[llvm] [llvm-lto2] Added llvm-lto2 -unified-lto descriptions (revised) (PR #155462)

[Jeremy Morse via llvm-commits]

jmorse wrote:

Narrowing down the CI failure,

```
2025-08-27T16:03:16.7830674Z /home/gha/actions-runner/_work/llvm-project/llvm-project/llvm/test/LTO/Resolution/X86/unified-lto-check.ll:49:16: error: INVALIDMODE: expected string not found in input
2025-08-27T16:03:16.7831783Z ; INVALIDMODE: invalid LTO mode
2025-08-27T16:03:16.7832139Z                ^
2025-08-27T16:03:16.7832461Z <stdin>:1:1: note: scanning from here
2025-08-27T16:03:16.7834187Z llvm-lto2: for the --unified-lto option: Cannot find option named 'foo'!
2025-08-27T16:03:16.7834718Z ^
2025-08-27T16:03:16.7835051Z <stdin>:1:61: note: possible intended match here
2025-08-27T16:03:16.7835606Z llvm-lto2: for the --unified-lto option: Cannot find option named 'foo'!
2025-08-27T16:03:16.7836510Z                                                             ^
2025-08-27T16:03:16.7836806Z 
2025-08-27T16:03:16.7836958Z Input file: <stdin>
2025-08-27T16:03:16.7837758Z Check file: /home/gha/actions-runner/_work/llvm-project/llvm-project/llvm/test/LTO/Resolution/X86/unified-lto-check.ll
2025-08-27T16:03:16.7838499Z 
2025-08-27T16:03:16.7838695Z -dump-input=help explains the following input dump.
2025-08-27T16:03:16.7839090Z 
2025-08-27T16:03:16.7839219Z Input was:
2025-08-27T16:03:16.7839481Z <<<<<<
2025-08-27T16:03:16.7839941Z             1: llvm-lto2: for the --unified-lto option: Cannot find option named 'foo'! 
2025-08-27T16:03:16.7840658Z check:49'0     X~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ error: no match found
2025-08-27T16:03:16.7841303Z check:49'1                                                                 ?             possible intended match
2025-08-27T16:03:16.7841754Z >>>>>>
2025-08-27T16:03:16.7841911Z 
```

I guess that's the correct behaviour, in that an error is produced if the wrong argument is given, it's just not quite the same error text as what you're' checking for?

https://github.com/llvm/llvm-project/pull/155462