modifyVars not being passed on

I have an index.less file that decides what variables file to load in by a variable like so:

@theme-variant: "a-theme.less";

@import "./@{theme-variant}";

I have less files that load in that index file:

@import "~theme-variant-variables";

I am setting a value for the variable in my webpack.config.js file:

lessOptions.modifyVars = {
   "theme-variant": `"${v}-theme.less"`
}

If I move the contents of the index.less file into a directly imported less file everything works as I expect, I can switch the variables file chosen based on the webpack config logic, sadly if I try and centralize those two lines of less into a file that the directly imported less files import themselves it stops working. I see less loader calls less with the expected config so I’m guessing the less compiler doesn’t propagate variables/options to imported less files. Is that expected?

[seven-phases-max]

I’ll close this then as it’s more like an expected (defined as “undefined/unspecified” in this case) behaviour rather than an issue that could be actually fixed somehow. Though any improvement ideas and especially PRs are always welcome… I don’t think anybody is going to get into this in a foreseeable future.

[seven-phases-max]

By the way. For your use-case (if the “*-theme.less” is only about variables/mixins for a specific theme), you could try something like:

• Leave the default @import "a-theme.less"; to be expicit there (i.e. w/o any interpolation) or remove it completely.
• With modifyVars set the importing statement itself (e.g. @import "custom-theme.less"; directly).

Note that while modifyVars pretends it’s only about variables bla-bla-bla - in fact it does nothing but appending an arbitrary text to the end of the root file. I.e. in case of lessc it’s realy just --modify-vars="whatever-less-code foo {bar: baz;}". I don’t know though what formats webpack’s less-loader can pass through, hmm… lessOptions.modifyVars = "an arbitrary code"; maybe?

That’s obviously a hack but in fact it is quite predictable hack (as it abuses only modifyVars format and not the language itself like the initial combo does).