crash with 'using enum' in combination with bitwise OR and brackets

[benjymous]

The following snippet causes llvm to crash:

struct Wrap {
enum Things {
    Value1,
    Value2
};
};

using enum Wrap::Things;

int main() {
    int i = ( Value1 | Value2 );
}

Removing the brackets

    int i = Value1 | Value2;

is a workaround

It appears to be related to #54746

original source, preprocessed file, run script, and stdout log attached:
llvm_crash.zip

godbolt link:
https://godbolt.org/z/8qjjajPn9

[llvmbot]

@llvm/issue-subscribers-clang-frontend

[shafik]

This also crashes on trunk: https://godbolt.org/z/Khfrfj9ca

stack trace:

PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace, preprocessed source, and associated run script.
Stack dump:
0.	Program arguments: /opt/compiler-explorer/clang-assertions-trunk-20220928/bin/clang-16 -cc1 -triple x86_64-unknown-linux-gnu -emit-obj -mrelax-all --mrelax-relocations -disable-free -clear-ast-before-backend -main-file-name example.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 -mllvm -treat-scalable-fixed-error-as-warning -debug-info-kind=constructor -dwarf-version=4 -debugger-tuning=gdb -fcoverage-compilation-dir=/app -resource-dir /opt/compiler-explorer/clang-assertions-trunk-20220928/lib/clang/16.0.0 -internal-isystem /opt/compiler-explorer/gcc-snapshot/lib/gcc/x86_64-linux-gnu/13.0.0/../../../../include/c++/13.0.0 -internal-isystem /opt/compiler-explorer/gcc-snapshot/lib/gcc/x86_64-linux-gnu/13.0.0/../../../../include/c++/13.0.0/x86_64-linux-gnu -internal-isystem /opt/compiler-explorer/gcc-snapshot/lib/gcc/x86_64-linux-gnu/13.0.0/../../../../include/c++/13.0.0/backward -internal-isystem /opt/compiler-explorer/clang-assertions-trunk-20220928/lib/clang/16.0.0/include -internal-isystem /usr/local/include -internal-isystem /opt/compiler-explorer/gcc-snapshot/lib/gcc/x86_64-linux-gnu/13.0.0/../../../../x86_64-linux-gnu/include -internal-externc-isystem /usr/include/x86_64-linux-gnu -internal-externc-isystem /include -internal-externc-isystem /usr/include -std=c++20 -fdeprecated-macro -fdebug-compilation-dir=/app -ferror-limit 19 -fgnuc-version=4.2.1 -fno-implicit-modules -fcxx-exceptions -fexceptions -fcolor-diagnostics -faddrsig -D__GCC_HAVE_DWARF2_CFI_ASM=1 -o /tmp/example-c825ec.o -x c++ <source>
1.	<source>:11:28: current parser token ')'
2.	<source>:10:12: parsing function body 'main'
3.	<source>:10:12: in compound statement ('{}')
 #0 0x0000557aa6384624 PrintStackTraceSignalHandler(void*) Signals.cpp:0:0
 #1 0x0000557aa6381de4 SignalHandler(int) Signals.cpp:0:0
 #2 0x00007f414bcf4420 __restore_rt (/lib/x86_64-linux-gnu/libpthread.so.0+0x14420)
 #3 0x0000557aa901dbc8 clang::Sema::FindAssociatedClassesAndNamespaces(clang::SourceLocation, llvm::ArrayRef<clang::Expr*>, llvm::SmallSetVector<clang::DeclContext*, 16u>&, llvm::SmallSetVector<clang::CXXRecordDecl*, 16u>&) (/opt/compiler-explorer/clang-assertions-trunk-20220928/bin/clang-16+0x6c0cbc8)
 #4 0x0000557aa901ea98 clang::Sema::ArgumentDependentLookup(clang::DeclarationName, clang::SourceLocation, llvm::ArrayRef<clang::Expr*>, clang::ADLResult&) (/opt/compiler-explorer/clang-assertions-trunk-20220928/bin/clang-16+0x6c0da98)
 #5 0x0000557aa9174c61 clang::Sema::AddArgumentDependentLookupCandidates(clang::DeclarationName, clang::SourceLocation, llvm::ArrayRef<clang::Expr*>, clang::TemplateArgumentListInfo*, clang::OverloadCandidateSet&, bool) (/opt/compiler-explorer/clang-assertions-trunk-20220928/bin/clang-16+0x6d63c61)
 #6 0x0000557aa9176be0 clang::Sema::LookupOverloadedBinOp(clang::OverloadCandidateSet&, clang::OverloadedOperatorKind, clang::UnresolvedSetImpl const&, llvm::ArrayRef<clang::Expr*>, bool) (/opt/compiler-explorer/clang-assertions-trunk-20220928/bin/clang-16+0x6d65be0)
 #7 0x0000557aa917a03f clang::Sema::CreateOverloadedBinOp(clang::SourceLocation, clang::BinaryOperatorKind, clang::UnresolvedSetImpl const&, clang::Expr*, clang::Expr*, bool, bool, clang::FunctionDecl*) (/opt/compiler-explorer/clang-assertions-trunk-20220928/bin/clang-16+0x6d6903f)
 #8 0x0000557aa8dd2cfd BuildOverloadedBinOp(clang::Sema&, clang::Scope*, clang::SourceLocation, clang::BinaryOperatorKind, clang::Expr*, clang::Expr*) SemaExpr.cpp:0:0
 #9 0x0000557aa8e397a7 clang::Sema::BuildBinOp(clang::Scope*, clang::SourceLocation, clang::BinaryOperatorKind, clang::Expr*, clang::Expr*) (/opt/compiler-explorer/clang-assertions-trunk-20220928/bin/clang-16+0x6a287a7)
#10 0x0000557aa8e3a081 clang::Sema::ActOnBinOp(clang::Scope*, clang::SourceLocation, clang::tok::TokenKind, clang::Expr*, clang::Expr*) (/opt/compiler-explorer/clang-assertions-trunk-20220928/bin/clang-16+0x6a29081)
#11 0x0000557aa8964fb0 clang::Parser::ParseRHSOfBinaryExpression(clang::ActionResult<clang::Expr*, true>, clang::prec::Level) (/opt/compiler-explorer/clang-assertions-trunk-20220928/bin/clang-16+0x6553fb0)
#12 0x0000557aa896774d clang::Parser::ParseExpression(clang::Parser::TypeCastState) (/opt/compiler-explorer/clang-assertions-trunk-20220928/bin/clang-16+0x655674d)
#13 0x0000557aa896badd clang::Parser::ParseParenExpression(clang::Parser::ParenParseOption&, bool, bool, clang::OpaquePtr<clang::QualType>&, clang::SourceLocation&) (/opt/compiler-explorer/clang-assertions-trunk-20220928/bin/clang-16+0x655aadd)
#14 0x0000557aa89616b7 clang::Parser::ParseCastExpression(clang::Parser::CastParseKind, bool, bool&, clang::Parser::TypeCastState, bool, bool*) (/opt/compiler-explorer/clang-assertions-trunk-20220928/bin/clang-16+0x65506b7)
#15 0x0000557aa896346b clang::Parser::ParseCastExpression(clang::Parser::CastParseKind, bool, clang::Parser::TypeCastState, bool, bool*) (/opt/compiler-explorer/clang-assertions-trunk-20220928/bin/clang-16+0x655246b)
#16 0x0000557aa896350d clang::Parser::ParseAssignmentExpression(clang::Parser::TypeCastState) (/opt/compiler-explorer/clang-assertions-trunk-20220928/bin/clang-16+0x655250d)
#17 0x0000557aa896774d clang::Parser::ParseExpression(clang::Parser::TypeCastState) (/opt/compiler-explorer/clang-assertions-trunk-20220928/bin/clang-16+0x655674d)
#18 0x0000557aa89d3d8a clang::Parser::ParseReturnStatement() (/opt/compiler-explorer/clang-assertions-trunk-20220928/bin/clang-16+0x65c2d8a)
#19 0x0000557aa89d6e1c clang::Parser::ParseStatementOrDeclarationAfterAttributes(llvm::SmallVector<clang::Stmt*, 32u>&, clang::Parser::ParsedStmtContext, clang::SourceLocation*, clang::ParsedAttributes&, clang::ParsedAttributes&) (/opt/compiler-explorer/clang-assertions-trunk-20220928/bin/clang-16+0x65c5e1c)
#20 0x0000557aa89d85b5 clang::Parser::ParseStatementOrDeclaration(llvm::SmallVector<clang::Stmt*, 32u>&, clang::Parser::ParsedStmtContext, clang::SourceLocation*) (/opt/compiler-explorer/clang-assertions-trunk-20220928/bin/clang-16+0x65c75b5)
#21 0x0000557aa89d961a clang::Parser::ParseCompoundStatementBody(bool) (/opt/compiler-explorer/clang-assertions-trunk-20220928/bin/clang-16+0x65c861a)
#22 0x0000557aa89daf2a clang::Parser::ParseFunctionStatementBody(clang::Decl*, clang::Parser::ParseScope&) (/opt/compiler-explorer/clang-assertions-trunk-20220928/bin/clang-16+0x65c9f2a)
#23 0x0000557aa890c1e1 clang::Parser::ParseFunctionDefinition(clang::ParsingDeclarator&, clang::Parser::ParsedTemplateInfo const&, clang::Parser::LateParsedAttrList*) (/opt/compiler-explorer/clang-assertions-trunk-20220928/bin/clang-16+0x64fb1e1)
#24 0x0000557aa893ff5f clang::Parser::ParseDeclGroup(clang::ParsingDeclSpec&, clang::DeclaratorContext, clang::ParsedAttributes&, clang::SourceLocation*, clang::Parser::ForRangeInit*) (/opt/compiler-explorer/clang-assertions-trunk-20220928/bin/clang-16+0x652ef5f)
#25 0x0000557aa8900d69 clang::Parser::ParseDeclOrFunctionDefInternal(clang::ParsedAttributes&, clang::ParsingDeclSpec&, clang::AccessSpecifier) (/opt/compiler-explorer/clang-assertions-trunk-20220928/bin/clang-16+0x64efd69)
#26 0x0000557aa89015c0 clang::Parser::ParseDeclarationOrFunctionDefinition(clang::ParsedAttributes&, clang::ParsingDeclSpec*, clang::AccessSpecifier) (.part.0) Parser.cpp:0:0
#27 0x0000557aa8906d7b clang::Parser::ParseExternalDeclaration(clang::ParsedAttributes&, clang::ParsingDeclSpec*) (/opt/compiler-explorer/clang-assertions-trunk-20220928/bin/clang-16+0x64f5d7b)
#28 0x0000557aa8907c0a clang::Parser::ParseTopLevelDecl(clang::OpaquePtr<clang::DeclGroupRef>&, clang::Sema::ModuleImportState&) (/opt/compiler-explorer/clang-assertions-trunk-20220928/bin/clang-16+0x64f6c0a)
#29 0x0000557aa88fc0ba clang::ParseAST(clang::Sema&, bool, bool) (/opt/compiler-explorer/clang-assertions-trunk-20220928/bin/clang-16+0x64eb0ba)
#30 0x0000557aa769fbb8 clang::CodeGenAction::ExecuteAction() (/opt/compiler-explorer/clang-assertions-trunk-20220928/bin/clang-16+0x528ebb8)
#31 0x0000557aa6f390d9 clang::FrontendAction::Execute() (/opt/compiler-explorer/clang-assertions-trunk-20220928/bin/clang-16+0x4b280d9)
#32 0x0000557aa6ec093e clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) (/opt/compiler-explorer/clang-assertions-trunk-20220928/bin/clang-16+0x4aaf93e)
#33 0x0000557aa701e683 clang::ExecuteCompilerInvocation(clang::CompilerInstance*) (/opt/compiler-explorer/clang-assertions-trunk-20220928/bin/clang-16+0x4c0d683)
#34 0x0000557aa3837df4 cc1_main(llvm::ArrayRef<char const*>, char const*, void*) (/opt/compiler-explorer/clang-assertions-trunk-20220928/bin/clang-16+0x1426df4)
#35 0x0000557aa3830ed8 ExecuteCC1Tool(llvm::SmallVectorImpl<char const*>&) driver.cpp:0:0
#36 0x0000557aa3834395 clang_main(int, char**) (/opt/compiler-explorer/clang-assertions-trunk-20220928/bin/clang-16+0x1423395)
#37 0x00007f414b7a2083 __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x24083)
#38 0x0000557aa3830ace _start (/opt/compiler-explorer/clang-assertions-trunk-20220928/bin/clang-16+0x141face)
clang-16: error: unable to execute command: Segmentation fault (core dumped)
clang-16: error: clang frontend command failed due to signal (use -v to see invocation)

[shafik]

So it looks like we are hitting a weird edge case in Sema::ClassifyName(...) where we should be returning NameClassification::NonType but because of using enum combined with the fact that the enum is a member of a class we are hitting this !FirstDecl->isCXXClassMember() and skipping.

We end up then treating it like an overload and overload set:

 return NameClassification::OverloadSet(UnresolvedLookupExpr::Create(
      Context, Result.getNamingClass(), SS.getWithLocInContext(Context),
      Result.getLookupNameInfo(), ADL, Result.isOverloadedResult(),
      Result.begin(), Result.end()));

and this will fail later on when FindAssociatedClassesAndNamespaces(...) tries to treat it as a FunctionDecl:

   // Look through any using declarations to find the underlying function.
      const FunctionDecl *FDecl = D->getUnderlyingDecl()->getAsFunction();

      // Add the classes and namespaces associated with the parameter
      // types and return type of this function.
      addAssociatedClassesAndNamespaces(Result, FDecl->getType());

I think the right fix is to modify the check in Sema::ClassifyName(...) to allow an EnumDeclConstant to be treated as a NonType even if it is a class member:

if (Result.isSingleResult() && !ADL && (!FirstDecl->isCXXClassMember() || isa<EnumConstantDecl>(FirstDecl)) )
    return NameClassification::NonType(Result.getRepresentativeDecl());

I ran check-clang and this passes but I need to think about it a little more.

[shafik]

PR: https://reviews.llvm.org/D138091

[llvmbot]

@llvm/issue-subscribers-c-20