fix: lsp panics when processing paths containing %

[codesuki]

Bazel uses % in its temporary paths which is not a valid URI.
Therefore url.PathUnescape will panic.
See golang/go#37984

[googlebot]

Thanks for your pull request. It looks like this may be your first contribution to a Google open source project (if not, look below for help). Before we can look at your pull request, you'll need to sign a Contributor License Agreement (CLA).

📝 Please visit https://cla.developers.google.com/ to sign.

Once you've signed (or fixed any issues), please reply here with @googlebot I signed it! and we'll verify it.

---

What to do if you already signed the CLA

Individual signers

• It's possible we don't have your GitHub username or you're using a different email address on your commit. Check your existing CLA data and verify that your email is set on your git commits.

Corporate signers

• Your company has a Point of Contact who decides which employees are authorized to participate. Ask your POC to be added to the group of authorized contributors. If you don't know who your Point of Contact is, direct the Google project maintainer to go/cla#troubleshoot (Public version).
• The email used to register you as an authorized contributor must be the email used for the Git commit. Check your existing CLA data and verify that your email is set on your git commits.
• The email used to register you as an authorized contributor must also be attached to your GitHub account.

ℹ️ Googlers: Go here for more info.

[codesuki]

@googlebot I signed it!

[googlebot]

CLAs look good, thanks!

ℹ️ Googlers: Go here for more info.

[gopherbot]

This PR (HEAD: 81f0ca7) has been imported to Gerrit for code review.

Please visit https://go-review.googlesource.com/c/tools/+/228640 to see it.

Tip: You can toggle comments from me using the comments slash command (e.g. /comments off)
See the Wiki page for more info

[gopherbot]

Message from Gobot Gobot:

Patch Set 1:

Congratulations on opening your first change. Thank you for your contribution!

Next steps:
Within the next week or so, a maintainer will review your change and provide
feedback. See https://golang.org/doc/contribute.html#review for more info and
tips to get your patch through code review.

Most changes in the Go project go through a few rounds of revision. This can be
surprising to people new to the project. The careful, iterative review process
is our way of helping mentor contributors and ensuring that their contributions
have a lasting impact.

During May-July and Nov-Jan the Go project is in a code freeze, during which
little code gets reviewed or merged. If a reviewer responds with a comment like
R=go1.11, it means that this CL will be reviewed as part of the next development
cycle. See https://golang.org/s/release for more details.

---

Please don’t reply on this GitHub thread. Visit golang.org/cl/228640.
After addressing review feedback, remember to publish your drafts!

[gopherbot]

This PR (HEAD: e85b4cb) has been imported to Gerrit for code review.

Please visit https://go-review.googlesource.com/c/tools/+/228640 to see it.

Tip: You can toggle comments from me using the comments slash command (e.g. /comments off)
See the Wiki page for more info

[gopherbot]

This PR (HEAD: 612ea11) has been imported to Gerrit for code review.

Please visit https://go-review.googlesource.com/c/tools/+/228640 to see it.

Tip: You can toggle comments from me using the comments slash command (e.g. /comments off)
See the Wiki page for more info

[gopherbot]

This PR (HEAD: 1cc03be) has been imported to Gerrit for code review.

Please visit https://go-review.googlesource.com/c/tools/+/228640 to see it.

Tip: You can toggle comments from me using the comments slash command (e.g. /comments off)
See the Wiki page for more info

[gopherbot]

This PR (HEAD: ebf74c5) has been imported to Gerrit for code review.

Please visit https://go-review.googlesource.com/c/tools/+/228640 to see it.

Tip: You can toggle comments from me using the comments slash command (e.g. /comments off)
See the Wiki page for more info

[gopherbot]

This PR (HEAD: 4d34305) has been imported to Gerrit for code review.

Please visit https://go-review.googlesource.com/c/tools/+/228640 to see it.

Tip: You can toggle comments from me using the comments slash command (e.g. /comments off)
See the Wiki page for more info

[gopherbot]

Message from Neri Marschik:

Patch Set 6:

Hi, more context below.

Emacs lsp-mode uses the the function url-hexify-string to convert a path to an URI.
Following down the rabbit hole you find this line
;; Allow % to avoid re-encoding %-encoded sequences.
https://github.com/emacs-mirror/emacs/blob/master/lisp/url/url-util.el#L415

The following PR would solve the issue I think, but it breaks with emacs < 26.x
emacs-lsp/lsp-mode#1089

This PR to gopls then broke it.
f8e42dc

Questionable whether or not this should be fixed in gopls, but it makes gopls useless for emacs users.
Also there is prior art here, fixing gopls for visual studio code.

---

Please don’t reply on this GitHub thread. Visit golang.org/cl/228640.
After addressing review feedback, remember to publish your drafts!

[gopherbot]

Message from Rebecca Stambler:

Patch Set 6:

Patch Set 6:

Hi, more context below.

Emacs lsp-mode uses the the function url-hexify-string to convert a path to an URI.
Following down the rabbit hole you find this line
;; Allow % to avoid re-encoding %-encoded sequences.
https://github.com/emacs-mirror/emacs/blob/master/lisp/url/url-util.el#L415

The following PR would solve the issue I think, but it breaks with emacs < 26.x
emacs-lsp/lsp-mode#1089

This PR to gopls then broke it.
f8e42dc

Questionable whether or not this should be fixed in gopls, but it makes gopls useless for emacs users.
Also there is prior art here, fixing gopls for visual studio code.

Thank you for the thorough explanation and contribution!

However, it seems to me that it's the responsibility of Emacs to create a valid URI that gets sent to gopls. We have worked around VS Code in the past, but we want to avoid overfitting to specific clients. Also, VS Code over escapes, whereas here, it seems like Emacs is sending incorrectly escaped URIs.

I'll let Heschi make the final decision here, but it seems to me like the PR that fixes the issue in Emacs is the right approach. It's unfortunate that it requires a later version of Emacs, but maybe that can still be handled.

---

Please don’t reply on this GitHub thread. Visit golang.org/cl/228640.
After addressing review feedback, remember to publish your drafts!

[gopherbot]

Message from Neri Marschik:

Patch Set 6:

However, it seems to me that it's the responsibility of Emacs to create a valid URI that gets sent to gopls. We have worked around VS Code in the past, but we want to avoid overfitting to specific clients. Also, VS Code over escapes, whereas here, it seems like Emacs is sending incorrectly escaped URIs.
Totally agree. Unfortunately I did the root cause analysis after submitting this patch :)
I didn't know how LSP works, at all, so never thought this was an emacs problem.
I submitted a patch there: emacs-lsp/lsp-mode#1593

---

Please don’t reply on this GitHub thread. Visit golang.org/cl/228640.
After addressing review feedback, remember to publish your drafts!

[gopherbot]

Message from Rebecca Stambler:

Patch Set 6:

Patch Set 6:

However, it seems to me that it's the responsibility of Emacs to create a valid URI that gets sent to gopls. We have worked around VS Code in the past, but we want to avoid overfitting to specific clients. Also, VS Code over escapes, whereas here, it seems like Emacs is sending incorrectly escaped URIs.
Totally agree. Unfortunately I did the root cause analysis after submitting this patch :)
I didn't know how LSP works, at all, so never thought this was an emacs problem.
I submitted a patch there: emacs-lsp/lsp-mode#1593

Wonderful - thank you so much for doing this work!

---

Please don’t reply on this GitHub thread. Visit golang.org/cl/228640.
After addressing review feedback, remember to publish your drafts!

[codesuki]

This is merged in emacs lsp-mode now. emacs-lsp/lsp-mode#1593