fix some comments

Signed-off-by: cui fliter <imcusg@gmail.com>

clippy_utils/src/source.rs

@@ -362,7 +362,7 @@ pub fn snippet_block_with_context<'a>(
 }
 
 /// Same as `snippet_with_applicability`, but first walks the span up to the given context. This
-/// will result in the macro call, rather then the expansion, if the span is from a child context.
+/// will result in the macro call, rather than the expansion, if the span is from a child context.
 /// If the span is not from a child context, it will be used directly instead.
 ///
 /// e.g. Given the expression `&vec![]`, getting a snippet from the span for `vec![]` as a HIR node

clippy_utils/src/sugg.rs

@@ -88,7 +88,7 @@ pub fn hir_with_applicability(
     }
 
     /// Same as `hir`, but first walks the span up to the given context. This will result in the
-    /// macro call, rather then the expansion, if the span is from a child context. If the span is
+    /// macro call, rather than the expansion, if the span is from a child context. If the span is
     /// not from a child context, it will be used directly instead.
     ///
     /// e.g. Given the expression `&vec![]`, getting a snippet from the span for `vec![]` as a HIR

clippy_utils/src/ty/type_certainty/mod.rs

@@ -150,7 +150,7 @@ fn generic_args_certainty(cx: &LateContext<'_>, args: &GenericArgs<'_>) -> Certa
 }
 
 /// Tries to tell whether a `QPath` resolves to something certain, e.g., whether all of its path
-/// segments generic arguments are are instantiated.
+/// segments generic arguments are instantiated.
 ///
 /// `qpath` could refer to either a type or a value. The heuristic never needs the `DefId` of a
 /// value. So `DefId`s are retained only when `resolves_to_type` is true.