SERVER-34218 Always reinitialize fields in FieldRef::parse().

Previously, calling FieldRef::FieldRef(StringData) never initialized
_cachedSize, resulting in unpredictable build failures.

Additionally, calling FieldRef::parse(StringData) with the empty
string did not reinitialize the FieldRef.

1 files changed, 3 insertions, 5 deletions

diff --git a/src/mongo/db/field_ref.cpp b/src/mongo/db/field_ref.cpp
index 3a759febe3c..3070aafebb3 100644
--- a/src/mongo/db/field_ref.cpp
+++ b/src/mongo/db/field_ref.cpp
@@ -38,19 +38,17 @@ const size_t FieldRef::kReserveAhead;
 
 FieldRef::FieldRef() : _size(0), _cachedSize(0) {}
 
-FieldRef::FieldRef(StringData path) : _size(0) {
+FieldRef::FieldRef(StringData path) {
     parse(path);
 }
 
 void FieldRef::parse(StringData path) {
+    clear();
+
     if (path.size() == 0) {
         return;
     }
 
-    if (_size != 0) {
-        clear();
-    }
-
     // We guarantee that accesses through getPart() will be valid while 'this' is. So we
     // keep a copy in a local sting.