88 lines
2.3 KiB
Diff
88 lines
2.3 KiB
Diff
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2021-01-15 Jakub Jelinek <jakub@redhat.com>
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PR c++/98672
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* constexpr.c (potential_constant_expression_1) <case FOR_STMT>,
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<case WHILE_STMT>: If the condition isn't constant true, check if
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the loop body can contain a return stmt.
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* g++.dg/cpp1y/constexpr-98672.C: New test.
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--- gcc/cp/constexpr.c.jj 2021-01-13 19:19:44.368469462 +0100
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+++ gcc/cp/constexpr.c 2021-01-14 12:02:27.347042704 +0100
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@@ -8190,7 +8190,17 @@ potential_constant_expression_1 (tree t,
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/* If we couldn't evaluate the condition, it might not ever be
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true. */
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if (!integer_onep (tmp))
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- return true;
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+ {
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+ /* Before returning true, check if the for body can contain
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+ a return. */
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+ hash_set<tree> pset;
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+ check_for_return_continue_data data = { &pset, NULL_TREE };
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+ if (tree ret_expr
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+ = cp_walk_tree (&FOR_BODY (t), check_for_return_continue,
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+ &data, &pset))
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+ *jump_target = ret_expr;
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+ return true;
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+ }
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}
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if (!RECUR (FOR_EXPR (t), any))
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return false;
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@@ -8219,7 +8229,17 @@ potential_constant_expression_1 (tree t,
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tmp = cxx_eval_outermost_constant_expr (tmp, true);
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/* If we couldn't evaluate the condition, it might not ever be true. */
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if (!integer_onep (tmp))
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- return true;
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+ {
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+ /* Before returning true, check if the while body can contain
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+ a return. */
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+ hash_set<tree> pset;
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+ check_for_return_continue_data data = { &pset, NULL_TREE };
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+ if (tree ret_expr
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+ = cp_walk_tree (&WHILE_BODY (t), check_for_return_continue,
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+ &data, &pset))
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+ *jump_target = ret_expr;
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+ return true;
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+ }
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if (!RECUR (WHILE_BODY (t), any))
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return false;
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if (breaks (jump_target) || continues (jump_target))
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--- gcc/testsuite/g++.dg/cpp1y/constexpr-98672.C.jj 2021-01-14 12:19:24.842438847 +0100
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+++ gcc/testsuite/g++.dg/cpp1y/constexpr-98672.C 2021-01-14 12:07:33.935551155 +0100
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@@ -0,0 +1,35 @@
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+// PR c++/98672
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+// { dg-do compile { target c++14 } }
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+
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+void
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+foo ()
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+{
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+}
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+
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+constexpr int
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+bar ()
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+{
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+ for (int i = 0; i < 5; ++i)
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+ return i;
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+ foo ();
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+ return 0;
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+}
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+
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+constexpr int
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+baz ()
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+{
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+ int i = 0;
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+ while (i < 5)
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+ {
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+ if (i == 3)
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+ return i;
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+ else
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+ ++i;
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+ }
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+ foo ();
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+ return 0;
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+}
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+
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+constexpr int i = bar ();
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+constexpr int j = baz ();
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+static_assert (i == 0 && j == 3, "");
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