fix all clippy::use_self pedantic warnings found in the codebase.

cc #3172

clippy_dev/src/lib.rs

@@ -35,8 +35,8 @@ pub struct Lint {
 }
 
 impl Lint {
-    pub fn new(name: &str, group: &str, desc: &str, deprecation: Option<&str>, module: &str) -> Lint {
-        Lint {
+    pub fn new(name: &str, group: &str, desc: &str, deprecation: Option<&str>, module: &str) -> Self {
+        Self {
             name: name.to_lowercase(),
             group: group.to_string(),
             desc: NL_ESCAPE_RE.replace(&desc.replace("\\\"", "\""), "").to_string(),
@@ -46,12 +46,12 @@ impl Lint {
     }
 
     /// Returns all non-deprecated lints
-    pub fn active_lints(lints: &[Lint]) -> impl Iterator<Item=&Lint> {
+    pub fn active_lints(lints: &[Self]) -> impl Iterator<Item=&Self> {
         lints.iter().filter(|l| l.deprecation.is_none())
     }
 
     /// Returns the lints in a HashMap, grouped by the different lint groups
-    pub fn by_lint_group(lints: &[Lint]) -> HashMap<String, Vec<Lint>> {
+    pub fn by_lint_group(lints: &[Self]) -> HashMap<String, Vec<Self>> {
         lints.iter().map(|lint| (lint.group.to_string(), lint.clone())).into_group_map()
     }
 }

clippy_lints/src/consts.rs

@@ -123,11 +123,11 @@ impl Constant {
             (&Constant::Tuple(ref l), &Constant::Tuple(ref r)) | (&Constant::Vec(ref l), &Constant::Vec(ref r)) => l
                 .iter()
                 .zip(r.iter())
-                .map(|(li, ri)| Constant::partial_cmp(tcx, cmp_type, li, ri))
+                .map(|(li, ri)| Self::partial_cmp(tcx, cmp_type, li, ri))
                 .find(|r| r.map_or(true, |o| o != Ordering::Equal))
                 .unwrap_or_else(|| Some(l.len().cmp(&r.len()))),
             (&Constant::Repeat(ref lv, ref ls), &Constant::Repeat(ref rv, ref rs)) => {
-                match Constant::partial_cmp(tcx, cmp_type, lv, rv) {
+                match Self::partial_cmp(tcx, cmp_type, lv, rv) {
                     Some(Equal) => Some(ls.cmp(rs)),
                     x => x,
                 }

clippy_lints/src/inherent_impl.rs

@@ -46,7 +46,7 @@ pub struct Pass {
 
 impl Default for Pass {
     fn default() -> Self {
-        Pass { impls: FxHashMap::default() }
+        Self { impls: FxHashMap::default() }
     }
 }
 

clippy_lints/src/utils/conf.rs

@@ -148,7 +148,7 @@ define_Conf! {
 }
 
 impl Default for Conf {
-    fn default() -> Conf {
+    fn default() -> Self {
         toml::from_str("").expect("we never error on empty config files")
     }
 }