[all-commits] [llvm/llvm-project] 38b34c: Reland "[Support]Look up in top-level subcommand a...

[Mingming Liu via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 38b34c61e028751b6778493d6185d07a8af1a3b5
      https://github.com/llvm/llvm-project/commit/38b34c61e028751b6778493d6185d07a8af1a3b5
  Author: Mingming Liu <mingmingl at google.com>
  Date:   2023-11-12 (Sun, 12 Nov 2023)

  Changed paths:
    M llvm/lib/Support/CommandLine.cpp
    M llvm/unittests/Support/CommandLineTest.cpp

  Log Message:
  -----------
  Reland "[Support]Look up in top-level subcommand as a fallback when looking options for a custom subcommand (#71981)

Fixed build bot errors. 

- Use `StackOption<std::string>` type for the top level option. This
way, a per test-case option is unregistered when destructor of
`StackOption` cleans up state for subsequent test cases.
- Repro the crash with no test sharding `/usr/bin/python3
/path/to/llvm-project/build/./bin/llvm-lit -vv --no-gtest-sharding -j128
/path/to/llvm-project/llvm/test/Unit`. The crash is gone with the fix
(same no-sharding repro)

**Original commit message:**
**Context:**

- In https://lists.llvm.org/pipermail/llvm-dev/2016-June/101804.html and
commit
https://github.com/llvm/llvm-project/commit/07670b3e984db32f291373fe12c392959f2aff67,
`cl::SubCommand` is introduced.
- Options that don't specify subcommand goes into a special 'top level'
subcommand.

**Motivating Use Case:**
- The motivating use case is to refactor `llvm-profdata` to use
`cl::SubCommand` to organize subcommands. See
https://github.com/llvm/llvm-project/pull/71328. A valid use case that's
not supported before this patch is shown below

```
  // show-option{1,2} are associated with 'show' subcommand.
  // top-level-option3 is in top-level subcomand (e.g., `profile-isfs` in SampleProfReader.cpp)
  llvm-profdata show --show-option1 --show-option2 --top-level-option3
```

- Before this patch, option handler look-up will fail with the following
error message "Unknown command line argument --top-level-option3".
- After this patch, option handler look-up will look up in sub-command
options first, and use top-level subcommand as a fallback, so
'top-level-option3' is parsed correctly.