Clang frontend assertion failure when parsing function with certain pragma combinations #169910
Description
Link for quick verification: https://godbolt.org/z/EvsxTrnbj
typedef struct {
int m_keys[8];
} map;
map create_map() {
map result;
#pragma clang loop unroll(disable)
#pragma STDC FENV_ACCESS ON
for (int i = 0; i < 8; i++) {
result.m_keys[i] = 0;
}
return result;
}When I put #pragma STDC FENV_ACCESS ON at the wrong place, the compiler went crash.
The stack dump:
clang-21: /workspace/install/llvm/src/llvm-project/clang/lib/Parse/ParseStmt.cpp:81: clang::StmtResult clang::Parser::ParseStatementOrDeclaration(StmtVector&, ParsedStmtContext, clang::SourceLocation*): Assertion `(CXX11Attrs.empty() || Res.isInvalid() || Res.isUsable()) && "attributes on empty statement"' failed.
PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace, preprocessed source, and associated run script.
Stack dump:
0. Program arguments: /workspace/install/llvm/build_21.1.4/bin/clang-21 -cc1 -triple x86_64-unknown-linux-gnu -O3 -emit-obj -dumpdir a- -disable-free -clear-ast-before-backend -main-file-name 34412.fuzz -mrelocation-model pic -pic-level 2 -pic-is-pie -mframe-pointer=none -fmath-errno -ffp-contract=on -fno-rounding-math -mconstructor-aliases -funwind-tables=2 -target-cpu x86-64 -tune-cpu generic -debugger-tuning=gdb -fdebug-compilation-dir=/workspace/exps -fcoverage-compilation-dir=/workspace/exps -resource-dir /workspace/install/llvm/build_21.1.4/lib/clang/21 -internal-isystem /workspace/install/llvm/build_21.1.4/lib/clang/21/include -internal-isystem /usr/local/include -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/13/../../../../x86_64-linux-gnu/include -internal-externc-isystem /usr/include/x86_64-linux-gnu -internal-externc-isystem /include -internal-externc-isystem /usr/include -ferror-limit 19 -fmessage-length=167 -fgnuc-version=4.2.1 -fskip-odr-check-in-gmf -fcolor-diagnostics -vectorize-loops -vectorize-slp -faddrsig -D__GCC_HAVE_DWARF2_CFI_ASM=1 -o /tmp/34412-039020.o -x c /workspace/exps/featurefuzz/generate_feature_fine_tuning_qwen_4b_choose_3_1_exp/cases/34412.fuzz
1. /workspace/exps/featurefuzz/generate_feature_fine_tuning_qwen_4b_choose_3_1_exp/cases/34412.fuzz:35:14: at annotation token
2. /workspace/exps/featurefuzz/generate_feature_fine_tuning_qwen_4b_choose_3_1_exp/cases/34412.fuzz:30:18: parsing function body 'create_map'
3. /workspace/exps/featurefuzz/generate_feature_fine_tuning_qwen_4b_choose_3_1_exp/cases/34412.fuzz:30:18: in compound statement ('{}')
#0 0x00006181b3047c2a llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/workspace/install/llvm/build_21.1.4/bin/clang-21+0x9691c2a)
#1 0x00006181b3048457 PrintStackTraceSignalHandler(void*) Signals.cpp:0:0
#2 0x00006181b3041f57 llvm::sys::RunSignalHandlers() (/workspace/install/llvm/build_21.1.4/bin/clang-21+0x968bf57)
#3 0x00006181b30421c7 SignalHandler(int, siginfo_t*, void*) Signals.cpp:0:0
#4 0x0000711b9b10e330 (/lib/x86_64-linux-gnu/libc.so.6+0x45330)
#5 0x0000711b9b167b2c __pthread_kill_implementation ./nptl/pthread_kill.c:44:76
#6 0x0000711b9b167b2c __pthread_kill_internal ./nptl/pthread_kill.c:78:10
#7 0x0000711b9b167b2c pthread_kill ./nptl/pthread_kill.c:89:10
#8 0x0000711b9b10e27e raise ./signal/../sysdeps/posix/raise.c:27:6
#9 0x0000711b9b0f18ff abort ./stdlib/abort.c:81:7
#10 0x0000711b9b0f181b _nl_load_domain ./intl/loadmsgcat.c:1177:9
#11 0x0000711b9b104517 (/lib/x86_64-linux-gnu/libc.so.6+0x3b517)
#12 0x00006181b6697607 clang::Parser::ParseStatementOrDeclaration(llvm::SmallVector<clang::Stmt*, 24u>&, clang::Parser::ParsedStmtContext, clang::SourceLocation*) (/workspace/install/llvm/build_21.1.4/bin/clang-21+0xcce1607)
#13 0x00006181b6698e9e clang::Parser::ParseCompoundStatementBody(bool) (/workspace/install/llvm/build_21.1.4/bin/clang-21+0xcce2e9e)
#14 0x00006181b66998c2 clang::Parser::ParseFunctionStatementBody(clang::Decl*, clang::Parser::ParseScope&) (/workspace/install/llvm/build_21.1.4/bin/clang-21+0xcce38c2)
#15 0x00006181b653d337 clang::Parser::ParseFunctionDefinition(clang::ParsingDeclarator&, clang::Parser::ParsedTemplateInfo const&, clang::Parser::LateParsedAttrList*) (/workspace/install/llvm/build_21.1.4/bin/clang-21+0xcb87337)
#16 0x00006181b6596d18 clang::Parser::ParseDeclGroup(clang::ParsingDeclSpec&, clang::DeclaratorContext, clang::ParsedAttributes&, clang::Parser::ParsedTemplateInfo&, clang::SourceLocation*, clang::Parser::ForRangeInit*) (/workspace/install/llvm/build_21.1.4/bin/clang-21+0xcbe0d18)
#17 0x00006181b6533307 clang::Parser::ParseDeclOrFunctionDefInternal(clang::ParsedAttributes&, clang::ParsedAttributes&, clang::ParsingDeclSpec&, clang::AccessSpecifier) (/workspace/install/llvm/build_21.1.4/bin/clang-21+0xcb7d307)
#18 0x00006181b6533e9e clang::Parser::ParseDeclarationOrFunctionDefinition(clang::ParsedAttributes&, clang::ParsedAttributes&, clang::ParsingDeclSpec*, clang::AccessSpecifier) (/workspace/install/llvm/build_21.1.4/bin/clang-21+0xcb7de9e)
#19 0x00006181b653ff98 clang::Parser::ParseExternalDeclaration(clang::ParsedAttributes&, clang::ParsedAttributes&, clang::ParsingDeclSpec*) (/workspace/install/llvm/build_21.1.4/bin/clang-21+0xcb89f98)
#20 0x00006181b654159d clang::Parser::ParseTopLevelDecl(clang::OpaquePtr<clang::DeclGroupRef>&, clang::Sema::ModuleImportState&) (/workspace/install/llvm/build_21.1.4/bin/clang-21+0xcb8b59d)
#21 0x00006181b65279d0 clang::ParseAST(clang::Sema&, bool, bool) (/workspace/install/llvm/build_21.1.4/bin/clang-21+0xcb719d0)
#22 0x00006181b426f92b clang::ASTFrontendAction::ExecuteAction() (/workspace/install/llvm/build_21.1.4/bin/clang-21+0xa8b992b)
#23 0x00006181b3e5d360 clang::CodeGenAction::ExecuteAction() (/workspace/install/llvm/build_21.1.4/bin/clang-21+0xa4a7360)
#24 0x00006181b42779cf clang::FrontendAction::Execute() (/workspace/install/llvm/build_21.1.4/bin/clang-21+0xa8c19cf)
#25 0x00006181b41bdf46 clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) (/workspace/install/llvm/build_21.1.4/bin/clang-21+0xa807f46)
#26 0x00006181b43fff7b clang::ExecuteCompilerInvocation(clang::CompilerInstance*) (/workspace/install/llvm/build_21.1.4/bin/clang-21+0xaa49f7b)
#27 0x00006181ae16e523 cc1_main(llvm::ArrayRef<char const*>, char const*, void*) (/workspace/install/llvm/build_21.1.4/bin/clang-21+0x47b8523)
#28 0x00006181ae15ec58 ExecuteCC1Tool(llvm::SmallVectorImpl<char const*>&, llvm::ToolContext const&) driver.cpp:0:0
#29 0x00006181ae164b28 clang_main(int, char**, llvm::ToolContext const&) (/workspace/install/llvm/build_21.1.4/bin/clang-21+0x47aeb28)
#30 0x00006181adfbfb4a main (/workspace/install/llvm/build_21.1.4/bin/clang-21+0x4609b4a)
#31 0x0000711b9b0f31ca __libc_start_call_main ./csu/../sysdeps/nptl/libc_start_call_main.h:74:3
#32 0x0000711b9b0f328b call_init ./csu/../csu/libc-start.c:128:20
#33 0x0000711b9b0f328b __libc_start_main ./csu/../csu/libc-start.c:347:5
#34 0x00006181ae15cf55 _start (/workspace/install/llvm/build_21.1.4/bin/clang-21+0x47a6f55)
clang: error: unable to execute command: Aborted (core dumped)
The Clang version:
clang version 21.1.4 (https://github.com/llvm/llvm-project.git 222fc11f2b8f25f6a0f4976272ef1bb7bf49521d)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /workspace/install/llvm/build_21.1.4/bin
Build config: +assertions
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/13
Selected GCC installation: /usr/lib/gcc/x86_64-linux-gnu/13
Candidate multilib: .;@m64
Selected multilib: .;@m64