Silence jsvector.h strict-aliasing warning

js/src/jsvector.h

@@ -229,6 +229,21 @@ class Vector : AllocPolicy
     union {
         BufferPtrs ptrs;
         char mBuf[sInlineBytes];
+
+#if __GNUC__
+        /*
+         * GCC thinks there is a strict aliasing warning since mBuf is a char
+         * array but we read and write to it as a T array. This is not an error
+         * since there are no reads and writes to the mBuf memory except those
+         * that treat it as a T array. Sadly,
+         *   #pragma GCC diagnostic ignore "-Wstrict-aliasing"
+         * doesn't silence the warning. Type punning is allowed through a union
+         * of the involved types, so, for now, this error can be silenced by
+         * adding each offending T to this union. (This won't work for non-POD
+         * T's, but there don't seem to be any with warnings yet...)
+         */
+        jschar unused1_;
+#endif
     } u;
 
     /* Only valid when usingInlineStorage() */