[gcc r9-9429] c++: Fix -fstrong-eval-order for operator &&, || and , [PR82959]

[gcc r9-9429] c++: Fix -fstrong-eval-order for operator &&, || and , [PR82959]

[Jakub Jelinek]

https://gcc.gnu.org/g:6c085d6d783f38f008ea54f80b43f6b8e8f6b971

commit r9-9429-g6c085d6d783f38f008ea54f80b43f6b8e8f6b971
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Wed Mar 3 16:12:23 2021 +0100

    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.
    
    (cherry picked from commit 529e3b3402bd2a97b02318bd834df72815be5f0f)

Diff:
---
 gcc/cp/call.c                             |  9 +++++++++
 gcc/testsuite/g++.dg/cpp1z/eval-order10.C | 27 +++++++++++++++++++++++++++
 2 files changed, 36 insertions(+)

diff --git a/gcc/cp/call.c b/gcc/cp/call.c
index 7191a4945b1..5822a85f520 100644
--- a/gcc/cp/call.c
+++ b/gcc/cp/call.c
@@ -5790,6 +5790,15 @@ 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 00000000000..02719b7e810
--- /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 ();
+}