Filename completion doesn't work for conditional imports

[DanTup]

Filed by @mosuem at #4529. Splitting it up because the issues may be fixed separately.

2. There is no code completion for source file paths in conditional imports.

[DanTup]

@bwilkerson I thought this would be a trivial fix, but I hit some issues because when completing at eof in code like:

import '' if (a) '^

The completion entity is a synthetic ; whose parent is ImportDirective. This means in a few places where I'd like to see Configuration I see ImportDirective. There are a few places that assume given an ImportDirective we'd be completing its uri, for example:

https://github.com/dart-lang/sdk/blob/a41d1b5813b4e463cff6876bb24730642ffa8405/pkg/analyzer_plugin/lib/src/utilities/completion/completion_target.dart#L487

So I'm not sure whether the fix is to try and handle this in those places (another is UriContributor which only visits ImportDirective as a result, and not Configuration), or whether the completion target/containingNode should be more specific for Configurations?

(I'm also aware you wanted to make some changes in this area, so if this is best left until after, that's fine - I thought this would be a two-line fix 😄)

[bwilkerson]

It will probably be easier to fix in the design I've proposed, but they key here is to notice when we're completing in an ImportDirective, the offset is inside a configuration, and the offset is after a synthetic string and before a synthetic semicolon (or something like that, there's probably other structures produced if it's followed by another configuration).

Unfortunately, with code completion, there's generally nothing easier than trying all of the possible inputs you can think of and figuring out what structure you're looking at, and it's sometimes the case that the structure doesn't match what the user has in mind at all.

[DanTup]

Fixed by dart-lang/sdk@dd72682 (an SDK change, so it'll show up in an SDK release rather than a Dart-Code release).