Re: PR fortran/125092 -checks for binding label argument mismatch

On 5/13/26 9:29 AM, Thomas Koenig wrote:
> Hello world,
> 
> the patch below is regression-tested.  OK for trunk?
> 
> Best regards
> 
>      Thomas
> 
> PR fortran/125092 - checks for binding label argument mismatch.
> 
> This patch implements some checks on different interfaces to the same
> C binding functions. It contains a few policy changes, and is somewhat
> more permissive than the standard, but there are no constraint
> violations (to my knowledge) that it misses.
> 
> Apart from checking for standards conformance, this should also
> help proof code against (now or future) type-based aliasing mishaps.
> 
> Checks for global identifiers are performed on a case-insensitive
> basis by default, and only sensitive when -pedantic is in force.
> This makes sense if Fortran code wants to interface to "FOO" and
> "foo".  The restriction to case-insensitive labels comes from a time
> when relevant systems had linkers which were case-insensitive, and
> it is not possible to implement C (especially the C versions referenced
> in the standard) with such a linker.
> 
> Return types of functions, ranks, number, type and rank of arguments
> are checked. In non-pedantic mode, arguments which have the same
> prototype on the C side are permitted, for example passing a scalar
> or an array by reference, or arrays of different rank (both for pass
> by reference and pass by descriptors). Assumed types are also
> assumed to bee OK. This functionality was checked in a few test
> cases, so it would make little sense to remove it.
> 
> C_PTR is *not* compatible with a random argument passed by reference.
> For example, a TYPE(C_PTR), VALUE argument is not compatible
> with an INTEGER argument (without VALUE); C_LOC has to be used.
> 
> The one-liner in decl.cc may fix some ENTRY problems, I didn't check.
> 
> gcc/fortran/ChangeLog:
> 
>      * decl.cc (add_global_entry): Use string from the heap instead
>      of a pointer to stack-allocated memory.
>      * frontend-passes.cc (check_against_globals): If there is an error
>      already, return early.
>      * gfortran.h (gfc_symbol_rank): New prototype.
>      * interface.cc (symbol_rank): Rename to
>      (gfc_symbol_rank): this.
>      (gfc_check_dummy_characteristics): Use new function name.
>      (gfc_check_result_characteristics): Likewise.
>      (gfc_compare_interfaces): Likewise.
>      (compare_parameter): Likewise.
>      (get_sym_storage_size): Likewise.
>      (gfc_procedure_use): Likewise.
>      * resolve.cc (decays_to_pointer): New function.
>      (c_types_conform): New function.
>      (compare_c_binding_arglists): New function.
>      (gfc_verify_binding_labels): Check return types and rank
>      plus argument lists if there is a pre-exisiting global
>      symbol.
> 
> gcc/testsuite/ChangeLog:
> 
>      * gfortran.dg/PR100906.f90: Add -Wno-pedantic to options.
>      * gfortran.dg/PR100911.f90: Likewise.
>      * gfortran.dg/PR100915.f90: Likewise.
>      * gfortran.dg/PR94327.f90: Likewise.
>      * gfortran.dg/PR94331.f90: Likewise.
>      * gfortran.dg/bind_c_procs_4.f90: Add error messages, remove
>      warning.
>      * gfortran.dg/binding_label_tests_25.f90: Add error messages.
>      * gfortran.dg/binding_label_tests_3.f03: Add error messages.
>      * gfortran.dg/binding_label_tests_34.f90: Add -Wno-pedantic to
>      options.
>      * gfortran.dg/c_char_tests_4.f90: Likewise.
>      * gfortran.dg/c_char_tests_5.f90: Likewise.
>      * gfortran.dg/binding_label_tests_36.f90: New test.
>      * gfortran.dg/binding_label_tests_37.f90: New test.
> 

Looks good to go. I wondered about the TO DO in one of the comments. Are you 
planning to do this later? Any thoughts about it?

Thanks for the work,

Jerry