clang rejects ia32_signal.i (anonymous unions)

[edwintorok]

Bugzilla Link	1750
Resolution	FIXED
Resolved on	Mar 12, 2010 00:57
Version	unspecified
OS	Linux
Blocks	llvm/llvm-bugzilla-archive#2923
CC	@DougGregor,@nunoplopes

Extended Description

When compiling http://llvm.org/bugs/attachment.cgi?id=1169:
clang -fsyntax-only ia32_signal.i
clang: /home/edwin/llvm-svn/llvm/include/llvm/Support/Casting.h:199: typename llvm::cast_retty<To, From>::ret_type llvm::cast(const Y&) [with X = clang::TypedefType, Y = const clang::Type*]: Assertion `isa(Val) && "cast() argument of incompatible type!"' failed.
clang[0x788b46]
clang[0x788db2]
/lib/libc.so.6[0x32d1c31710]
/lib/libc.so.6(gsignal+0x35)[0x32d1c316a5]
/lib/libc.so.6(abort+0x110)[0x32d1c33100]
/lib/libc.so.6(__assert_fail+0xef)[0x32d1c2ac2f]
clang(llvm::cast_retty<clang::TypedefType, clang::Type const*>::ret_type llvm::cast<clang::TypedefType, clang::Type const*>(clang::Type const* const&)+0x44)[0x6718b4]
clang(clang::Type::getAsPointerType() const+0x4c)[0x66f738]
clang(clang::Sema::CheckPointerTypesForAssignment(clang::QualType, clang::QualType)+0x55)[0x632fbb]
clang(clang::Sema::CheckAssignmentConstraints(clang::QualType, clang::QualType)+0x1b7)[0x6332db]
clang(clang::Sema::CheckSingleAssignmentConstraints(clang::QualType, clang::Expr*&)+0x55)[0x6336b9]
clang(clang::Sema::CheckSingleInitializer(clang::Expr*&, bool, clang::QualType)+0x136)[0x62661a]
clang(clang::Sema::CheckInitializer(clang::Expr*&, clang::QualType&, bool)+0x49)[0x626df7]
clang(clang::Sema::AddInitializerToDecl(void*, void*)+0x123)[0x627151]
clang(clang::Parser::ParseInitDeclaratorListAfterFirstDeclarator(clang::Declarator&)+0x147)[0x678e57]
clang(clang::Parser::ParseSimpleDeclaration(unsigned int)+0xcc)[0x67901c]
clang(clang::Parser::ParseDeclaration(unsigned int)+0x41)[0x679083]
clang(clang::Parser::ParseStatementOrDeclaration(bool)+0x307)[0x685f49]
clang(clang::Parser::ParseCompoundStatementBody(bool)+0x7c)[0x688ae0]
clang(clang::Parser::ParseFunctionDefinition(clang::Declarator&)+0x156)[0x6743c2]
clang(clang::Parser::ParseDeclarationOrFunctionDefinition()+0x2ca)[0x674748]
clang(clang::Parser::ParseExternalDeclaration()+0x213)[0x674c59]
clang(clang::Parser::ParseTopLevelDecl(void*&)+0x43)[0x674ca7]
clang[0x61d081]
clang(clang::ParseAST(clang::Preprocessor&, unsigned int, clang::ASTConsumer&, bool)+0xeb)[0x61d221]
clang[0x5e247c]
clang(main+0x335)[0x5e3e57]
/lib/libc.so.6(__libc_start_main+0xf4)[0x32d1c1db44]
clang[0x5c9f99]
Aborted

$ clang --version
Low Level Virtual Machine (http://llvm.org/):
llvm version 2.2svn
DEBUG build with assertions.

[lattner]

The immediate crash was due to improper handling of typeof. This is fixed here:
http://lists.cs.uiuc.edu/pipermail/cfe-commits/Week-of-Mon-20071022/002556.html

but there are other issues.

[lattner]

Inline asm in the AST:
http://lists.cs.uiuc.edu/pipermail/cfe-commits/Week-of-Mon-20071022/002557.html

[lattner]

inline asm parser bug:
http://lists.cs.uiuc.edu/pipermail/cfe-commits/Week-of-Mon-20071022/002558.html

[lattner]

__builtin_memcpy not defined:
http://lists.cs.uiuc.edu/pipermail/cfe-commits/Week-of-Mon-20071022/002559.html
bug handling cast to void:
http://lists.cs.uiuc.edu/pipermail/cfe-commits/Week-of-Mon-20071022/002560.html

[lattner]

Something I don't plan to tackle in the immediate future:

Sema::MergeFunctionDecl is way too simple. It rejects:

void foo() {}
void foo();

[lattner]

Another issue I don't plan to fix in the immediate future:

GCC's anonymous union feature:
struct x {
int a;
union {
int b;
float c;
};
int d;
};

Now parses, but we have two problems:

1. we emit "warning: declaration does not declare anything" on the union.
2. we don't inject the b/c names into the enclosing struct (or we don't search anon types names when looking up a field).

Getting it to parse right did require this bugfix:
http://lists.cs.uiuc.edu/pipermail/cfe-commits/Week-of-Mon-20071022/002561.html

[lattner]

*** Bug llvm/llvm-bugzilla-archive#1751 has been marked as a duplicate of this bug. ***

[lattner]

We incorrectly reject this:
typedef struct foo { int a, b; } x;
void bar(const x);
void foo() { x y; bar(y); }

I asked Steve to investigate.

[lattner]

Ok, I believe all the subproblems are listed here.

[nunoplopes]

Something I don't plan to tackle in the immediate future:
Sema::MergeFunctionDecl is way too simple. It rejects:
void foo() {}
void foo();

ok, so my first try to fix this problem: http://web.ist.utl.pt/nuno.lopes/clang-bug1750-5.txt

[lattner]

Thanks Nuno, the patch looks great, applied:
http://lists.cs.uiuc.edu/pipermail/cfe-commits/Week-of-Mon-20071105/002717.html

[lattner]

This currently crashes in inlineasm handling.

[llvmbot]

asm problems should be fixed now.

[DougGregor]

Anonymous structs and unions are now supported in Clang, and Clang now handles ia32_signal.i with -fsyntax-only. However, we now in CodeGen due to the presence of inline assembly.

[DougGregor]

Closing this bug; we've dealt with all of the subproblems.