Fail when #:project doesn't have any argument

[jjonescz]

Fixes #49670.

[Copilot]

Pull Request Overview

This PR ensures that the #:project directive fails when no argument is provided by updating the parsing logic and test coverage.

• Adds "project" to the empty-name directive test to verify failure for project directives.
• Extends Project.Parse signature to include directiveKind, checks for whitespace/empty names, and reports a missing-name error.
• Updates the directive dispatch in CSharpDirective to call the new overload of Project.Parse.

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
test/dotnet.Tests/CommandTests/Project/Convert/DotnetProjectConvertTests.cs	Include "project" in Directives_EmptyName theory
src/Cli/dotnet/Commands/Run/VirtualProjectBuildingCommand.cs	Fix call site to use new Project.Parse overload and add check for empty directive name

Comments suppressed due to low confidence (3)

test/dotnet.Tests/CommandTests/Project/Convert/DotnetProjectConvertTests.cs:813

• Consider adding an assertion that inspects the thrown error's message to verify the MissingDirectiveName formatting for the project directive, ensuring the correct error text is emitted.

        [CombinatorialValues("sdk", "property", "package", "project")] string directive,

src/Cli/dotnet/Commands/Run/VirtualProjectBuildingCommand.cs:1216

• [nitpick] The new modifier hides a potential Parse method in the base class (Named). Verify whether the base class defines a static Parse and remove new if hiding is unintentional.

        public static new Project? Parse(ImmutableArray<SimpleDiagnostic>.Builder? errors, SourceFile sourceFile, TextSpan span, string directiveKind, string directiveText)

src/Cli/dotnet/Commands/Run/VirtualProjectBuildingCommand.cs:1057

• Double-check that all other invocations of Project.Parse have been updated to the new four-parameter overload to prevent missing-method compilation errors elsewhere.

            "project" => Project.Parse(errors, sourceFile, span, directiveKind, directiveText),

[RikkiGibson]

A virtual project will still be produced in this case right? I guess we also do that for the empty name cases for the other directives listed here.

[jjonescz]

In case of run-api, yes, that one collects all errors and produces the virtual project file (without directives that have errors), there are tests for that in general (Api_Diagnostic_*), albeit not this particular case. In case of other commands like run, the first error makes the whole command fail, so there is no virtual project produced.