[#4365] [#4907] Add test cases related to issue #4365

[kfcripps]

#5123 made it very easy to add tests for functionality that is dependent on command-line options, so this PR does that and adds the following test cases:

• Ensure that errors cannot be disabled or demoted to warning or info messages ([#4365] Do not allow --Wdisable or --Wwarn to demote errors. Allow --Winfo=diagnostic to work for diagnostics that can be both warnings and errors. #4366)
• Ensure that --Wdisable takes precedence over --Werror for warnings (Allow --Wdisable to take precedence over --Werror for warning messages #4894)

This also closes #4907.

[ChrisDodd]

Looks good.

For future work, maybe make @command_line errors not trigger the full command line help message?

[kfcripps]

Looks good.

For future work, maybe make @command_line errors not trigger the full command line help message?

@ChrisDodd I don't think that's related to @command_line. Even without using @command_line, the full command line help message gets printed for this error:

[--Werror=invalid] error: Error type-error cannot be demoted.

[ChrisDodd]

Looks good.
For future work, maybe make @command_line errors not trigger the full command line help message?

@ChrisDodd I don't think that's related to @command_line. Even without using @command_line, the full command line help message gets printed for this error:

[--Werror=invalid] error: Error type-error cannot be demoted.

It's related to command line processing -- the help list occurs whenever there is an error from that. We probably want to be more sparing in general, as that help list is large and causes the actual error message to scroll off the screen. Mostly just an annoyance, however.

[fruffy]

Lovely.

[fruffy]

Mostly just an annoyance, however.

I agree, I often run into this problem and the error message gets completely lost in the help output.