[css-grid-2] Computed value for integer repeats on grid-template-columns and grid-template-rows for non-subgrids #8555
Description
I'm working on implementing this in Chromium, and I see that Firefox and Safari have implemented this case differently.
To repro, you can paste this in your browser's address bar and look at the computed value in developer tools:
data:text/html,<div style="grid-template-columns: subgrid repeat(2, [a]);"></div>
Firefox reports subgrid [a][a], while Safari preserves the repeat syntax and reports subgrid repeat(2, [a])
https://www.w3.org/TR/css-grid-2/#computed-tracks
"The computed track list of a subgridded axis is the subgrid keyword followed by a list of line name sets representing each line in that axis."
There's also a section below (https://www.w3.org/TR/css-grid-2/#resolved-track-list-standalone) which explains what to do for grid-template-rows on a non-grid, and has an example that expands integer auto repeaters. It doesn't say what to do for when subgrid is included, however. It also doesn't say whether to expand for auto-fill or auto-fit in either case.
I think the most consistent behavior here is to expand the integer auto repeaters, as Firefox does, as that's most consistent with standalone grids. Since auto-fit can't be expanded (as this requires grid layout to compute), it makes sense to preserve the specified repeat(auto-fit, ...).
But that's my opinion. I'm curious what the working group thinks, and if this should be clarified more in the spec. I'm happy to implement whichever is preferred in Chromium.