clang++: assertion `DS.getAttributes().empty() && "No attribute expected"' failed

[llvmbot]

Bugzilla Link	49168
Version	11.0
OS	Linux
Reporter	LLVM Bugzilla Contributor
CC	@zygoloid

Extended Description

Hi,

An assertion failed on /llvm-project/clang/lib/Sema/SemaDecl.cpp. Built on Ubuntu 18.04, x86-64. Detailed information is attached below.

=== detailed information ===

$ ./clang poc.cc
poc.cc:1:27: error: expected '}'
attribute((a)) union {
^
poc.cc:1:26: note: to match this '{'
attribute((a)) union {
^
poc.cc:1:27: error: expected ';' after union
attribute((a)) union {
^
;
poc.cc:1:20: error: anonymous unions at namespace or global scope must be declared 'static'
attribute((a)) union {
^
static
poc.cc:1:1: warning: declaration does not declare anything [-Wmissing-declarations]
attribute((a)) union {
^
clang-11: /home/xxx/data/git/llvm-project/clang/lib/Sema/SemaDecl.cpp:5188: clang::Decl *clang::Sema::BuildAnonymousStructOrUnion(clang::Scope *, clang::DeclSpec &, clang::AccessSpecifier, clang::RecordDecl *, const clang::PrintingPolicy &): Assertion `DS.getAttributes().empty() && "No attribute expected"' failed.
PLEASE submit a bug report to https://bugs.llvm.org/ and include the crash backtrace, preprocessed source, and associated run script.
Stack dump:
0. Program arguments: /data/xxx/git/llvm-project/build/bin/clang-11 -cc1 -triple x86_64-unknown-linux-gnu -emit-obj -mrelax-all -disable-free -main-file-name poc.cc -mrelocation-model static -mframe-pointer=all -fmath-errno -fno-rounding-math -mconstructor-aliases -munwind-tables -target-cpu x86-64 -fno-split-dwarf-inlining -debugger-tuning=gdb -resource-dir /data/xxx/git/llvm-project/build/lib/clang/11.1.0 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/7.5.0/../../../../include/c++/7.5.0 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/7.5.0/../../../../include/x86_64-linux-gnu/c++/7.5.0 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/7.5.0/../../../../include/x86_64-linux-gnu/c++/7.5.0 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/7.5.0/../../../../include/c++/7.5.0/backward -internal-isystem /usr/local/include -internal-isystem /data/xxx/git/llvm-project/build/lib/clang/11.1.0/include -internal-externc-isystem /usr/include/x86_64-linux-gnu -internal-externc-isystem /include -internal-externc-isystem /usr/include -fdeprecated-macro -fdebug-compilation-dir /data/xxx/docker_share/clang/11.x -ferror-limit 19 -fgnuc-version=4.2.1 -fcxx-exceptions -fexceptions -fcolor-diagnostics -faddrsig -o /tmp/poc-a96549.o -x c++ poc.cc

1.  <eof> parser at end of file
   

#​0 0x0000000006e97306 llvm::sys::PrintStackTrace(llvm::raw_ostream&) /home/xxx/data/git/llvm-project/llvm/lib/Support/Unix/Signals.inc:560:7
#​1 0x0000000006e9266e llvm::sys::RunSignalHandlers() /home/xxx/data/git/llvm-project/llvm/lib/Support/Signals.cpp:69:18
#​2 0x0000000006e97caa SignalHandler(int) /home/xxx/data/git/llvm-project/llvm/lib/Support/Unix/Signals.inc:396:3
#​3 0x00007fa5d28938a0 __restore_rt (/lib/x86_64-linux-gnu/libpthread.so.0+0x128a0)
#​4 0x00007fa5d1559f47 gsignal /build/glibc-2ORdQG/glibc-2.27/signal/../sysdeps/unix/sysv/linux/raise.c:51:0
#​5 0x00007fa5d155b8b1 abort /build/glibc-2ORdQG/glibc-2.27/stdlib/abort.c:81:0
#​6 0x00007fa5d154b42a __assert_fail_base /build/glibc-2ORdQG/glibc-2.27/assert/assert.c:89:0
#​7 0x00007fa5d154b4a2 (/lib/x86_64-linux-gnu/libc.so.6+0x304a2)
#​8 0x000000000cea3434 llvm::cast_retty<clang::FieldDecl, clang::NamedDecl*>::ret_type llvm::cast<clang::FieldDecl, clang::NamedDecl>(clang::NamedDecl*) /home/xxx/data/git/llvm-project/llvm/include/llvm/Support/Casting.h:269:3
#​9 0x000000000cea3434 clang::Sema::BuildAnonymousStructOrUnion(clang::Scope*, clang::DeclSpec&, clang::AccessSpecifier, clang::RecordDecl*, clang::PrintingPolicy const&) /home/xxx/data/git/llvm-project/clang/lib/Sema/SemaDecl.cpp:5176:0
#​10 0x000000000ce9ac6c clang::Sema::ParsedFreeStandingDeclSpec(clang::Scope*, clang::AccessSpecifier, clang::DeclSpec&, llvm::MutableArrayRefclang::TemplateParameterList*, bool, clang::RecordDecl*&) /home/xxx/data/git/llvm-project/clang/lib/Sema/SemaDecl.cpp:4657:16
#​11 0x000000000ce99126 clang::Sema::ParsedFreeStandingDeclSpec(clang::Scope*, clang::AccessSpecifier, clang::DeclSpec&, clang::RecordDecl*&) /home/xxx/data/git/llvm-project/clang/lib/Sema/SemaDecl.cpp:4334:10
#​12 0x000000000c82f9c0 clang::ParsingDeclSpec::complete(clang::Decl*) /home/xxx/data/git/llvm-project/clang/include/clang/Parse/RAIIObjectsForParser.h:0:0
#​13 0x000000000c82f9c0 clang::Parser::ParseDeclOrFunctionDefInternal(clang::Parser::ParsedAttributesWithRange&, clang::ParsingDeclSpec&, clang::AccessSpecifier) /home/xxx/data/git/llvm-project/clang/lib/Parse/Parser.cpp:1046:0
#​14 0x000000000c82e939 clang::Parser::ObjCDeclContextSwitch::~ObjCDeclContextSwitch() /home/xxx/data/git/llvm-project/clang/include/clang/Parse/Parser.h:0:0
#​15 0x000000000c82e939 clang::Parser::ParseDeclarationOrFunctionDefinition(clang::Parser::ParsedAttributesWithRange&, clang::ParsingDeclSpec*, clang::AccessSpecifier) /home/xxx/data/git/llvm-project/clang/lib/Parse/Parser.cpp:1116:0
#​16 0x000000000c82c6a1 clang::Parser::ParseExternalDeclaration(clang::Parser::ParsedAttributesWithRange&, clang::ParsingDeclSpec*) /home/xxx/data/git/llvm-project/clang/lib/Parse/Parser.cpp:935:12
#​17 0x000000000c827ecc clang::Parser::ParseTopLevelDecl(clang::OpaquePtrclang::DeclGroupRef&, bool) /home/xxx/data/git/llvm-project/clang/lib/Parse/Parser.cpp:683:10
#​18 0x000000000c826ccc clang::Parser::ParseFirstTopLevelDecl(clang::OpaquePtrclang::DeclGroupRef&) /home/xxx/data/git/llvm-project/clang/lib/Parse/Parser.cpp:555:26
#​19 0x000000000c81cf4a clang::ParseAST(clang::Sema&, bool, bool) /home/xxx/data/git/llvm-project/clang/lib/Parse/ParseAST.cpp:157:15
#​20 0x000000000861c2a2 clang::ASTFrontendAction::ExecuteAction() /home/xxx/data/git/llvm-project/clang/lib/Frontend/FrontendAction.cpp:1059:1
#​21 0x00000000099decd8 clang::CodeGenAction::ExecuteAction() /home/xxx/data/git/llvm-project/clang/lib/CodeGen/CodeGenAction.cpp:1184:28
#​22 0x000000000861a51a clang::FrontendAction::Execute() /home/xxx/data/git/llvm-project/clang/lib/Frontend/FrontendAction.cpp:954:10
#​23 0x000000000854eaa7 llvm::Error::operator bool() /home/xxx/data/git/llvm-project/llvm/include/llvm/Support/Error.h:0:0
#​24 0x000000000854eaa7 clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) /home/xxx/data/git/llvm-project/clang/lib/Frontend/CompilerInstance.cpp:984:0
#​25 0x00000000088f183f clang::CompilerInstance::getFrontendOpts() /home/xxx/data/git/llvm-project/clang/include/clang/Frontend/CompilerInstance.h:0:0
#​26 0x00000000088f183f clang::ExecuteCompilerInvocation(clang::CompilerInstance*) /home/xxx/data/git/llvm-project/clang/lib/FrontendTool/ExecuteCompilerInvocation.cpp:279:0
#​27 0x0000000000b094cc llvm::TimeTraceScope::~TimeTraceScope() /home/xxx/data/git/llvm-project/llvm/include/llvm/Support/TimeProfiler.h:0:0
#​28 0x0000000000b094cc cc1_main(llvm::ArrayRef<char const*>, char const*, void*) /home/xxx/data/git/llvm-project/clang/tools/driver/cc1_main.cpp:241:0
#​29 0x0000000000afaf3b ExecuteCC1Tool(llvm::SmallVectorImpl<char const*>&) /home/xxx/data/git/llvm-project/clang/tools/driver/driver.cpp:330:12
#​30 0x0000000000af6966 main /home/xxx/data/git/llvm-project/clang/tools/driver/driver.cpp:407:12
#​31 0x00007fa5d153cb97 __libc_start_main /build/glibc-2ORdQG/glibc-2.27/csu/../csu/libc-start.c:344:0
#​32 0x0000000000af38ea _start (/data/xxx/git/llvm-project/build/bin/clang-11+0xaf38ea)
clang-11: error: unable to execute command: Aborted (core dumped)
clang-11: error: clang frontend command failed due to signal (use -v to see invocation)
clang version 11.1.0 (https://github.com/llvm/llvm-project.git 1fdec59)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /data/xxx/git/llvm-project/build/bin
clang-11: note: diagnostic msg:

---

PLEASE ATTACH THE FOLLOWING FILES TO THE BUG REPORT:
Preprocessed source(s) and associated run script(s) are located at:
clang-11: note: diagnostic msg: /tmp/poc-871f06.cpp
clang-11: note: diagnostic msg: /tmp/poc-871f06.sh
clang-11: note: diagnostic msg:

---

$ cat /tmp/poc-871f06.cpp

1 ""

1 "poc.cc"

attribute((a)) union {

$ cat /tmp/poc-871f06.sh

Crash reproducer for clang version 11.1.0 (https://github.com/llvm/llvm-project.git 1fdec59)

Driver args: "poc.cc"

Original command: "/data/xxx/git/llvm-project/build/bin/clang-11" "-cc1" "-triple" "x86_64-unknown-linux-gnu" "-emit-obj" "-mrelax-all" "-disable-free" "-main-file-name" "poc.cc" "-mrelocation-model" "static" "-mframe-pointer=all" "-fmath-errno" "-fno-rounding-math" "-mconstructor-aliases" "-munwind-tables" "-target-cpu" "x86-64" "-fno-split-dwarf-inlining" "-debugger-tuning=gdb" "-resource-dir" "/data/xxx/git/llvm-project/build/lib/clang/11.1.0" "-internal-isystem" "/usr/lib/gcc/x86_64-linux-gnu/7.5.0/../../../../include/c++/7.5.0" "-internal-isystem" "/usr/lib/gcc/x86_64-linux-gnu/7.5.0/../../../../include/x86_64-linux-gnu/c++/7.5.0" "-internal-isystem" "/usr/lib/gcc/x86_64-linux-gnu/7.5.0/../../../../include/x86_64-linux-gnu/c++/7.5.0" "-internal-isystem" "/usr/lib/gcc/x86_64-linux-gnu/7.5.0/../../../../include/c++/7.5.0/backward" "-internal-isystem" "/usr/local/include" "-internal-isystem" "/data/xxx/git/llvm-project/build/lib/clang/11.1.0/include" "-internal-externc-isystem" "/usr/include/x86_64-linux-gnu" "-internal-externc-isystem" "/include" "-internal-externc-isystem" "/usr/include" "-fdeprecated-macro" "-fdebug-compilation-dir" "/data/xxx/docker_share/clang/11.x" "-ferror-limit" "19" "-fgnuc-version=4.2.1" "-fcxx-exceptions" "-fexceptions" "-fcolor-diagnostics" "-faddrsig" "-o" "/tmp/poc-a96549.o" "-x" "c++" "poc.cc"

"/data/xxx/git/llvm-project/build/bin/clang-11" "-cc1" "-triple" "x86_64-unknown-linux-gnu" "-emit-obj" "-mrelax-all" "-disable-free" "-main-file-name" "poc.cc" "-mrelocation-model" "static" "-mframe-pointer=all" "-fmath-errno" "-fno-rounding-math" "-mconstructor-aliases" "-munwind-tables" "-target-cpu" "x86-64" "-fno-split-dwarf-inlining" "-debugger-tuning=gdb" "-fdeprecated-macro" "-ferror-limit" "19" "-fgnuc-version=4.2.1" "-fcxx-exceptions" "-fexceptions" "-fcolor-diagnostics" "-faddrsig" "-x" "c++" "poc-871f06.cpp"

[llvmbot]

@llvm/issue-subscribers-clang-frontend

[llvmbot]

@llvm/issue-subscribers-c-1

[AaronBallman]

The issue reproduces as of Clang 16.0.0 and will trigger an assertion on valid code: https://gcc.godbolt.org/z/s8P99jxPq

Note, this requires an asserts build to see the issue and only occurs in C++ mode.

[AaronBallman]

Assertion added in 304d130 from review https://reviews.llvm.org/D71619