Check if target might be a project-level configuration file, not a missing directory

[philderbeast]

A rough fix for #6032. If it merits more work, I'll be happy to tidy it up, add a change log and some tests. What do you think?

The new behaviour:

$ stack build stack-yaml ghc-9.2.4.cabal2stack.yaml --dry-run

Error: [S-8506]
       Stack failed to parse the target(s).
       
       While parsing, Stack encountered the error:
       
           Directory not found: ghc-9.2.4.cabal2stack.yaml. Is this a typo? Can I suggest: --stack-yaml ghc-9.2.4.cabal2stack.yaml
       
       Stack expects a target to be a package name (e.g. my-package), a package identifier (e.g. my-package-0.1.2.3), a package component
       (e.g. my-package:test:my-test-suite), or, failing that, a relative path to a directory that is a local package directory or a parent
       directory of one or more local package directories.

$ stack build stack-yaml=ghc-9.2.4.cabal2stack.yaml --dry-run

Error: [S-8506]
       Stack failed to parse the target(s).
       
       While parsing, Stack encountered the error:
       
           Directory not found: stack-yaml=ghc-9.2.4.cabal2stack.yaml. Is this a typo? Can I suggest:
           --stack-yaml=ghc-9.2.4.cabal2stack.yaml
       
       Stack expects a target to be a package name (e.g. my-package), a package identifier (e.g. my-package-0.1.2.3), a package component
       (e.g. my-package:test:my-test-suite), or, failing that, a relative path to a directory that is a local package directory or a parent
       directory of one or more local package directories.

[mpilgrem]

@philderbeast, that looks helpful to me. A few suggestions:

1. I would put the hint on its own line following the problem:

   Stack failed to parse the target(s).
      
   While parsing, Stack encountered the error:
      
       Directory not found: stack-yaml=ghc-9.2.4.cabal2stack.yaml. 
   
       Is this a typo? May I suggest: --stack-yaml=ghc-9.2.4.cabal2stack.yaml.
   

2. It is highly nuanced (see https://www.merriam-webster.com/words-at-play/when-to-use-can-and-may, for example) but 'May I ...?' may be better than 'Can I ...?' when asking permission.
3. I am introducing proper punctuation into Stack's messages. You might add the final fullstop to the hint message.
4. On the hint and styling, I am consistently using the Shell style for things typed, or to be typed, at the command line (rather than Dir).
5. For your alternative test 'Does it end in .yaml?', --stack-yaml is not the only possibility. Very remotely, it could be --setup-info-yaml. I suggest to allow for that case:

   Stack failed to parse the target(s).
     
   While parsing, Stack encountered the error:
     
      Directory not found: ghc-9.2.4.cabal2stack.yaml. 
   
      Is there a typo? Did you mean to use the --stack-yaml option or, perhaps, the --setup-info-yaml option?
   

6. If you wanted to be comprehensive, you could also cater for the setup-info-yaml=... type mistake.
7. EDIT: Perhaps 'May I suggest: ...' is too anthropomorphic? How about 'Did you mean: ...' as the hint?

[mpilgrem]

PS, I am on to the CI failing; that is nothing to do with your code. GitHub's rate limiting for its API is being triggered.

[philderbeast]

This is what I'm heading towards:

[philderbeast]

Here's how it is looking now (not showing the colors or the "Stack expects a target to be ..." ending of the message):

$ stack run stack -- build stack-yaml=ghc-9.2.4.cabal2stack.yaml --dry-run
...
Error: [S-8506]
       Stack failed to parse the target(s).
       
       While parsing, Stack encountered the error:
       
             stack-yaml=ghc-9.2.4.cabal2stack.yaml is not a directory.
           --stack-yaml=ghc-9.2.4.cabal2stack.yaml might work as a project option.

$ stack run stack -- build stack-yaml ghc-9.2.4.cabal2stack.yaml --dry-run

Error: [S-8506]
       Stack failed to parse the target(s).
       
       While parsing, Stack encountered the error:
       
                        ghc-9.2.4.cabal2stack.yaml is not a directory.
           --stack-yaml ghc-9.2.4.cabal2stack.yaml might work as a project option.

[philderbeast]

6. If you wanted to be comprehensive, you could also cater for the setup-info-yaml=... type mistake.

@mpilgrem I've never dealt with setup-info-yaml= and would like to move onto something else (picking up the multiple library support again) so will leave this extra case for now.