Lessc error with nested calc()

[turnerhayes]

I'm trying to compile Bootstrap's CSS with lessc and getting the following error:

Bootstrap version: 4.0.0-beta.3
Lessc version: lessc 2.7.3 (Less Compiler) [JavaScript]

$ lessc node_modules/bootstrap/dist/css/bootstrap.css
OperationError: Operation on an invalid type in [project directory]/node_modules/bootstrap/dist/css/bootstrap.css on line 3719, column 3:
3718   display: block;
3719   height: calc(calc(2.25rem + 2px) - 1px * 2);
3720   padding: 0.375rem 0.75rem;

Seems to be objecting to the nested calc(). According to MDN, this is valid syntax (although I read on SO that that clarification was added in the past year or two, so maybe lessc was correct at some point).

[seven-phases-max]

See https://lesscss.org/usage/#command-line-usage-strict-math.

[seven-phases-max]

Closing in favour of #1880.

[turnerhayes]

That seemed to work, but shouldn't lessc accept any valid CSS without flags?

[seven-phases-max]

but shouldn't lessc accept any valid CSS without flags?

The default --strict-math=on will break too much legacy code (for more details see #1880, #974 etc.).

[turnerhayes]

I guess I don't really understand why nested calc()s can't be passed through as is, rather than being regarded as something to (potentially) calculate during compilation.

[matthew-dean]

@turnerhayes This works in 3.x.