From d337a80ff5b2646c0cf44923bc4ddbaacc8eddb5 Mon Sep 17 00:00:00 2001
From: Richard Feldman <oss@rtfeldman.com>
Date: Thu, 5 May 2022 18:00:47 -0400
Subject: [PATCH] Use matches.value_of_t

---
 cli/src/lib.rs  |  8 ++++----
 cli/src/main.rs | 16 +++++++---------
 2 files changed, 11 insertions(+), 13 deletions(-)

diff --git a/cli/src/lib.rs b/cli/src/lib.rs
index 11469c82aa..dbeab8b027 100644
--- a/cli/src/lib.rs
+++ b/cli/src/lib.rs
@@ -669,15 +669,15 @@ impl std::fmt::Display for Target {
 }
 
 impl std::str::FromStr for Target {
-    type Err = ();
+    type Err = String;
 
-    fn from_str(s: &str) -> Result<Self, Self::Err> {
-        match s {
+    fn from_str(string: &str) -> Result<Self, Self::Err> {
+        match string {
             "system" => Ok(Target::System),
             "linux32" => Ok(Target::Linux32),
             "linux64" => Ok(Target::Linux64),
             "wasm32" => Ok(Target::Wasm32),
-            _ => Err(()),
+            _ => Err(format!("Roc does not know how to compile to {}", string)),
         }
     }
 }
diff --git a/cli/src/main.rs b/cli/src/main.rs
index 3c2c413f0b..0a21c66ed5 100644
--- a/cli/src/main.rs
+++ b/cli/src/main.rs
@@ -67,14 +67,7 @@ fn main() -> io::Result<()> {
             }
         }
         Some((CMD_BUILD, matches)) => {
-            use std::str::FromStr;
-
-            let target = match matches.value_of(FLAG_TARGET) {
-                Some(name) => Target::from_str(name).unwrap(),
-                None => Target::default(),
-            };
-
-            let triple = target.to_triple();
+            let target: Target = matches.value_of_t(FLAG_TARGET).unwrap_or_default();
 
             let link_type = match (
                 matches.is_present(FLAG_LIB),
@@ -86,7 +79,12 @@ fn main() -> io::Result<()> {
                 (false, false) => LinkType::Executable,
             };
 
-            Ok(build(matches, BuildConfig::BuildOnly, triple, link_type)?)
+            Ok(build(
+                matches,
+                BuildConfig::BuildOnly,
+                target.to_triple(),
+                link_type,
+            )?)
         }
         Some((CMD_CHECK, matches)) => {
             let arena = bumpalo::Bump::new();