commit 663415f51a43d47db981c7157b191890f2e82767
author Louis Dionne <ldionne@apple.com> Mon Oct 05 16:16:13 2020 -0400
committer Copybara-Service <copybara-worker@google.com> Wed Oct 07 06:32:03 2020 -0700
tree eed80bccd08ab90065cee4c7a3ccdfd77da51c11
parent 1b114a598ea5068ec517afb95f8e37402e1dfa4d

[libc++] Make sure __clear_and_shrink() maintains string invariants

__clear_and_shrink() was added in D41976, and a test was added alongside
it to make sure that the string invariants were maintained. However, it
appears that the test never ran under UBSan before, which would have
highlighted the fact that it doesn't actually maintain the string
invariants.

Differential Revision: https://reviews.llvm.org/D88849

GitOrigin-RevId: 602c193e2aeb19f5d2e48075281601a2386e8758

include/string

diff --git a/include/string b/include/string
index b6380da..c900d96 100644
--- a/include/string
+++ b/include/string
@@ -3941,7 +3941,7 @@
         return false;
     if (data() == 0)
         return false;
-    if (data()[size()] != value_type(0))
+    if (data()[size()] != value_type())
         return false;
     return true;
 }
@@ -3959,6 +3959,7 @@
         __alloc_traits::deallocate(__alloc(), __get_long_pointer(), capacity() + 1);
         __set_long_cap(0);
         __set_short_size(0);
+        traits_type::assign(*__get_short_pointer(), value_type());
     }
 }