Support :exclude-pattern in :unused-binding

CHANGELOG.md

@@ -27,6 +27,7 @@ For a list of breaking changes, check [here](#breaking-changes).
 - [#2025](https://github.com/clj-kondo/clj-kondo/issues/2025): support namespace groups with `:unresolved-namespace` linter
 - [#2039](https://github.com/clj-kondo/clj-kondo/issues/2039): :analysis `:symbols` + `:aliased-namespace-symbol` linter gives false positive in quoted symbol
 - [#2043](https://github.com/clj-kondo/clj-kondo/issues/2043): support ignore annotation on private calls
+- Support `:exclude-pattern` in `:unused-binding`
 
 ## 2023.03.17
 

doc/linters.md

@@ -1288,7 +1288,7 @@ You can add or override type annotations. See
 *Config:*
 
 To exclude unused bindings from being reported, start their names with
-underscores: `_x`.
+underscores: `_x` or add regex patterns to `:exclude-patterns []`.
 
 To exclude warnings about key-destructured function arguments, use:
 
@@ -1329,6 +1329,14 @@ This will disable the warning in:
 (defmulti f (fn [a b] a))
 ```
 
+To exclude bindings named "this" use:
+
+``` clojure
+{:linters {:unused-binding {:exclude-patterns ["^this"]}}}
+```
+
+Patterns are matched via `re-find`.
+
 ### Unused value
 
 *Keyword*: `:unused-value`

src/clj_kondo/impl/config.clj

@@ -450,6 +450,17 @@
     (let [excluded (delayed-cfg config)]
       (contains? excluded sym-ns))))
 
+(let [delayed-cfg (fn [config]
+                    (let [excluded (get-in config [:linters :unused-binding :exclude-patterns])
+                          regexes (map re-pattern (filter string? excluded))]
+                      {:regexes regexes}))
+      delayed-cfg (memoize delayed-cfg)]
+  (defn unused-binding-excluded? [config binding-sym]
+    (let [{:keys [:regexes]} (delayed-cfg config)
+          binding-str (str binding-sym)]
+      (boolean (some (fn [regex]
+                       (re-find regex binding-str)) regexes)))))
+
 (let [delayed-cfg (fn [config]
                     (let [excluded (get-in config [:linters :used-underscored-binding :exclude])
                           syms (set (filter symbol? excluded))

src/clj_kondo/impl/linters.clj

@@ -618,8 +618,8 @@
               defaults (:destructuring-defaults ns)]
           (doseq [binding diff]
             (let [nm (:name binding)]
-              (when-not (str/starts-with? (str nm) "_")
-                ;; (prn binding)
+              (when-not (or (str/starts-with? (str nm) "_")
+                            (config/unused-binding-excluded? (:config ctx) nm))
                 (findings/reg-finding!
                  ctx
                  {:type :unused-binding

test/clj_kondo/bindings_test.clj

@@ -241,7 +241,10 @@
   (is (empty?  (lint! "(let [_x 0 {:keys [a b] :as _c} v]  [a b _x _c])"
                       '{:linters {:used-underscored-binding {:level :off}}})))
   (is (empty? (lint! "(doto (Object.) (.method))"
-                     '{:linters {:used-underscored-binding {:level :warning}}}))))
+                     '{:linters {:used-underscored-binding {:level :warning}}})))
+  (is (empty? (lint! "(defmulti foo (fn [this x] x))"
+                     '{:linters {:unused-binding {:level :warning :exclude-patterns ["this"]}}}))))
+
 
 
 (deftest unused-destructuring-default-test