Merge trunk.

Add more clarity why refCount should be decremented AFTER checking for <2. 
Protect 8.x extensions for being loadable in "novem", by changing Tcl_PkgProvide into a macro.

1 files changed, 7 insertions, 0 deletions

diff --git a/generic/tclInt.h b/generic/tclInt.h
index 7c699c9..742d957 100644
--- a/generic/tclInt.h
+++ b/generic/tclInt.h
@@ -3934,6 +3934,13 @@ typedef const char *TclDTraceStr;
  * Invalidate the string rep first so we can use the bytes value for our
  * pointer chain, and signal an obj deletion (as opposed to shimmering) with
  * 'length == -1'.
+ *
+ * Use do/while0 idiom for optimum correctness without compiler warnings.
+ * http://c2.com/cgi/wiki?TrivialDoWhileLoop
+ *
+ * Decrement refCount AFTER checking it for 0 or 1 (<2), because
+ * we cannot assume anymore that refCount is a signed type; In
+ * Tcl8 it was but in Tcl9 it is subject to change.
  */
 
 # define TclDecrRefCount(objPtr) \