Add .slnx to XML extensions

[kasperk81]

Description

Checklist:

• I am adding a new extension to a language.
  • The new extension is used in hundreds of repositories on GitHub.com
    • Search results for each extension:
      • https://github.com/search?type=code&q=NOT+is%3Afork+path%3A*.slnx+solution
  • I have included a real-world usage sample for all extensions added in this PR:
    • Sample source(s):
      • https://github.com/visose/Robots/blob/aa2be4ba40947b950b79d68fae3e22f32a0184c2/Robots.slnx
    • Sample license(s):
  • I have included a change to the heuristics to distinguish my language from others using the same extension.

Fix #7083

[kasperk81]

cc @visose fyi, i've used your slnx file as a sample for syntax highlighting support. https://github.com/visose/Robots/blob/aa2be4ba40947b950b79d68fae3e22f32a0184c2/Robots.slnx

[kasperk81]

fyi @rainersigwald @davkean (dotnet/msbuild#1730 (comment) it was simpler than i thought 😉)

[rainersigwald]

Ah yeah, getting the default XML highlighting is a great low-cost way to do this!

[lildude]

Your sample should be in the samples/XML directory.

[kasperk81]

@lildude ok, but can you tell me why? there is an existing .sln, i'm adding .slnx next to it https://github.com/github-linguist/linguist/tree/main/samples/Microsoft%20Visual%20Studio%20Solution
this is from vs library open sourced last week https://github.com/microsoft/vs-solutionpersistence (handles both .sln and .slnx)

[lildude]

@lildude ok, but can you tell me why?

Sure... it's what you want 😉

As you're adding the extension to the XML language entry, you're saying these files are XML and should be highlighted as XML and as such, the sample needs to go into the XML language directory. This is why the tests were failing.

[kasperk81]

Ah, I didn't realize that the samples are structured per language, and "Microsoft Visual Studio Solution" is treated as a language. The new format, however, is based on the XML language. :)

[lildude]

You need to add this to the list of no-root-tag entries in the test too:

linguist/test/test_strategies.rb

Lines 176 to 194 in f164d13

	def test_xml
	no_root_tag = [
	"#{samples_path}/XML/libsomething.dll.config",
	"#{samples_path}/XML/real-estate.mjml",
	"#{samples_path}/XML/XmlIO.pluginspec",
	"#{samples_path}/XML/MainView.ux",
	"#{samples_path}/XML/MyApp.ux",
	"#{samples_path}/XML/xhtml-struct-1.mod",
	"#{samples_path}/XML/wixdemo.wixproj",
	"#{samples_path}/XML/msbuild-example.proj",
	"#{samples_path}/XML/sample.targets",
	"#{samples_path}/XML/Default.props",
	"#{samples_path}/XML/racoon.mjml",
	"#{samples_path}/XML/some-ideas.mm",
	"#{samples_path}/XML/GMOculus.project.gmx",
	"#{samples_path}/XML/obj_control.object.gmx",
	"#{samples_path}/XML/MainView.axaml"
	]
	assert_all_xml all_xml_fixtures("*") - no_root_tag

This will exclude the sample from the XML strategy testing which is what is failing here (we're not using the strategy to detect the language).

All good now. I'll review usage again when I start preparing the next release.

[kasperk81]

@lildude the search indicator is only going to improve significantly until dotnet/sdk#40913 is resolved (support for slnx in dotnet sdk which is scheduled for .NET 9 release 2 which usually happen at the end of Feb). Rest assured, it is happening; the whole community was waiting for new solution format for a very long time dotnet/msbuild#1730 and VS has just added its support (as a preview feature).