Fix call and new expression parsenode beginning line number, where the arglist is on another line from the function or constructor, to avoid a bogus assertion in UPDATE_LINENO_NOTES, which is now replaced by better comments and an avoided gratuitous store to cg->currentLine (123371, r=rginda, sr=shaver).

js/src/jsemit.c

@@ -1768,24 +1768,29 @@ js_EmitFunctionBody(JSContext *cx, JSCodeGenerator *cg, JSParseNode *body,
 /* A macro for inlining at the top of js_EmitTree (whence it came). */
 #define UPDATE_LINENO_NOTES(cx, cg, pn)                                       \
     JS_BEGIN_MACRO                                                            \
-        uintN _line = (pn)->pn_pos.begin.lineno;                              \
-        uintN _delta = _line - (cg)->currentLine;                             \
-        (cg)->currentLine = _line;                                            \
-        if (_delta) {                                                         \
+        uintN line_ = (pn)->pn_pos.begin.lineno;                              \
+        uintN delta_ = line_ - (cg)->currentLine;                             \
+        if (delta_ != 0) {                                                    \
             /*                                                                \
              * Encode any change in the current source line number by using   \
-             * either several SRC_NEWLINE notes or one SRC_SETLINE note,      \
+             * either several SRC_NEWLINE notes or just one SRC_SETLINE note, \
              * whichever consumes less space.                                 \
+             *                                                                \
+             * NB: We handle backward line number deltas (possible with for   \
+             * loops where the update part is emitted after the body, but its \
+             * line number is <= any line number in the body) here by letting \
+             * unsigned delta_ wrap to a very large number, which triggers a  \
+             * SRC_SETLINE.                                                   \
              */                                                               \
-            if (_delta >= (uintN)(2 + ((_line > SN_3BYTE_OFFSET_MASK)<<1))) { \
-                JS_ASSERT(_line != 0);                                        \
-                if (js_NewSrcNote2(cx, cg, SRC_SETLINE, (ptrdiff_t)_line) < 0)\
+            (cg)->currentLine = line_;                                        \
+            if (delta_ >= (int32)(2 + ((line_ > SN_3BYTE_OFFSET_MASK)<<1))) { \
+                if (js_NewSrcNote2(cx, cg, SRC_SETLINE, (ptrdiff_t)line_) < 0)\
                     return JS_FALSE;                                          \
             } else {                                                          \
                 do {                                                          \
                     if (js_NewSrcNote(cx, cg, SRC_NEWLINE) < 0)               \
                         return JS_FALSE;                                      \
-                } while (--_delta != 0);                                      \
+                } while (--delta_ != 0);                                      \
             }                                                                 \
         }                                                                     \
     JS_END_MACRO

js/src/jsparse.c

@@ -2536,7 +2536,7 @@ UnaryExpr(JSContext *cx, JSTokenStream *ts, JSTreeContext *tc)
     return pn;
 }
 
-static JSParseNode *
+static JSBool
 ArgumentList(JSContext *cx, JSTokenStream *ts, JSTreeContext *tc,
              JSParseNode *listNode)
 {
@@ -2549,13 +2549,13 @@ ArgumentList(JSContext *cx, JSTokenStream *ts, JSTreeContext *tc,
         do {
             JSParseNode *argNode = AssignExpr(cx, ts, tc);
             if (!argNode)
-                return NULL;
+                return JS_FALSE;
             PN_APPEND(listNode, argNode);
         } while (js_MatchToken(cx, ts, TOK_COMMA));
 
         MUST_MATCH_TOKEN(TOK_RP, JSMSG_PAREN_AFTER_ARGS);
     }
-    return listNode;
+    return JS_TRUE;
 }
 
 static JSParseNode *
@@ -2580,12 +2580,10 @@ MemberExpr(JSContext *cx, JSTokenStream *ts, JSTreeContext *tc,
             return NULL;
         pn->pn_op = JSOP_NEW;
         PN_INIT_LIST_1(pn, pn2);
+        pn->pn_pos.begin = pn2->pn_pos.begin;
 
-        if (js_MatchToken(cx, ts, TOK_LP)) {
-            pn = ArgumentList(cx, ts, tc, pn);
-            if (!pn)
-                return NULL;
-        }
+        if (js_MatchToken(cx, ts, TOK_LP) && !ArgumentList(cx, ts, tc, pn))
+            return NULL;
         if (pn->pn_count - 1 >= ARGC_LIMIT) {
             JS_ReportErrorNumber(cx, js_GetErrorMessage, NULL,
                                  JSMSG_TOO_MANY_CON_ARGS);
@@ -2647,9 +2645,9 @@ MemberExpr(JSContext *cx, JSTokenStream *ts, JSTreeContext *tc,
             }
 
             PN_INIT_LIST_1(pn2, pn);
+            pn2->pn_pos.begin = pn->pn_pos.begin;
 
-            pn2 = ArgumentList(cx, ts, tc, pn2);
-            if (!pn2)
+            if (!ArgumentList(cx, ts, tc, pn2))
                 return NULL;
             if (pn2->pn_count - 1 >= ARGC_LIMIT) {
                 JS_ReportErrorNumber(cx, js_GetErrorMessage, NULL,