Help flag is awfully slow

[AllanRegush]

Describe the issue

Running the help flag is awfully slow.

Vapor version

4.115.0

Operating system and version

macOS 26.0.1

Swift version

Swift 6.2.0-dev

Steps to reproduce

vapor -h

Outcome

$ time vapor -h
OVERVIEW: Vapor Toolbox (Server-side Swift web framework)

USAGE: vapor <subcommand>

OPTIONS:
  --version               Show the version.
  -h, --help              Show help information.

SUBCOMMANDS:
  new (default)           Generates a new app.

  See 'vapor help <subcommand>' for detailed help.
vapor -h  1.37s user 0.44s system 50% cpu 3.584 total

This command should be pretty quick. We might be doing a bunch of unnecessary work.

Additional notes

This is run on a M1 MacBook Air 2020, 8GB Model

[gwynne]

Confirmed; in fact, it's even worse for me:

$ time vapor -h
OVERVIEW: Vapor Toolbox (Server-side Swift web framework)

USAGE: vapor <subcommand>

OPTIONS:
  --version               Show the version.
  -h, --help              Show help information.

SUBCOMMANDS:
  new (default)           Generates a new app.

  See 'vapor help <subcommand>' for detailed help.

real	0m2.213s
user	0m0.842s
sys	0m0.265s

@fpseverino Can you have a look?

[AllanRegush]

Would this be an acceptable patch?

static func preprocess(_ arguments: [String]) throws {
  guard !arguments.contains(where: Set(["-help", "-h", "--help", "--version"]).contains) else {
    return
}

[AllanRegush]

Results

time ./vapor -h    
OVERVIEW: Vapor Toolbox (Server-side Swift web framework)

USAGE: vapor <subcommand>

OPTIONS:
  --version               Show the version.
  -h, --help              Show help information.

SUBCOMMANDS:
  new (default)           Generates a new app.

  See 'vapor help <subcommand>' for detailed help.
./vapor -h  0.01s user 0.01s system 34% cpu 0.053 total

[fpseverino]

"This is a feature, not a bug".
The Toolbox clones the template repository so that all the dynamic variables show up in the help page

I could probably tune it so that the template is cloned only for the vapor new command help page, but I'm not sure it's doable since the new subcommand it's also the default one (for example you can just use vapor MyProject --no-fluent --leaf)

[gwynne]

Can we maybe have it pull down just the manifest file instead of cloning the whole repo for the help command? That ought to be substantially faster.

[fpseverino]

Yeah I can look into that. Another solution could be #383

[0xTim]

Don't we use argument parser for this now? I don't think we should be cloning the template unless explicitly asked to