[Bug ada/42412] New: Illegal program accepted, RM 8.5.1(3), renames of classwide object

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

package pak1 is
   type T1 is tagged null record;
   x1: T1;
   x2: T1'class := x1;
   x3: T1'class renames x1;  --ERROR: (detected)  T1'class vs T1
   x4: T1 renames x2;        --ERROR: (missed)    T1 vs T1'class
end pak1;

$ gnatmake pak1
gcc-4.3 -c pak1.ads
pak1.ads:5:25: expected type "T1'class" defined at line 2
pak1.ads:5:25: found type "T1" defined at line 2
gnatmake: "pak1.ads" compilation error

RM 8.5.1(3) says "The type of the object_name shall resolve to the
type determined by the subtype_mark."  T and T'class are considered
to be different types, and shouldn't match.  There is flexibility in
RM 8.6(23) for T'class to sometimes match T, but only when the rules
provide an "expected type".  But this flexibility doesn't apply when
the rules say "shall resolve to", as in this case, without giving an
expected type.  This subtle wording distinction can also be seen in
other places in the RM, such as 12.4(4) vs. 12.4(5).


-- 
           Summary: Illegal program accepted, RM 8.5.1(3), renames of
                    classwide object
           Product: gcc
           Version: 4.3.4
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: ada
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: ludovic at ludovic-brenta dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42412