c++: Fix -fstrong-eval-order for operator &&, || and , [PR82959]

P0145R3 added
"However, the operands are sequenced in the order prescribed for the built-in
operator" rule for overloaded operator calls when using the operator syntax.
op_is_ordered follows that, but added just the overloaded operators
added in that paper.  &&, || and comma operators had rules that
lhs is sequenced before rhs already in C++98.
The following patch adds those cases to op_is_ordered.

2021-03-03  Jakub Jelinek  <jakub@redhat.com>

	PR c++/82959
	* call.c (op_is_ordered): Handle TRUTH_ANDIF_EXPR, TRUTH_ORIF_EXPR
	and COMPOUND_EXPR.

	* g++.dg/cpp1z/eval-order10.C: New test.

2 files changed, 36 insertions, 0 deletions

diff --git a/gcc/cp/call.c b/gcc/cp/call.c
index b00334d..123f06b 100644
--- a/gcc/cp/call.c
+++ b/gcc/cp/call.c
@@ -6083,6 +6083,15 @@ op_is_ordered (tree_code code)
     case LSHIFT_EXPR:
       // 8. a >> b
     case RSHIFT_EXPR:
+      // a && b
+      // Predates P0145R3.
+    case TRUTH_ANDIF_EXPR:
+      // a || b
+      // Predates P0145R3.
+    case TRUTH_ORIF_EXPR:
+      // a , b
+      // Predates P0145R3.
+    case COMPOUND_EXPR:
       return (flag_strong_eval_order ? 1 : 0);
 
     default:
diff --git a/gcc/testsuite/g++.dg/cpp1z/eval-order10.C b/gcc/testsuite/g++.dg/cpp1z/eval-order10.C
new file mode 100644
index 0000000..02719b7
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp1z/eval-order10.C
@@ -0,0 +1,27 @@
+// PR c++/82959
+// { dg-do run }
+// { dg-additional-options -fstrong-eval-order }
+
+struct A {};
+
+void operator && (const A x, const A) {}
+void operator || (const A x, const A) {}
+void operator , (const A x, const A) {}
+
+int i;
+
+A f () { if (i != 0) __builtin_abort (); i = 1; return A (); }
+A g () { if (i != 1) __builtin_abort (); i = 2; return A (); }
+
+int
+main ()
+{
+  f () && g ();
+  if (i != 2) __builtin_abort ();
+  i = 0;
+  f () || g ();
+  if (i != 2) __builtin_abort ();
+  i = 0;
+  f (), g ();
+  if (i != 2) __builtin_abort ();
+}