[Bug fortran/99922] Bind(C) with assumed length character should work

[sandra at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99922

sandra at gcc dot gnu.org changed:

   What|Removed |Added

 CC||sandra at gcc dot gnu.org
 Status|NEW |RESOLVED
 Resolution|--- |DUPLICATE

--- Comment #3 from sandra at gcc dot gnu.org ---
This is a duplicate of now-fixed PR 92482.

*** This bug has been marked as a duplicate of bug 92482 ***

[Bug fortran/99922] Bind(C) with assumed length character should work

[everythingfunctional at protonmail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99922

--- Comment #2 from Brad Richardson  ---
Output from compiling and running with Intel:

[pop-os:~/tmp/c_string_interop] ifort -V
Intel(R) Fortran Intel(R) 64 Compiler Classic for applications running on
Intel(R) 64, Version 2021.2.0 Build 20210228_00
Copyright (C) 1985-2021 Intel Corporation.  All rights reserved.

[pop-os:~/tmp/c_string_interop] ifort -c say_hello_fortran.f90 -o
say_hello_fortran.f90.o
[pop-os:~/tmp/c_string_interop] icc -c say_hello_c.c -o say_hello_c.c.o
[pop-os:~/tmp/c_string_interop] ifort -c main.f90 -o main.f90.o
[pop-os:~/tmp/c_string_interop] ifort say_hello_fortran.f90.o say_hello_c.c.o
main.f90.o -o main.exe
[pop-os:~/tmp/c_string_interop] ./main.exe 
 Hello from Fortran, World!

[Bug fortran/99922] Bind(C) with assumed length character should work

[kargl at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99922

kargl at gcc dot gnu.org changed:

   What|Removed |Added

   Last reconfirmed||2021-04-06
 Status|UNCONFIRMED |NEW
 CC||kargl at gcc dot gnu.org
   Priority|P3  |P4
 Ever confirmed|0   |1

--- Comment #1 from kargl at gcc dot gnu.org ---
(In reply to Brad Richardson from comment #0)
> 
> So this is supposed to be allowed, and I can confirm that I can compile and
> execute the above example and obtain the expected result with Intel (ifort
> and icc).
> 

What result did Intel produce?

This patch suppresses the error message, which allows the code
to compile.  gfortran may produces wrong code.  Someone else can
investigate that issue

diff --git a/gcc/fortran/decl.c b/gcc/fortran/decl.c
index 9039c9dca2a..b10a92ca234 100644
--- a/gcc/fortran/decl.c
+++ b/gcc/fortran/decl.c
@@ -1549,19 +1549,21 @@ gfc_verify_c_interop_param (gfc_symbol *sym)
 sym->ns->proc_name->name);
}

-  /* Character strings are only C interoperable if they have a
- length of 1.  */
-  if (sym->ts.type == BT_CHARACTER && !sym->attr.dimension)
+  /* In F2008 (and earlier?) a character string is only C
+interoperable if it has a length of 1.  With F2018, if the
+string is a dummy argument, it can have an assumed length if
+the formal argument is CFI_cdesc_t.  */
+  if (sym->ts.type == BT_CHARACTER && !sym->attr.dimension
+ && !((gfc_option.allow_std & GFC_STD_F2018) && sym->attr.dummy))
{
  gfc_charlen *cl = sym->ts.u.cl;
+
  if (!cl || !cl->length || cl->length->expr_type != EXPR_CONSTANT
   || mpz_cmp_si (cl->length->value.integer, 1) != 0)
{
- gfc_error ("Character argument %qs at %L "
-"must be length 1 because "
-"procedure %qs is BIND(C)",
-sym->name, >declared_at,
-sym->ns->proc_name->name);
+ gfc_error ("Character argument %qs at %L must be length 1 "
+"because procedure %qs is BIND(C)", sym->name, 
+>declared_at, sym->ns->proc_name->name);
  retval = false;
}
}