[Patch, fortran] PR29821 - Failure to resolve variable parameter array sections

[Paul Thomas]

:ADDPATCH fortran:

This patch and its testcase are self-explanatory. I spent a lot of time 
trying to fix the rules of engagement of gfc_simplify_expr, as described 
in its heading comment.  In principle, this should return FAILURE only 
if an error has been found.  If simplification has not occurred, it 
should be up to the caller to detect this.  Apparently, this rule has 
been multiply violated and FAILURE is being used to indicate a lack of 
simplification.  The most immediate example of this is my fault; in 
find_array_section, where non-constant index expressions return 
FAILURE.  Changing this to SUCCESS fixes this problem but breaks other 
things.   Fixing those, cascades down to cause more breakages.  I 
therefore took a middle path and did a test in the caller, which is 
resolve_operator here, to see if the expression is constant before 
returning the result of the  call to gfc_simplify_expr.  In fact, I am 
not convinced that the result should be returned here at all - removing 
it breaks nothing.  I would be open to the reviewer suggesting that 
course of action :-)

Regtested on suse10.1/amd64  - OK for trunk, 4.2 and 4.1?

Paul

2006-11-21 Paul Thomas  <pault@gcc.gnu.org>

    PR fortran/29821
    * resolve.c (resolve_operator): Only return result of
    gfc_simplify_expr if expression is constant.

2006-11-21 Paul Thomas  <pault@gcc.gnu.org>

    PR fortran/29821
    * gfortran.dg/parameter_array_section_1.f90: New test.

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