don't error out if cargo metadata can't be read

Author: hellow554

clippy_lints/src/lib.rs

@@ -469,18 +469,13 @@ pub fn read_conf(sess: &Session) -> Conf {
 
     if conf.msrv.is_none() {
         // let's try to get msrv from `Cargo.toml`s field `rust-version`
-        match MetadataCommand::new().no_deps().exec() {
-            Ok(metadata) => {
-                conf.msrv = metadata
-                    .packages
-                    .get(0)
-                    .and_then(|x| x.rust_version.as_ref())
-                    .and_then(|r| r.comparators.get(0))
-                    .map(|v| format!("{}.{}.{}", v.major, v.minor.unwrap_or(0), v.patch.unwrap_or(0)));
-            },
-            Err(e) => {
-                sess.struct_err(&format!("could not read cargo metadata: {}", e)).emit();
-            },
+        if let Ok(metadata) = MetadataCommand::new().no_deps().exec() {
+            conf.msrv = metadata
+                .packages
+                .get(0)
+                .and_then(|x| x.rust_version.as_ref())
+                .and_then(|r| r.comparators.get(0))
+                .map(|v| format!("{}.{}.{}", v.major, v.minor.unwrap_or(0), v.patch.unwrap_or(0)));
         }
     }