Mark __clear_and_shrink() as noexcept. This prevents the generation of a catch block and call to terminate in string's move assignment. Thanks to Howard for the 'catch'.

llvm-svn: 333435
Cr-Mirrored-From: sso://chromium.googlesource.com/_direct/external/github.com/llvm/llvm-project
Cr-Mirrored-Commit: 5a823d8d63402dd6477cbb6f6c3fd07a1ccfeb1e
diff --git a/include/string b/include/string
index 7218aa2..bfdd141 100644
--- a/include/string
+++ b/include/string
@@ -1259,7 +1259,7 @@
 
     _LIBCPP_INLINE_VISIBILITY bool __invariants() const;
 
-    _LIBCPP_INLINE_VISIBILITY void __clear_and_shrink();
+    _LIBCPP_INLINE_VISIBILITY void __clear_and_shrink() _NOEXCEPT;
     
     _LIBCPP_INLINE_VISIBILITY
     bool __is_long() const _NOEXCEPT
@@ -3585,7 +3585,7 @@
 template<class _CharT, class _Traits, class _Allocator>
 inline _LIBCPP_INLINE_VISIBILITY
 void 
-basic_string<_CharT, _Traits, _Allocator>::__clear_and_shrink()
+basic_string<_CharT, _Traits, _Allocator>::__clear_and_shrink() _NOEXCEPT
 {
     clear();
     if(__is_long())