manifest: Skip non-directories when resolving workspace members

If globs provided in the `members` array resolve to files, even if
none of its results are (symlinks to) directories or if the path is a
relative path to a file without any globbing directives, `cargo` skips
it without error.  Cargo only errors out if the glob (or again relative
path) didn't resolve to any files at all (which is what `glob::glob()`
should also be doing for us).

It does however support symlinks, meaning we need to canonicalize
every result to follow any symlinks before deducing if the entry is a
directory that needs to be treated as a workspace member crate.

src/lib.rs

@@ -11,6 +11,6 @@ pub use args::Args;
 pub use artifact::{Artifact, ArtifactType};
 pub use config::{EnvError, EnvOption, LocalizedConfig};
 pub use error::Error;
-pub use manifest::CrateType;
+pub use manifest::{CrateType, Manifest};
 pub use profile::Profile;
 pub use subcommand::Subcommand;

src/manifest.rs

@@ -36,8 +36,16 @@ impl Manifest {
         let mut all_members = HashMap::new();
 
         for member in &workspace.members {
+            // XXX: Cargo would fail if the glob yielded no file results.  But it allows cases where
+            // the only results are non-directories, including non-glob *file* paths in `members`...
             for manifest_dir in glob::glob(workspace_root.join(member).to_str().unwrap())? {
                 let manifest_dir = manifest_dir?;
+                if !dunce::canonicalize(&manifest_dir)
+                    .map_err(|e| Error::Io(manifest_dir.clone(), e))?
+                    .is_dir()
+                {
+                    continue;
+                }
                 let manifest_path = manifest_dir.join("Cargo.toml");
                 let manifest = Manifest::parse_from_toml(&manifest_path)?;
 

src/subcommand.rs

@@ -30,7 +30,7 @@ impl Subcommand {
             args.package.len() < 2,
             "Multiple packages are not supported yet by `cargo-subcommand`"
         );
-        let package = args.package.get(0).map(|s| s.as_str());
+        let package = args.package.first().map(|s| s.as_str());
         assert!(
             !args.workspace,
             "`--workspace` is not supported yet by `cargo-subcommand`"