571174 - syntax error is silently discarded, makes debugging hard

Status: NEW

(Core :: XUL, defect)

Description

[Justin Dolske [:Dolske]]

See bug 563274, Patch v.3:

+function commonDialogOnAccept() {
...
+// XXX SOB! leave off a case colon and XUL borks the loading of the whole JS
+// file without an error!
+    // Return textfield values
+    switch (promptType) {
+      case "prompt":

This script is included via <script src=""> in commonDialog.xul. While writing the patch, I left off the colon in |case "prompt":|, and was frustrated to discover that the script fails to parse but no error was reported. [Of course it took far too much time to figure out what my mistake was.]

Not sure if this was the JS engine's fault, or something above it was silently suppressing the error.

Comment 1

[Boris Zbarsky [:bzbarsky]]

Attachment: Browser testcases showing this is probably not a jseng problem

When I load this testcase in the browser, my error console shows:

Error: missing : after case label
Source File: file:///Users/bzbarsky/test.html
Line: 5, Column: 8
Source Code:
        alert("foo passed"); 

That said, maybe the exact script text of your script is relevant?  Can you attach a testcase that uses your exact script text?

Comment 2

[Boris Zbarsky [:bzbarsky]]

Unless I'm missing something, XUL proto globals don't set a JS error reporter.  They should do something similar to what XBL does with XBL_ProtoErrorReporter.  Compare nsXBLDocGlobalObject::EnsureScriptEnvironment to nsXULPDGlobalObject::EnsureScriptEnvironment

So compile-time errors would never be reported for <script> in XUL.  I have a hard time believing we don't have bugs on this already, but it should be easy to fix!  Justin, do you want to do it?