Fix more typos, “an”→“a” and “an”→“and”

src/cargo/core/source/source_id.rs

@@ -164,7 +164,7 @@ impl SourceId {
     }
 
     /// Creates a SourceId from a remote registry URL when the registry name
-    /// cannot be determined, e.g. an user passes `--index` directly from CLI.
+    /// cannot be determined, e.g. a user passes `--index` directly from CLI.
     ///
     /// Use [`SourceId::for_alt_registry`] if a name can provided, which
     /// generates better messages for cargo.

tests/testsuite/features_namespaced.rs

@@ -77,7 +77,7 @@ required by package `foo v0.1.0 ([..]/foo)`
         .run();
 
     // Publish a version without namespaced features, it should ignore 1.0.0
-    // an use this instead.
+    // and use this instead.
     Package::new("bar", "1.0.1")
         .add_dep(Dependency::new("baz", "1.0").optional(true))
         .feature("feat", &["baz"])

tests/testsuite/weak_dep_features.rs

@@ -94,7 +94,7 @@ required by package `foo v0.1.0 ([..]/foo)`
         .run();
 
     // Publish a version without the ? feature, it should ignore 1.0.0
-    // an use this instead.
+    // and use this instead.
     Package::new("bar", "1.0.1")
         .add_dep(Dependency::new("baz", "1.0").optional(true))
         .feature("feat", &["baz"])