tvanslyke updated this revision to Diff 130775.
tvanslyke added a comment.
Since `__clear_and_shrink()` is private the test covers copy and move
assignment. I also ran the libcxx/strings/basic.string and std/strings tests
with a hard-coded `assert(__invariants());` at the end of
`__clear_and_shrink()` and saw no failures.
I don't have commit access myself so I've added the test to the diff.
https://reviews.llvm.org/D41976
Files:
include/string
test/libcxx/strings/basic.string/string.modifiers/copy_assign_move_assign_db1.pass.cpp
Index: test/libcxx/strings/basic.string/string.modifiers/copy_assign_move_assign_db1.pass.cpp
===================================================================
--- test/libcxx/strings/basic.string/string.modifiers/copy_assign_move_assign_db1.pass.cpp
+++ test/libcxx/strings/basic.string/string.modifiers/copy_assign_move_assign_db1.pass.cpp
@@ -0,0 +1,66 @@
+//===----------------------------------------------------------------------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// <string>
+
+// Call __clear_and_shrink() and ensure string invariants hold
+
+#if _LIBCPP_DEBUG >= 1
+
+#define _LIBCPP_ASSERT(x, m) ((x) ? (void)0 : std::exit(0))
+
+#include <string>
+#include <cassert>
+
+int main()
+{
+ std::string l = "Long string so that allocation definitely, for sure, absolutely happens. Probably.";
+ std::string l2 = l;
+ std::string s = "short";
+ std::string s2 = s;
+ std::string empty = "";
+
+ assert(l.__invariants());
+ assert(s.__invariants());
+ assert(l2.__invariants());
+ assert(s2.__invariants());
+ assert(empty.__invariants());
+
+
+ s2 = empty;
+ assert(s2.__invariants());
+ assert(s2.size() == 0);
+ assert(empty.__invariants());
+ s2 = empty;
+ assert(s2.__invariants());
+ assert(s2.size() == 0);
+ assert(empty.__invariants());
+
+ {
+ std::string::size_type cap = l.capacity();
+ l = empty;
+ assert(l.__invariants());
+ assert(l.size() == 0);
+ assert(empty.__invariants());
+ cap = l2.capacity();
+ l2 = std::move(empty);
+ assert(l2.capacity() < cap);
+ assert(l2.__invariants());
+ assert(l2.size() == 0);
+ assert(empty.__invariants());
+ }
+}
+
+#else
+
+int main()
+{
+}
+
+#endif
Index: include/string
===================================================================
--- include/string
+++ include/string
@@ -1407,24 +1407,34 @@
__alloc_traits::propagate_on_container_copy_assignment::value>());}
_LIBCPP_INLINE_VISIBILITY
+ void __clear_and_shrink()
+ {
+ clear();
+ if(__is_long())
+ {
+ __alloc_traits::deallocate(__alloc(), __get_long_pointer(), capacity() + 1);
+ __set_long_cap(0);
+ __set_short_size(0);
+ }
+ }
+
+ _LIBCPP_INLINE_VISIBILITY
void __copy_assign_alloc(const basic_string& __str, true_type)
{
if (__alloc() == __str.__alloc())
__alloc() = __str.__alloc();
else
{
if (!__str.__is_long())
{
- clear();
- shrink_to_fit();
+ __clear_and_shrink();
__alloc() = __str.__alloc();
}
else
{
allocator_type __a = __str.__alloc();
pointer __p = __alloc_traits::allocate(__a, __str.__get_long_cap());
- clear();
- shrink_to_fit();
+ __clear_and_shrink();
__alloc() = _VSTD::move(__a);
__set_long_pointer(__p);
__set_long_cap(__str.__get_long_cap());
@@ -2102,8 +2112,7 @@
_NOEXCEPT_(is_nothrow_move_assignable<allocator_type>::value)
#endif
{
- clear();
- shrink_to_fit();
+ __clear_and_shrink();
__r_.first() = __str.__r_.first();
__move_assign_alloc(__str);
__str.__zero();
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