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[v3] Fix libstdc++/40518
- From: Paolo Carlini <paolo dot carlini at oracle dot com>
- To: "gcc-patches at gcc dot gnu dot org" <gcc-patches at gcc dot gnu dot org>
- Cc: libstdc++ <libstdc++ at gcc dot gnu dot org>
- Date: Tue, 23 Jun 2009 14:37:47 +0200
- Subject: [v3] Fix libstdc++/40518
Hi,
tested x86_64-linux, committed to mainline.
Paolo.
///////////////////////////
2009-06-23 Paolo Carlini <paolo.carlini@oracle.com>
PR libstdc++/40518
* include/bits/basic_string.h (basic_string<>::_Rep::
_M_set_length_and_sharable): Do not write the empty rep.
(basic_string<>::erase(iterator, iterator)): Likewise,
move out of line...
* include/bits/basic_string.tcc: ... here.
Index: include/bits/basic_string.h
===================================================================
--- include/bits/basic_string.h (revision 148848)
+++ include/bits/basic_string.h (working copy)
@@ -197,12 +197,17 @@
void
_M_set_length_and_sharable(size_type __n)
- {
- this->_M_set_sharable(); // One reference.
- this->_M_length = __n;
- traits_type::assign(this->_M_refdata()[__n], _S_terminal);
- // grrr. (per 21.3.4)
- // You cannot leave those LWG people alone for a second.
+ {
+#ifndef _GLIBCXX_FULLY_DYNAMIC_STRING
+ if (__builtin_expect(this != &_S_empty_rep(), false))
+#endif
+ {
+ this->_M_set_sharable(); // One reference.
+ this->_M_length = __n;
+ traits_type::assign(this->_M_refdata()[__n], _S_terminal);
+ // grrr. (per 21.3.4)
+ // You cannot leave those LWG people alone for a second.
+ }
}
_CharT*
@@ -1226,16 +1231,8 @@
* The value of the string doesn't change if an error is thrown.
*/
iterator
- erase(iterator __first, iterator __last)
- {
- _GLIBCXX_DEBUG_PEDASSERT(__first >= _M_ibegin() && __first <= __last
- && __last <= _M_iend());
- const size_type __pos = __first - _M_ibegin();
- _M_mutate(__pos, __last - __first, size_type(0));
- _M_rep()->_M_set_leaked();
- return iterator(_M_data() + __pos);
- }
-
+ erase(iterator __first, iterator __last);
+
/**
* @brief Replace characters with value from another string.
* @param pos Index of first character to replace.
Index: include/bits/basic_string.tcc
===================================================================
--- include/bits/basic_string.tcc (revision 148848)
+++ include/bits/basic_string.tcc (working copy)
@@ -386,6 +386,29 @@
}
template<typename _CharT, typename _Traits, typename _Alloc>
+ typename basic_string<_CharT, _Traits, _Alloc>::iterator
+ basic_string<_CharT, _Traits, _Alloc>::
+ erase(iterator __first, iterator __last)
+ {
+ _GLIBCXX_DEBUG_PEDASSERT(__first >= _M_ibegin() && __first <= __last
+ && __last <= _M_iend());
+
+ // NB: This isn't just an optimization (bail out early when
+ // there is nothing to do, really), it's also a correctness
+ // issue vs MT, see libstdc++/40518.
+ const size_type __size = __last - __first;
+ if (__size)
+ {
+ const size_type __pos = __first - _M_ibegin();
+ _M_mutate(__pos, __size, size_type(0));
+ _M_rep()->_M_set_leaked();
+ return iterator(_M_data() + __pos);
+ }
+ else
+ return __first;
+ }
+
+ template<typename _CharT, typename _Traits, typename _Alloc>
basic_string<_CharT, _Traits, _Alloc>&
basic_string<_CharT, _Traits, _Alloc>::
replace(size_type __pos, size_type __n1, const _CharT* __s,