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* [gcc r11-9930] c++: wrong error with constexpr COMPOUND_EXPR [PR105321]
@ 2022-04-22 21:00 Marek Polacek
0 siblings, 0 replies; only message in thread
From: Marek Polacek @ 2022-04-22 21:00 UTC (permalink / raw)
To: gcc-cvs
https://gcc.gnu.org/g:afec66b054a7603ef394dc712ccbba37ae645fd9
commit r11-9930-gafec66b054a7603ef394dc712ccbba37ae645fd9
Author: Marek Polacek <polacek@redhat.com>
Date: Wed Apr 20 16:02:52 2022 -0400
c++: wrong error with constexpr COMPOUND_EXPR [PR105321]
Here we issue a bogus error for the first assert in the test. Therein
we have
<retval> = (void) (VIEW_CONVERT_EXPR<bool>(yes) || handle_error ());, VIEW_CONVERT_EXPR<int>(value);
which has a COMPOUND_EXPR, so we get to cxx_eval_constant_expression
<case COMPOUND_EXPR>. The problem here is that we call
7044 /* Check that the LHS is constant and then discard it. */
7045 cxx_eval_constant_expression (ctx, op0,
7046 true, non_constant_p, overflow_p,
7047 jump_target);
where lval is always true, so the PARM_DECL 'yes' is not evaluated into
its value.
Fixed by always passing false for 'lval' in cxx_eval_logical_expression;
there's no case where we actually expect an lvalue from a TRUTH_*.
PR c++/105321
gcc/cp/ChangeLog:
* constexpr.c (cxx_eval_logical_expression): Always pass false for lval
to cxx_eval_constant_expression.
gcc/testsuite/ChangeLog:
* g++.dg/cpp0x/constexpr-105321.C: New test.
(cherry picked from commit 93b65ed9706e2ceb4be7b28c9ff9be759e68a614)
Diff:
---
gcc/cp/constexpr.c | 9 ++++-----
gcc/testsuite/g++.dg/cpp0x/constexpr-105321.C | 18 ++++++++++++++++++
2 files changed, 22 insertions(+), 5 deletions(-)
diff --git a/gcc/cp/constexpr.c b/gcc/cp/constexpr.c
index c13c920ade3..d72a8712dab 100644
--- a/gcc/cp/constexpr.c
+++ b/gcc/cp/constexpr.c
@@ -4280,19 +4280,18 @@ cxx_eval_bit_cast (const constexpr_ctx *ctx, tree t, bool *non_constant_p,
static tree
cxx_eval_logical_expression (const constexpr_ctx *ctx, tree t,
tree bailout_value, tree continue_value,
- bool lval,
- bool *non_constant_p, bool *overflow_p)
+ bool, bool *non_constant_p, bool *overflow_p)
{
tree r;
tree lhs = cxx_eval_constant_expression (ctx, TREE_OPERAND (t, 0),
- lval,
- non_constant_p, overflow_p);
+ /*lval*/false, non_constant_p,
+ overflow_p);
VERIFY_CONSTANT (lhs);
if (tree_int_cst_equal (lhs, bailout_value))
return lhs;
gcc_assert (tree_int_cst_equal (lhs, continue_value));
r = cxx_eval_constant_expression (ctx, TREE_OPERAND (t, 1),
- lval, non_constant_p,
+ /*lval*/false, non_constant_p,
overflow_p);
VERIFY_CONSTANT (r);
return r;
diff --git a/gcc/testsuite/g++.dg/cpp0x/constexpr-105321.C b/gcc/testsuite/g++.dg/cpp0x/constexpr-105321.C
new file mode 100644
index 00000000000..adb6830ff22
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/constexpr-105321.C
@@ -0,0 +1,18 @@
+// PR c++/105321
+// { dg-do compile { target c++11 } }
+
+bool handle_error();
+
+constexpr int echo(int value, bool yes = true) noexcept
+{
+ return (yes || handle_error()), value;
+}
+
+static_assert(echo(10) == 10, "");
+
+constexpr int echo2(int value, bool no = false) noexcept
+{
+ return (!no || handle_error()), value;
+}
+
+static_assert(echo2(10) == 10, "");
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