CLJ-2822: nth error message

.github/workflows/build.yml

@@ -0,0 +1,26 @@
+name: Java CI
+
+on: [push]
+
+jobs:
+  build:
+    timeout-minutes: 5
+    strategy:
+      matrix:
+        jdk: ['11', '17', '19']
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v5
+      - name: Set up JDK ${{ matrix.jdk }}
+        uses: actions/setup-java@v5
+        with:
+          java-version: ${{ matrix.jdk }}
+          distribution: 'temurin'
+          cache: maven
+      - name: Build with Maven
+        run: mvn test
+      - name: Configure settings.xml
+        run: |
+          mkdir -p ~/.m2
+          echo "<settings><servers><server><id>clojars</id><username>${{ secrets.CLOJARS_USER }}-clojars</username><password>${{ secrets.CLOJARS_PASSWORD }}</password></server></servers></settings>" > ~/.m2/settings.xml

.github/workflows/test.yml

@@ -10,7 +10,7 @@ jobs:
       fail-fast: false
       matrix:
         os: [ubuntu-latest] # macOS-latest, windows-latest]
-        java-version: ["8", "11", "17", "21"]
+        java-version: ["11", "17", "21"]
         distribution: ["temurin", "corretto"]
         profile: ["test-direct", "test-no-direct"]
     runs-on: ${{ matrix.os }}

deps.edn

@@ -0,0 +1,38 @@
+;; https://clojure.org/dev/developing_patches#_run_an_individual_test
+{:paths ["test"
+         "target/test-classes"]
+ :deps
+ {org.clojure/clojure {:local/root "."
+                       :deps/manifest :pom} #_{:mvn/version "RELEASE"}
+  org.clojure/test.check {:mvn/version "1.1.1"}
+  org.clojure/test.generative {:mvn/version "1.0.0"}}
+ :aliases
+ {:dbg {:classpath-overrides {org.clojure/clojure "target/classes"}
+        :extra-deps {criterium/criterium {:mvn/version "0.4.4"}}}
+  :cognitest {:extra-deps {io.github.cognitect-labs/test-runner 
+                           {:git/tag "v0.5.0" :git/sha "b3fd0d2"}}
+              :main-opts ["-m" "cognitect.test-runner"]
+              :exec-fn cognitect.test-runner.api/test
+              :exec-args {:dirs ["test"]
+                          :patterns [;; FIXME clojure.test-clojure.ns-libs has a test that is sensitive to loading order
+                                     ;; FIXME clojure.test-clojure.java-interop doesn't seem to work on JDK 17 (untested on others)
+                                     ;; regex ref: https://stackoverflow.com/a/2387072
+                                     "^((?!(clojure.test-clojure.ns-libs|clojure.test-clojure.java-interop)).)*$"
+                                     ]}}
+  :test-example-script {:jvm-opts [;; from build.xml
+                                   "-Dclojure.test-clojure.exclude-namespaces=#{clojure.test-clojure.compilation.load-ns clojure.test-clojure.ns-libs-load-later}"
+                                   "-Dclojure.compiler.direct-linking=true"]
+                        :main-opts ["-e" "(load-file,\"src/script/run_test.clj\")"]}
+  :test-generative-script {:jvm-opts [;; from build.xml
+                                      "-Dclojure.compiler.direct-linking=true"]
+                           :main-opts ["-e" "(load-file,\"src/script/run_test_generative.clj\")"]}
+
+  :kaocha {:extra-deps {lambdaisland/kaocha {:mvn/version "1.60.977"}}
+           :exec-fn kaocha.runner/exec-fn
+           :exec-args {;:watch? true
+                       :tests [{:id          :unit
+                                :test-paths  ["test"]
+                                :ns-patterns [".*"]}]
+                       :reporter kaocha.report/dots
+                       ;; :plugins [:kaocha.plugin/profiling :kaocha.plugin/notifier]
+                       }}}}

src/clj/clojure/core.clj

@@ -893,11 +893,11 @@
   bounds, nth throws an exception unless not-found is supplied.  nth
   also works for strings, Java arrays, regex Matchers and Lists, and,
   in O(n) time, for sequences."
-  {:inline (fn  [c i & nf] `(. clojure.lang.RT (nth ~c ~i ~@nf)))
+  {:inline (fn  [c i & nf] `(. clojure.lang.RT (nthImpl ~c ~i ~@nf)))
    :inline-arities #{2 3}
    :added "1.0"}
-  ([coll index] (. clojure.lang.RT (nth coll index)))
-  ([coll index not-found] (. clojure.lang.RT (nth coll index not-found))))
+  ([coll index] (. clojure.lang.RT (nthImpl coll index)))
+  ([coll index not-found] (. clojure.lang.RT (nthImpl coll index not-found))))
 
 (defn <
   "Returns non-nil if nums are in monotonically increasing order,

src/jvm/clojure/lang/RT.java

@@ -917,6 +917,24 @@ static public Object nth(Object coll, int n){
 	return nthFrom(Util.ret1(coll, coll = null), n);
 }
 
+static int castNthIdx(Object o) {
+	if (o instanceof Number) {
+		return intCast(o);
+	}
+	throw new UnsupportedOperationException(
+			"nth idx not supported on this type: " + o.getClass().getSimpleName());
+}
+
+/**
+ * Only for use in `clojure.core/nth`.
+ */
+static public Object nthImpl(Object coll, Object n){
+	int idx = castNthIdx(n);
+	if(coll instanceof Indexed)
+		return ((Indexed) coll).nth(idx);
+	return nthFrom(Util.ret1(coll, coll = null), idx);
+}
+
 static Object nthFrom(Object coll, int n){
 	if(coll == null)
 		return null;
@@ -960,6 +978,18 @@ static public Object nth(Object coll, int n, Object notFound){
 	return nthFrom(coll, n, notFound);
 }
 
+/**
+ * Only for use in `clojure.core/nth`.
+ */
+static public Object nthImpl(Object coll, Object n, Object notFound){
+	int idx = castNthIdx(n);
+	if(coll instanceof Indexed) {
+		Indexed v = (Indexed) coll;
+		return v.nth(idx, notFound);
+	}
+	return nthFrom(coll, idx, notFound);
+}
+
 static Object nthFrom(Object coll, int n, Object notFound){
 	if(coll == null)
 		return notFound;

test/clojure/test_clojure/sequences.clj

@@ -641,6 +641,16 @@
   (is (thrown? IndexOutOfBoundsException (nth (java.util.ArrayList. []) -1)))       ; ???
   (is (thrown? IndexOutOfBoundsException (nth (java.util.ArrayList. [1 2 3]) -1)))  ; ???
 
+  ;; CLJ-2822
+  (is (thrown? UnsupportedOperationException (nth 1 [1 2 3])))
+  (is (try ^{:line 12345} (nth 1 [1 2 3])
+           (catch UnsupportedOperationException e
+             (let [line (->> (.getStackTrace e)
+                             (drop-while #(= "clojure.lang.RT" (.getClassName ^StackTraceElement %)))
+                             (first)
+                             (#(.getLineNumber ^StackTraceElement %)))]
+               (= 12345 line)))))
+
   (are [x y] (= x y)
       (nth '(1) 0) 1
       (nth '(1 2 3) 0) 1