re PR c++/91415 (Invalid warning for C++17 sequencing of shift operator E1<<E2.)

	PR c++/91415
	* c-common.c (verify_tree): For LSHIFT_EXPR, RSHIFT_EXPR,
	COMPONENT_REF and ARRAY_REF in cxx_dialect >= cxx17 mode handle it
	like COMPOUND_EXPR rather than normal expression.

	* g++.dg/warn/sequence-pt-4.C: New test.

From-SVN: r274952

gcc/c-family/ChangeLog

+2019-08-27  Jakub Jelinek  <jakub@redhat.com>
+
+	PR c++/91415
+	* c-common.c (verify_tree): For LSHIFT_EXPR, RSHIFT_EXPR,
+	COMPONENT_REF and ARRAY_REF in cxx_dialect >= cxx17 mode handle it
+	like COMPOUND_EXPR rather than normal expression.
+
 2019-08-23  Iain Sandoe  <iain@sandoe.co.uk>
 
 	PR pch/61250

gcc/c-family/c-common.c

@@ -1889,6 +1889,7 @@ verify_tree (tree x, struct tlist **pbefore_sp, struct tlist **pno_sp,
     case COMPOUND_EXPR:
     case TRUTH_ANDIF_EXPR:
     case TRUTH_ORIF_EXPR:
+    sequenced_binary:
       tmp_before = tmp_nosp = tmp_list2 = tmp_list3 = 0;
       verify_tree (TREE_OPERAND (x, 0), &tmp_before, &tmp_nosp, NULL_TREE);
       warn_for_collisions (tmp_nosp);
@@ -2031,8 +2032,18 @@ verify_tree (tree x, struct tlist **pbefore_sp, struct tlist **pno_sp,
 	  x = TREE_OPERAND (x, 0);
 	  goto restart;
 	}
-      gcc_fallthrough ();
+      goto do_default;
+
+    case LSHIFT_EXPR:
+    case RSHIFT_EXPR:
+    case COMPONENT_REF:
+    case ARRAY_REF:
+      if (cxx_dialect >= cxx17)
+	goto sequenced_binary;
+      goto do_default;
+
     default:
+    do_default:
       /* For other expressions, simply recurse on their operands.
 	 Manual tail recursion for unary expressions.
 	 Other non-expressions need not be processed.  */

gcc/testsuite/ChangeLog

+2019-08-27  Jakub Jelinek  <jakub@redhat.com>
+
+	PR c++/91415
+	* g++.dg/warn/sequence-pt-4.C: New test.
+
 2019-08-27  Robin Dapp  <rdapp@linux.ibm.com>
 
 	PR testsuite/91549

gcc/testsuite/g++.dg/warn/sequence-pt-4.C

+/* More sequence point warning tests  */
+/* { dg-do compile } */
+/* { dg-options "-Wsequence-point" } */
+
+struct S { int a[10]; };
+void bar (int, int, int, int, int, int, int, int);
+
+int
+foo (int i, int x[10][10], int y[10], struct S z[10], struct S *w[10])
+{
+  int b = x[i++][i++];	/* { dg-warning "undefined" "sequence point warning" { target c++14_down } } */
+  int c = i++ << i++;	/* { dg-warning "undefined" "sequence point warning" { target c++14_down } } */
+  int d = i++ >> i++;	/* { dg-warning "undefined" "sequence point warning" { target c++14_down } } */
+  int e = i++ && i++;
+  int f = i++ ? i++ : i++;
+  int g = (i++, i++);
+  int h = z[i++].a[i++];	/* { dg-warning "undefined" "sequence point warning" { target c++14_down } } */
+  int j = w[i++]->a[i++];	/* { dg-warning "undefined" "sequence point warning" { target c++14_down } } */
+  bar (b, c, d, e, f,g, h, j);
+  return i;
+}