Eli,
Hi,
This patch enables unnamed structure or union fields withing structs/unions
when -std=gnu99 is used. Cf [1].
Note, as stated in [1], struct { int a; union { int a; } } is discouraged,
but won't produce any error nor warning.
It is unclear for me that we really want to add anonymous structure support
in RecordDecl::getMember, as implementation could vary given the language
standard. Yet, not implementing here could lead to easy and unoticeable
mistakes if the caller doesn't implement anonymous structure resolving.
I'll be happy to ear your thoughts...
It looks generally fine to me. It's probably a good idea for someone
else to review it, though.
A couple of small comments:
1. Do we want to support this extension in gnu89 mode?
Right.
The docs does not state that explicitly, yet it is supported.
$ gcc -c -std=gnu89 test/Sema/unnamed-struct-in-struct.c
$
Doug suggested to do that always unless NoExtensions is specify this is what I've done... Yet, -std=c99 doesn't enable NoExtensions... Weird.
2. Does this correctly deal with "struct foo {int a,b;}; struct bar
{int a; struct foo;};"
Well, nice catch as well:
$ gcc -c test-2.c
test-2.c:2: warning: declaration does not declare anything
test-2.c: In function 'dummy':
test-2.c:8: error: 'struct bar' has no member named 'b'
$
Previous version enables such an anonymous struct usage. Attached patch filters this out as well.
"struct bar {int a; struct foo {int a,b;};};"?
$ gcc -c test-3.c
test-3.c:1: warning: declaration does not declare anything
test-3.c: In function 'dummy':
test-3.c:6: error: 'struct bar' has no member named 'b'
$
Previous version enables such an anonymous struct usage. Attached patch filters this out as well.
3. For "struct { int a; union { int a; } }", can we produce an error?
The gcc docs seem to imply that's it's illegal, and it's usually
better to produce an error where we can.
Actually current gcc does not produce error as stated in the doc. Yet, I agree that this would be way better to output error.
Patch is attached to next email in this thread.
Pierre.
