Format string literal syntax highlighting is broken for escapes and interpolations simultaneously

[Veetaha]

cc #4006, @ltentrup

As you can see, the string is bold starting from the escape sequence up until the first placeholder symbol.

This happens only inside of format strings as far as I can tell

[ltentrup]

Where does the highlighting for the escape string come from? It is not implemented in https://github.com/rust-analyzer/rust-analyzer/blob/master/crates/ra_ide/src/syntax_highlighting.rs where the logic for the format specifier is implemented.

[Veetaha]

Hmm, this is strange, if you take a look with the inspector you won't see where the bold styling comes from... Can't it be vscode bug? Can you reproduce it in your editor?

[ltentrup]

I just checked with the latest nightly, there is no escape sequence highlighting on my machine:

Maybe this is related to another extension or VSCode setting?

[ian-h-chamberlain]

I have been experiencing I think the same issue, which I thought was caused by some interaction between rust-analyzer and another extension I have installed. However, I can reproduce when rust-analyzer is the only extension enabled as well.

Initial state while window loads and rust-analyzer still starting up looks like this

This is expected, I think, as the semantic highlight has not been initialized yet?

Then, once it loads and I type a bit, this happens:

It seems like once semantic highlighting starts something changes. Strangely, all the output from the inspector window seems to be unchanged:

Escape before

Escape after

Format string before

Format string after

---

Let me know if there is additional info I can get you. This appears to be 100% reproducible on window reloads.

Name: rust-analyzer
Id: matklad.rust-analyzer
Description: An alternative rust language server to the RLS
Version: 0.3.206-nightly
Publisher: matklad
VS Marketplace Link: https://marketplace.visualstudio.com/items?itemName=matklad.rust-analyzer

VSCode
Version: 1.46.0
Commit: a5d1cc28bb5da32ec67e86cc50f84c67cc690321
Date: 2020-06-10T08:59:06.977Z (5 days ago)
Electron: 7.3.1
Chrome: 78.0.3904.130
Node.js: 12.8.1
V8: 7.8.279.23-electron.0
OS: Darwin x64 19.4.0

[ltentrup]

Does this issue persist in the latest nightly? There is now support for highlighting escape sequences (although it has to be enabled manually)

[ian-h-chamberlain]

@ltentrup yes, it works as expected for me now, thank you! I didn't have to enable anything specific, it seemed to activate alongside the rest of semantic syntax highlighting. Is that expected?

[ltentrup]

No, I did not expect escape sequences to be highlighted as we introduced a custom/non-standard semantic token escapeSequence.
If you do not style escapeSequence manually in your settings.json it should just style as a string.

[ian-h-chamberlain]

It looks like the escapeSequence allows the default semantic highlighting (looks like constant.character.escape.rust) to kick in, instead of just treating the token as as string?
Compare this inspector output to the one I posted above:

In any case it now looks like it did before, so I would consider this issue resolved. Thanks again!

[lnicola]

Sounds like this was resolved, please shout if there's still something to do here.