Fix issue using String.concat with flash strings (fix #2268)

espruino · Oct 6, 2023 · ffd2ce1 · ffd2ce1
1 parent 4f0d396
commit ffd2ce1
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Showing 2 changed files with 5 additions and 2 deletions.
diff --git a/ChangeLog b/ChangeLog
@@ -9,7 +9,8 @@
             nRF52: bootloader asks for connection interval 7.5->30ms now, not just 15ms. Should improve DFU on iOS 16 which doesn't honour 15ms request
             Fix unicode in object keys when UTF8 support enabled, eg.  {'\u00e4':1}
             Bangle.js: Change order of items in the Recovery Menu (hold BTN at boot) to put more common options first
-            Tidying up error messages (no trailing '.' or '\n'), making almost-similar error messages the same
+            Tidying up error messages (no trailing '.' or '\n'), making almost-similar error messages the same 
+            Fix issue using `String.concat` with flash strings (fix #2268)
 
      2v19 : Fix Object.values/entries for numeric keys after 2v18 regression (fix #2375)
             nRF52: for SD>5 use static buffers for advertising and scan response data (#2367)

diff --git a/src/jswrap_string.c b/src/jswrap_string.c
@@ -750,7 +750,9 @@ original `String`.
 */
 JsVar *jswrap_string_concat(JsVar *parent, JsVar *args) {
   if (!jsvIsString(parent)) return 0;
-  JsVar *str = jsvNewFromStringVar(parent, 0, JSVAPPENDSTRINGVAR_MAXLENGTH);
+  // don't use jsvNewFromStringVar here because it has an optimisation for Flash Strings that just clones (rather than copying)
+  JsVar *str = jsvNewFromEmptyString();
+  jsvAppendStringVarComplete(str, parent);
   JsVar *extra = jsvArrayJoin(args, NULL/*filler*/, false/*ignoreNull*/);
   jsvAppendStringVarComplete(str, extra);
   jsvUnLock(extra);