[PATCH] D70105: [lit] Better/earlier errors for empty runs

[Julian Lettner via Phabricator via llvm-commits]

yln created this revision.
Herald added subscribers: llvm-commits, delcypher.
Herald added a project: LLVM.

Fail early, when we discover no tests at all, or filter out all of them.

There is also `--allow-empty-runs` to disable test to allow workflows
like `LIT_FILTER=abc ninja check-all`.  Apparently `check-all` invokes
lit multiple times if certain projects are enabled, which would produce
unwanted "empty runs". Specify via `LIT_OPTS=--allow-empty-runs`.

There are 3 causes for empty runs:

1. No tests discovered.  This is always an error.  Fix test suite config or command line.
2. All tests filtered out.  This is an error by default, but can be suppressed via `--alow-empty-runs`.  Should prevent accidentally passing empty runs, but allow the workflow above.
3. The number of shards is greater than the number of tests.  Currently, this is never an error.  Personally, I think we should consider making this an error by default; if this happens, you are doing something wrong. I added a warning but did not change the behavior, since this warrants more discussion.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D70105

Files:
  llvm/utils/lit/lit/cl_arguments.py
  llvm/utils/lit/lit/main.py
  llvm/utils/lit/lit/run.py
  llvm/utils/lit/tests/selecting.py

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