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From: Jonathan Wakely <redi@gcc.gnu.org>
To: gcc-cvs@gcc.gnu.org, libstdc++-cvs@gcc.gnu.org
Subject: [gcc r12-9716] libstdc++: avoid bogus -Wrestrict [PR105651]
Date: Wed, 21 Jun 2023 12:18:54 +0000 (GMT)	[thread overview]
Message-ID: <20230621121854.67BE83858D28@sourceware.org> (raw)

https://gcc.gnu.org/g:636795a6dfc17ead7b22b9f76b0fc47bdb9d357d

commit r12-9716-g636795a6dfc17ead7b22b9f76b0fc47bdb9d357d
Author: Jason Merrill <jason@redhat.com>
Date:   Thu Aug 18 23:53:16 2022 -0400

    libstdc++: avoid bogus -Wrestrict [PR105651]
    
            PR tree-optimization/105651
    
    libstdc++-v3/ChangeLog:
    
            * include/bits/basic_string.tcc (_M_replace): Add an assert
            to avoid -Wrestrict false positive.

Diff:
---
 libstdc++-v3/include/bits/basic_string.tcc | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/libstdc++-v3/include/bits/basic_string.tcc b/libstdc++-v3/include/bits/basic_string.tcc
index 0696b96604c..48fa28e6466 100644
--- a/libstdc++-v3/include/bits/basic_string.tcc
+++ b/libstdc++-v3/include/bits/basic_string.tcc
@@ -529,6 +529,10 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 		    {
 		      const size_type __nleft = (__p + __len1) - __s;
 		      this->_S_move(__p, __s, __nleft);
+		      // Tell the middle-end that the copy can't overlap
+		      // (PR105651).
+		      if (__len2 < __nleft)
+			__builtin_unreachable();
 		      this->_S_copy(__p + __nleft, __p + __len2,
 				    __len2 - __nleft);
 		    }

                 reply	other threads:[~2023-06-21 12:18 UTC|newest]

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