Add keyword whitelist to similar_names lint

changelog: [`similar_names`] lint no longer warns when an underscore was added to a name to avoid a keyword clash

Author: th1000s

clippy_lints/src/non_expressive_names.rs

@@ -168,6 +168,16 @@ fn allowed_to_be_similar(interned_name: &str, list: &[&str]) -> bool {
         .any(|&name| interned_name.starts_with(name) || interned_name.ends_with(name))
 }
 
+fn avoiding_keyword_clash(maybe_keyword: &str) -> bool {
+    let rust_keywords = [
+        "as", "break", "const", "continue", "crate", "else", "enum", "extern", "false", "fn", "for", "if", "impl",
+        "in", "let", "loop", "match", "mod", "move", "mut", "pub", "ref", "return", "self", "Self", "static", "struct",
+        "super", "trait", "true", "type", "unsafe", "use", "where", "while", "async", "await", "dyn", "abstract",
+        "become", "box", "do", "final", "macro", "override", "priv", "typeof", "unsized", "virtual", "yield", "union",
+    ];
+    rust_keywords.iter().any(|kw| *kw == maybe_keyword)
+}
+
 impl<'a, 'tcx, 'b> SimilarNamesNameVisitor<'a, 'tcx, 'b> {
     fn check_short_ident(&mut self, ident: Ident) {
         // Ignore shadowing
@@ -205,6 +215,13 @@ impl<'a, 'tcx, 'b> SimilarNamesNameVisitor<'a, 'tcx, 'b> {
             // these bindings are typically unused or represent an ignored portion of a destructuring pattern
             return;
         }
+        if interned_name
+            .strip_suffix('_')
+            .map_or(false, |maybe_keyword| avoiding_keyword_clash(&maybe_keyword))
+        {
+            // do not warn if an underscore was added to avoid a keyword clash, e.g. types = [..] and type_ = x
+            return;
+        }
         let count = interned_name.chars().count();
         if count < 3 {
             if count == 1 {

tests/ui/similar_names.rs

@@ -106,3 +106,16 @@ fn ignore_underscore_prefix() {
     let hello: ();
     let _hello: ();
 }
+
+fn ignore_keywords_with_underscore_suffix() {
+    let types: ();
+    let type_: ();
+    let continues: ();
+    let continue_: ();
+    let ifa: ();
+    let if_: ();
+    let structs: ();
+    let struct_: ();
+    let ins: ();
+    let in_: ();
+}