Replace --no-user-output with --output-format none (or similar)

[Marcono1234]

Currently there are two command line arguments to control the output format:

• --no-user-output
• --output-format <format>

This creates the following issues:

• It is syntactically valid to combine both arguments: cargo msrv verify --no-user-output --output-format human
  But semantically this makes no sense and is rather confusing.
• The struct modelling the output configuration similarly allows both values to be set:
  

  cargo-msrv/src/cli/shared_opts.rs

  Lines 27 to 41 in ab2870f

  	pub struct UserOutputOpts {
  	/// Set the format of user output
  	#[arg(
  	long,
  	value_enum,
  	default_value_t,
  	value_name = "FORMAT",
  	global = true
  	)]
  	pub output_format: OutputFormat,
  	/// Disable user output
  	#[arg(long, global = true)]
  	pub no_user_output: bool,
  	}

• There is custom conversion code needed
  

  cargo-msrv/src/context.rs

  Lines 316 to 328 in ab2870f

  	impl From<UserOutputOpts> for UserOutputContext {
  	fn from(opts: UserOutputOpts) -> Self {
  	if opts.no_user_output {
  	Self {
  	output_format: OutputFormat::None,
  	}
  	} else {
  	Self {
  	output_format: opts.output_format,
  	}
  	}
  	}
  	}

In total this makes usage a bit confusing, and the implementation rather complex. What do you think about replacing --no-user-output with a new none output format (or similar)? For example: --output-format none

This should hopefully solve the issues mentioned above.

[foresterre]

I originally added it because I felt the --no-{} signalled that something was not enabled (a boolean). For this case there would be two options: "print user output" (enabled) and "do not print user output" (disabled).
It is true that I only provided one flag (for disabled), because it is the opposite of the default (enabled).

The type of user output I reasoned is something different. If user output is enabled, then we can still print json output, or something a little more human readable.

[foresterre]

I suppose I could have coded this difference more explicitly by making the output format Option<OutputFormat> (although the default should be Some(OutputFormat::Human), instead of the default of Option which is None.

[foresterre]

Perhaps another idea could be to add a conflicts_with [1] method on --no-output-format and have it conflict with --output-format <value>.

[1] https://docs.rs/clap/latest/clap/struct.Arg.html#method.conflicts_with

[Marcono1234]

Yes conflicts_with works, thanks for the suggestion. I have created a pull request for it now: #979

Together the with UserOutputOpts::effective_output_format() I added in #963 this issue is in my opinion then mostly resolved.