[Bug ada/42411] New: Illegal program accepted, RM 4.1(8), 8.6(27)/2

[Bug ada/42411] New: Illegal program accepted, RM 4.1(8), 8.6(27)/2

[ludovic at ludovic-brenta dot org]

package pak1 is
   type T1 is new integer;
   type T1_access is access all T1;
   x1: aliased T1;
   x2: T1 := x1'access.all;                --ERROR: 4.1(8) (missed)
   x3: T1_access := T1_access(x1'access);  --ERROR: 4.6(6) (detected)
end pak1;


Gnat misses the error involving x1'access.all.
RM 3.10.2(2)/2 says "the expected type (for 'access) shall be
a single access type".  But ".all" doesn't provide a single
access type.  Instead, by RM 4.1(8), the name in a dereference
"is expected to be of any access type".

The rule for type_conversions (x3) is similar.  RM 4.6(6) says
"The operand of a type_conversion is expected to be of any type."
Gnat does detect this error.

$ gnatmake pak1
gcc-4.3 -c pak1.ads
pak1.ads:6:21: argument of conversion cannot be access
pak1.ads:6:21: use qualified expression instead
gnatmake: "pak1.ads" compilation error


-- 
           Summary: Illegal program accepted, RM 4.1(8), 8.6(27)/2
           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=42411

[Bug ada/42411] Illegal program accepted, RM 4.1(8), 8.6(27)/2

[ludovic at ludovic-brenta dot org]

------- Comment #1 from ludovic at ludovic-brenta dot org  2009-12-17 19:47 -------
RM 8.6(27)/2 is also relevant:
   When a construct is one that requires that its expected type be a
   single type in a given class, the type of the construct shall be
   determinable solely from the context in which the construct appears,
   excluding the construct itself, but using the requirement that it be in
   the given class. Furthermore, the context shall not be one that expects
   any type in some class that contains types of the given class; in
   particular, the construct shall not be the operand of a
   type_conversion.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42411