[Bug fortran/69185] New: bounds-check gives false positive on assignment to allocatable array

[townsend at astro dot wisc.edu]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69185

            Bug ID: 69185
           Summary: bounds-check gives false positive on assignment to
                    allocatable array
           Product: gcc
           Version: 4.9.3
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: fortran
          Assignee: unassigned at gcc dot gnu.org
          Reporter: townsend at astro dot wisc.edu
  Target Milestone: ---

Created attachment 37255
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=37255&action=edit
Source code of program reproducing the problem

Compile the attached code with:

gfortran -fbounds-check -std=f2003 -o foo foo.f90

On execution, the assignment to b should be OK, since b will be allocated to
match the shape of the RHS (as per F2003). However, the following run-time
error instead occurs:

At line 8 of file foo.f90
Fortran runtime error: Array bound mismatch for dimension 1 of array 'b' (20/4)

The problem does not arise if I use, e.g., 'a' on the RHS instead of 'exp(a)'.