no-unused-vars confused when var is re-assigned with return value of function that takes it as argument

[ahocevar]

What version of ESLint are you using?

3.0.1

What parser (default, Babel-ESLint, etc.) are you using?

default

Please show your full configuration:

https://github.com/openlayers/eslint-config-openlayers/blob/master/index.js

What did you do? Please include the actual source code causing the issue.

https://github.com/openlayers/ol3/blob/9b3c4294c146dd929ecd4c8c0188dfc01580e30c/src/ol/render/canvas/canvasreplay.js#L1085-L1090

What did you expect to happen?

Like in v2.x, I would expect that eslint does not complain, since offset is clearly used.

What actually happened? Please include the actual, raw output from ESLint.

eslint complains about offset being defined but never used:

/home/travis/build/openlayers/ol3/src/ol/render/canvas/canvasreplay.js
  1085:7  error  'offset' is defined but never used  no-unused-vars
  1357:7  error  'offset' is defined but never used  no-unused-vars

This problem came up in openlayers/openlayers#5569.

[ilyavolodin]

This should've been fixed with v3.0.1. @mysticatea could you take a quick look please?

[laurent-le-graverend]

Having the same issue with the following code and version 3.0.1:

function someFunction() {
  var a = 0, i;
  for (i = 0; i < 2; i++) {
    a = myFunction(a);
  }
}

'a' is defined but never used (no-unused-var)

[mysticatea]

Thank you for this issue.
I confirmed. I will fix this.

[ahocevar]

Thanks for fixing this!