[gcc r12-5874] libstdc++: Disable over-zealous warnings about std::string copies [PR103332]

[Jonathan Wakely <redi@gcc.gnu.org>]

https://gcc.gnu.org/g:f8463b0e3ec2438b4cfb8c9a468d59761db2c8a0

commit r12-5874-gf8463b0e3ec2438b4cfb8c9a468d59761db2c8a0
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Thu Dec 2 13:19:41 2021 +0000

    libstdc++: Disable over-zealous warnings about std::string copies [PR103332]
    
    These warnings are triggered by perfectly valid code using std::string.
    They're particularly bad when --enable-fully-dynamic-string is used,
    because even std::string().begin() will give a warning.
    
    Use pragmas to stop the troublesome warnings for copies done by
    std::char_traits.
    
    libstdc++-v3/ChangeLog:
    
            PR libstdc++/103332
            PR libstdc++/102958
            PR libstdc++/103483
            * include/bits/char_traits.h: Suppress stringop and array-bounds
            warnings.

Diff:
---
 libstdc++-v3/include/bits/char_traits.h | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/libstdc++-v3/include/bits/char_traits.h b/libstdc++-v3/include/bits/char_traits.h
index da3e0ffffaa..3f7befcf8b2 100644
--- a/libstdc++-v3/include/bits/char_traits.h
+++ b/libstdc++-v3/include/bits/char_traits.h
@@ -54,6 +54,11 @@ namespace __gnu_cxx _GLIBCXX_VISIBILITY(default)
 {
 _GLIBCXX_BEGIN_NAMESPACE_VERSION
 
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wstringop-overflow"
+#pragma GCC diagnostic ignored "-Wstringop-overread"
+#pragma GCC diagnostic ignored "-Warray-bounds"
+
   /**
    *  @brief  Mapping from character type to associated types.
    *
@@ -990,6 +995,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
   } // namespace __detail
 #endif // C++20
 
+#pragma GCC diagnostic push
+
 _GLIBCXX_END_NAMESPACE_VERSION
 } // namespace