Behavior of detecting the file language

[simpleapples]

• VSCode Version: 1.46.1
• OS Version: macOS 10.15.5

Steps to Reproduce:

1. create a file named dockerfile.go, dockerfile.py or other extensions.
2. you can see the file is detected as a Dockerfile, but it should be a go file or python file.

Related logic:
I found the file detecting logic is here:

vscode/src/vs/base/common/mime.ts

Lines 195 to 208 in 697b702

	// 1.) Exact name match has second highest prio
	if (filenameMatch) {
	return filenameMatch.mime;
	}
	// 2.) Match on pattern
	if (patternMatch) {
	return patternMatch.mime;
	}
	// 3.) Match on extension comes next
	if (extensionMatch) {
	return extensionMatch.mime;
	}

Filename Match has the higher priority than Extension Match, I think it should be reconsidered. Extension Match should have the highest priority.

Does this issue occur when all extensions are disabled?: Yes/No
Yes

[bpasero]

I can reproduce in Code stable, but not Insiders, but have no clue what has changed.

@simpleapples can you try to reproduce with our insiders?

[simpleapples]

Hi, @bpasero, thank you for your response.

I can't reproduce the same result on the latest insider build. There is no essential change between insider build and stable build on the file mime.ts.

So I have the same confusion about the different behaviors.

[bpasero]

Ok, looks like this got fixed somehow I cannot explain why. We can reopen if this comes back next month after we have released.

[simpleapples]

I got reasons about this issue.

1. Why a dockerfile.go is recognized as a Dockerfile?
   Recently, developers of vscode-docker added a Dockerfile.* file association (Add Dockerfile.* file association vscode-docker#1908), If a file is called dockerfile.go, it will match this pattern and will be recognized as a Dockerfile.

2. Why detection behaviors are different between insider and stable?
   The extension/docker/package.json of vscode is different from extension/docker/package.json of vscode-docker after Add Dockerfile.* file association vscode-docker#1908. So, it will function properly with docker extension installed, whether in insider or in stable.

Next step:
I'm trying to argue with developers of vscode-docker to remove the Dockerfile.* file association (microsoft/vscode-docker#2128), because it will disrupt normal operation of file associaitons of other languages.

Just to explain.

[simpleapples]

Hi, @bpasero , I'm confused about the mechanism of file type detecting.

As you know, there is a filenameMatch and a extensionMatch. extensionMatch is responsible for checking the extension of files. filenameMatch for the filename.

But, if we add a pattern filename.* on filenameMatch, it can match any extensions. For my perspective, filenameMatch should just match filenames without extension.

What do you think about it ?