Move cd out of Config::from_matches (#513)

Move `env::set_current_dir` outside of `Config::from_matches()` and into
`run()`. It's a bit cleaner this way, and sets us up to make the just
process not change its own directory at all, instead explicitly changing
the working directory of its child processes.

src/config.rs

@@ -17,6 +17,7 @@ pub(crate) struct Config<'a> {
   pub(crate) justfile: Option<&'a Path>,
   pub(crate) working_directory: Option<&'a Path>,
   pub(crate) invocation_directory: Result<PathBuf, String>,
+  pub(crate) search_directory: Option<&'a Path>,
 }
 
 mod cmd {
@@ -248,6 +249,8 @@ impl<'a> Config<'a> {
       overrides.insert(name, value);
     }
 
+    let mut search_directory = None;
+
     let arguments = raw_arguments
       .into_iter()
       .skip_while(is_override)
@@ -261,9 +264,7 @@ impl<'a> Config<'a> {
 
             let (dir, recipe) = argument.split_at(i + 1);
 
-            if let Err(error) = env::set_current_dir(dir) {
-              die!("Error changing directory: {}", error);
-            }
+            search_directory = Some(Path::new(dir));
 
             if recipe.is_empty() {
               return None;
@@ -300,6 +301,7 @@ impl<'a> Config<'a> {
       shell: matches.value_of(arg::SHELL).unwrap(),
       justfile: matches.value_of(arg::JUSTFILE).map(Path::new),
       working_directory: matches.value_of(arg::WORKING_DIRECTORY).map(Path::new),
+      search_directory,
       invocation_directory,
       subcommand,
       verbosity,
@@ -326,6 +328,7 @@ impl<'a> Default for Config<'a> {
       working_directory: None,
       invocation_directory: env::current_dir()
         .map_err(|e| format!("Error getting current directory: {}", e)),
+      search_directory: None,
     }
   }
 }

src/run.rs

@@ -55,6 +55,16 @@ pub fn run() -> Result<(), i32> {
 
   let justfile = config.justfile;
 
+  if let Some(directory) = config.search_directory {
+    if let Err(error) = env::set_current_dir(&directory) {
+      die!(
+        "Error changing directory to {}: {}",
+        directory.display(),
+        error
+      );
+    }
+  }
+
   let mut working_directory = config.working_directory.map(PathBuf::from);
 
   if let (Some(justfile), None) = (justfile, working_directory.as_ref()) {