Bug 1713935 - Make rust mozprofile pass clippy, r=webdriver-reviewers,whimboo

Differential Revision: https://phabricator.services.mozilla.com/D116591

testing/mozbase/rust/mozprofile/src/prefreader.rs

@@ -11,7 +11,6 @@ use std::fmt;
 use std::io::{self, Write};
 use std::iter::Iterator;
 use std::mem;
-use std::ops::Deref;
 use std::str;
 
 impl PrefReaderError {
@@ -44,10 +43,7 @@ impl Error for PrefReaderError {
     }
 
     fn cause(&self) -> Option<&dyn Error> {
-        match self.parent {
-            None => None,
-            Some(ref cause) => Some(cause.deref()),
-        }
+        self.parent.as_deref()
     }
 }
 
@@ -247,8 +243,7 @@ impl<'a> PrefTokenizer<'a> {
             TokenType::Comma => PrefToken::Comma(position),
             TokenType::String => PrefToken::String(buf, position),
             TokenType::Int => {
-                let value =
-                    i64::from_str_radix(buf.borrow(), 10).expect("Integer wasn't parsed as an i64");
+                let value = buf.parse::<i64>().expect("Integer wasn't parsed as an i64");
                 PrefToken::Int(value, position)
             }
             TokenType::Bool => {
@@ -380,7 +375,7 @@ impl<'a> PrefTokenizer<'a> {
                 }
             }
         }
-        if first && value >= 0xD800 && value <= 0xDBFF {
+        if first && (0xD800..=0xDBFF).contains(&value) {
             // First part of a surrogate pair
             if self.get_char() != Some('\\') || self.get_char() != Some('u') {
                 return Err(PrefReaderError::new(
@@ -395,13 +390,13 @@ impl<'a> PrefTokenizer<'a> {
             let high_value = (high_surrogate - 0xD800) << 10;
             let low_value = low_surrogate - 0xDC00;
             value = high_value + low_value + 0x10000;
-        } else if first && value >= 0xDC00 && value <= 0xDFFF {
+        } else if first && (0xDC00..=0xDFFF).contains(&value) {
             return Err(PrefReaderError::new(
                 "Lone low surrogate",
                 self.position,
                 None,
             ));
-        } else if !first && (value < 0xDC00 || value > 0xDFFF) {
+        } else if !first && !(0xDC00..=0xDFFF).contains(&value) {
             return Err(PrefReaderError::new(
                 "Invalid low surrogate in surrogate pair",
                 self.position,
@@ -876,7 +871,7 @@ fn skip_comments<'a>(tokenizer: &mut PrefTokenizer<'a>) -> Option<PrefToken<'a>>
     }
 }
 
-pub fn parse_tokens<'a>(tokenizer: &mut PrefTokenizer<'a>) -> Result<Preferences, PrefReaderError> {
+pub fn parse_tokens(tokenizer: &mut PrefTokenizer<'_>) -> Result<Preferences, PrefReaderError> {
     let mut state = ParserState::Function;
     let mut current_pref = PrefBuilder::new();
     let mut rv = Preferences::new();