[llvm-dev] [llvm-lit] Old echo causes test failure on windows

[via llvm-dev]

> I assumed that when using the internal shell (non-optional under
> Windows), lit would only use its implementation of shell-builtins [1].
> If this is not the case yet, I'd vote to do so since I would
> understand the option to replace the environment's shell. Shell's
> generally prioritize their builtins over executables found in $PATH, I
> think lit should do the same.

It looks like that is the case for builtins that are not echo [2]. Presumably
the reason is related to the comment nearby which was added in D35093:

```
        # FIXME: Standardize on the builtin echo implementation. We can use a
        # temporary file to sidestep blocking pipe write issues.
```

That might be a clue to the question "why can't we always use lit's echo", but I
don't know what the required work is just looking at this comment.

cc Reid (author of D35093) in case you remember what needs to be done for
lit's echo to be used here?

Thanks,
Orlando

> Michael 

> [1] https://urldefense.com/v3/__https://github.com/llvm/llvm-project/blob/2ac199993764e068494a69a85af098c0ae1ff37e/llvm/utils/lit/lit/TestRunner.py*L624__;Iw!!JmoZiZGBv3RvKRSx!p1AhbwjYZ8K0b1l4vzhjIlkFVpysqYbPGSLfYkiD4ou7gB-sXy64tQtNw80KvO-GEQ$

[2] https://github.com/llvm/llvm-project/blob/2ac199993764e068494a69a85af098c0ae1ff37e/llvm/utils/lit/lit/TestRunner.py#L680