[Bug c++/50012] [4.5/4.6/4.7 Regression] C++ front end misses -Wsign-compare warnings when extraneous parentheses are present

[ian at airs dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50012

--- Comment #7 from Ian Lance Taylor <ian at airs dot com> 2012-01-07 01:31:36 
UTC ---
Created attachment 26260
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=26260
Possible patch

I did not like the first approach because I think that checking c_dialect_cxx
in the generic C family code is quite ugly.  But clearly the current approach
is problematic, and it's actually easy to implement Richi's suggestion.  This
patch is a possible approach, but it doesn't work as is.  It issues a warning
for

  if (TYPE_QUALS (type) == memfn_quals)

in cp;typeck.c.  Here memfn_quals is signed int but TYPE_QUALS, an expression
of enum values winds up unsigned.