Support whitespace before target name for make completions

[ddanier]

TL;DR: The "simple" example from https://www.gnu.org/software/make/manual/html_node/Simple-Makefile.html is currently not compatible with the custom completion script found in custom-completions/make/make-completions.nu. This PR tries to fix that.

As I was working on nur (https://github.com/ddanier/nur) and the nurify script to convert to nur from different task runners (https://github.com/ddanier/nur/blob/main/scripts/nurify.nu) I wanted to create a good way to convert from using make. So I thought the make completion would for sure implement a good way to get a list of all possible make targets. Hence I started looking at custom-completions/make/make-completions.nu.

Then I searched for a good documentation for how Makefiles work, as the last time I was using this myself is about 5 to 10 years ago. If you for example look at the documentation on gnu.org you may find examples of Makefiles not working with the current autocompletion. See https://www.gnu.org/software/make/manual/html_node/Simple-Makefile.html for example, the "simple" example they provide.

The reason for this not working is that the targets use some whitespace after the target name. This is somehow allowed and thus valid. See https://www.gnu.org/software/make/manual/html_node/Rule-Introduction.html for a quick overview about how the Makefiles syntax works. I quickly checked this to ensure make actually parses this correctly, it really does.

This means that the current make completion does miss support for the "simple" example provided my make itself. So I went on to fix this.

My suggested solution is:

• Filter all lines by regex '^[\w\.-]+\s*:' to ensure possible targets
  • start with some word (also allowing . and -)
  • may have some whitespaces after the word
  • has ":" after this
• Split by the ":"
• Use first column
• Trim the remaining target name to remove those nasty whitespaces
• Use result for completion

For me this did fix the issue with the "simple" Makefile, allowing me to put this into my nurify script.

Would be nice to get this "backported" to nu scripts as well. Might help others 😉

[fdncred]

Looks good. Thanks! I'm excited about nur and it's fun to see people using nushell in creative ways.