Fix clippy hints

src/file.rs

@@ -355,7 +355,7 @@ where
     }
 
     pub fn source_span(&self) -> Span {
-        Span::from_str(self.source.as_ref())
+        Span::from_string(self.source.as_ref())
     }
 
     pub fn source_slice(&self, span: Span) -> Result<&str, Error> {

src/index.rs

@@ -33,6 +33,7 @@ impl LineIndex {
     }
 }
 
+#[allow(clippy::derivable_impls)]
 impl Default for LineIndex {
     fn default() -> LineIndex {
         LineIndex(0)
@@ -82,6 +83,7 @@ impl fmt::Display for LineNumber {
 #[derive(Clone, Copy, PartialEq, Eq, Hash, PartialOrd, Ord)]
 pub struct LineOffset(pub RawOffset);
 
+#[allow(clippy::derivable_impls)]
 impl Default for LineOffset {
     fn default() -> LineOffset {
         LineOffset(0)
@@ -125,6 +127,7 @@ impl ColumnIndex {
     }
 }
 
+#[allow(clippy::derivable_impls)]
 impl Default for ColumnIndex {
     fn default() -> ColumnIndex {
         ColumnIndex(0)
@@ -167,6 +170,7 @@ impl fmt::Display for ColumnNumber {
 #[derive(Clone, Copy, PartialEq, Eq, Hash, PartialOrd, Ord)]
 pub struct ColumnOffset(pub RawOffset);
 
+#[allow(clippy::derivable_impls)]
 impl Default for ColumnOffset {
     fn default() -> ColumnOffset {
         ColumnOffset(0)
@@ -198,6 +202,7 @@ impl ByteIndex {
     }
 }
 
+#[allow(clippy::derivable_impls)]
 impl Default for ByteIndex {
     fn default() -> ByteIndex {
         ByteIndex(0)

src/span.rs

@@ -37,7 +37,7 @@ impl Span {
     ///
     /// assert_eq!(span, Span::new(0, 5));
     /// ```
-    pub fn from_str(s: &str) -> Span {
+    pub fn from_string(s: &str) -> Span {
         Span::new(0, s.len() as u32)
     }