Fix autocomplete panic when condition has wrong type

[mapno]

What this PR does:

It prevents a panic when a filtering query is passed to /search/tag/<tag>/values with a attribute condition (.a=b) where b is a special type (server/client, ok/error/unset) but .a is of a different type (string, int). For example, span.http.status_code=server. This would create iterators with nil predicates and panics when it called iter.Next().

Now, such conditions are ignored and iterators are not built for them.

Which issue(s) this PR fixes:
Fixes #

Checklist

• Tests updated
• Documentation added
• CHANGELOG.md updated - the order of entries should be [CHANGE], [FEATURE], [ENHANCEMENT], [BUGFIX]

[mapno]

Another option is returning an error, but instead opted for ignoring the condition.

The reasoning is that autocomplete should be a smooth experience to the user. If the filtering query has an error, they'll get that feedback via normal search—ie. when they execute the query.

[joe-elliott]

are we missing case statements for things like kind = server and status = ok?

it seems like we should support auto complete on things like:

{ name = "foo" && kind = server && status = error && span.foo = ...

[mapno]

That function builds the iterators for the generic attribute columns which don't support those special types.

[joe-elliott]

thx for the clarification.

agree with your initial thought we should just ignore the bad condition over returning an error.

[joe-elliott]

are we missing case statements for things like kind = server and status = ok?

it seems like we should support auto complete on things like:

{ name = "foo" && kind = server && status = error && span.foo = ...

[github-actions]

Hello @mapno!
Backport pull requests need to be either:

• Pull requests which address bugs,
• Urgent fixes which need product approval, in order to get merged,
• Docs changes.

Please, if the current pull request addresses a bug fix, label it with the type/bug label.
If it already has the product approval, please add the product-approved label. For docs changes, please add the type/docs label.
If the pull request modifies CI behaviour, please add the type/ci label.
If none of the above applies, please consider removing the backport label and target the next major/minor release.
Thanks!

[github-actions]

The backport to release-v2.3 failed:

The process '/usr/bin/git' failed with exit code 1

To backport manually, run these commands in your terminal:

# Fetch latest updates from GitHub
git fetch
# Create a new branch
git switch --create backport-3277-to-release-v2.3 origin/release-v2.3
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x b61b12acd8844f37f7fee1d6ad15d1acf410755e

When the conflicts are resolved, stage and commit the changes:

git add . && git cherry-pick --continue

If you have the GitHub CLI installed:

# Push the branch to GitHub:
git push --set-upstream origin backport-3277-to-release-v2.3
# Create the PR body template
PR_BODY=$(gh pr view 3277 --json body --template 'Backport b61b12acd8844f37f7fee1d6ad15d1acf410755e from #3277{{ "\n\n---\n\n" }}{{ index . "body" }}')
# Create the PR on GitHub
echo "${PR_BODY}" | gh pr create --title "[release-v2.3] Fix autocomplete panic when condition has wrong type" --body-file - --label "type/bug" --label "area/query" --label "backport" --base release-v2.3 --milestone release-v2.3 --web

Or, if you don't have the GitHub CLI installed (we recommend you install it!):

# Push the branch to GitHub:
git push --set-upstream origin backport-3277-to-release-v2.3

# Create a pull request where the `base` branch is `release-v2.3` and the `compare`/`head` branch is `backport-3277-to-release-v2.3`.

# Remove the local backport branch
git switch main
git branch -D backport-3277-to-release-v2.3

[mapno]

The autocomplete changes weren't released in v2.3. Nothing to backport! 😅