rustfmt's `--config-path` help text is misleading

[tmfink]

As of 8b0b213, the help text is:

$ rustfmt -h
...
        --config-path [Path for the configuration file]
                        Recursively searches the given path for the
                        rustfmt.toml config file. If not found reverts to the
                        input file path

Some points of confusion:

1. How can there be a recursive search if the configure is a "file": [Path for the configuration file]?
   a. It seems like this option can take a directory with rustfmt.toml OR the file itself.
2. When passed a directory, rustfmt does not appear to search recursively for a config file through ancestors or decedent directories:

   $ mkdir -p /tmp/dir1/dir2/dir3
   $ find /tmp/dir1/
   /tmp/dir1/
   /tmp/dir1/dir2
   /tmp/dir1/dir2/dir3
   $ strace target/debug/rustfmt --config-path=/tmp/dir1/dir2/ /dev/null |& rg dir1 -C1
   execve("target/debug/rustfmt", ["target/debug/rustfmt", "--config-path=/tmp/dir1/dir2/", "/dev/null"], 0x7ffc4c2ad340 /* 61 vars */) = 0
   brk(NULL)                               = 0x5607c5058000
   --
   statx(0, NULL, AT_STATX_SYNC_AS_STAT, STATX_ALL, NULL) = -1 EFAULT (Bad address)
   statx(AT_FDCWD, "/tmp/dir1/dir2/", AT_STATX_SYNC_AS_STAT, STATX_ALL, {stx_mask=STATX_ALL|0x1000, stx_attributes=0, stx_mode=S_IFDIR|0775, stx_size=4096, ...}) = 0
   statx(AT_FDCWD, "/tmp/dir1/dir2/", AT_STATX_SYNC_AS_STAT, STATX_ALL, {stx_mask=STATX_ALL|0x1000, stx_attributes=0, stx_mode=S_IFDIR|0775, stx_size=4096, ...}) = 0
   statx(AT_FDCWD, "/tmp/dir1/dir2/.rustfmt.toml", AT_STATX_SYNC_AS_STAT, STATX_ALL, 0x7ffc9118d8b0) = -1 ENOENT (No such file or directory)
   statx(AT_FDCWD, "/tmp/dir1/dir2/rustfmt.toml", AT_STATX_SYNC_AS_STAT, STATX_ALL, 0x7ffc9118d8b0) = -1 ENOENT (No such file or directory)
   write(2, "Error: unable to find a config f"..., 73Error: unable to find a config file for the given path: `/tmp/dir1/dir2/`) = 73
   write(2, "\n", 1
   

3. The last sentence says that if the file is not found, then "reverts to the input file path", but it seems like rustfmt will emit an error when the file does not exist

   rustfmt --config-path=/does/not/exist /dev/null
   Error: unable to find a config file for the given path: `/does/not/exist`
   

[calebcartwright]

Thanks for following up. With the caveat that there are some outstanding bugs relative to config loading (especially recursive loading and dealing with conflicting keys):

1. How can there be a recursive search...

I think this could either be addressed via some wording enhancements to provide clarity, or potentially view some parts of current behavior as a bug that could be addressed. My recollection is that both file and directory paths supported, and in the case of the former direct load if file path is valid, or if not, using the parent as the starting directory for descendant recursion.

2. When passed a directory, rustfmt does not appear to search recursively for a config file through ancestors or decedent directories

Could be related to the aforementioned recursion issues, but worth some additional investigation regardless

3. The last sentence says that if the file is not found, then "reverts to the input file path", but it seems like rustfmt will emit an error when the file does not exist

I suspect the problem in this case is the input file is invalid, so even though that's the fallback check, the error is still surfacing with only the details of the overridden config path. If that's indeed what's happening then I'd think an extended error message that noted the absence for both locations