[Bug fortran/44265] New: Link error with reference to parameter array in specification expression

[Bug fortran/44265] New: Link error with reference to parameter array in specification expression

[ian_harvey at bigpond dot com]

The following program compiles successfully, but results in an undefined
reference to `___MOD_names' during linking.  It compiles and links successfully
with g95 0.92! (May 31, 2009)and ifort 11.1.065.

Using gfortran built from svn trunk revision 159797.  Command line was simply
"gfortran filename.f90".  Some experimentation shows that the problem is
related to the use of an module procedure scoped array parameter in the
specification expression for the function result.  The type of the parameter
array doesn't seem to matter.

MODULE Fruits
  IMPLICIT NONE    
  PRIVATE
  PUBLIC :: Get
CONTAINS
  FUNCTION Get(i) RESULT(s)    
    CHARACTER(*), PARAMETER :: names(3) = [  &
        'Apple  ',  &
        'Orange ',  &
        'Mango  ' ];              
    INTEGER, INTENT(IN) :: i
    CHARACTER(LEN_TRIM(names(i))) :: s    
    !****    
    s = names(i)    
  END FUNCTION Get
END MODULE Fruits

PROGRAM WheresThatbLinkingConstantGone
  USE Fruits  
  IMPLICIT NONE
  !****
  WRITE (*, "('Eat the tasty ',A)") Get(1)
END PROGRAM WheresThatbLinkingConstantGone


-- 
           Summary: Link error with reference to parameter array in
                    specification expression
           Product: gcc
           Version: 4.6.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: fortran
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: ian_harvey at bigpond dot com
 GCC build triplet: i686-pc-mingw32
  GCC host triplet: i686-pc-mingw32
GCC target triplet: i686-pc-mingw32


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44265

[Bug fortran/44265] Link error with reference to parameter array in specification expression

[burnus at gcc dot gnu dot org]

------- Comment #1 from burnus at gcc dot gnu dot org  2010-05-25 09:50 -------
CONFIRM
(No regression: GCC 4.1/4.2/4.3 reject the code ["names" invalid in expression]
while 4.4/4.5/4.6 show either the link error or ICE. Other compilers simply
work.)

One has the local parameter:
    CHARACTER(*), PARAMETER :: names(3) = ...

And the characteristics of the result variable
    INTEGER, INTENT(IN) :: i
    CHARACTER(LEN_TRIM(names(i))) :: s
which depend on the argument. (While "len(names(i))" is constant,
"len_trim(names(i))"  is not.)

Thus, I see two possibilities: Mark the return length (in .MOD) as unknown
(which g95 and NAG f95 seemingly do) - or to properly handle the PARAMETER.

Looking at gfortran's .mod file, one finds:
 4 'names' '' 'names' 6 ((PARAMETER UNKNOWN-INTENT UNKNOWN-PROC UNKNOWN ...
Thus, the symbol is already saved.

 * * *

Variant: If one adds a
  subroutine test()
    print *, get(1)
  end subroutine test
in the module itself, one gets an ICE:

foo.f90:18:0: internal compiler error: in gfc_generate_function_code, at
fortran/trans-decl.c:4378


-- 

burnus at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |pault at gcc dot gnu dot org
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|0                           |1
           Keywords|                            |ice-on-valid-code, rejects-
                   |                            |valid
   Last reconfirmed|0000-00-00 00:00:00         |2010-05-25 09:50:41
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44265