!-- -->2 0x0000000003de8488 CrashRecoverySignalHandler(int) CrashRecoveryContext.cpp:0:0
#<!-- -->3 0x00007a01e8642520 (/lib/x86_64-linux-gnu/libc.so.6+0x42520)
#<!-- -->4 0x00007a01e86969fc pthread_kill (/lib/x86_64-linux-gnu/libc.so.6+0x969fc)
#<!-- -->5 0x00007a01e8642476 gsignal (/lib/x86_64-linux-gnu/libc.so.6+0x42476)
#<!-- -->6 0x00007a01e86287f3 abort (/lib/x86_64-linux-gnu/libc.so.6+0x287f3)
#<!-- -->7 0x00007a01e862871b (/lib/x86_64-linux-gnu/libc.so.6+0x2871b)
#<!-- -->8 0x00007a01e8639e96 (/lib/x86_64-linux-gnu/libc.so.6+0x39e96)
#<!-- -->9 0x00000000067ad2ee clang::Sema::addInstantiatedCapturesToScope(clang::FunctionDecl*, clang::FunctionDecl const*, clang::LocalInstantiationScope&, clang::MultiLevelTemplateArgumentList const&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x67ad2ee)
#<!-- -->10 0x0000000006be427f clang::Sema::LambdaScopeForCallOperatorInstantiationRAII::LambdaScopeForCallOperatorInstantiationRAII(clang::Sema&, clang::FunctionDecl*, clang::MultiLevelTemplateArgumentList, clang::LocalInstantiationScope&, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6be427f)
#<!-- -->11 0x00000000067ba8bf clang::Sema::CheckFunctionConstraints(clang::FunctionDecl const*, clang::ConstraintSatisfaction&, clang::SourceLocation, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x67ba8bf)
#<!-- -->12 0x0000000006df3895 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+++0x6df3895)
#<!-- -->13 0x0000000006dfbea2 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+++0x6dfbea2)
#<!-- -->14 0x0000000006e13022 clang::Sema::BuildCallToObjectOfClassType(clang::Scope*, clang::Expr*, clang::SourceLocation, llvm::MutableArrayRef<clang::Expr*>, clang::SourceLocation) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6e13022)
#<!-- -->15 0x0000000006a1c643 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+++0x6a1c643)
#<!-- -->16 0x0000000006a1cf2c 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+++0x6a1cf2c)
#<!-- -->17 0x0000000007088c48 clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformCallExpr(clang::CallExpr*) SemaTemplateInstantiate.cpp:0:0
#<!-- -->18 0x0000000007077642 clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformExpr(clang::Expr*) SemaTemplateInstantiate.cpp:0:0
#<!-- -->19 0x00000000070a5d87 clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformStmt(clang::Stmt*, clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::StmtDiscardKind) SemaTemplateInstantiate.cpp:0:0
#<!-- -->20 0x00000000070a699e clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformCompoundStmt(clang::CompoundStmt*, bool) SemaTemplateInstantiate.cpp:0:0
#<!-- -->21 0x00000000070769d4 clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformLambdaExpr(clang::LambdaExpr*) SemaTemplateInstantiate.cpp:0:0
#<!-- -->22 0x0000000007077d2e clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformExpr(clang::Expr*) SemaTemplateInstantiate.cpp:0:0
#<!-- -->23 0x000000000707a865 clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformInitializer(clang::Expr*, bool) (.part.0) SemaTemplateInstantiate.cpp:0:0
#<!-- -->24 0x000000000707ac0c clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformReturnStmt(clang::ReturnStmt*) SemaTemplateInstantiate.cpp:0:0
#<!-- -->25 0x00000000070a699e clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformCompoundStmt(clang::CompoundStmt*, bool) SemaTemplateInstantiate.cpp:0:0
#<!-- -->26 0x00000000070af9d4 clang::Sema::SubstStmt(clang::Stmt*, clang::MultiLevelTemplateArgumentList const&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x70af9d4)
#<!-- -->27 0x000000000712b29d clang::Sema::InstantiateFunctionDefinition(clang::SourceLocation, clang::FunctionDecl*, bool, bool, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x712b29d)
#<!-- -->28 0x0000000007db96d1 clang::StackExhaustionHandler::runWithSufficientStackSpace(clang::SourceLocation, llvm::function_ref<void ()>) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x7db96d1)
#<!-- -->29 0x0000000006f8924a clang::Sema::DeduceReturnType(clang::FunctionDecl*, clang::SourceLocation, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6f8924a)
#<!-- -->30 0x00000000069d43c6 clang::Sema::DiagnoseUseOfDecl(clang::NamedDecl*, llvm::ArrayRef<clang::SourceLocation>, clang::ObjCInterfaceDecl const*, bool, bool, clang::ObjCInterfaceDecl*, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x69d43c6)
#<!-- -->31 0x0000000006dd1ef7 CreateFunctionRefExpr(clang::Sema&, clang::FunctionDecl*, clang::NamedDecl*, clang::Expr const*, bool, clang::SourceLocation, clang::DeclarationNameLoc const&) SemaOverload.cpp:0:0
#<!-- -->32 0x0000000006e139aa clang::Sema::BuildCallToObjectOfClassType(clang::Scope*, clang::Expr*, clang::SourceLocation, llvm::MutableArrayRef<clang::Expr*>, clang::SourceLocation) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6e139aa)
#<!-- -->33 0x0000000006a1c643 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+++0x6a1c643)
#<!-- -->34 0x0000000006a1cf2c 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+++0x6a1cf2c)
#<!-- -->35 0x00000000065581f2 clang::Parser::ParsePostfixExpressionSuffix(clang::ActionResult<clang::Expr*, true>) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x65581f2)
#<!-- -->36 0x0000000006550b71 clang::Parser::ParseCastExpression(clang::Parser::CastParseKind, bool, bool&, clang::Parser::TypeCastState, bool, bool*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6550b71)
#<!-- -->37 0x0000000006552cd7 clang::Parser::ParseCastExpression(clang::Parser::CastParseKind, bool, clang::Parser::TypeCastState, bool, bool*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6552cd7)
#<!-- -->38 0x0000000006552d69 clang::Parser::ParseAssignmentExpression(clang::Parser::TypeCastState) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6552d69)
#<!-- -->39 0x0000000006557739 clang::Parser::ParseExpression(clang::Parser::TypeCastState) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6557739)
#<!-- -->40 0x00000000065db339 clang::Parser::ParseExprStatement(clang::Parser::ParsedStmtContext) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x65db339)
#<!-- -->41 0x00000000065d3052 clang::Parser::ParseStatementOrDeclarationAfterAttributes(llvm::SmallVector<clang::Stmt*, 24u>&, clang::Parser::ParsedStmtContext, clang::SourceLocation*, clang::ParsedAttributes&, clang::ParsedAttributes&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x65d3052)
#<!-- -->42 0x00000000065d3f7d clang::Parser::ParseStatementOrDeclaration(llvm::SmallVector<clang::Stmt*, 24u>&, clang::Parser::ParsedStmtContext, clang::SourceLocation*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x65d3f7d)
#<!-- -->43 0x00000000065dba33 clang::Parser::ParseCompoundStatementBody(bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x65dba33)
#<!-- -->44 0x00000000065dc1fa clang::Parser::ParseFunctionStatementBody(clang::Decl*, clang::Parser::ParseScope&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x65dc1fa)
#<!-- -->45 0x00000000064e5c93 clang::Parser::ParseFunctionDefinition(clang::ParsingDeclarator&, clang::Parser::ParsedTemplateInfo const&, clang::Parser::LateParsedAttrList*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x64e5c93)
#<!-- -->46 0x000000000651b22d clang::Parser::ParseDeclGroup(clang::ParsingDeclSpec&, clang::DeclaratorContext, clang::ParsedAttributes&, clang::Parser::ParsedTemplateInfo&, clang::SourceLocation*, clang::Parser::ForRangeInit*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x651b22d)
#<!-- -->47 0x00000000064d98ae clang::Parser::ParseDeclOrFunctionDefInternal(clang::ParsedAttributes&, clang::ParsedAttributes&, clang::ParsingDeclSpec&, clang::AccessSpecifier) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x64d98ae)
#<!-- -->48 0x00000000064da069 clang::Parser::ParseDeclarationOrFunctionDefinition(clang::ParsedAttributes&, clang::ParsedAttributes&, clang::ParsingDeclSpec*, clang::AccessSpecifier) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x64da069)
#<!-- -->49 0x00000000064e1933 clang::Parser::ParseExternalDeclaration(clang::ParsedAttributes&, clang::ParsedAttributes&, clang::ParsingDeclSpec*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x64e1933)
#<!-- -->50 0x00000000064e284d clang::Parser::ParseTopLevelDecl(clang::OpaquePtr<clang::DeclGroupRef>&, clang::Sema::ModuleImportState&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x64e284d)
#<!-- -->51 0x00000000064d4d9a clang::ParseAST(clang::Sema&, bool, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x64d4d9a)
#<!-- -->52 0x000000000483cac8 clang::CodeGenAction::ExecuteAction() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x483cac8)
#<!-- -->53 0x0000000004b2b555 clang::FrontendAction::Execute() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4b2b555)
#<!-- -->54 0x0000000004aad19e clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4aad19e)
#<!-- -->55 0x0000000004c1bb1e clang::ExecuteCompilerInvocation(clang::CompilerInstance*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4c1bb1e)
#<!-- -->56 0x0000000000d5dc0f cc1_main(llvm::ArrayRef<char const*>, char const*, void*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xd5dc0f)
#<!-- -->57 0x0000000000d553ca ExecuteCC1Tool(llvm::SmallVectorImpl<char const*>&, llvm::ToolContext const&) driver.cpp:0:0
#<!-- -->58 0x00000000048a2469 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
#<!-- -->59 0x0000000003de8924 llvm::CrashRecoveryContext::RunSafely(llvm::function_ref<void ()>) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3de8924)
#<!-- -->60 0x00000000048a2a7f 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
#<!-- -->61 0x000000000486543d clang::driver::Compilation::ExecuteCommand(clang::driver::Command const&, clang::driver::Command const*&, bool) const (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x486543d)
#<!-- -->62 0x00000000048664ce 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+++0x48664ce)
#<!-- -->63 0x000000000486dbd5 clang::driver::Driver::ExecuteCompilation(clang::driver::Compilation&, llvm::SmallVectorImpl<std::pair<int, clang::driver::Command const*>>&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x486dbd5)
#<!-- -->64 0x0000000000d5aa08 clang_main(int, char**, llvm::ToolContext const&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xd5aa08)
#<!-- -->65 0x0000000000c20d34 main (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xc20d34)
#<!-- -->66 0x00007a01e8629d90 (/lib/x86_64-linux-gnu/libc.so.6+0x29d90)
#<!-- -->67 0x00007a01e8629e40 __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x29e40)
#<!-- -->68 0x0000000000d54e75 _start (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xd54e75)</details> |
shafik
added
confirmed
|
You'll get a crash on invalid prior to 20 if you somehow use the init-captured variable: |
Do you think they are the same bug or two different bugs? |
|
clang accepts this but other implementations don't: https://godbolt.org/z/bzafoj14f void f() {
auto f{
[](auto arg) {
return [a = arg]()
requires (a == 1)
{ return a;};
}
};
f(10);
} |
|
@LYP951018 git bisect point to 52126dc as the cause, my guess is that this just uncovers the previous issue. |
|
@erichkeane git bisect the crash that goes back further is linked to babdef2 |
They're different. I filed #134193 to track these. |
llvm-sync bot
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…7e6c (#133863) In ecc7e6c, we tried to inspect the `LambdaScopeInfo` on stack to recover the instantiating lambda captures. However, there was a mismatch in how we compared the pattern declarations of lambdas: the constraint instantiation used a tailored `getPatternFunctionDecl()` which is localized in SemaLambda that finds the very primal template declaration of a lambda, while `FunctionDecl::getTemplateInstantiationPattern` finds the latest template pattern of a lambda. This difference causes issues when lambdas are nested, as we always want the primary template declaration. This corrects that by moving `Sema::addInstantiatedCapturesToScope` from SemaConcept to SemaLambda, allowing it to use the localized version of `getPatternFunctionDecl`. It is also worth exploring to coalesce the implementation of `getPatternFunctionDecl` with `FunctionDecl::getTemplateInstantiationPattern`. But I’m leaving that for the future, as I’d like to backport this fix (ecc7e6c made the issue more visible in clang 20, sorry!), and changing Sema’s ABI would not be suitable in that regards. Hence, no release note. Fixes llvm/llvm-project#133719
swift-ci
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Apr 15, 2025
…133863) In ecc7e6c, we tried to inspect the `LambdaScopeInfo` on stack to recover the instantiating lambda captures. However, there was a mismatch in how we compared the pattern declarations of lambdas: the constraint instantiation used a tailored `getPatternFunctionDecl()` which is localized in SemaLambda that finds the very primal template declaration of a lambda, while `FunctionDecl::getTemplateInstantiationPattern` finds the latest template pattern of a lambda. This difference causes issues when lambdas are nested, as we always want the primary template declaration. This corrects that by moving `Sema::addInstantiatedCapturesToScope` from SemaConcept to SemaLambda, allowing it to use the localized version of `getPatternFunctionDecl`. It is also worth exploring to coalesce the implementation of `getPatternFunctionDecl` with `FunctionDecl::getTemplateInstantiationPattern`. But I’m leaving that for the future, as I’d like to backport this fix (ecc7e6c made the issue more visible in clang 20, sorry!), and changing Sema’s ABI would not be suitable in that regards. Hence, no release note. Fixes llvm#133719 (cherry picked from commit dcc2182)
llvm-sync bot
pushed a commit
to arm/arm-toolchain
that referenced
this issue
May 15, 2025
…7e6c (#133863) In ecc7e6c, we tried to inspect the `LambdaScopeInfo` on stack to recover the instantiating lambda captures. However, there was a mismatch in how we compared the pattern declarations of lambdas: the constraint instantiation used a tailored `getPatternFunctionDecl()` which is localized in SemaLambda that finds the very primal template declaration of a lambda, while `FunctionDecl::getTemplateInstantiationPattern` finds the latest template pattern of a lambda. This difference causes issues when lambdas are nested, as we always want the primary template declaration. This corrects that by moving `Sema::addInstantiatedCapturesToScope` from SemaConcept to SemaLambda, allowing it to use the localized version of `getPatternFunctionDecl`. It is also worth exploring to coalesce the implementation of `getPatternFunctionDecl` with `FunctionDecl::getTemplateInstantiationPattern`. But I’m leaving that for the future, as I’d like to backport this fix (ecc7e6c made the issue more visible in clang 20, sorry!), and changing Sema’s ABI would not be suitable in that regards. Hence, no release note. Fixes llvm/llvm-project#133719 (cherry picked from commit dcc2182)
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The following C++20 code causes a crash since Clang 20:
See https://compiler-explorer.com/z/Gh6soKaEE.
See also #128175.
Assertion:
Stack dump
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