[PATCH] PR fortran/90166 -- check F2018:C1547

[Steve Kargl <sgk@troutmask.apl.washington.edu>]

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The attached patch fixes PR fortran/91066.  The original 
code was feeding a nonsense string of tokens to the
assembler causing it to toss its cookies.  It turns out
that gfortran was not enforcing the constraint C1547
from Fortran 2018.  The attached patch now performs 
that check.  Regression tested on x86_64-*-freebsd.
OK to commit?

2019-04-19  Steven G. Kargl  <kargl@gcc.gnu.org>

	PR fortran/90166
	* decl.c (in_module_or_interface): New function to check that the
	current state is in a module, submodule, or interface.
	(gfc_match_prefix): Use it.

	PR fortran/90166
	* gfortran.dg/submodule_22.f08: Add additional dg-error comments.

-- 
Steve

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Index: gcc/fortran/decl.c
===================================================================
--- gcc/fortran/decl.c	(revision 270181)
+++ gcc/fortran/decl.c	(working copy)
@@ -6070,7 +6070,29 @@ cleanup:
   return m;
 }
 
+static bool
+in_module_or_interface(void)
+{
+  if (gfc_current_state () == COMP_MODULE
+      || gfc_current_state () == COMP_SUBMODULE 
+      || gfc_current_state () == COMP_INTERFACE)
+    return true;
 
+  if (gfc_state_stack->state == COMP_CONTAINS
+      || gfc_state_stack->state == COMP_FUNCTION
+      || gfc_state_stack->state == COMP_SUBROUTINE)
+    {
+      gfc_state_data *p;
+      for (p = gfc_state_stack->previous; p ; p = p->previous)
+	{
+	  if (p->state == COMP_MODULE || p->state == COMP_SUBMODULE 
+	      || p->state == COMP_INTERFACE)
+	    return true;
+	}
+    }
+    return false;
+}
+
 /* Match a prefix associated with a function or subroutine
    declaration.  If the typespec pointer is nonnull, then a typespec
    can be matched.  Note that if nothing matches, MATCH_YES is
@@ -6102,6 +6124,13 @@ gfc_match_prefix (gfc_typespec *ts)
 	{
 	  if (!gfc_notify_std (GFC_STD_F2008, "MODULE prefix at %C"))
 	    goto error;
+
+	  if (!in_module_or_interface ())
+	    {
+	      gfc_error ("MODULE prefix at %C found outside of a module, "
+			 "submodule, or INTERFACE");
+	      goto error;
+	    }
 
 	  current_attr.module_procedure = 1;
 	  found_prefix = true;
Index: gcc/testsuite/gfortran.dg/submodule_22.f08
===================================================================
--- gcc/testsuite/gfortran.dg/submodule_22.f08	(revision 270181)
+++ gcc/testsuite/gfortran.dg/submodule_22.f08	(working copy)
@@ -40,8 +40,10 @@ end
 
 submodule (mtop:submod:subsubmod) subsubsubmod ! { dg-error "Syntax error in SUBMODULE statement" }
 contains
-  module subroutine sub3
-    r = 2.0
-    s = 2.0
-  end subroutine sub3
+  module subroutine sub3  ! { dg-error "found outside of a module" }
+    r = 2.0               ! { dg-error "Unexpected assignment" }
+    s = 2.0               ! { dg-error "Unexpected assignment" }
+  end subroutine sub3     ! { dg-error "Expecting END PROGRAM statement" }
 end
+
+found outside of a module