Fortran: Fix incompatible types between INTEGER(8) and TYPE(c_ptr)

In the context of an OpenMP declare variant directive, arguments of type C_PTR
are sometimes recognised as C_PTR in the base function and as INTEGER(8) in the
variant - or the other way around, depending on the parsing order.
This patch prevents such situation from turning into a compile error.

2023-10-20  Paul-Antoine Arras  <pa@codesourcery.com>
	    Tobias Burnus  <tobias@codesourcery.com>

gcc/fortran/ChangeLog:

	* interface.cc (gfc_compare_types): Return true if one type is C_PTR
	and the other is a compatible INTEGER(8).
	* misc.cc (gfc_typename): Handle the case where an INTEGER(8) actually
	holds a TYPE(C_PTR).

gcc/testsuite/ChangeLog:

	* gfortran.dg/c_ptr_tests_20.f90: New test, checking that INTEGER(8)
	and TYPE(C_PTR) are recognised as compatible.
	* gfortran.dg/c_ptr_tests_21.f90: New test, exercising the error
	detection for C_FUNPTR.

4 files changed, 132 insertions, 5 deletions

diff --git a/gcc/fortran/interface.cc b/gcc/fortran/interface.cc
index c01df04..8c4571e 100644
--- a/gcc/fortran/interface.cc
+++ b/gcc/fortran/interface.cc
@@ -736,10 +736,18 @@ gfc_compare_types (gfc_typespec *ts1, gfc_typespec *ts2)
      better way of doing this.  When ISO C binding is cleared up,
      this can probably be removed.  See PR 57048.  */
 
-  if (((ts1->type == BT_INTEGER && ts2->type == BT_DERIVED)
-       || (ts1->type == BT_DERIVED && ts2->type == BT_INTEGER))
-      && ts1->u.derived && ts2->u.derived
-      && ts1->u.derived == ts2->u.derived)
+  if ((ts1->type == BT_INTEGER
+       && ts2->type == BT_DERIVED
+       && ts1->f90_type == BT_VOID
+       && ts2->u.derived->from_intmod == INTMOD_ISO_C_BINDING
+       && ts1->u.derived
+       && strcmp (ts1->u.derived->name, ts2->u.derived->name) == 0)
+      || (ts2->type == BT_INTEGER
+	  && ts1->type == BT_DERIVED
+	  && ts2->f90_type == BT_VOID
+	  && ts1->u.derived->from_intmod == INTMOD_ISO_C_BINDING
+	  && ts2->u.derived
+	  && strcmp (ts1->u.derived->name, ts2->u.derived->name) == 0))
     return true;
 
   /* The _data component is not always present, therefore check for its
diff --git a/gcc/fortran/misc.cc b/gcc/fortran/misc.cc
index bae6d29..edffba0 100644
--- a/gcc/fortran/misc.cc
+++ b/gcc/fortran/misc.cc
@@ -138,7 +138,12 @@ gfc_typename (gfc_typespec *ts, bool for_hash)
   switch (ts->type)
     {
     case BT_INTEGER:
-      sprintf (buffer, "INTEGER(%d)", ts->kind);
+      if (ts->f90_type == BT_VOID
+	  && ts->u.derived
+	  && ts->u.derived->from_intmod == INTMOD_ISO_C_BINDING)
+	sprintf (buffer, "TYPE(%s)", ts->u.derived->name);
+      else
+	sprintf (buffer, "INTEGER(%d)", ts->kind);
       break;
     case BT_REAL:
       sprintf (buffer, "REAL(%d)", ts->kind);
diff --git a/gcc/testsuite/gfortran.dg/c_ptr_tests_20.f90 b/gcc/testsuite/gfortran.dg/c_ptr_tests_20.f90
new file mode 100644
index 0000000..7dd5104
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/c_ptr_tests_20.f90
@@ -0,0 +1,57 @@
+! { dg-do compile }
+! { dg-additional-options "-fopenmp" }
+!
+! This failed to compile the declare variant directive due to the C_PTR 
+! arguments to foo being recognised as INTEGER(8)
+
+program adjust_args
+  use iso_c_binding, only: c_loc
+  implicit none
+
+  integer, parameter :: N = 1024
+  real, allocatable, target :: av(:), bv(:), cv(:)
+
+  call foo(c_loc(bv), c_loc(av), N)
+
+  !$omp target data map(to: av(:N)) map(from: cv(:N))
+      !$omp parallel
+      call foo(c_loc(cv), c_loc(av), N)
+      !$omp end parallel
+  !$omp end target data
+    
+contains
+  subroutine foo_variant(c_d_bv, c_d_av, n)
+    use iso_c_binding, only: c_ptr, c_f_pointer
+    type(c_ptr), intent(in) :: c_d_bv, c_d_av
+    integer, intent(in) :: n
+    real, pointer :: f_d_bv(:)
+    real, pointer :: f_d_av(:)
+    integer :: i
+  
+    call c_f_pointer(c_d_bv, f_d_bv, [n])
+    call c_f_pointer(c_d_av, f_d_av, [n])
+    !$omp target teams loop is_device_ptr(f_d_bv, f_d_av)
+    do i = 1, n
+      f_d_bv(i) = f_d_av(i) * i
+    end do
+  end subroutine
+  
+  
+  subroutine foo(c_bv, c_av, n)
+    use iso_c_binding, only: c_ptr, c_f_pointer
+    type(c_ptr), intent(in) :: c_bv, c_av
+    integer, intent(in) :: n
+    real, pointer :: f_bv(:)
+    real, pointer :: f_av(:)
+    integer :: i
+    !$omp declare variant(foo_variant)          &
+    !$omp         match(construct={parallel})       
+  
+    call c_f_pointer(c_bv, f_bv, [n])
+    call c_f_pointer(c_av, f_av, [n])
+    !$omp parallel loop
+    do i = 1, n
+      f_bv(i) = f_av(i) * i
+    end do
+  end subroutine
+end program
diff --git a/gcc/testsuite/gfortran.dg/c_ptr_tests_21.f90 b/gcc/testsuite/gfortran.dg/c_ptr_tests_21.f90
new file mode 100644
index 0000000..05ccb77
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/c_ptr_tests_21.f90
@@ -0,0 +1,57 @@
+! { dg-do compile }
+! { dg-additional-options "-fopenmp" }
+!
+! Ensure that C_PTR and C_FUNPTR are reported as incompatible types in variant 
+! argument lists
+
+program adjust_args
+  use iso_c_binding, only: c_loc
+  implicit none
+
+  integer, parameter :: N = 1024
+  real, allocatable, target :: av(:), bv(:), cv(:)
+
+  call foo(c_loc(bv), c_loc(av), N)
+
+  !$omp target data map(to: av(:N)) map(from: cv(:N))
+      !$omp parallel
+      call foo(c_loc(cv), c_loc(av), N)
+      !$omp end parallel
+  !$omp end target data
+    
+contains
+  subroutine foo_variant(c_d_bv, c_d_av, n)
+    use iso_c_binding, only: c_funptr, c_f_pointer
+    type(c_funptr), intent(in) :: c_d_bv, c_d_av
+    integer, intent(in) :: n
+    real, pointer :: f_d_bv(:)
+    real, pointer :: f_d_av(:)
+    integer :: i
+  
+!     call c_f_pointer(c_d_bv, f_d_bv, [n])
+!     call c_f_pointer(c_d_av, f_d_av, [n])
+    !$omp target teams loop is_device_ptr(f_d_bv, f_d_av)
+    do i = 1, n
+      f_d_bv(i) = f_d_av(i) * i
+    end do
+  end subroutine
+  
+  
+  subroutine foo(c_bv, c_av, n)
+    use iso_c_binding, only: c_ptr, c_f_pointer
+    type(c_ptr), intent(in) :: c_bv, c_av
+    integer, intent(in) :: n
+    real, pointer :: f_bv(:)
+    real, pointer :: f_av(:)
+    integer :: i
+    !$omp declare variant(foo_variant)          & ! { dg-error "variant 'foo_variant' and base 'foo' at .1. have incompatible types: Type mismatch in argument 'c_bv' .TYPE.c_ptr./TYPE.c_funptr.." }
+    !$omp         match(construct={parallel})       
+  
+    call c_f_pointer(c_bv, f_bv, [n])
+    call c_f_pointer(c_av, f_av, [n])
+    !$omp parallel loop
+    do i = 1, n
+      f_bv(i) = f_av(i) * i
+    end do
+  end subroutine
+end program