[Patch, Fortran] PR fortran/49648 ICE with use-associated array-returning function

[Patch, Fortran] PR fortran/49648 ICE with use-associated array-returning function

[Mikael Morin]

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Hello,

this is the patch I posted yesterday on bugzilla at 
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49648#c8

The problem is a NULL pointer encountered during code generation when trying 
to get the rank from the array spec.

The array ref's array spec is normally copied in resolve_ref from the symbol's 
one. It is not the case, however, in this special case (use-associated 
function return variable whose shape involves a function call).

This patch calls gfc_resolve_array_spec on sym->result, which calls 
gfc_resolve_expr on every bound, which in turn calls resolve_ref on them.

As pointed out by Tobias in the PR audit trail, there could be some similar 
bugs with character lengths. The character length variant of the testcase 
doesn't ICE however, so I have decided to propose the patch as is, because it 
should be a step forward anyway.

Regression tested on x86_64-unknown-freebsd8.2. OK for trunk? Should I 
backport to the branches?

Mikael

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2011-07-07  Mikael Morin  <mikael.morin@sfr.fr>

gcc/fortran
	PR fortran/49648
	* resolve.c (resolve_symbol): Force resolution of function result's
	array specification.

gcc/testsuite
	PR fortran/49648
	* gfortran.dg/result_in_spec_4.f90: New test.

diff --git a/resolve.c b/resolve.c
index f484a22..cbf403c 100644
--- a/resolve.c
+++ b/resolve.c
@@ -12198,6 +12198,8 @@ resolve_symbol (gfc_symbol *sym)
 	    }
 	}
     }
+  else if (mp_flag && sym->attr.flavor == FL_PROCEDURE && sym->attr.function)
+    gfc_resolve_array_spec (sym->result->as, false);
 
   /* Assumed size arrays and assumed shape arrays must be dummy
      arguments.  Array-spec's of implied-shape should have been resolved to

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! { dg-do compile }
!
! PR fortran/49648
! ICE for calls to a use-associated function returning an array whose spec
! depends on a function call.

! Contributed by Tobias Burnus <burnus@net-b.de>

module m2
  COMPLEX, SAVE, ALLOCATABLE :: P(:)
contains
  FUNCTION getPhaseMatrix() RESULT(PM)
    COMPLEX:: PM(SIZE(P),3)
    PM=0.0
  END FUNCTION
end module m2

module m
  use m2
contains
   SUBROUTINE gf_generateEmbPot()
      COMPLEX :: sigma2(3,3)
      sigma2 = MATMUL(getPhaseMatrix(), sigma2)
   END SUBROUTINE
end module m

! { dg-final { cleanup-modules "m m2" } }

Re: [Patch, Fortran] PR fortran/49648 ICE with use-associated array-returning function

[Tobias Burnus]

Dear Mikael,

On 07/07/2011 12:42 PM, Mikael Morin wrote:
> this is the patch I posted yesterday on bugzilla at
> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49648#c8
>
> This patch calls gfc_resolve_array_spec on sym->result, which calls
> gfc_resolve_expr on every bound, which in turn calls resolve_ref on them.
>
> As pointed out by Tobias in the PR audit trail, there could be some similar
> bugs with character lengths. The character length variant of the testcase
> doesn't ICE however, so I have decided to propose the patch as is, because it
> should be a step forward anyway.

My impression is that the type-spec - contrary to the array spec - is 
shared between the function symbol and the result symbol. That's also 
what I get for the example you posted, when looking at the expressions 
in the debugger. Thus, it seems as the array spec is the only case where 
one needs to do something.

> Regression tested on x86_64-unknown-freebsd8.2. OK for trunk? Should I
> backport to the branches?

OK. Regarding backporting: I don't know; I don't have a strong opinion. 
It's not a regression - but it is also a simple fix. Thus, backporting 
to 4.6 should be OK, but I wouldn't port it to older versions.

Thanks a lot for the patch and going though resolve.c!

Tobias