[Bug ada/25782] New: Garbage string returned from function call chain with mixture of constrained and unconstrained return types

["holmana at adsmr dot co dot za" <gcc-bugzilla at gcc dot gnu dot org>]

Using gcc 4.0.2, with gcc -v giving:
----------------------------------------
Using built-in specs.
Target: i686-pc-linux-gnu
Configured with: ../src/configure --disable-nls --enable-languages=c,ada
--prefix=/disc/gbcc/home/allan/play/koala/gcc4/native1 --enable-libada
Thread model: posix
gcc version 4.0.2
----------------------------------------

and compiling the following code:
----------------------------------------
With Text_Io;

procedure testbugmain is

    subtype IntermediateStringType is String(1..12);
    Strings : Array(Boolean) of IntermediateStringType :=
("0123456789ab","ba9876543210");


    Function translatePhrase(phraseToTranslate : in String) return String is
    begin
        return phraseToTranslate;
    end;


    Function intermediateString(flag : in Boolean) return
IntermediateStringType is
    begin
        declare
            returnString : constant String := translatePhrase(Strings(flag));
        begin
           null;
-- Return A
--           return returnString;
        end;

-- Return B
        return translatePhrase(Strings(flag));
    end;


begin
   Text_Io.put_line("<" & intermediateString(TRUE) & ">");
   Text_Io.put_line("<" & intermediateString(FALSE) & ">");

end testbugmain;
--------------------------------------------------------------

with compile command line and results:
------------------------------------------------------------
gnatmake -gnatf -gnatv -gnatVa -gnatwa testbugmain.adb 
gcc -c -gnatf -gnatv -gnatVa -gnatwa testbugmain.adb

GNAT 4.0.2
Copyright 1992-2005 Free Software Foundation, Inc.

Compiling: testbugmain.adb (source file time stamp: 2006-01-13 14:16:28)

     6.     Strings : Array(Boolean) of IntermediateStringType :=
("0123456789ab","ba9876543210");
            |
        >>> warning: "Strings" is not modified, could be declared constant

    18.             returnString : constant String :=
translatePhrase(Strings(flag));
                    |
        >>> warning: constant "returnString" is not referenced

 34 lines: No errors, 2 warnings
gnatbind -x testbugmain.ali
gnatlink testbugmain.ali
-----------------------------------------------------------------------

Expected Behaviour:
Two lines should be printed, each containing the corresponding string from the
Strings array.


Actual Behaviour:
A run of the resulting executable prints out garbage.  Specifically, the value
returned from the intermediateString function does not match the string looked
up in the Strings array; rather, the byte values seem as if they might be two
pointers.

If the return statement just after the "Return A" comment is uncommented, then
the code works as expected: The values looked up in the Strings array are
printed out.


-- 
           Summary: Garbage string returned from function call chain with
                    mixture of constrained and unconstrained return types
           Product: gcc
           Version: 4.0.2
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: ada
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: holmana at adsmr dot co dot za
 GCC build triplet: i686-pc-linux-gnu
  GCC host triplet: i686-pc-linux-gnu
GCC target triplet: i686-pc-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25782