GNU extension: support forward declarations of enums

[pwo]

Bugzilla Link	3688
Resolution	FIXED
Resolved on	Mar 06, 2009 12:38
Version	unspecified
OS	FreeBSD
Blocks	llvm/llvm-bugzilla-archive#3696
Attachments	Pre-processed annotate.c
CC	@DougGregor,@EdSchouten,@efriedma-quic

Extended Description

clang crashes when building libgdb on FreeBSD. (gdb 6.1.1)

ccc -march=nocona -Dxregcomp=regcomp -Dxre_exec=re_exec -Dxregexec=regexec -Dxre_search=re_search -Dxre_compile_fastmap=re_compile_fastmap -Dxregerror=regerror -Dxre_comp=re_comp -Dxre_set_syntax=re_set_syntax -DHAVE_CONFIG_H -DRL_NO_COMPAT -DMI_OUT=1 -DTUI=1 -I. -I/usr/src/gnu/usr.bin/gdb/libgdb/../arch/amd64 -I/usr/src/gnu/usr.bin/gdb/libgdb/../../binutils/libbfd -I/usr/src/gnu/usr.bin/gdb/libgdb/../../binutils/libbfd/amd64 -I/usr/src/gnu/usr.bin/gdb/libgdb/../../../../contrib/gdb/gdb -I/usr/src/gnu/usr.bin/gdb/libgdb/../../../../contrib/gdb/gdb/config -I/usr/src/gnu/usr.bin/gdb/libgdb/../../../../contrib/gdb/include -I/usr/src/gnu/usr.bin/gdb/libgdb/../../../../contrib/binutils/include -I/usr/src/gnu/usr.bin/gdb/libgdb/../../../../contrib/binutils/bfd -fstack-protector -c /usr/src/gnu/usr.bin/gdb/libgdb/../../../../contrib/gdb/gdb/annotate.c
*** Error code 245

(gdb) thread apply all bt

Thread 1 (Thread 801c021c0 (LWP 100136)):
#​0 0x000000000070a5b1 in clang::NamedDecl::declarationReplaces ()
#​1 0x00000000004957ba in main ()

[efriedma-quic]

Reduced testcase:
enum teste1 (*test1)(void);
Related:
struct tests2 (*test2)(void);
struct tests3;
void (*test3)(struct tests3);

This falls under IRGen. Rather nasty. We probably need to delay constructing function types until the return type and all parameter types are defined.

gcc accepts all of the testcases without any warnings/errors. Also, as far as I can tell, the latter two cases are legal per C99.

[efriedma-quic]

Fixed in r66128.

[EdSchouten]

Reduced testcase
The following test case still fails. Based on GDB sources.

[EdSchouten]

Proper testcase
Errr... Upload the correct testcase.

[EdSchouten]

Looks like I only reopened this ticket and added some new testcases.

Anyway, even though the crash has been resolved, the attached testcase will not compile:

test.c:14:9: error: incompatible type returning 'enum bar', expected 'enum bar'

[efriedma-quic]

The remaining issue is a Sema scoping issue; the testcase works if you add "enum bar;" at the beginning. I'm not very familiar with how that works, though.

[DougGregor]

I'll tackle the Sema scoping issue.

[DougGregor]

Quick update: this is using the GNU C extension for forward-declaring enums, which we don't yet support. Changing the title appropriately.

[efriedma-quic]

Quick update: this is using the GNU C extension for forward-declaring enums,
which we don't yet support. Changing the title appropriately.

What do you mean, "don't yet support"? The attached testcase works fine if you add "enum bar;" at the beginning, and a lot of other cases work fine (including some tests in test/Sema/enum.c).

[DougGregor]

I thought our support for forward declaration of enums was worse off. Fixed the remaining Sema issue here:

http://lists.cs.uiuc.edu/pipermail/cfe-commits/Week-of-Mon-20090302/013558.html

[EdSchouten]

mentioned in issue llvm/llvm-bugzilla-archive#3696