change name to

`is_trait_with_maybe_impl_restriction_in_front`
and fix some comments

Author: CoCo-Japan-pan

compiler/rustc_parse/src/parser/item.rs

@@ -1026,7 +1026,7 @@ impl<'a> Parser<'a> {
     }
 
     /// Is there an `[ impl(in? path) ]? trait` item `dist` tokens ahead?
-    fn is_impl_restriction_in_front_matter(&self, dist: usize) -> bool {
+    fn is_trait_with_maybe_impl_restriction_in_front(&self, dist: usize) -> bool {
         // `trait`
         if self.is_keyword_ahead(dist, &[kw::Trait]) {
             return true;
@@ -1057,42 +1057,42 @@ impl<'a> Parser<'a> {
                 .unwrap_or(false)
     }
 
-    /// Is this an `(const unsafe? auto? [ impl(in? path) ]?| unsafe auto? [ impl(in? path) ]? | auto [ impl(in? path) ]? | [ impl(in? path) ]) trait` item?
+    /// Is this an `(const unsafe? auto? [ impl(in? path) ]? | unsafe auto? [ impl(in? path) ]? | auto [ impl(in? path) ]? | [ impl(in? path) ]?) trait` item?
     fn check_trait_front_matter(&mut self) -> bool {
-        // [ impl(in? path) ]) trait
-        if self.is_impl_restriction_in_front_matter(0) {
+        // `[ impl(in? path) ]? trait`
+        if self.is_trait_with_maybe_impl_restriction_in_front(0) {
             return true;
         }
-        // auto [ impl(in? path) ]? trait
-        if self.check_keyword(exp!(Auto)) && self.is_impl_restriction_in_front_matter(1) {
+        // `auto [ impl(in? path) ]? trait`
+        if self.check_keyword(exp!(Auto)) && self.is_trait_with_maybe_impl_restriction_in_front(1) {
             return true;
         }
-        // unsafe auto? [ impl(in? path) ]? trait
+        // `unsafe auto? [ impl(in? path) ]? trait`
         if self.check_keyword(exp!(Unsafe))
-            && (self.is_impl_restriction_in_front_matter(1)
+            && (self.is_trait_with_maybe_impl_restriction_in_front(1)
                 || self.is_keyword_ahead(1, &[kw::Auto])
-                    && self.is_impl_restriction_in_front_matter(2))
+                    && self.is_trait_with_maybe_impl_restriction_in_front(2))
         {
             return true;
         }
-        // const ...
+        // `const` ...
         if !self.check_keyword(exp!(Const)) {
             return false;
         }
-        // const [ impl(in? path) ]? trait
-        if self.is_impl_restriction_in_front_matter(1) {
+        // `const [ impl(in? path) ]? trait`
+        if self.is_trait_with_maybe_impl_restriction_in_front(1) {
             return true;
         }
-        // const (unsafe | auto) [ impl(in? path) ]? trait
+        // `const (unsafe | auto) [ impl(in? path) ]? trait`
         if self.is_keyword_ahead(1, &[kw::Unsafe, kw::Auto])
-            && self.is_impl_restriction_in_front_matter(2)
+            && self.is_trait_with_maybe_impl_restriction_in_front(2)
         {
             return true;
         }
-        // const unsafe auto [ impl(in? path) ]? trait
+        // `const unsafe auto [ impl(in? path) ]? trait`
         self.is_keyword_ahead(1, &[kw::Unsafe])
             && self.is_keyword_ahead(2, &[kw::Auto])
-            && self.is_impl_restriction_in_front_matter(3)
+            && self.is_trait_with_maybe_impl_restriction_in_front(3)
     }
 
     /// Parses `const? unsafe? auto? [impl(in? path)]? trait Foo { ... }` or `trait Foo = Bar;`.