[Bug c++/19989] [4.0/4.1 regression] Inconsistency with zero-sized arrays

["mmitchel at gcc dot gnu dot org" <gcc-bugzilla at gcc dot gnu dot org>]

------- Comment #4 from mmitchel at gcc dot gnu dot org  2005-10-18 06:28 -------
We all agree that in pedantic mode all three lines are erroneous, so let's just
consider the non-pedantic case.  

We can choose not to be picky about the non-dependent declarations because such
code makes the program ill-formed; accepting such a program clearly does not
change the behavior of any conforming program.

But, for dependent declarations, we must be careful of SFINAE.  If we do not
reject instantiations that create types where type deduction fails, we can
change the meaning of conforming programs -- and the absence of -pedantic
should never change the meaning of a conforming program.  So, we must issue an
error for the dependent cases.

I think that the right fix for this is to make the use of this extension an
unconditional pedwarn in GNU C++, instead of "if (pedantic) pedwarn (...)" as
it is now.  That would still allow people to use -fpermissive to allow
non-dependent zero-length arrays.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19989