Fixed the should_implement_trait clippy warning

RustPython · windelbouwman · Feb 12, 2019 · Feb 12, 2019 · Feb 12, 2019 · Feb 12, 2019
commit 00cfa47f6401ad09d9871434332a81e1f60783ca
diff --git a/vm/src/format.rs b/vm/src/format.rs
@@ -496,8 +496,12 @@ impl FormatString {
             None => Err(FormatParseError::UnmatchedBracket),
         }
     }
+}
+
+impl FromStr for FormatString {
+    type Err = FormatParseError;
 
-    pub fn from_str(text: &str) -> Result<FormatString, FormatParseError> {
+    fn from_str(text: &str) -> Result<Self, Self::Err> {
         let mut cur_text: &str = text;
         let mut parts: Vec<FormatPart> = Vec::new();
         while !cur_text.is_empty() {

diff --git a/vm/src/obj/objstr.rs b/vm/src/obj/objstr.rs
@@ -9,6 +9,7 @@ use super::objtype;
 use num_traits::ToPrimitive;
 use std::hash::{Hash, Hasher};
 use std::ops::Range;
+use std::str::FromStr;
 // rust's builtin to_lowercase isn't sufficient for casefold
 extern crate caseless;
 extern crate unicode_segmentation;