Get rid of Backend::Unknown variant

src/dvcs.rs

@@ -6,16 +6,18 @@ use std::process::Command;
 pub enum Backend {
     Git,
     Mercurial,
-    Unknown(String),
 }
 
 impl Backend {
-    pub fn from_setting(setting: Option<String>) -> Backend {
+    /// Generates Some(Backend) from an optional String, or defaults to Git,
+    /// or None when the backend is not recognized
+    /// TODO: fallback backend should be customizable
+    pub fn from_setting(setting: Option<String>) -> Option<Backend> {
         // Git is the default setting until further notice
-        setting.map_or(Backend::Git, |name| match name.as_ref() {
-            "git" => Backend::Git,
-            "mercurial" => Backend::Mercurial,
-            _ => Backend::Unknown(name.to_string()),
+        setting.map_or(Some(Backend::Git), |name| match name.as_ref() {
+            "git" => Some(Backend::Git),
+            "mercurial" => Some(Backend::Mercurial),
+            _ => None,
         })
     }
 }
@@ -55,10 +57,6 @@ impl Repo {
             Backend::Mercurial => {
                 unreachable!("UNIMPLEMENTED!");
             }
-            Backend::Unknown(name) => {
-                // TODO: This should be a forgebuild error message
-                panic!("Uknown backend: {}. Cannot find branch", name);
-            }
         }
     }
 
@@ -77,11 +75,6 @@ impl Repo {
             Backend::Mercurial => {
                 unreachable!("Unimplemented");
             }
-            Backend::Unknown(name) => {
-                // TODO: This should be a forgebuild error message
-                eprintln!("Unknown DVCS: {}", name);
-                false
-            }
         };
 
         // If the clone was successful and subupdates is enabled,
@@ -124,11 +117,6 @@ impl Repo {
             Backend::Mercurial => {
                 unreachable!("UNIMPLEMENTED");
             }
-            Backend::Unknown(name) => {
-                // TODO: This should be a forgebuild error message
-                eprintln!("Unknown DVCS: {}", name);
-                false
-            }
         }
     }
 
@@ -160,11 +148,6 @@ impl Repo {
             },
             Backend::Mercurial => {
                 unimplemented!("Soon");
-            },
-            Backend::Unknown(name) => {
-                // TODO: This should be a forgebuild error message
-                eprintln!("Unknown DVCS:{}!", name);
-                Vec::new()
             }
         }
     }
@@ -205,11 +188,6 @@ impl Repo {
             Backend::Mercurial => {
                 unimplemented!();
             },
-            Backend::Unknown(name) => {
-                // TODO: This should be a forgebuild error message
-                eprintln!("Unknown DVCS:{}!", name);
-                false
-            }
         }
     }
 
@@ -259,11 +237,6 @@ impl Repo {
             Backend::Mercurial => {
                 unreachable!("unimplemented");
             }
-            Backend::Unknown(name) => {
-                // TODO: This should be a forgebuild error message
-                eprintln!("Unknown DVCS:{}!", name);
-                false
-            }
         }
     }
 }

src/task.rs

@@ -76,13 +76,19 @@ impl Task {
             context.insert("$i18n_source".to_string(), source_url.clone());
         }
 
+        let dvcs = if let Some(dvcs) = Backend::from_setting(read_extension(path, "dvcs")) { dvcs } else {
+            // TODO: forgebuild error message
+            eprintln!("Unrecognized dvcs for task {}, possible options are 'git' or 'mercurial'. Skipped", &name);
+            return None;
+        };
+
         Some(Task {
             name,
             bin: path.to_path_buf(),
             // None source = None repo
             repo: source.as_ref().map(|s| {
                 Repo::new(
-                    Backend::from_setting(read_extension(path, "dvcs")),
+                    dvcs,
                     s,
                     &dest,
                     subupdates,