[WIP] Fix line comments issue breaking highlighting after directives

[Copilot]

Thanks for assigning this issue to me. I'm starting to work on it and will keep this PR's description up to date as I form a plan and make progress.

Original prompt

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This section details on the original issue you should resolve

<issue_title>Line comments right after preprocessor directives break highlighting.</issue_title>
<issue_description>Consider the following snippet:

public class Foo
{
    void Bar()
    {
#pragma warning disable CS0000 // Internal compiler error
        var x = Baz(1, 2, 3, out object error);
#pragma warning restore CS0000 // Internal compiler error
    }
}

We have a preprocessor directive, a line comment on the same line, and some code right on the next line (not very unusual in real-world code). The line after the directive gets weirdly highlighted:

This does not happen we remove the line comment, or add a blank line or block comment after the directive. It also happens if we add some more line comments in the lines between the directive and the code.

From what I saw, the whole line belongs to textmate scopes meta.preprocessor.cs, source.cs. Maybe that happens because the line comment consumes the end of line, and the directive cannot match (?<=$)?</issue_description>

<agent_instructions>Be sure to include a test for this scenario.</agent_instructions>

Comments on the Issue (you are @copilot in this section)

• Fixes Line comments right after preprocessor directives break highlighting. #335

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[JoeRobich]

@copilot can you try again?