re PR c++/72868 (Constexpr expressions mistreat case ranges)

	PR c++/72868
	* constexpr.c (label_matches): Handle case range expressions.

	* g++.dg/cpp1y/constexpr-switch4.C: New test.

From-SVN: r239379

gcc/cp/ChangeLog

+2016-08-11  Jakub Jelinek  <jakub@redhat.com>
+
+	PR c++/72868
+	* constexpr.c (label_matches): Handle case range expressions.
+
 2016-08-11  Jason Merrill  <jason@redhat.com>
 
 	PR c++/73456

gcc/cp/constexpr.c

@@ -3448,6 +3448,12 @@ label_matches (tree *jump_target, tree_stmt_iterator i,
 	{
 	  if (!CASE_LOW (stmt))
 	    default_label = i;
+	  else if (CASE_HIGH (stmt))
+	    {
+	      if (tree_int_cst_le (CASE_LOW (stmt), *jump_target)
+		  && tree_int_cst_le (*jump_target, CASE_HIGH (stmt)))
+		return true;
+	    }
 	  else if (tree_int_cst_equal (*jump_target, CASE_LOW (stmt)))
 	    return true;
 	}

gcc/testsuite/ChangeLog

+2016-08-11  Jakub Jelinek  <jakub@redhat.com>
+
+	PR c++/72868
+	* g++.dg/cpp1y/constexpr-switch4.C: New test.
+
 2015-08-11  H.J. Lu  <hongjiu.lu@intel.com>
 
 	* gcc.target/i386/pieces-memcpy-1.c: New test.

gcc/testsuite/g++.dg/cpp1y/constexpr-switch4.C

+// PR c++/72868
+// { dg-do compile }
+// { dg-options "-std=gnu++14" }
+
+constexpr int
+foo (int i)
+{
+  switch (i)
+    {
+    case 11 ... 12:
+      return 4;
+    case 0 ... 9:
+      return 3;
+    default:
+      return 7;
+    }
+}
+
+#define SA(X) static_assert((X),#X)
+SA (foo (-1) == 7);
+SA (foo (0) == 3);
+SA (foo (3) == 3);
+SA (foo (9) == 3);
+SA (foo (10) == 7);
+SA (foo (11) == 4);
+SA (foo (12) == 4);
+SA (foo (13) == 7);