Razor files that use HTML Tag Helpers, clicking Format Document messes up the code formatting instead of formatting it correctly

[vsfeedback]

This issue has been moved from a ticket on Developer Community.

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Following is the code before formatting,

and following is the code after formatting.

When I click Format Document in a .cshtml file that uses HTML Tag Helpers, the formatter breaks/messes up the code structure instead of formatting it correctly.

I already tried enabling “Use legacy Razor Editor for ASP.NET Core” (and also disabling it), but the issue remains the same.

My current Visual Studio settings are attached for reference.

[davidwengier]

We always have problems with code that Roslyn doesn't format, because we essentially force it to. In this case, we don't emit the literal C# code to Roslyn, so when Roslyn doesn't know its a single multi-line expression, and applies standard formatting rules (ie, line everything up neatly). If we do start emitting the actual code, this should work fine.

The challenge is the first line, which is half html, and half C#, and we need to format both separately. Currently our engine can't handle that, and so we fallback to Html for the first line, but that prevents us being smart enough in this specific case.

[davidwengier]

Note we have a similar issue in #12785, where the first line of the block is both html and C#, so any fix here should be applied there.

[davidwengier]

Argh, I can't repro this, and I don't remember if was able to repro it when I moved the issue here 3 weeks ago. I would imagine this bug could be fixed by #12623 but that didn't go in until 18.5, and I can't repro the bug in 18.4 🤦‍♂️

[davidwengier]

That PR did go into 18.4! Excellent. I'm closing this as fixed then, as that makes perfect sense (and I fixed the milestone on the PR)