[PATCH] PR fortran/85780 -- alternate return and BIND(C) conflict

[PATCH] PR fortran/85780 -- alternate return and BIND(C) conflict

[Steve Kargl]

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All,

My original patch for this PR simply fixed an ICE, which
then allowed the code to compile.  In reality, an alternate
return is not ISO C interoperable, so an error message is
a more appropriate response.  So, I re-opened the PR.

The attached patch has been tested on x86_64-*-freebsd.
OK to commit?

2019-01-24  Steven G. Kargl  <kargl@gcc.gnu.org>

	PR fortran/85780
	* decl.c (gfc_match_subroutine): Check for conflict between BIND(C)
	and alternative return.

2019-01-24  Steven G. Kargl  <kargl@gcc.gnu.org>

	PR fortran/85780
	* gfortran.dg/pr85780.f90: Update testcase for error message.

-- 
Steve

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Index: gcc/fortran/decl.c
===================================================================
--- gcc/fortran/decl.c	(revision 268256)
+++ gcc/fortran/decl.c	(working copy)
@@ -7558,6 +7558,7 @@ gfc_match_subroutine (void)
   match is_bind_c;
   char peek_char;
   bool allow_binding_name;
+  locus loc;
 
   if (gfc_current_state () != COMP_NONE
       && gfc_current_state () != COMP_INTERFACE
@@ -7623,6 +7624,8 @@ gfc_match_subroutine (void)
   /* Here, we are just checking if it has the bind(c) attribute, and if
      so, then we need to make sure it's all correct.  If it doesn't,
      we still need to continue matching the rest of the subroutine line.  */
+  gfc_gobble_whitespace ();
+  loc = gfc_current_locus;
   is_bind_c = gfc_match_bind_c (sym, allow_binding_name);
   if (is_bind_c == MATCH_ERROR)
     {
@@ -7634,6 +7637,8 @@ gfc_match_subroutine (void)
 
   if (is_bind_c == MATCH_YES)
     {
+      gfc_formal_arglist *arg;
+
       /* The following is allowed in the Fortran 2008 draft.  */
       if (gfc_current_state () == COMP_CONTAINS
 	  && sym->ns->proc_name->attr.flavor != FL_MODULE
@@ -7647,8 +7652,17 @@ gfc_match_subroutine (void)
           gfc_error ("Missing required parentheses before BIND(C) at %C");
           return MATCH_ERROR;
         }
-      if (!gfc_add_is_bind_c (&(sym->attr), sym->name,
-			      &(sym->declared_at), 1))
+
+      /* Scan the dummy arguments for an alternate return.  */
+      for (arg = sym->formal; arg; arg = arg->next)
+	if (!arg->sym)
+	  {
+	    gfc_error ("Alternate return dummy argument cannot appear in a "
+		       "SUBROUTINE with the BIND(C) attribute at %L", &loc);
+	    return MATCH_ERROR;
+	  }
+
+      if (!gfc_add_is_bind_c (&(sym->attr), sym->name, &(sym->declared_at), 1))
         return MATCH_ERROR;
     }
 
Index: gcc/testsuite/gfortran.dg/pr85780.f90
===================================================================
--- gcc/testsuite/gfortran.dg/pr85780.f90	(revision 268256)
+++ gcc/testsuite/gfortran.dg/pr85780.f90	(working copy)
@@ -1,5 +1,6 @@
 ! { dg-do compile }
-! { dg-options "-std=legacy" }
+! { dg-options "-fmax-errors=1" }
 ! PR fortran/85780
-subroutine s(*) bind(c)
+subroutine s(*) bind(c)    ! { dg-error "Alternate return dummy argument" }
 end
+! { dg-prune-output "compilation terminated" } 

Re: [PATCH] PR fortran/85780 -- alternate return and BIND(C) conflict

[Paul Richard Thomas]

Hi Steve,

That's OK. Thanks

Paul

On Fri, 25 Jan 2019 at 01:50, Steve Kargl
<sgk@troutmask.apl.washington.edu> wrote:
>
> All,
>
> My original patch for this PR simply fixed an ICE, which
> then allowed the code to compile.  In reality, an alternate
> return is not ISO C interoperable, so an error message is
> a more appropriate response.  So, I re-opened the PR.
>
> The attached patch has been tested on x86_64-*-freebsd.
> OK to commit?
>
> 2019-01-24  Steven G. Kargl  <kargl@gcc.gnu.org>
>
>         PR fortran/85780
>         * decl.c (gfc_match_subroutine): Check for conflict between BIND(C)
>         and alternative return.
>
> 2019-01-24  Steven G. Kargl  <kargl@gcc.gnu.org>
>
>         PR fortran/85780
>         * gfortran.dg/pr85780.f90: Update testcase for error message.
>
> --
> Steve



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