Implement P1152R4: Deprecating some uses of volatile.

	PR c++/91361
	* c-opts.c (c_common_post_options): Enable -Wvolatile by
	default for C++2a, unless -Wno-deprecated.
	* c.opt (Wvolatile): New warning.

	* cp-gimplify.c (cp_fold): Set TREE_THIS_VOLATILE.
	* decl.c (grokdeclarator): Warn about a volatile-qualified structured
	binding and return type.
	(grokparms): Warn about a volatile-qualified function parameter.
	* expr.c (mark_use) <case MODIFY_EXPR>: Emit a -Wvolatile warning.
	* typeck.c (cp_build_unary_op): Emit a -Wvolatile warning for pre and
	post ++/-- on a volatile operand.
	(genericize_compound_lvalue): Use a better location.  Don't lose
	TREE_THIS_VOLATILE.
	(cp_build_modify_expr): Emit a -Wvolatile warning for a compound
	assignment whose LHS is volatile-qualified.  Build the assignment with
	a more precise location.

	* doc/invoke.texi: Document -Wvolatile.

	* c-c++-common/Wbool-operation-1.c: Use -Wno-volatile in C++.
	* c-c++-common/gomp/atomic-1.c: Likewise.
	* c-c++-common/gomp/atomic-9.c: Likewise.
	* c-c++-common/gomp/depend-iterator-1.c: Likewise.
	* c-c++-common/gomp/loop-1.c: Adjust warning location for C++.
	* c-c++-common/gomp/order-3.c: Likewise.
	* c-c++-common/pr69733.c: Use -Wno-volatile in C++.
	* c-c++-common/spec-barrier-2.c: Likewise.
	* c-c++-common/tm/pr54893.c: Likewise.
	* g++.dg/cpp0x/pr65327.C: Add dg-warning.
	* g++.dg/cpp0x/rv-conv2.C: Likewise.
	* g++.dg/cpp0x/rv1n.C: Likewise.
	* g++.dg/cpp0x/rv1p.C: Likewise.
	* g++.dg/cpp0x/rv2n.C: Likewise.
	* g++.dg/cpp0x/rv2p.C: Likewise.
	* g++.dg/cpp0x/rv3n.C: Likewise.
	* g++.dg/cpp0x/rv3p.C: Likewise.
	* g++.dg/cpp0x/rv4n.C: Likewise.
	* g++.dg/cpp0x/rv4p.C: Likewise.
	* g++.dg/cpp0x/rv5n.C: Likewise.
	* g++.dg/cpp0x/rv5p.C: Likewise.
	* g++.dg/cpp0x/rv6n.C: Likewise.
	* g++.dg/cpp0x/rv6p.C: Likewise.
	* g++.dg/cpp0x/rv7n.C: Likewise.
	* g++.dg/cpp0x/rv7p.C: Likewise.
	* g++.dg/cpp0x/rv8p.C: Likewise.
	* g++.dg/cpp0x/trailing14.C: Use -Wno-volatile.
	* g++.dg/cpp1y/new1.C: Add dg-warning.
	* g++.dg/cpp2a/volatile1.C: New test.
	* g++.dg/cpp2a/volatile2.C: New test.
	* g++.dg/cpp2a/volatile3.C: New test.
	* g++.dg/cpp2a/volatile4.C: New test.
	* g++.dg/expr/bool3.C: Add dg-warning.
	* g++.dg/expr/bool4.C: Likewise.
	* g++.dg/expr/cond9.C: Likewise.
	* g++.dg/ext/vector25.C: Likewise.
	* g++.dg/gomp/depend-iterator-1.C: Use -Wno-volatile.
	* g++.dg/inherit/covariant21.C: Add dg-warning.
	* g++.dg/init/ref18.C: Likewise.
	* g++.dg/ipa/pr63838.C: Likewise.
	* g++.dg/overload/rvalue2.C: Likewise.
	* g++.dg/parse/semicolon4.C: Likewise.
	* g++.dg/warn/Wreturn-type-4.C: Likewise.
	* g++.dg/warn/pr36069.C: Likewise.
	* g++.old-deja/g++.mike/p9506.C: Likewise.
	* g++.old-deja/g++.other/volatile1.C: Likewise.

From-SVN: r275022

1 files changed, 22 insertions, 0 deletions

diff --git a/gcc/cp/expr.c b/gcc/cp/expr.c
index 9160043..212a7f9 100644
--- a/gcc/cp/expr.c
+++ b/gcc/cp/expr.c
@@ -207,6 +207,28 @@ mark_use (tree expr, bool rvalue_p, bool read_p,
       recurse_op[0] = true;
       break;
 
+    case MODIFY_EXPR:
+	{
+	  tree lhs = TREE_OPERAND (expr, 0);
+	  /* [expr.ass] "A simple assignment whose left operand is of
+	     a volatile-qualified type is deprecated unless the assignment
+	     is either a discarded-value expression or appears in an
+	     unevaluated context."  */
+	  if (read_p
+	      && !cp_unevaluated_operand
+	      && (TREE_THIS_VOLATILE (lhs)
+		  || CP_TYPE_VOLATILE_P (TREE_TYPE (lhs)))
+	      && !TREE_THIS_VOLATILE (expr))
+	    {
+	      warning_at (location_of (expr), OPT_Wvolatile,
+			  "using value of simple assignment with %<volatile%>-"
+			  "qualified left operand is deprecated");
+	      /* Make sure not to warn about this assignment again.  */
+	      TREE_THIS_VOLATILE (expr) = true;
+	    }
+	  break;
+	}
+
     default:
       break;
     }