Avoid using memset on a not-trivial type like nsTabSizes

nsTabSizes is non-trivial only because of the user-defined constructor.  The idea desired here is certainly to zero all the members without listing them -- but the very act of doing so with a user-defined constructor, makes the idea impossible.

Arguably this is something that is permissible in the language, and that the warning should be tailored to permit.  I don't think this falls afoul of any of the issues flagged in https://gcc.gnu.org/ml/gcc-patches/2017-06/msg01527.html for example.  In the meantime, just explicitly zeroing the three member fields is easy and fixes the warnings.

1 files changed, 6 insertions, 1 deletions

diff --git a/layout/base/nsArenaMemoryStats.h b/layout/base/nsArenaMemoryStats.h
index ba09baaa4..2a872cfe8 100644
--- a/layout/base/nsArenaMemoryStats.h
+++ b/layout/base/nsArenaMemoryStats.h
@@ -18,7 +18,12 @@ public:
       Other       // Everything else.
   };
 
-  nsTabSizes() { mozilla::PodZero(this); }
+  nsTabSizes()
+    : mDom(0)
+    , mStyle(0)
+    , mOther(0)
+  {
+  }
 
   void add(Kind kind, size_t n)
   {