Don't skip argument parsing when running rustc
with no arguments
#135716
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Setting up the argument parser to parse no arguments is a tiny bit of wasted work, but avoids an otherwise-unnecessary special case, in a scenario (printing a help message and quitting) where perf at this scale really doesn't matter anyway.
In particular, this lets us avoid having to deal with multiple different APIs to determine whether the compiler is nightly or not.
This special-case handling for rustc with no arguments is very very old (long predating 1.0), and used to be much simpler, without any need to set up boolean values to handle various conditional cases. So I don't think it was ever explicitly decided that having this special case was worth the extra complexity; it just started out simple and accumulated complexity over time.