[Bug ada/42618] New: Problem reading discriminated values from streams

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

The test program writes 3 values of a discriminated record to a stream
('Output) and then reads them back ('Input).
It then uses 'Write and 'Read for a single value.

No problem arises with 32-bit compilations, or with 64-bit compilations with
-O0.

With -O1 or -O2, the values read back are incorrect (in some cases).

Same behaviour reported on Debian:
gnat-4.4_4.4.2-5_amd64.deb: 
 -O0 OK 
 -O1 bug 
 -O2 bug 
gnat-4.4_4.4.2-5_i386.deb: 
 -O0 OK 
 -O1 OK 
 -O2 OK 
That version of GNAT was taken from the FSF's gcc-4_4-branch on 
2009-12-28 so is very recent.

The correct output is
 1234
'z'
 4.32100E-01
 4.32100E-01

The incorrect output is
 1234
NUL
 0.00000E+00
 0.00000E+00


-- 
           Summary: Problem reading discriminated values from streams
           Product: gcc
           Version: 4.4.2
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: ada
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: simon at pushface dot org
  GCC host triplet: x86_64-apple-darwin10


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42618