[gfortran,patch] Improve error messages for bounds-checking and a few other cases

[FX Coudert <fxcoudert at gmail dot com>]

Hi all,

Attached patch yields detailed error messages with -fbounds-check. A  
sample of the error messages is:

> $ cat a1.f90
>   integer x(1,1)
>   x(1,2) = 1
>   end
> $ gfortran -fbounds-check a1.f90 -w && ./a.out
> Fortran runtime error: Array reference out of bounds for array 'x',  
> upper bound of dimension 2 exceeded (in file 'a1.f90', at line 2)
>
> $ cat a1bis.f90
>   integer x(1,1)
>   x(1:2,1) = 1
>   end
> $ gfortran -fbounds-check a1bis.f90 -w && ./a.out
> Fortran runtime error: Array bound mismatch, upper bound of  
> dimension 1 of array 'x' exceeded (in file 'a1bis.f90', at line 2)
>
> $ cat a2.f
>       integer i
>       assign 800 to i
>   800 continue
>       read(*,i)
>       end
> $ gfortran -fbounds-check a2.f -w && ./a.out
> Fortran runtime error: Label assigned to variable 'i' is not a  
> format label (in file 'a2.f', at line 4)
>
> $ cat a3.f
>       integer i
>       assign 800 to i
>       goto i
>   800 format(A)
>       end
> $ gfortran -fbounds-check a3.f -w && ./a.out
> Fortran runtime error: Assigned label is not a target label (in  
> file 'a3.f', at line 3)
>
> $ cat a4.f
>       integer i
>       assign 800 to i
>       goto i, (200)
>   800 continue
>   200 continue
>       end
> $ gfortran -fbounds-check a4.f -w && ./a.out
> Fortran runtime error: Assigned label is not in the list (in file  
> 'a4.f', at line 3)
>
> $ cat a5.f90
> program alloc_dummy
>
>     implicit none
>     integer, allocatable :: a(:)
>
>     allocate(a(5))
>     print *, whatever(a)
>
> contains
>
>     function whatever(x)
>         integer, allocatable :: x(:)
>         integer :: whatever(size(x)+1)
>
>         whatever = x
>     end function whatever
> end program alloc_dummy
> $ gfortran -fbounds-check a5.f90 -w && ./a.out
> Fortran runtime error: Array bound mismatch, size mismatch for  
> dimension 1 of array 'whatever' (in file 'a5.f90', at line 15)

I hope you think, like me, that it's better than the current error  
message: "Fortran runtime error: Array bound mismatch", with no  
source file, line and variable name :)

Now, to what the patch does:
  -- _gfortran_runtime_error takes only one argument, so we stop  
generating calls with three arguments! :)
  -- instead of passing a string tree to gfc_trans_runtime_check,  
give it a string (it will build the tree itself) and a locus (from  
which it will extract the source file and source line number); if the  
locus is NULL, then gfc_trans_runtime_check will use the fallback  
method of gfc_source_file and input_line
  -- modify everywhere to pass locus to gfc_trans_runtime_check,  
whenever possible
  -- for every call to gfc_trans_runtime_check, build more precise  
error messages, including variable name, the dimension involved for  
out-of-bounds index message, whether it's the lower or upper bound  
that was exceeded.

There still are some calls to gfc_trans_runtime_check that I don't  
understand in which cases they are reached:
  * in trans-intrinsic.c, at line 764
  * in trans-expr.c, at line 2156
For these cases, we now generate the same error message than we  
previously did, added with source file and approximate line location.


Bootstrapped and tested on i686-linux. OK for mainline?

Thanks,
FX





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Attachment: bounds_check.ChangeLog
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Attachment: bounds_check.diff
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