From 0e2b3dba5179c9becbff0730febbdce3a088bae3 Mon Sep 17 00:00:00 2001
From: Jonathan Wakely <jwakely@redhat.com>
Date: Wed, 28 Aug 2024 12:09:58 +0100
Subject: [PATCH] libstdc++: Fix -Wunused-variable warning in <format>
libstdc++-v3/ChangeLog:
* include/std/format (format_parse_context::check_dynamic_spec):
Add [[maybe_unused]] attribute and comment.
---
libstdc++-v3/include/std/format | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/libstdc++-v3/include/std/format b/libstdc++-v3/include/std/format
index 3280dadfb90e..52243eb54792 100644
--- a/libstdc++-v3/include/std/format
+++ b/libstdc++-v3/include/std/format
@@ -4323,6 +4323,11 @@ namespace __format
constexpr void
basic_format_parse_context<_CharT>::check_dynamic_spec(size_t __id) noexcept
{
+ // This call enforces the Mandates: condition that _Ts contains valid
+ // types and each type appears at most once. It could be a static_assert
+ // but this way failures give better diagnostics, due to calling the
+ // non-constexpr __invalid_dynamic_spec function.
+ [[maybe_unused]]
constexpr bool __ok = __check_dynamic_spec_types<_Ts...>();
if consteval {
--
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