[Bug fortran/101308] New: Bind(C): gfortran does not create C descriptors for scalar pointer/allocatable arguments

[Bug fortran/101308] New: Bind(C): gfortran does not create C descriptors for scalar pointer/allocatable arguments

[sandra at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101308

            Bug ID: 101308
           Summary: Bind(C): gfortran does not create C descriptors for
                    scalar pointer/allocatable arguments
           Product: gcc
           Version: 12.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: fortran
          Assignee: unassigned at gcc dot gnu.org
          Reporter: sandra at gcc dot gnu.org
  Target Milestone: ---

gfortran is completely failing to create C descriptors for scalar arguments to
bind(c) functions that have the POINTER or ALLOCATABLE attribute.  E.g. for
this trivial test case

subroutine f ()
  use iso_c_binding

  interface
    subroutine ctest (pp) bind (c)
      use iso_c_binding
      integer(C_INT), pointer :: pp
    end subroutine
  end interface

  integer(C_INT), pointer :: p
  p => NULL ()

  call ctest (p)
end subroutine

-fdump-tree-original produces this output:

__attribute__((fn spec (". ")))
void f ()
{
  integer(kind=4) * p;

  p = 0B;
  ctest (&p);
}

showing that it is passing a raw pointer by reference instead.

The 2018 Fortran standard is clear that pointers/allocatables are passed as
pointers to C descriptors; it's item (5) in section 18.3.6.

This bug is causing many failures in my WIP TS29113 testsuite, posted at

https://gcc.gnu.org/pipermail/gcc-patches/2021-July/574115.html

interoperability/fc-descriptor-3.f90
interoperability/fc-out-descriptor-3.f90
interoperability/typecodes-scalar.f90
interoperability/typecodes-scalar-ext.f90
procedures/allocatable-dummy.f90

Is it an accident that the related tests passing descriptors from C to Fortran
functions for pointer/allocatable scalars appear to work?  The called Fortran
function expects a pointer to a pointer to the effective argument, and the C
function is passing a pointer to a descriptor structure whose first element
happens to be a pointer to the effective argument.

[Bug fortran/101308] Bind(C): gfortran does not create C descriptors for scalar pointer/allocatable arguments

[burnus at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101308

Tobias Burnus <burnus at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |burnus at gcc dot gnu.org

--- Comment #1 from Tobias Burnus <burnus at gcc dot gnu.org> ---
The mentioned testsuite has been committed in r12-3320 (Sep 2, 2021)

The bug itself is fixed by
https://gcc.gnu.org/pipermail/gcc-patches/2021-September/578904.html (pending
review)

[Bug fortran/101308] Bind(C): gfortran does not create C descriptors for scalar pointer/allocatable arguments

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101308

--- Comment #2 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Tobias Burnus <burnus@gcc.gnu.org>:

https://gcc.gnu.org/g:64f9623765da3306b0ab6a47997dc5d62c2ea261

commit r12-4467-g64f9623765da3306b0ab6a47997dc5d62c2ea261
Author: Tobias Burnus <tobias@codesourcery.com>
Date:   Mon Oct 18 09:51:36 2021 +0200

    Fortran: Fix Bind(C) Array-Descriptor Conversion

    gfortran uses internally a different array descriptor ("gfc") as
    Fortran 2018 alias TS291113 defines for C interoperability via
    ISO_Fortran_binding.h ("CFI").  Hence, when calling a C function
    from Fortran, it has to be converted in the callee - and if a
    BIND(C) procedure is written in Fortran, the CFI argument has
    to be converted to gfc in order work with the rest of the FE
    code and the library calls.

    Before this patch, part was handled in the FE generated code and
    other parts in libgfortran.  With this patch, all code is generated
    and CFI is defined as proper type - visible in the debugger and to
    the middle end - avoiding both alias issues and missed optimization
    issues.

    This patch also fixes issues like: intent(out) deallocation in
    the bind(C) callee, using the CFI descriptor also for allocatable
    and pointer scalars and for len=* character strings.
    For 'select rank', it also optimizes the code + avoid accessing
    uninitialized memory if the dummy argument is allocatable/a pointer.
    It additionally rejects passing a descriptorless type(*) to an
    assumed-rank dummy argument. [F2018:C711]

            PR fortran/102086
            PR fortran/92189
            PR fortran/92621
            PR fortran/101308
            PR fortran/101309
            PR fortran/101635
            PR fortran/92482

    gcc/fortran/ChangeLog:

            * decl.c (gfc_verify_c_interop_param): Remove 'sorry' for
            scalar allocatable/pointer and len=*.
            * expr.c (is_CFI_desc): Return true for for those.
            * gfortran.h (CFI_type_kind_shift, CFI_type_mask,
            CFI_type_from_type_kind, CFI_VERSION, CFI_MAX_RANK,
            CFI_attribute_pointer, CFI_attribute_allocatable,
            CFI_attribute_other, CFI_type_Integer, CFI_type_Logical,
            CFI_type_Real, CFI_type_Complex, CFI_type_Character,
            CFI_type_ucs4_char, CFI_type_struct, CFI_type_cptr,
            CFI_type_cfunptr, CFI_type_other): New #define.
            * trans-array.c (CFI_FIELD_BASE_ADDR, CFI_FIELD_ELEM_LEN,
            CFI_FIELD_VERSION, CFI_FIELD_RANK, CFI_FIELD_ATTRIBUTE,
            CFI_FIELD_TYPE, CFI_FIELD_DIM, CFI_DIM_FIELD_LOWER_BOUND,
            CFI_DIM_FIELD_EXTENT, CFI_DIM_FIELD_SM,
            gfc_get_cfi_descriptor_field, gfc_get_cfi_desc_base_addr,
            gfc_get_cfi_desc_elem_len, gfc_get_cfi_desc_version,
            gfc_get_cfi_desc_rank, gfc_get_cfi_desc_type,
            gfc_get_cfi_desc_attribute, gfc_get_cfi_dim_item,
            gfc_get_cfi_dim_lbound, gfc_get_cfi_dim_extent,
gfc_get_cfi_dim_sm):
            New define/functions to access the CFI array descriptor.
            (gfc_conv_descriptor_type): New function for the GFC descriptor.
            (gfc_get_array_span): Handle expr of CFI descriptors and
            assumed-type descriptors.
            (gfc_trans_array_bounds): Remove 'static'.
            (gfc_conv_expr_descriptor): For assumed type, use the dtype of
            the actual argument.
            (structure_alloc_comps): Remove ' ' inside tabs.
            * trans-array.h (gfc_trans_array_bounds, gfc_conv_descriptor_type,
            gfc_get_cfi_desc_base_addr, gfc_get_cfi_desc_elem_len,
            gfc_get_cfi_desc_version, gfc_get_cfi_desc_rank,
            gfc_get_cfi_desc_type, gfc_get_cfi_desc_attribute,
            gfc_get_cfi_dim_lbound, gfc_get_cfi_dim_extent,
gfc_get_cfi_dim_sm):
            New prototypes.
            * trans-decl.c (gfor_fndecl_cfi_to_gfc, gfor_fndecl_gfc_to_cfi):
            Remove global vars.
            (gfc_build_builtin_function_decls): Remove their initialization.
            (gfc_get_symbol_decl, create_function_arglist,
            gfc_trans_deferred_vars): Update for CFI.
            (convert_CFI_desc): Remove and replace by ...
            (gfc_conv_cfi_to_gfc): ... this function
            (gfc_generate_function_code): Call it; create local GFC var for
CFI.
            * trans-expr.c (gfc_maybe_dereference_var): Handle CFI.
            (gfc_conv_subref_array_arg): Handle the if-noncontigous-only copy
in
            when the result should be a descriptor.
            (gfc_conv_gfc_desc_to_cfi_desc): Completely rewritten.
            (gfc_conv_procedure_call): CFI fixes.
            * trans-openmp.c (gfc_omp_is_optional_argument,
            gfc_omp_check_optional_argument): Handle optional
            CFI.
            * trans-stmt.c (gfc_trans_select_rank_cases): Cleanup, avoid
invalid
            code for allocatable/pointer dummies, which cannot be assumed size.
            * trans-types.c (gfc_cfi_descriptor_base): New global var.
            (gfc_get_dtype_rank_type): Skip rank init for rank < 0.
            (gfc_sym_type): Handle CFI dummies.
            (gfc_get_function_type): Update call.
            (gfc_get_cfi_dim_type, gfc_get_cfi_type): New.
            * trans-types.h (gfc_sym_type): Update prototype.
            (gfc_get_cfi_type): New prototype.
            * trans.c (gfc_trans_runtime_check): Make conditions more
consistent
            to avoid '<logical> AND_THEN <long int>' in conditions.
            * trans.h (gfor_fndecl_cfi_to_gfc, gfor_fndecl_gfc_to_cfi): Remove
            global-var declaration.

    libgfortran/ChangeLog:

            * ISO_Fortran_binding.h (CFI_type_cfunptr): Make unique type again.
            * runtime/ISO_Fortran_binding.c (cfi_desc_to_gfc_desc,
            gfc_desc_to_cfi_desc): Add comment that those are no longer called
            by new code.

    libgomp/ChangeLog:

            * testsuite/libgomp.fortran/optional-bind-c.f90: New test.

    gcc/testsuite/ChangeLog:

            * gfortran.dg/ISO_Fortran_binding_4.f90: Extend testcase.
            * gfortran.dg/PR100914.f90: Remove xfail.
            * gfortran.dg/PR100915.c: Expect CFI_type_cfunptr.
            * gfortran.dg/PR100915.f90: Handle CFI_type_cfunptr !=
CFI_type_cptr.
            * gfortran.dg/PR93963.f90: Extend select-rank tests.
            * gfortran.dg/bind-c-intent-out.f90: Change to dg-do run,
            update scan-dump.
            * gfortran.dg/bind_c_array_params_2.f90: Update/extend scan-dump.
            * gfortran.dg/bind_c_char_10.f90: Update scan-dump.
            * gfortran.dg/bind_c_char_8.f90: Remove dg-error "sorry".
            * gfortran.dg/c-interop/allocatable-dummy.f90: Remove xfail.
            * gfortran.dg/c-interop/c1255-1.f90: Likewise.
            * gfortran.dg/c-interop/c407c-1.f90: Update dg-error.
            * gfortran.dg/c-interop/cf-descriptor-5.f90: Remove xfail.
            * gfortran.dg/c-interop/cf-out-descriptor-3.f90: Likewise.
            * gfortran.dg/c-interop/cf-out-descriptor-4.f90: Likewise.
            * gfortran.dg/c-interop/cf-out-descriptor-5.f90: Likewise.
            * gfortran.dg/c-interop/contiguous-2.f90: Likewise.
            * gfortran.dg/c-interop/contiguous-3.f90: Likewise.
            * gfortran.dg/c-interop/deferred-character-1.f90: Likewise.
            * gfortran.dg/c-interop/deferred-character-2.f90: Likewise.
            * gfortran.dg/c-interop/fc-descriptor-3.f90: Likewise.
            * gfortran.dg/c-interop/fc-descriptor-5.f90: Likewise.
            * gfortran.dg/c-interop/fc-descriptor-6.f90: Likewise.
            * gfortran.dg/c-interop/fc-out-descriptor-3.f90: Likewise.
            * gfortran.dg/c-interop/fc-out-descriptor-4.f90: Likewise.
            * gfortran.dg/c-interop/fc-out-descriptor-5.f90: Likewise.
            * gfortran.dg/c-interop/fc-out-descriptor-6.f90: Likewise.
            * gfortran.dg/c-interop/ff-descriptor-5.f90: Likewise.
            * gfortran.dg/c-interop/ff-descriptor-6.f90: Likewise.
            * gfortran.dg/c-interop/fc-descriptor-7.f90: Remove xfail + extend.
            * gfortran.dg/c-interop/fc-descriptor-7-c.c: Update for changes.
            * gfortran.dg/c-interop/shape.f90: Add implicit none.
            * gfortran.dg/c-interop/typecodes-array-char-c.c: Add kind=4 char.
            * gfortran.dg/c-interop/typecodes-array-char.f90: Likewise.
            * gfortran.dg/c-interop/typecodes-array-float128.f90: Remove xfail.
            * gfortran.dg/c-interop/typecodes-scalar-basic.f90: Likewise.
            * gfortran.dg/c-interop/typecodes-scalar-float128.f90: Likewise.
            * gfortran.dg/c-interop/typecodes-scalar-int128.f90: Likewise.
            * gfortran.dg/c-interop/typecodes-scalar-longdouble.f90: Likewise.
            * gfortran.dg/iso_c_binding_char_1.f90: Remove dg-error "sorry".
            * gfortran.dg/pr93792.f90: Turn XFAIL into PASS.
            * gfortran.dg/ISO_Fortran_binding_19.f90: New test.
            * gfortran.dg/assumed_type_12.f90: New test.
            * gfortran.dg/assumed_type_13.c: New test.
            * gfortran.dg/assumed_type_13.f90: New test.
            * gfortran.dg/bind-c-char-descr.f90: New test.
            * gfortran.dg/bind-c-contiguous-1.c: New test.
            * gfortran.dg/bind-c-contiguous-1.f90: New test.
            * gfortran.dg/bind-c-contiguous-2.f90: New test.
            * gfortran.dg/bind-c-contiguous-3.c: New test.
            * gfortran.dg/bind-c-contiguous-3.f90: New test.
            * gfortran.dg/bind-c-contiguous-4.c: New test.
            * gfortran.dg/bind-c-contiguous-4.f90: New test.
            * gfortran.dg/bind-c-contiguous-5.c: New test.
            * gfortran.dg/bind-c-contiguous-5.f90: New test.

[Bug fortran/101308] Bind(C): gfortran does not create C descriptors for scalar pointer/allocatable arguments

[burnus at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101308

Tobias Burnus <burnus at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|---                         |FIXED

--- Comment #3 from Tobias Burnus <burnus at gcc dot gnu.org> ---
FIXED (in GCC 12)

The committed c-interop / TS29113 testsuite now passes – and the testcase from
comment 0 gives:

{
  integer(kind=4) * p;

  p = 0B;
  {
    struct CFI_cdesc_t00 cfi.0;

    cfi.0.version = 1;
    cfi.0.rank = 0;
    cfi.0.type = 1025;
    cfi.0.attribute = 0;
    cfi.0.base_addr = (void *) p;
    cfi.0.elem_len = 4;
    ctest (&cfi.0);
    p = (integer(kind=4) *) cfi.0.base_addr;
  }
}

[Bug fortran/101308] Bind(C): gfortran does not create C descriptors for scalar pointer/allocatable arguments

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101308

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |12.0