Linter replaces MDN url anchor when page is now redirecting to anchor

[caugner]

What type of issue is this?

Linter issue

What is the issue?

If a feature has an mdn_url that points to an anchor of an MDN page, and that page is removed and redirected to another page with an anchor, then this redirect target replaces the mdn_url and the current anchor gets lost, even if the redirect target has an anchor corresponding to the old mdn_url.

See: https://github.com/mdn/browser-compat-data/pull/25138/commits/4c58e86a0317f28a7ada2d5f9d6daa5f55f711f0

diff --git a/http/headers/Content-Security-Policy.json b/http/headers/Content-Security-Policy.json
index 6c1ee46a99cd45..64dc4a85df7bdc 100644
--- a/http/headers/Content-Security-Policy.json
+++ b/http/headers/Content-Security-Policy.json
@@ -746,7 +746,7 @@
         "report-sample": {
           "__compat": {
             "description": "`report-sample` source value",
-            "mdn_url": "https://developer.mozilla.org/docs/Web/HTTP/Headers/Content-Security-Policy/Sources#report-sample",
+            "mdn_url": "https://developer.mozilla.org/docs/Web/HTTP/Headers/Content-Security-Policy#fetch_directive_syntax",
             "support": {
               "chrome": {
                 "version_added": "59"
@@ -1152,7 +1152,7 @@
         "strict-dynamic": {
           "__compat": {
             "description": "`strict-dynamic` source value",
-            "mdn_url": "https://developer.mozilla.org/docs/Web/HTTP/Headers/Content-Security-Policy/Sources#strict-dynamic",
+            "mdn_url": "https://developer.mozilla.org/docs/Web/HTTP/Headers/Content-Security-Policy#fetch_directive_syntax",
             "support": {
               "chrome": {
                 "version_added": "52"
@@ -1338,7 +1338,7 @@
         "unsafe-hashes": {
           "__compat": {
             "description": "`unsafe-hashes` source value",
-            "mdn_url": "https://developer.mozilla.org/docs/Web/HTTP/Headers/Content-Security-Policy/Sources#unsafe-hashes",
+            "mdn_url": "https://developer.mozilla.org/docs/Web/HTTP/Headers/Content-Security-Policy#fetch_directive_syntax",
             "support": {
               "chrome": {
                 "version_added": "69"

What behavior were you expecting?

We should have not overwritten these specific MDN urls.

What version(s) of BCD is the issue present in?

• [ ] The current BCD release
• [ ] The current version of the main branch

Do you have anything more you want to share?

No response

[caugner]

This specific occurrence seems to have been a side-effect of https://github.com/mdn/content/pull/36792, where /docs/Web/HTTP/Headers/Content-Security-Policy/Sources was removed and redirected to docs/Web/HTTP/Headers/Content-Security-Policy#fetch_directive_syntax.

https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Content-Security-Policy#report-sample exists, so what we should have done in this case almost is to fetch the page, look if an id corresponding to the current hash exists, and use that.

/cc @fiji-flo It would be useful, if the index.json contained a list or map of all anchors of the page. Is this something you have considered, or would consider for a future version of rari? (Side-note: This would also be useful for "redirecting" en-US anchors on other locales to the localized anchor, which I have mentioned recently.)

[fiji-flo]

Anchors are a lovely topic. One of my biggest goals is to move to GFM like anchors which would help a lot.

I don't want to add more redundant data to the index.json. However, validating id/anchors and using them for redirects and and other task is on the agenda.

For this case it would not be straight forward, just because and id (and thereby a heading) matches doesn't imply that where we should point. There's lot of pages that have the same id many times (with a unique added suffix) which makes this even worth.

Thanks for raising this.

[caugner]

Thanks Florian.

@queengooborg Maybe what we should do is to change the behavior as follows: _Error if the current mdn_url contains an anchor, and don't auto-fix it._ Wdyt?