[Bug c/49768] C99 style union initializations does not work as expected with optimizations

[mikpe at it dot uu.se]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49768

Mikael Pettersson <mikpe at it dot uu.se> changed:

           What    |Removed                     |Added
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                 CC|                            |hubicka at gcc dot gnu.org,
                   |                            |mikpe at it dot uu.se

--- Comment #2 from Mikael Pettersson <mikpe at it dot uu.se> 2011-07-17 18:22:21 UTC ---
It started with r164688:

Author: hubicka
Date: Tue Sep 28 16:28:39 2010
New Revision: 164688

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=164688
Log:
    * tree-ssa-ccp.c (fold_ctor_reference): New function.
    (fold_const_aggregate_ref): Use it.
    * fold-const.c (canonicalize_constructor_val): Check that we don't fold
    into external static.

The dumps from r164687 and r164688 start to differ in pr49768.c.061t.ccp2, when
r164688 removes the runtime check and the static object, and makes the abort()
call unconditional.

Removing the unused initial padding bit field unbreaks the test case.