[clang++ 17.0.6] Segfault from using a concept which has immediatly invoked generic lambda with constrained template parameter.

[MiroPalmu]

Following C++ program results in segfault when compiling with: clang++ -std=c++2c ~/clang-bug.cpp

template <typename>
concept trivial_concept = (true);

template <typename>
concept bug = ([]<trivial_concept T = int>() { return true; }());

template <typename>
concept no_bug = ([] { return true; }());

// If this is present, the crash does not happen.
// static_assert(bug<int>);

int main() { 
    bug auto x = 0;
    no_bug auto y = 0;

    [](auto...){}(x, y);
}

My LLVM is obtained from Arch Linux Extra repository.

g++ 14.1.1 compiles the snipped fine.

Here is the log clang++ outputs:

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: /usr/bin/clang++ -cc1 -triple x86_64-pc-linux-gnu -emit-obj -mrelax-all -dumpdir a- -disable-free -clear-ast-before-backend -disable-llvm-verifier -discard-value-names -main-file-name clang-bug.cpp -mrelocation-model pic -pic-level 2 -pic-is-pie -mframe-pointer=all -fmath-errno -ffp-contract=on -fno-rounding-math -mconstructor-aliases -funwind-tables=2 -target-cpu x86-64 -tune-cpu generic -debugger-tuning=gdb -fcoverage-compilation-dir=/home/pamiro/repos/guilander/build -resource-dir /usr/lib/clang/17 -internal-isystem /usr/bin/../lib64/gcc/x86_64-pc-linux-gnu/14.1.1/../../../../include/c++/14.1.1 -internal-isystem /usr/bin/../lib64/gcc/x86_64-pc-linux-gnu/14.1.1/../../../../include/c++/14.1.1/x86_64-pc-linux-gnu -internal-isystem /usr/bin/../lib64/gcc/x86_64-pc-linux-gnu/14.1.1/../../../../include/c++/14.1.1/backward -internal-isystem /usr/lib/clang/17/include -internal-isystem /usr/local/include -internal-isystem /usr/bin/../lib64/gcc/x86_64-pc-linux-gnu/14.1.1/../../../../x86_64-pc-linux-gnu/include -internal-externc-isystem /include -internal-externc-isystem /usr/include -std=c++2c -fdeprecated-macro -fdebug-compilation-dir=/home/pamiro/repos/guilander/build -ferror-limit 19 -stack-protector 2 -fgnuc-version=4.2.1 -fno-implicit-modules -fcxx-exceptions -fexceptions -fcolor-diagnostics -faddrsig -D__GCC_HAVE_DWARF2_CFI_ASM=1 -o /tmp/clang-bug-e8cc84.o -x c++ /home/pamiro/clang-bug.cpp
1.	/home/pamiro/clang-bug.cpp:14:19: current parser token ';'
2.	/home/pamiro/clang-bug.cpp:13:12: parsing function body 'main'
3.	/home/pamiro/clang-bug.cpp:13:12: in compound statement ('{}')
Stack dump without symbol names (ensure you have llvm-symbolizer in your PATH or set the environment var `LLVM_SYMBOLIZER_PATH` to point to it):
0  libLLVM-17.so      0x0000739c0537bcb0 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) + 64
1  libLLVM-17.so      0x0000739c05378f1d
2  libc.so.6          0x0000739c04650ae0
3  libclang-cpp.so.17 0x0000739c0d6b3feb
4  libclang-cpp.so.17 0x0000739c0d66dc30
5  libclang-cpp.so.17 0x0000739c0d68a866 clang::Expr::EvaluateAsConstantExpr(clang::Expr::EvalResult&, clang::ASTContext const&, clang::Expr::ConstantExprKind) const + 1254
6  libclang-cpp.so.17 0x0000739c0dbfc5a2
7  libclang-cpp.so.17 0x0000739c0dbfcccd
8  libclang-cpp.so.17 0x0000739c0dbfd13b clang::Sema::CheckConstraintSatisfaction(clang::NamedDecl const*, llvm::ArrayRef<clang::Expr const*>, llvm::SmallVectorImpl<clang::Expr*>&, clang::MultiLevelTemplateArgumentList const&, clang::SourceRange, clang::ConstraintSatisfaction&) + 923
9  libclang-cpp.so.17 0x0000739c0dbfdf99 clang::Sema::CheckInstantiatedFunctionTemplateConstraints(clang::SourceLocation, clang::FunctionDecl*, llvm::ArrayRef<clang::TemplateArgument>, clang::ConstraintSatisfaction&) + 793
10 libclang-cpp.so.17 0x0000739c0e0ba11b 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 ()>) + 5019
11 libclang-cpp.so.17 0x0000739c0e0baf91
12 libclang-cpp.so.17 0x0000739c0dad33c1 clang::Sema::runWithSufficientStackSpace(clang::SourceLocation, llvm::function_ref<void ()>) + 113
13 libclang-cpp.so.17 0x0000739c0e0d9f08 clang::Sema::DeduceTemplateArguments(clang::FunctionTemplateDecl*, clang::TemplateArgumentListInfo*, llvm::ArrayRef<clang::Expr*>, clang::FunctionDecl*&, clang::sema::TemplateDeductionInfo&, bool, bool, llvm::function_ref<bool (llvm::ArrayRef<clang::QualType>)>) + 6424
14 libclang-cpp.so.17 0x0000739c0f344185
15 libclang-cpp.so.17 0x0000739c0dfc2b17 clang::Sema::AddMethodCandidate(clang::DeclAccessPair, clang::QualType, clang::Expr::Classification, llvm::ArrayRef<clang::Expr*>, clang::OverloadCandidateSet&, bool, clang::OverloadCandidateParamOrder) + 135
16 libclang-cpp.so.17 0x0000739c0dfda600 clang::Sema::BuildCallToObjectOfClassType(clang::Scope*, clang::Expr*, clang::SourceLocation, llvm::MutableArrayRef<clang::Expr*>, clang::SourceLocation) + 928
17 libclang-cpp.so.17 0x0000739c0dd86437 clang::Sema::ActOnCallExpr(clang::Scope*, clang::Expr*, clang::SourceLocation, llvm::MutableArrayRef<clang::Expr*>, clang::SourceLocation, clang::Expr*) + 87
18 libclang-cpp.so.17 0x0000739c0e105f2a
19 libclang-cpp.so.17 0x0000739c0e0fe11f clang::Sema::SubstExpr(clang::Expr*, clang::MultiLevelTemplateArgumentList const&) + 95
20 libclang-cpp.so.17 0x0000739c0dbfbd73
21 libclang-cpp.so.17 0x0000739c0dbfcccd
22 libclang-cpp.so.17 0x0000739c0dbfd13b clang::Sema::CheckConstraintSatisfaction(clang::NamedDecl const*, llvm::ArrayRef<clang::Expr const*>, llvm::SmallVectorImpl<clang::Expr*>&, clang::MultiLevelTemplateArgumentList const&, clang::SourceRange, clang::ConstraintSatisfaction&) + 923
23 libclang-cpp.so.17 0x0000739c0e0dae60 clang::Sema::DeduceAutoType(clang::TypeLoc, clang::Expr*, clang::QualType&, clang::sema::TemplateDeductionInfo&, bool, bool, clang::TemplateSpecCandidateSet*) + 3888
24 libclang-cpp.so.17 0x0000739c0dc57603 clang::Sema::deduceVarTypeFromInitializer(clang::VarDecl*, clang::DeclarationName, clang::QualType, clang::TypeSourceInfo*, clang::SourceRange, bool, clang::Expr*) + 1331
25 libclang-cpp.so.17 0x0000739c0dc57aa1 clang::Sema::DeduceVariableDeclarationType(clang::VarDecl*, bool, clang::Expr*) + 81
26 libclang-cpp.so.17 0x0000739c0dc72515 clang::Sema::AddInitializerToDecl(clang::Decl*, clang::Expr*, bool) + 437
27 libclang-cpp.so.17 0x0000739c0d30bcf2 clang::Parser::ParseDeclarationAfterDeclaratorAndAttributes(clang::Declarator&, clang::Parser::ParsedTemplateInfo const&, clang::Parser::ForRangeInit*) + 546
28 libclang-cpp.so.17 0x0000739c0d315e8b clang::Parser::ParseDeclGroup(clang::ParsingDeclSpec&, clang::DeclaratorContext, clang::ParsedAttributes&, clang::SourceLocation*, clang::Parser::ForRangeInit*) + 2715
29 libclang-cpp.so.17 0x0000739c0d3308b5 clang::Parser::ParseSimpleDeclaration(clang::DeclaratorContext, clang::SourceLocation&, clang::ParsedAttributes&, clang::ParsedAttributes&, bool, clang::Parser::ForRangeInit*, clang::SourceLocation*) + 837
30 libclang-cpp.so.17 0x0000739c0d330db2 clang::Parser::ParseDeclaration(clang::DeclaratorContext, clang::SourceLocation&, clang::ParsedAttributes&, clang::ParsedAttributes&, clang::SourceLocation*) + 290
31 libclang-cpp.so.17 0x0000739c0d3b23bc clang::Parser::ParseStatementOrDeclarationAfterAttributes(llvm::SmallVector<clang::Stmt*, 32u>&, clang::Parser::ParsedStmtContext, clang::SourceLocation*, clang::ParsedAttributes&, clang::ParsedAttributes&) + 3356
32 libclang-cpp.so.17 0x0000739c0d3b25cb clang::Parser::ParseStatementOrDeclaration(llvm::SmallVector<clang::Stmt*, 32u>&, clang::Parser::ParsedStmtContext, clang::SourceLocation*) + 331
33 libclang-cpp.so.17 0x0000739c0d3b7675 clang::Parser::ParseCompoundStatementBody(bool) + 1365
34 libclang-cpp.so.17 0x0000739c0d3b93aa clang::Parser::ParseFunctionStatementBody(clang::Decl*, clang::Parser::ParseScope&) + 218
35 libclang-cpp.so.17 0x0000739c0d3ba3fc clang::Parser::ParseFunctionDefinition(clang::ParsingDeclarator&, clang::Parser::ParsedTemplateInfo const&, clang::Parser::LateParsedAttrList*) + 1724
36 libclang-cpp.so.17 0x0000739c0d3161d0 clang::Parser::ParseDeclGroup(clang::ParsingDeclSpec&, clang::DeclaratorContext, clang::ParsedAttributes&, clang::SourceLocation*, clang::Parser::ForRangeInit*) + 3552
37 libclang-cpp.so.17 0x0000739c0d3a8009
38 libclang-cpp.so.17 0x0000739c0d3becc2 clang::Parser::ParseExternalDeclaration(clang::ParsedAttributes&, clang::ParsedAttributes&, clang::ParsingDeclSpec*) + 2594
39 libclang-cpp.so.17 0x0000739c0d3bf0ea clang::Parser::ParseTopLevelDecl(clang::OpaquePtr<clang::DeclGroupRef>&, clang::Sema::ModuleImportState&) + 618
40 libclang-cpp.so.17 0x0000739c0d2fbd99 clang::ParseAST(clang::Sema&, bool, bool) + 601
41 libclang-cpp.so.17 0x0000739c0ebc44f9 clang::FrontendAction::Execute() + 393
42 libclang-cpp.so.17 0x0000739c0ebb0df7 clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) + 391
43 libclang-cpp.so.17 0x0000739c0ec93c92 clang::ExecuteCompilerInvocation(clang::CompilerInstance*) + 450
44 clang++            0x00005670f2222c18 cc1_main(llvm::ArrayRef<char const*>, char const*, void*) + 3928
45 clang++            0x00005670f222810f
46 clang++            0x00005670f2228c2e clang_main(int, char**, llvm::ToolContext const&) + 1950
47 clang++            0x00005670f221ed54 main + 52
48 libc.so.6          0x0000739c04639c88
49 libc.so.6          0x0000739c04639d4c __libc_start_main + 140
50 clang++            0x00005670f221ed95 _start + 37
clang++: error: unable to execute command: Segmentation fault (core dumped)
clang++: error: clang frontend command failed due to signal (use -v to see invocation)
clang version 17.0.6
Target: x86_64-pc-linux-gnu
Thread model: posix
InstalledDir: /usr/bin
clang++: note: diagnostic msg: 
********************

PLEASE ATTACH THE FOLLOWING FILES TO THE BUG REPORT:
Preprocessed source(s) and associated run script(s) are located at:
clang++: note: diagnostic msg: /tmp/clang-bug-3bb744.cpp
clang++: note: diagnostic msg: /tmp/clang-bug-3bb744.sh
clang++: note: diagnostic msg: 

********************

Here are the requested files: clang-bug.zip

[llvmbot]

@llvm/issue-subscribers-clang-frontend

Author: Miro Palmu (MiroPalmu)

Following C++ program results in segfault when compiling with: `clang++ -std=c++2c ~/clang-bug.cpp`

template <typename>
concept trivial_concept = (true);

template <typename>
concept bug = ([]<trivial_concept T = int>() { return true; }());

template <typename>
concept no_bug = ([] { return true; }());

// If this is present, the crash does not happen.
// static_assert(bug<int>);

int main() { 
    bug auto x = 0;
    no_bug auto y = 0;

    [](auto...){}(x, y);
}

My LLVM is obtained from Arch Linux Extra repository.

g++ 14.1.1 is compiles the snipped fine.

Here is the log clang++ outputs:

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: /usr/bin/clang++ -cc1 -triple x86_64-pc-linux-gnu -emit-obj -mrelax-all -dumpdir a- -disable-free -clear-ast-before-backend -disable-llvm-verifier -discard-value-names -main-file-name clang-bug.cpp -mrelocation-model pic -pic-level 2 -pic-is-pie -mframe-pointer=all -fmath-errno -ffp-contract=on -fno-rounding-math -mconstructor-aliases -funwind-tables=2 -target-cpu x86-64 -tune-cpu generic -debugger-tuning=gdb -fcoverage-compilation-dir=/home/pamiro/repos/guilander/build -resource-dir /usr/lib/clang/17 -internal-isystem /usr/bin/../lib64/gcc/x86_64-pc-linux-gnu/14.1.1/../../../../include/c++/14.1.1 -internal-isystem /usr/bin/../lib64/gcc/x86_64-pc-linux-gnu/14.1.1/../../../../include/c++/14.1.1/x86_64-pc-linux-gnu -internal-isystem /usr/bin/../lib64/gcc/x86_64-pc-linux-gnu/14.1.1/../../../../include/c++/14.1.1/backward -internal-isystem /usr/lib/clang/17/include -internal-isystem /usr/local/include -internal-isystem /usr/bin/../lib64/gcc/x86_64-pc-linux-gnu/14.1.1/../../../../x86_64-pc-linux-gnu/include -internal-externc-isystem /include -internal-externc-isystem /usr/include -std=c++2c -fdeprecated-macro -fdebug-compilation-dir=/home/pamiro/repos/guilander/build -ferror-limit 19 -stack-protector 2 -fgnuc-version=4.2.1 -fno-implicit-modules -fcxx-exceptions -fexceptions -fcolor-diagnostics -faddrsig -D__GCC_HAVE_DWARF2_CFI_ASM=1 -o /tmp/clang-bug-e8cc84.o -x c++ /home/pamiro/clang-bug.cpp
1.	/home/pamiro/clang-bug.cpp:14:19: current parser token ';'
2.	/home/pamiro/clang-bug.cpp:13:12: parsing function body 'main'
3.	/home/pamiro/clang-bug.cpp:13:12: in compound statement ('{}')
Stack dump without symbol names (ensure you have llvm-symbolizer in your PATH or set the environment var `LLVM_SYMBOLIZER_PATH` to point to it):
0  libLLVM-17.so      0x0000739c0537bcb0 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) + 64
1  libLLVM-17.so      0x0000739c05378f1d
2  libc.so.6          0x0000739c04650ae0
3  libclang-cpp.so.17 0x0000739c0d6b3feb
4  libclang-cpp.so.17 0x0000739c0d66dc30
5  libclang-cpp.so.17 0x0000739c0d68a866 clang::Expr::EvaluateAsConstantExpr(clang::Expr::EvalResult&, clang::ASTContext const&, clang::Expr::ConstantExprKind) const + 1254
6  libclang-cpp.so.17 0x0000739c0dbfc5a2
7  libclang-cpp.so.17 0x0000739c0dbfcccd
8  libclang-cpp.so.17 0x0000739c0dbfd13b clang::Sema::CheckConstraintSatisfaction(clang::NamedDecl const*, llvm::ArrayRef<clang::Expr const*>, llvm::SmallVectorImpl<clang::Expr*>&, clang::MultiLevelTemplateArgumentList const&, clang::SourceRange, clang::ConstraintSatisfaction&) + 923
9  libclang-cpp.so.17 0x0000739c0dbfdf99 clang::Sema::CheckInstantiatedFunctionTemplateConstraints(clang::SourceLocation, clang::FunctionDecl*, llvm::ArrayRef<clang::TemplateArgument>, clang::ConstraintSatisfaction&) + 793
10 libclang-cpp.so.17 0x0000739c0e0ba11b 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 ()>) + 5019
11 libclang-cpp.so.17 0x0000739c0e0baf91
12 libclang-cpp.so.17 0x0000739c0dad33c1 clang::Sema::runWithSufficientStackSpace(clang::SourceLocation, llvm::function_ref<void ()>) + 113
13 libclang-cpp.so.17 0x0000739c0e0d9f08 clang::Sema::DeduceTemplateArguments(clang::FunctionTemplateDecl*, clang::TemplateArgumentListInfo*, llvm::ArrayRef<clang::Expr*>, clang::FunctionDecl*&, clang::sema::TemplateDeductionInfo&, bool, bool, llvm::function_ref<bool (llvm::ArrayRef<clang::QualType>)>) + 6424
14 libclang-cpp.so.17 0x0000739c0f344185
15 libclang-cpp.so.17 0x0000739c0dfc2b17 clang::Sema::AddMethodCandidate(clang::DeclAccessPair, clang::QualType, clang::Expr::Classification, llvm::ArrayRef<clang::Expr*>, clang::OverloadCandidateSet&, bool, clang::OverloadCandidateParamOrder) + 135
16 libclang-cpp.so.17 0x0000739c0dfda600 clang::Sema::BuildCallToObjectOfClassType(clang::Scope*, clang::Expr*, clang::SourceLocation, llvm::MutableArrayRef<clang::Expr*>, clang::SourceLocation) + 928
17 libclang-cpp.so.17 0x0000739c0dd86437 clang::Sema::ActOnCallExpr(clang::Scope*, clang::Expr*, clang::SourceLocation, llvm::MutableArrayRef<clang::Expr*>, clang::SourceLocation, clang::Expr*) + 87
18 libclang-cpp.so.17 0x0000739c0e105f2a
19 libclang-cpp.so.17 0x0000739c0e0fe11f clang::Sema::SubstExpr(clang::Expr*, clang::MultiLevelTemplateArgumentList const&) + 95
20 libclang-cpp.so.17 0x0000739c0dbfbd73
21 libclang-cpp.so.17 0x0000739c0dbfcccd
22 libclang-cpp.so.17 0x0000739c0dbfd13b clang::Sema::CheckConstraintSatisfaction(clang::NamedDecl const*, llvm::ArrayRef<clang::Expr const*>, llvm::SmallVectorImpl<clang::Expr*>&, clang::MultiLevelTemplateArgumentList const&, clang::SourceRange, clang::ConstraintSatisfaction&) + 923
23 libclang-cpp.so.17 0x0000739c0e0dae60 clang::Sema::DeduceAutoType(clang::TypeLoc, clang::Expr*, clang::QualType&, clang::sema::TemplateDeductionInfo&, bool, bool, clang::TemplateSpecCandidateSet*) + 3888
24 libclang-cpp.so.17 0x0000739c0dc57603 clang::Sema::deduceVarTypeFromInitializer(clang::VarDecl*, clang::DeclarationName, clang::QualType, clang::TypeSourceInfo*, clang::SourceRange, bool, clang::Expr*) + 1331
25 libclang-cpp.so.17 0x0000739c0dc57aa1 clang::Sema::DeduceVariableDeclarationType(clang::VarDecl*, bool, clang::Expr*) + 81
26 libclang-cpp.so.17 0x0000739c0dc72515 clang::Sema::AddInitializerToDecl(clang::Decl*, clang::Expr*, bool) + 437
27 libclang-cpp.so.17 0x0000739c0d30bcf2 clang::Parser::ParseDeclarationAfterDeclaratorAndAttributes(clang::Declarator&, clang::Parser::ParsedTemplateInfo const&, clang::Parser::ForRangeInit*) + 546
28 libclang-cpp.so.17 0x0000739c0d315e8b clang::Parser::ParseDeclGroup(clang::ParsingDeclSpec&, clang::DeclaratorContext, clang::ParsedAttributes&, clang::SourceLocation*, clang::Parser::ForRangeInit*) + 2715
29 libclang-cpp.so.17 0x0000739c0d3308b5 clang::Parser::ParseSimpleDeclaration(clang::DeclaratorContext, clang::SourceLocation&, clang::ParsedAttributes&, clang::ParsedAttributes&, bool, clang::Parser::ForRangeInit*, clang::SourceLocation*) + 837
30 libclang-cpp.so.17 0x0000739c0d330db2 clang::Parser::ParseDeclaration(clang::DeclaratorContext, clang::SourceLocation&, clang::ParsedAttributes&, clang::ParsedAttributes&, clang::SourceLocation*) + 290
31 libclang-cpp.so.17 0x0000739c0d3b23bc clang::Parser::ParseStatementOrDeclarationAfterAttributes(llvm::SmallVector<clang::Stmt*, 32u>&, clang::Parser::ParsedStmtContext, clang::SourceLocation*, clang::ParsedAttributes&, clang::ParsedAttributes&) + 3356
32 libclang-cpp.so.17 0x0000739c0d3b25cb clang::Parser::ParseStatementOrDeclaration(llvm::SmallVector<clang::Stmt*, 32u>&, clang::Parser::ParsedStmtContext, clang::SourceLocation*) + 331
33 libclang-cpp.so.17 0x0000739c0d3b7675 clang::Parser::ParseCompoundStatementBody(bool) + 1365
34 libclang-cpp.so.17 0x0000739c0d3b93aa clang::Parser::ParseFunctionStatementBody(clang::Decl*, clang::Parser::ParseScope&) + 218
35 libclang-cpp.so.17 0x0000739c0d3ba3fc clang::Parser::ParseFunctionDefinition(clang::ParsingDeclarator&, clang::Parser::ParsedTemplateInfo const&, clang::Parser::LateParsedAttrList*) + 1724
36 libclang-cpp.so.17 0x0000739c0d3161d0 clang::Parser::ParseDeclGroup(clang::ParsingDeclSpec&, clang::DeclaratorContext, clang::ParsedAttributes&, clang::SourceLocation*, clang::Parser::ForRangeInit*) + 3552
37 libclang-cpp.so.17 0x0000739c0d3a8009
38 libclang-cpp.so.17 0x0000739c0d3becc2 clang::Parser::ParseExternalDeclaration(clang::ParsedAttributes&, clang::ParsedAttributes&, clang::ParsingDeclSpec*) + 2594
39 libclang-cpp.so.17 0x0000739c0d3bf0ea clang::Parser::ParseTopLevelDecl(clang::OpaquePtr<clang::DeclGroupRef>&, clang::Sema::ModuleImportState&) + 618
40 libclang-cpp.so.17 0x0000739c0d2fbd99 clang::ParseAST(clang::Sema&, bool, bool) + 601
41 libclang-cpp.so.17 0x0000739c0ebc44f9 clang::FrontendAction::Execute() + 393
42 libclang-cpp.so.17 0x0000739c0ebb0df7 clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) + 391
43 libclang-cpp.so.17 0x0000739c0ec93c92 clang::ExecuteCompilerInvocation(clang::CompilerInstance*) + 450
44 clang++            0x00005670f2222c18 cc1_main(llvm::ArrayRef<char const*>, char const*, void*) + 3928
45 clang++            0x00005670f222810f
46 clang++            0x00005670f2228c2e clang_main(int, char**, llvm::ToolContext const&) + 1950
47 clang++            0x00005670f221ed54 main + 52
48 libc.so.6          0x0000739c04639c88
49 libc.so.6          0x0000739c04639d4c __libc_start_main + 140
50 clang++            0x00005670f221ed95 _start + 37
clang++: error: unable to execute command: Segmentation fault (core dumped)
clang++: error: clang frontend command failed due to signal (use -v to see invocation)
clang version 17.0.6
Target: x86_64-pc-linux-gnu
Thread model: posix
InstalledDir: /usr/bin
clang++: note: diagnostic msg: 
********************

PLEASE ATTACH THE FOLLOWING FILES TO THE BUG REPORT:
Preprocessed source(s) and associated run script(s) are located at:
clang++: note: diagnostic msg: /tmp/clang-bug-3bb744.cpp
clang++: note: diagnostic msg: /tmp/clang-bug-3bb744.sh
clang++: note: diagnostic msg: 

********************

Here are the requested files: clang-bug.zip

[llvmbot]

@llvm/issue-subscribers-c-20

Author: Miro Palmu (MiroPalmu)

Following C++ program results in segfault when compiling with: `clang++ -std=c++2c ~/clang-bug.cpp`

template <typename>
concept trivial_concept = (true);

template <typename>
concept bug = ([]<trivial_concept T = int>() { return true; }());

template <typename>
concept no_bug = ([] { return true; }());

// If this is present, the crash does not happen.
// static_assert(bug<int>);

int main() { 
    bug auto x = 0;
    no_bug auto y = 0;

    [](auto...){}(x, y);
}

My LLVM is obtained from Arch Linux Extra repository.

g++ 14.1.1 is compiles the snipped fine.

Here is the log clang++ outputs:

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: /usr/bin/clang++ -cc1 -triple x86_64-pc-linux-gnu -emit-obj -mrelax-all -dumpdir a- -disable-free -clear-ast-before-backend -disable-llvm-verifier -discard-value-names -main-file-name clang-bug.cpp -mrelocation-model pic -pic-level 2 -pic-is-pie -mframe-pointer=all -fmath-errno -ffp-contract=on -fno-rounding-math -mconstructor-aliases -funwind-tables=2 -target-cpu x86-64 -tune-cpu generic -debugger-tuning=gdb -fcoverage-compilation-dir=/home/pamiro/repos/guilander/build -resource-dir /usr/lib/clang/17 -internal-isystem /usr/bin/../lib64/gcc/x86_64-pc-linux-gnu/14.1.1/../../../../include/c++/14.1.1 -internal-isystem /usr/bin/../lib64/gcc/x86_64-pc-linux-gnu/14.1.1/../../../../include/c++/14.1.1/x86_64-pc-linux-gnu -internal-isystem /usr/bin/../lib64/gcc/x86_64-pc-linux-gnu/14.1.1/../../../../include/c++/14.1.1/backward -internal-isystem /usr/lib/clang/17/include -internal-isystem /usr/local/include -internal-isystem /usr/bin/../lib64/gcc/x86_64-pc-linux-gnu/14.1.1/../../../../x86_64-pc-linux-gnu/include -internal-externc-isystem /include -internal-externc-isystem /usr/include -std=c++2c -fdeprecated-macro -fdebug-compilation-dir=/home/pamiro/repos/guilander/build -ferror-limit 19 -stack-protector 2 -fgnuc-version=4.2.1 -fno-implicit-modules -fcxx-exceptions -fexceptions -fcolor-diagnostics -faddrsig -D__GCC_HAVE_DWARF2_CFI_ASM=1 -o /tmp/clang-bug-e8cc84.o -x c++ /home/pamiro/clang-bug.cpp
1.	/home/pamiro/clang-bug.cpp:14:19: current parser token ';'
2.	/home/pamiro/clang-bug.cpp:13:12: parsing function body 'main'
3.	/home/pamiro/clang-bug.cpp:13:12: in compound statement ('{}')
Stack dump without symbol names (ensure you have llvm-symbolizer in your PATH or set the environment var `LLVM_SYMBOLIZER_PATH` to point to it):
0  libLLVM-17.so      0x0000739c0537bcb0 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) + 64
1  libLLVM-17.so      0x0000739c05378f1d
2  libc.so.6          0x0000739c04650ae0
3  libclang-cpp.so.17 0x0000739c0d6b3feb
4  libclang-cpp.so.17 0x0000739c0d66dc30
5  libclang-cpp.so.17 0x0000739c0d68a866 clang::Expr::EvaluateAsConstantExpr(clang::Expr::EvalResult&, clang::ASTContext const&, clang::Expr::ConstantExprKind) const + 1254
6  libclang-cpp.so.17 0x0000739c0dbfc5a2
7  libclang-cpp.so.17 0x0000739c0dbfcccd
8  libclang-cpp.so.17 0x0000739c0dbfd13b clang::Sema::CheckConstraintSatisfaction(clang::NamedDecl const*, llvm::ArrayRef<clang::Expr const*>, llvm::SmallVectorImpl<clang::Expr*>&, clang::MultiLevelTemplateArgumentList const&, clang::SourceRange, clang::ConstraintSatisfaction&) + 923
9  libclang-cpp.so.17 0x0000739c0dbfdf99 clang::Sema::CheckInstantiatedFunctionTemplateConstraints(clang::SourceLocation, clang::FunctionDecl*, llvm::ArrayRef<clang::TemplateArgument>, clang::ConstraintSatisfaction&) + 793
10 libclang-cpp.so.17 0x0000739c0e0ba11b 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 ()>) + 5019
11 libclang-cpp.so.17 0x0000739c0e0baf91
12 libclang-cpp.so.17 0x0000739c0dad33c1 clang::Sema::runWithSufficientStackSpace(clang::SourceLocation, llvm::function_ref<void ()>) + 113
13 libclang-cpp.so.17 0x0000739c0e0d9f08 clang::Sema::DeduceTemplateArguments(clang::FunctionTemplateDecl*, clang::TemplateArgumentListInfo*, llvm::ArrayRef<clang::Expr*>, clang::FunctionDecl*&, clang::sema::TemplateDeductionInfo&, bool, bool, llvm::function_ref<bool (llvm::ArrayRef<clang::QualType>)>) + 6424
14 libclang-cpp.so.17 0x0000739c0f344185
15 libclang-cpp.so.17 0x0000739c0dfc2b17 clang::Sema::AddMethodCandidate(clang::DeclAccessPair, clang::QualType, clang::Expr::Classification, llvm::ArrayRef<clang::Expr*>, clang::OverloadCandidateSet&, bool, clang::OverloadCandidateParamOrder) + 135
16 libclang-cpp.so.17 0x0000739c0dfda600 clang::Sema::BuildCallToObjectOfClassType(clang::Scope*, clang::Expr*, clang::SourceLocation, llvm::MutableArrayRef<clang::Expr*>, clang::SourceLocation) + 928
17 libclang-cpp.so.17 0x0000739c0dd86437 clang::Sema::ActOnCallExpr(clang::Scope*, clang::Expr*, clang::SourceLocation, llvm::MutableArrayRef<clang::Expr*>, clang::SourceLocation, clang::Expr*) + 87
18 libclang-cpp.so.17 0x0000739c0e105f2a
19 libclang-cpp.so.17 0x0000739c0e0fe11f clang::Sema::SubstExpr(clang::Expr*, clang::MultiLevelTemplateArgumentList const&) + 95
20 libclang-cpp.so.17 0x0000739c0dbfbd73
21 libclang-cpp.so.17 0x0000739c0dbfcccd
22 libclang-cpp.so.17 0x0000739c0dbfd13b clang::Sema::CheckConstraintSatisfaction(clang::NamedDecl const*, llvm::ArrayRef<clang::Expr const*>, llvm::SmallVectorImpl<clang::Expr*>&, clang::MultiLevelTemplateArgumentList const&, clang::SourceRange, clang::ConstraintSatisfaction&) + 923
23 libclang-cpp.so.17 0x0000739c0e0dae60 clang::Sema::DeduceAutoType(clang::TypeLoc, clang::Expr*, clang::QualType&, clang::sema::TemplateDeductionInfo&, bool, bool, clang::TemplateSpecCandidateSet*) + 3888
24 libclang-cpp.so.17 0x0000739c0dc57603 clang::Sema::deduceVarTypeFromInitializer(clang::VarDecl*, clang::DeclarationName, clang::QualType, clang::TypeSourceInfo*, clang::SourceRange, bool, clang::Expr*) + 1331
25 libclang-cpp.so.17 0x0000739c0dc57aa1 clang::Sema::DeduceVariableDeclarationType(clang::VarDecl*, bool, clang::Expr*) + 81
26 libclang-cpp.so.17 0x0000739c0dc72515 clang::Sema::AddInitializerToDecl(clang::Decl*, clang::Expr*, bool) + 437
27 libclang-cpp.so.17 0x0000739c0d30bcf2 clang::Parser::ParseDeclarationAfterDeclaratorAndAttributes(clang::Declarator&, clang::Parser::ParsedTemplateInfo const&, clang::Parser::ForRangeInit*) + 546
28 libclang-cpp.so.17 0x0000739c0d315e8b clang::Parser::ParseDeclGroup(clang::ParsingDeclSpec&, clang::DeclaratorContext, clang::ParsedAttributes&, clang::SourceLocation*, clang::Parser::ForRangeInit*) + 2715
29 libclang-cpp.so.17 0x0000739c0d3308b5 clang::Parser::ParseSimpleDeclaration(clang::DeclaratorContext, clang::SourceLocation&, clang::ParsedAttributes&, clang::ParsedAttributes&, bool, clang::Parser::ForRangeInit*, clang::SourceLocation*) + 837
30 libclang-cpp.so.17 0x0000739c0d330db2 clang::Parser::ParseDeclaration(clang::DeclaratorContext, clang::SourceLocation&, clang::ParsedAttributes&, clang::ParsedAttributes&, clang::SourceLocation*) + 290
31 libclang-cpp.so.17 0x0000739c0d3b23bc clang::Parser::ParseStatementOrDeclarationAfterAttributes(llvm::SmallVector<clang::Stmt*, 32u>&, clang::Parser::ParsedStmtContext, clang::SourceLocation*, clang::ParsedAttributes&, clang::ParsedAttributes&) + 3356
32 libclang-cpp.so.17 0x0000739c0d3b25cb clang::Parser::ParseStatementOrDeclaration(llvm::SmallVector<clang::Stmt*, 32u>&, clang::Parser::ParsedStmtContext, clang::SourceLocation*) + 331
33 libclang-cpp.so.17 0x0000739c0d3b7675 clang::Parser::ParseCompoundStatementBody(bool) + 1365
34 libclang-cpp.so.17 0x0000739c0d3b93aa clang::Parser::ParseFunctionStatementBody(clang::Decl*, clang::Parser::ParseScope&) + 218
35 libclang-cpp.so.17 0x0000739c0d3ba3fc clang::Parser::ParseFunctionDefinition(clang::ParsingDeclarator&, clang::Parser::ParsedTemplateInfo const&, clang::Parser::LateParsedAttrList*) + 1724
36 libclang-cpp.so.17 0x0000739c0d3161d0 clang::Parser::ParseDeclGroup(clang::ParsingDeclSpec&, clang::DeclaratorContext, clang::ParsedAttributes&, clang::SourceLocation*, clang::Parser::ForRangeInit*) + 3552
37 libclang-cpp.so.17 0x0000739c0d3a8009
38 libclang-cpp.so.17 0x0000739c0d3becc2 clang::Parser::ParseExternalDeclaration(clang::ParsedAttributes&, clang::ParsedAttributes&, clang::ParsingDeclSpec*) + 2594
39 libclang-cpp.so.17 0x0000739c0d3bf0ea clang::Parser::ParseTopLevelDecl(clang::OpaquePtr<clang::DeclGroupRef>&, clang::Sema::ModuleImportState&) + 618
40 libclang-cpp.so.17 0x0000739c0d2fbd99 clang::ParseAST(clang::Sema&, bool, bool) + 601
41 libclang-cpp.so.17 0x0000739c0ebc44f9 clang::FrontendAction::Execute() + 393
42 libclang-cpp.so.17 0x0000739c0ebb0df7 clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) + 391
43 libclang-cpp.so.17 0x0000739c0ec93c92 clang::ExecuteCompilerInvocation(clang::CompilerInstance*) + 450
44 clang++            0x00005670f2222c18 cc1_main(llvm::ArrayRef<char const*>, char const*, void*) + 3928
45 clang++            0x00005670f222810f
46 clang++            0x00005670f2228c2e clang_main(int, char**, llvm::ToolContext const&) + 1950
47 clang++            0x00005670f221ed54 main + 52
48 libc.so.6          0x0000739c04639c88
49 libc.so.6          0x0000739c04639d4c __libc_start_main + 140
50 clang++            0x00005670f221ed95 _start + 37
clang++: error: unable to execute command: Segmentation fault (core dumped)
clang++: error: clang frontend command failed due to signal (use -v to see invocation)
clang version 17.0.6
Target: x86_64-pc-linux-gnu
Thread model: posix
InstalledDir: /usr/bin
clang++: note: diagnostic msg: 
********************

PLEASE ATTACH THE FOLLOWING FILES TO THE BUG REPORT:
Preprocessed source(s) and associated run script(s) are located at:
clang++: note: diagnostic msg: /tmp/clang-bug-3bb744.cpp
clang++: note: diagnostic msg: /tmp/clang-bug-3bb744.sh
clang++: note: diagnostic msg: 

********************

Here are the requested files: clang-bug.zip

[EugeneZelenko]

Could you please try 18 or main branch? https://godbolt.org should be helpful.

[MiroPalmu]

Trunk clang crashes in Compiler Explorer.

clang version 19.0.0git (https://github.com/llvm/llvm-project.git 3cee5672fd645cd58b8c4ee6187f10b509a34d77)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /opt/compiler-explorer/clang-trunk-20240530/bin
Compiler returned: 0

Stack dump:
0.	Program arguments: /opt/compiler-explorer/clang-trunk/bin/clang++ -gdwarf-4 -g -o /app/output.s -mllvm --x86-asm-syntax=intel -S --gcc-toolchain=/opt/compiler-explorer/gcc-snapshot -fcolor-diagnostics -fno-crash-diagnostics -std=c++2c <source>
1.	<source>:14:19: current parser token ';'
2.	<source>:13:12: parsing function body 'main'
3.	<source>:13:12: in compound statement ('{}')
 #0 0x0000000003769528 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x3769528)
 #1 0x0000000003767674 llvm::sys::CleanupOnSignal(unsigned long) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x3767674)
 #2 0x00000000036b2be8 CrashRecoverySignalHandler(int) CrashRecoveryContext.cpp:0:0
 #3 0x0000720e07c42520 (/lib/x86_64-linux-gnu/libc.so.6+0x42520)
 #4 0x000000000716fd65 clang::StmtVisitorBase<llvm::make_const_ptr, (anonymous namespace)::IntExprEvaluator, bool>::Visit(clang::Stmt const*) ExprConstant.cpp:0:0
 #5 0x0000000007154b0e Evaluate(clang::APValue&, (anonymous namespace)::EvalInfo&, clang::Expr const*) ExprConstant.cpp:0:0
 #6 0x0000000007177576 EvaluateInPlace(clang::APValue&, (anonymous namespace)::EvalInfo&, (anonymous namespace)::LValue const&, clang::Expr const*, bool) (.constprop.0) ExprConstant.cpp:0:0
 #7 0x0000000007185c8a clang::Expr::EvaluateAsConstantExpr(clang::Expr::EvalResult&, clang::ASTContext const&, clang::Expr::ConstantExprKind) const (/opt/compiler-explorer/clang-trunk/bin/clang+++0x7185c8a)
 #8 0x00000000061d2ddd clang::ActionResult<clang::Expr*, true> calculateConstraintSatisfaction<calculateConstraintSatisfaction(clang::Sema&, clang::NamedDecl const*, clang::SourceLocation, clang::MultiLevelTemplateArgumentList const&, clang::Expr const*, clang::ConstraintSatisfaction&)::'lambda'(clang::Expr const*)>(clang::Sema&, clang::Expr const*, clang::ConstraintSatisfaction&, calculateConstraintSatisfaction(clang::Sema&, clang::NamedDecl const*, clang::SourceLocation, clang::MultiLevelTemplateArgumentList const&, clang::Expr const*, clang::ConstraintSatisfaction&)::'lambda'(clang::Expr const*)&&) SemaConcept.cpp:0:0
 #9 0x00000000061d33e8 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
#10 0x00000000061d3988 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-trunk/bin/clang+++0x61d3988)
#11 0x00000000061d45f7 clang::Sema::CheckInstantiatedFunctionTemplateConstraints(clang::SourceLocation, clang::FunctionDecl*, llvm::ArrayRef<clang::TemplateArgument>, clang::ConstraintSatisfaction&) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x61d45f7)
#12 0x0000000006a9082a 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 0x0000000006a9133a 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 0x0000000006064871 clang::Sema::runWithSufficientStackSpace(clang::SourceLocation, llvm::function_ref<void ()>) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x6064871)
#15 0x0000000006aa7af3 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-trunk/bin/clang+++0x6aa7af3)
#16 0x000000000687bfff 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 0x000000000687c49d clang::Sema::AddMethodCandidate(clang::DeclAccessPair, clang::QualType, clang::Expr::Classification, llvm::ArrayRef<clang::Expr*>, clang::OverloadCandidateSet&, bool, clang::OverloadCandidateParamOrder) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x687c49d)
#18 0x0000000006896f83 clang::Sema::BuildCallToObjectOfClassType(clang::Scope*, clang::Expr*, clang::SourceLocation, llvm::MutableArrayRef<clang::Expr*>, clang::SourceLocation) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x6896f83)
#19 0x00000000064dac8b clang::Sema::BuildCallExpr(clang::Scope*, clang::Expr*, clang::SourceLocation, llvm::MutableArrayRef<clang::Expr*>, clang::SourceLocation, clang::Expr*, bool, bool) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x64dac8b)
#20 0x00000000064e077c clang::Sema::ActOnCallExpr(clang::Scope*, clang::Expr*, clang::SourceLocation, llvm::MutableArrayRef<clang::Expr*>, clang::SourceLocation, clang::Expr*) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x64e077c)
#21 0x0000000006adbd77 clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformCallExpr(clang::CallExpr*) SemaTemplateInstantiate.cpp:0:0
#22 0x0000000006ad2841 clang::TreeTransform<(anonymous namespace)::TemplateInstantiator>::TransformExpr(clang::Expr*) SemaTemplateInstantiate.cpp:0:0
#23 0x0000000006ade05b clang::Sema::SubstConstraintExpr(clang::Expr*, clang::MultiLevelTemplateArgumentList const&) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x6ade05b)
#24 0x00000000061d133e calculateConstraintSatisfaction(clang::Sema&, clang::NamedDecl const*, clang::SourceLocation, clang::MultiLevelTemplateArgumentList const&, clang::Expr const*, clang::ConstraintSatisfaction&)::'lambda'(clang::Expr const*)::operator()(clang::Expr const*) const SemaConcept.cpp:0:0
#25 0x00000000061d295d clang::ActionResult<clang::Expr*, true> calculateConstraintSatisfaction<calculateConstraintSatisfaction(clang::Sema&, clang::NamedDecl const*, clang::SourceLocation, clang::MultiLevelTemplateArgumentList const&, clang::Expr const*, clang::ConstraintSatisfaction&)::'lambda'(clang::Expr const*)>(clang::Sema&, clang::Expr const*, clang::ConstraintSatisfaction&, calculateConstraintSatisfaction(clang::Sema&, clang::NamedDecl const*, clang::SourceLocation, clang::MultiLevelTemplateArgumentList const&, clang::Expr const*, clang::ConstraintSatisfaction&)::'lambda'(clang::Expr const*)&&) SemaConcept.cpp:0:0
#26 0x00000000061d33e8 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
#27 0x00000000061d3988 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-trunk/bin/clang+++0x61d3988)
#28 0x0000000006a8c02f clang::Sema::DeduceAutoType(clang::TypeLoc, clang::Expr*, clang::QualType&, clang::sema::TemplateDeductionInfo&, bool, bool, clang::TemplateSpecCandidateSet*) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x6a8c02f)
#29 0x00000000062494fd clang::Sema::deduceVarTypeFromInitializer(clang::VarDecl*, clang::DeclarationName, clang::QualType, clang::TypeSourceInfo*, clang::SourceRange, bool, clang::Expr*) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x62494fd)
#30 0x00000000062630cb clang::Sema::DeduceVariableDeclarationType(clang::VarDecl*, bool, clang::Expr*) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x62630cb)
#31 0x000000000628eda4 clang::Sema::AddInitializerToDecl(clang::Decl*, clang::Expr*, bool) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x628eda4)
#32 0x0000000005f27bfa clang::Parser::ParseDeclarationAfterDeclaratorAndAttributes(clang::Declarator&, clang::Parser::ParsedTemplateInfo const&, clang::Parser::ForRangeInit*) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x5f27bfa)
#33 0x0000000005f3b95c clang::Parser::ParseDeclGroup(clang::ParsingDeclSpec&, clang::DeclaratorContext, clang::ParsedAttributes&, clang::Parser::ParsedTemplateInfo&, clang::SourceLocation*, clang::Parser::ForRangeInit*) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x5f3b95c)
#34 0x0000000005f3f51a clang::Parser::ParseSimpleDeclaration(clang::DeclaratorContext, clang::SourceLocation&, clang::ParsedAttributes&, clang::ParsedAttributes&, bool, clang::Parser::ForRangeInit*, clang::SourceLocation*) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x5f3f51a)
#35 0x0000000005f3fa3f clang::Parser::ParseDeclaration(clang::DeclaratorContext, clang::SourceLocation&, clang::ParsedAttributes&, clang::ParsedAttributes&, clang::SourceLocation*) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x5f3fa3f)
#36 0x0000000005ff37df clang::Parser::ParseStatementOrDeclarationAfterAttributes(llvm::SmallVector<clang::Stmt*, 32u>&, clang::Parser::ParsedStmtContext, clang::SourceLocation*, clang::ParsedAttributes&, clang::ParsedAttributes&) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x5ff37df)
#37 0x0000000005ff40f7 clang::Parser::ParseStatementOrDeclaration(llvm::SmallVector<clang::Stmt*, 32u>&, clang::Parser::ParsedStmtContext, clang::SourceLocation*) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x5ff40f7)
#38 0x0000000005ff4f31 clang::Parser::ParseCompoundStatementBody(bool) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x5ff4f31)
#39 0x0000000005ff749a clang::Parser::ParseFunctionStatementBody(clang::Decl*, clang::Parser::ParseScope&) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x5ff749a)
#40 0x0000000005ef43ab clang::Parser::ParseFunctionDefinition(clang::ParsingDeclarator&, clang::Parser::ParsedTemplateInfo const&, clang::Parser::LateParsedAttrList*) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x5ef43ab)
#41 0x0000000005f3bdee clang::Parser::ParseDeclGroup(clang::ParsingDeclSpec&, clang::DeclaratorContext, clang::ParsedAttributes&, clang::Parser::ParsedTemplateInfo&, clang::SourceLocation*, clang::Parser::ForRangeInit*) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x5f3bdee)
#42 0x0000000005eee3d7 clang::Parser::ParseDeclOrFunctionDefInternal(clang::ParsedAttributes&, clang::ParsedAttributes&, clang::ParsingDeclSpec&, clang::AccessSpecifier) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x5eee3d7)
#43 0x0000000005eef2c3 clang::Parser::ParseDeclarationOrFunctionDefinition(clang::ParsedAttributes&, clang::ParsedAttributes&, clang::ParsingDeclSpec*, clang::AccessSpecifier) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x5eef2c3)
#44 0x0000000005ef794a clang::Parser::ParseExternalDeclaration(clang::ParsedAttributes&, clang::ParsedAttributes&, clang::ParsingDeclSpec*) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x5ef794a)
#45 0x0000000005ef9737 clang::Parser::ParseTopLevelDecl(clang::OpaquePtr<clang::DeclGroupRef>&, clang::Sema::ModuleImportState&) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x5ef9737)
#46 0x0000000005ee888a clang::ParseAST(clang::Sema&, bool, bool) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x5ee888a)
#47 0x0000000003fed0ed clang::CodeGenAction::ExecuteAction() (/opt/compiler-explorer/clang-trunk/bin/clang+++0x3fed0ed)
#48 0x000000000428f3c1 clang::FrontendAction::Execute() (/opt/compiler-explorer/clang-trunk/bin/clang+++0x428f3c1)
#49 0x000000000421281b clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x421281b)
#50 0x0000000004376163 clang::ExecuteCompilerInvocation(clang::CompilerInstance*) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x4376163)
#51 0x0000000000c64f7c cc1_main(llvm::ArrayRef<char const*>, char const*, void*) (/opt/compiler-explorer/clang-trunk/bin/clang+++0xc64f7c)
#52 0x0000000000c5ee6d ExecuteCC1Tool(llvm::SmallVectorImpl<char const*>&, llvm::ToolContext const&) driver.cpp:0:0
#53 0x00000000040363f9 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
#54 0x00000000036b3003 llvm::CrashRecoveryContext::RunSafely(llvm::function_ref<void ()>) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x36b3003)
#55 0x0000000004036619 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
#56 0x0000000003ffc295 clang::driver::Compilation::ExecuteCommand(clang::driver::Command const&, clang::driver::Command const*&, bool) const (/opt/compiler-explorer/clang-trunk/bin/clang+++0x3ffc295)
#57 0x0000000003ffcc6d clang::driver::Compilation::ExecuteJobs(clang::driver::JobList const&, llvm::SmallVectorImpl<std::pair<int, clang::driver::Command const*>>&, bool) const (/opt/compiler-explorer/clang-trunk/bin/clang+++0x3ffcc6d)
#58 0x0000000004006b8c clang::driver::Driver::ExecuteCompilation(clang::driver::Compilation&, llvm::SmallVectorImpl<std::pair<int, clang::driver::Command const*>>&) (/opt/compiler-explorer/clang-trunk/bin/clang+++0x4006b8c)
#59 0x0000000000c62371 clang_main(int, char**, llvm::ToolContext const&) (/opt/compiler-explorer/clang-trunk/bin/clang+++0xc62371)
#60 0x0000000000b401c4 main (/opt/compiler-explorer/clang-trunk/bin/clang+++0xb401c4)
#61 0x0000720e07c29d90 (/lib/x86_64-linux-gnu/libc.so.6+0x29d90)
#62 0x0000720e07c29e40 __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x29e40)
#63 0x0000000000c5e90e _start (/opt/compiler-explorer/clang-trunk/bin/clang+++0xc5e90e)
clang++: error: clang frontend command failed with exit code 139 (use -v to see invocation)
Compiler returned: 139

[zyn0217]

template <typename>
concept trivial_concept = true;

template <typename T>
concept bug = []<trivial_concept U = int>() { return true; }();

Per our type constraint substitution algorithm, we're supposed to extract the argument for T and U when evaluating bug. However, we can't make it in getTemplateInstantiationArgs because there's nothing left to look into at the time the call to the lambda being established - the parent DC of the lambda is not the concept DC but rather the TU.

@erichkeane do you have any ideas? I suppose we should preserve the argument for T in a somewhat ImplicitConceptSpecializationDecl but I have no idea how we can connect it to a LambdaExpr.

[zyn0217]

Interestingly enough, if we had instantiated the bug earlier, then we would have CXXRecordDecl::getLambdaContextDecl() pointed to an ImplicitConceptSpecializationDecl, which then helps us find out outer arguments for T.

So, we probably failed to propagate contexts to lambdaData.ContextDecl in some scenarios?