[patch, fortran] PR39239 Warning about EQUIVALENCE and VOLATILE

[Nicolas Koenig <koenigni at student dot ethz dot ch>]

Hello everyone,

a simple patch to throw a warning if not all and not none of the 
equivalence objects are volatile. (And the according modification of 
gfortran.dg/volatile11.f90)

Nicolas

Regression tested for:

GNU Fortran (GCC) 7.0.1 20170311 (experimental)

Changelog:

2017-03-13  Nicolas Koenig  <koenigni@student.ethz.ch>

                PR fortran/39239
                * resolve.c (resolve_equivalence): Warn if not either 
none or all equivalence objects are volatile
                * gfortran.dg/volatile11.f90: Changed test to test for 
the new warning


Index: fortran/resolve.c
===================================================================
--- fortran/resolve.c	(revision 246070)
+++ fortran/resolve.c	(working copy)
@@ -15560,7 +15560,7 @@ resolve_equivalence (gfc_equiv *eq)
   locus *last_where = NULL;
   seq_type eq_type, last_eq_type;
   gfc_typespec *last_ts;
-  int object, cnt_protected;
+  int object, cnt_protected, cnt_volatile;
   const char *msg;
 
   last_ts = &eq->expr->symtree->n.sym->ts;
@@ -15569,6 +15569,8 @@ resolve_equivalence (gfc_equiv *eq)
 
   cnt_protected = 0;
 
+  cnt_volatile = 0;
+
   for (object = 1; eq; eq = eq->eq, object++)
     {
       e = eq->expr;
@@ -15641,6 +15643,17 @@ resolve_equivalence (gfc_equiv *eq)
 
       sym = e->symtree->n.sym;
 
+      if(sym->attr.volatile_)
+        cnt_volatile++;
+      if(cnt_volatile > 0 && cnt_volatile != object)
+	{
+	  gfc_warning (0, "Either all or none of the objects in "
+	  	       "the EQUIVALENCE set at %L shall have the "
+		       "VOLATILE attribute",
+		       &e->where);
+	  break;
+	}
+
       if (sym->attr.is_protected)
 	cnt_protected++;
       if (cnt_protected > 0 && cnt_protected != object)
Index: testsuite/gfortran.dg/volatile11.f90
===================================================================
--- testsuite/gfortran.dg/volatile11.f90	(revision 246070)
+++ testsuite/gfortran.dg/volatile11.f90	(working copy)
@@ -1,8 +1,9 @@
 ! { dg-do compile }
-! { dg-options "-O2 -fdump-tree-optimized" }
+! { dg-options "-Wall -O2 -fdump-tree-optimized" }
 ! Tests that volatile can be applied to members of common blocks or
 ! equivalence groups (PR fortran/35037)
 !
+
 subroutine wait1
   logical event
   volatile event
@@ -14,26 +15,10 @@ subroutine wait1
 end subroutine
 
 subroutine wait2
-  logical event, foo
-  volatile event
-  equivalence (event, foo)
-  event = .false.
-  do
-    if (event) print *, 'NotOptimizedAway2'
-  end do
-end subroutine
-
-subroutine wait3
   logical event
   integer foo
   volatile foo
-  equivalence (event, foo)
-  event = .false.
-  do
-    if (event) print *, 'IsOptimizedAway'
-  end do
+  equivalence (event, foo) ! { dg-warning "in the EQUIVALENCE set" } 
 end subroutine
 
 ! { dg-final { scan-tree-dump "NotOptimizedAway1" "optimized" } } */
-! { dg-final { scan-tree-dump "NotOptimizedAway2" "optimized" } } */
-! { dg-final { scan-tree-dump-not "IsOptimizedAway" "optimized" } } */