[Bug c/28289] New: composite_types called to do two different things

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

composite_types is called in c-decl.c to merge function declarations, but in
c-typeck.c to merge the types of two arms of a COND_EXPR.  The former should
result in a union of traits of the inputs, which composite_types computes, but
the latter should give the intersection of traits unless the C standard
says otherwise.
In particular, when TREE_READONLY is set for a function type, that means that
this function has no side effect, i.e. it is pure.  When a cond expression
yields a function type, it is pure only if both functions are pure.
When a call is made through a COND_EXPR which is improperly marked as yielding
a pure function pointer, and the result is ignored, the actual function call
is not emitted.

Likewise, when we merge the type of a function with a noreturn attribute
with the type of a function without that attribute, merging the types for
a COND_EXPR should yield a function type without this attribute.


-- 
           Summary: composite_types called to do two different things
           Product: gcc
           Version: 4.2.0
            Status: UNCONFIRMED
          Keywords: wrong-code
          Severity: normal
          Priority: P3
         Component: c
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: amylaar at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=28289