[llvm] [lit] Are all RUN lines skipped in windows cmd? (PR #65242)

[Henrik G. Olsson via llvm-commits]

hnrklssn wrote:

> > What is `%dbg` actually used for? I couldn't find any references to it in the main LLVM tests, nor is there any reference to it in the Testing Guid docs, so I suspect I'm missing something crucial to understanding this situation...
> 
> It's something like an internal substitution. When parsing a RUN line, [lit inserts it before the RUN line's commands](https://github.com/llvm/llvm-project/blob/2f8690b1e2bf09174660cd66ef8a27066848555e/llvm/utils/lit/lit/TestRunner.py#L1913) like this:
> 
> ```
> %dbg(RUN: at line N) commands
> ```
> 
> Later, lit expands it based on the shell (internal, external sh-like shell, external windows `cmd`, etc.). For example, [for sh-like shells](https://github.com/llvm/llvm-project/blob/2f8690b1e2bf09174660cd66ef8a27066848555e/llvm/utils/lit/lit/TestRunner.py#L1186-L1189):
> 
> ```
> : 'RUN: at line N'; commands
> ```

Ah, thanks for the explanation. Then it's used a lot more than I thought.

https://github.com/llvm/llvm-project/pull/65242