unused variable or function

[knobo]

3 problems here.

1. only var0 is not used, but there is not warning for that.
2. Variable ’var1’ referenced but never initialized But it fact it is destructed
3. Unused variable or function ’var2’ even tough it is used 2 times.

[dgutov]

/Cc @lelit

[lelit]

I see, thank you for the report: will try to fix the issue as soon as time permits.

[knobo]

And on line 82 var4 should have a warning about not beeing initialized.

[lelit]

@dgutov, about var4: trying out the code in NodeJS, it errors out with ReferenceError: var4 is not defined, but that's not catched by js2-highlight-undeclared-vars(). Is that a bug by its own?

NodeJS raises a ReferenceError for both x and z in the following code (executing the functions, I mean):

function foo(a) {
    const x = {a, x};
}

function bar() {
    const y = z;
    const z = 1;
}

Should js2-highlight-undeclared-vars() consider the position of the declaration?

[UwUnyaa]

@lelit considering that declaring a const without an initial value throws an error, it should be marked as an error.

While we're at it, it would be nice to take care of temporal dead zone for variables declared with let and const.

[dgutov]

@lelit, I think so. Unless there's evidence that NodeJS behaves against the spec, which is unlikely.

[lelit]

The above changes seems to cure one half of the reported problem.

I wasn't so lucky trying to solve the other half, the undefined reference in the const assignment. First I checked with both Firefox and Chrome, and they raise an error executing the simple functions above. Then I tried to tweak js2-get-defining-scope to handle also js2-CONST assignment, something like:

diff --git a/js2-mode.el b/js2-mode.el
index 567d629..0c2e881 100644
--- a/js2-mode.el
+++ b/js2-mode.el
@@ -2314,7 +2314,7 @@ Returns nil if there is no enclosing scope node."
 Returns `js2-scope' in which NAME is defined, or nil if not found.
 
 If POINT is non-nil, and if the found declaration type is
-`js2-LET', also check that the declaration node is before POINT."
+`js2-LET' or `js2-CONST', also check that the declaration node is before POINT."
   (let ((sym (if (symbolp name)
                  name
                (intern name)))
@@ -2325,7 +2325,7 @@ If POINT is non-nil, and if the found declaration type is
            (let ((entry (cdr (assq sym (js2-scope-symbol-table scope)))))
              (and entry
                   (or (not point)
-                      (not (eq js2-LET (js2-symbol-decl-type entry)))
+                      (not (memq (js2-symbol-decl-type entry) (list js2-LET js2-CONST)))
                       (>= point
                           (js2-node-abs-pos (js2-symbol-ast-node entry))))))
            (and (eq sym 'arguments)

but that has not the expected outcome... Will try harder, but maybe you can point me in the right direction :-)

[lelit]

Please let me know if you prefer splitting that into a separate issue, opening a PR with these changes alone, or if instead it would be better to wait for a fix to the const thingie.

[knobo]

I'll open a seperate issue for the missing var4 warning/error.

[lelit]

If you can test my branch and tell if it effectively cures your case, it would be great!

[knobo]

Yes, I have tested it a bit now. And it looks like it works.
But how do I override elpa dependencies to load your git version instead of elpa version?

[lelit]

Sorry, can't help there. But usually Dmitry is very responsive in releasing bug-fixes :-)

[knobo]

I consider myself done testing now :)

[lelit]

Thanks a lot!

[knobo]

Thank you for fixing the bugs :)

[dgutov]

Merged, thanks for the report.