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authordgp <dgp@users.sourceforge.net>2016-10-28 14:27:59 (GMT)
committerdgp <dgp@users.sourceforge.net>2016-10-28 14:27:59 (GMT)
commita81f6b904b3b6777ed2da4e55b669b7e4770dcc9 (patch)
tree91dfd482cf979d51bf3be729dc624b83b1f7ac37
parent4968966c028c3577f5ef3e604cf1e98b7c37d824 (diff)
parent597d65b1e9b9c0c40782bc5ee8b372bf4bb6b995 (diff)
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Add warning commentary making important assumptions explicit.
-rw-r--r--generic/tclCmdIL.c8
-rw-r--r--generic/tclStringObj.c2
2 files changed, 10 insertions, 0 deletions
diff --git a/generic/tclCmdIL.c b/generic/tclCmdIL.c
index 7420538..bb3c9b7 100644
--- a/generic/tclCmdIL.c
+++ b/generic/tclCmdIL.c
@@ -2179,6 +2179,14 @@ Tcl_JoinObjCmd(
resObjPtr = Tcl_NewObj();
for (i = 0; i < listLen; i++) {
if (i > 0) {
+
+ /*
+ * NOTE: This code is relying on Tcl_AppendObjToObj() **NOT**
+ * to shimmer joinObjPtr. If it did, then the case where
+ * objv[1] and objv[2] are the same value would not be safe.
+ * Accessing elemPtrs would crash.
+ */
+
Tcl_AppendObjToObj(resObjPtr, joinObjPtr);
}
Tcl_AppendObjToObj(resObjPtr, elemPtrs[i]);
diff --git a/generic/tclStringObj.c b/generic/tclStringObj.c
index e878167..fefb014 100644
--- a/generic/tclStringObj.c
+++ b/generic/tclStringObj.c
@@ -1182,6 +1182,8 @@ Tcl_AppendUnicodeToObj(
* Side effects:
* The string rep of appendObjPtr is appended to the string
* representation of objPtr.
+ * IMPORTANT: This routine does not and MUST NOT shimmer appendObjPtr.
+ * Callers are counting on that.
*
*----------------------------------------------------------------------
*/