From: Jonathan Wakely <jwakely@redhat.com>
Date: Mon, 10 Jun 2024 12:51:52 +0000 (+0100)
Subject: libstdc++: Do not use memset in _Hashtable::clear()
X-Git-Tag: basepoints/gcc-16~8341
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=3f2f9059c7f76ff888e9d0e8f10dec6f48e346c9;p=thirdparty%2Fgcc.git

libstdc++: Do not use memset in _Hashtable::clear()

Using memset is incorrect if the __bucket_ptr type is non-trivial, or
does not use an all-zero bit pattern for its null value.

Replace the three uses of memset with std::fill_n to set the pointers to
nullptr.

libstdc++-v3/ChangeLog:

	* include/bits/hashtable.h (_Hashtable::clear): Do not use
	memset to zero out bucket pointers.
	(_Hashtable::_M_assign_elements): Likewise.
---

diff --git a/libstdc++-v3/include/bits/hashtable.h b/libstdc++-v3/include/bits/hashtable.h
index 6e78cb7d9c0..983aa909d6c 100644
--- a/libstdc++-v3/include/bits/hashtable.h
+++ b/libstdc++-v3/include/bits/hashtable.h
@@ -34,6 +34,7 @@
 
 #include <bits/hashtable_policy.h>
 #include <bits/enable_special_members.h>
+#include <bits/stl_algobase.h> // fill_n
 #include <bits/stl_function.h> // __has_is_transparent_t
 #if __cplusplus > 201402L
 # include <bits/node_handle.h>
@@ -1376,8 +1377,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 	    _M_bucket_count = __ht._M_bucket_count;
 	  }
 	else
-	  __builtin_memset(_M_buckets, 0,
-			   _M_bucket_count * sizeof(__node_base_ptr));
+	  std::fill_n(_M_buckets, _M_bucket_count, nullptr);
 
 	__try
 	  {
@@ -1400,8 +1400,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 		_M_buckets = __former_buckets;
 		_M_bucket_count = __former_bucket_count;
 	      }
-	    __builtin_memset(_M_buckets, 0,
-			     _M_bucket_count * sizeof(__node_base_ptr));
+	    std::fill_n(_M_buckets, _M_bucket_count, nullptr);
 	    __throw_exception_again;
 	  }
       }
@@ -2582,8 +2581,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     clear() noexcept
     {
       this->_M_deallocate_nodes(_M_begin());
-      __builtin_memset(_M_buckets, 0,
-		       _M_bucket_count * sizeof(__node_base_ptr));
+      std::fill_n(_M_buckets, _M_bucket_count, nullptr);
       _M_element_count = 0;
       _M_before_begin._M_nxt = nullptr;
     }