From: François Dumont <frs.dumont@gmail.com>
Date: Sat, 1 Jun 2024 20:17:19 +0000 (+0200)
Subject: libstdc++: Fix -Wstringop-overflow warning coming from std::vector [PR109849]
X-Git-Tag: basepoints/gcc-16~8557
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=0426be454448f8cfb9db21f4f669426afb7b57c8;p=thirdparty%2Fgcc.git

libstdc++: Fix -Wstringop-overflow warning coming from std::vector [PR109849]

libstdc++-v3/ChangeLog:

	PR libstdc++/109849
	* include/bits/vector.tcc
	(std::vector<>::_M_range_insert(iterator, _FwdIt, _FwdIt,
	forward_iterator_tag))[__cplusplus < 201103L]: Add __builtin_unreachable
	expression to tell the compiler that the allocated buffer is large enough to
	receive current elements plus the elements of the range to insert.
---

diff --git a/libstdc++-v3/include/bits/vector.tcc b/libstdc++-v3/include/bits/vector.tcc
index 36b27dce7b9..c500aab9e56 100644
--- a/libstdc++-v3/include/bits/vector.tcc
+++ b/libstdc++-v3/include/bits/vector.tcc
@@ -933,6 +933,11 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
 
 		const size_type __len =
 		  _M_check_len(__n, "vector::_M_range_insert");
+#if __cplusplus < 201103LL
+		if (__len < (__n + (__old_start - __old_finish)))
+		  __builtin_unreachable();
+#endif
+
 		pointer __new_start(this->_M_allocate(__len));
 		pointer __new_finish(__new_start);
 		__try