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* [gcc r12-9716] libstdc++: avoid bogus -Wrestrict [PR105651]
@ 2023-06-21 12:18 Jonathan Wakely
  0 siblings, 0 replies; only message in thread
From: Jonathan Wakely @ 2023-06-21 12:18 UTC (permalink / raw)
  To: gcc-cvs, libstdc++-cvs

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);
 		    }

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