From 4e0568a461b4ac91b78c17ef84137f434f0e4db8 Mon Sep 17 00:00:00 2001
From: VasilevNStas <ctac@outlook.com>
Date: Sun, 9 Aug 2026 15:07:39 +0300
Subject: [PATCH] fix(#364): run only referenced lints in
 unlint-non-existing-defect

---
 .../lints/LtUnlintNonExistingDefect.java      | 55 ++++++++++++-----
 .../lints/LtUnlintNonExistingDefectTest.java  | 60 +++++++++++++++++++
 2 files changed, 99 insertions(+), 16 deletions(-)

diff --git a/src/main/java/org/eolang/lints/LtUnlintNonExistingDefect.java b/src/main/java/org/eolang/lints/LtUnlintNonExistingDefect.java
index a9da877da..d0fdf0424 100644
--- a/src/main/java/org/eolang/lints/LtUnlintNonExistingDefect.java
+++ b/src/main/java/org/eolang/lints/LtUnlintNonExistingDefect.java
@@ -7,9 +7,11 @@
 import com.github.lombrozo.xnav.Xnav;
 import com.jcabi.xml.XML;
 import java.io.IOException;
+import java.util.ArrayList;
 import java.util.Collection;
 import java.util.List;
 import java.util.Map;
+import java.util.Set;
 import java.util.stream.Collectors;
 import java.util.stream.StreamSupport;
 import org.cactoos.list.ListOf;
@@ -55,10 +57,18 @@ public String name() {
 
     @Override
     public Collection<Defect> defects(final XML xmir) throws IOException {
-        return new Xnav(xmir.inner()).path("/object/metas/meta[head='unlint']/tail")
+        final List<String> unlints = new Xnav(xmir.inner())
+            .path("/object/metas/meta[head='unlint']/tail")
             .map(xnav -> xnav.text().get())
             .distinct()
-            .filter(new DefectMissing(this.existingDefects(xmir), this.excluded)::apply).flatMap(
+            .collect(Collectors.toList());
+        final Collection<Defect> messages;
+        if (unlints.isEmpty()) {
+            messages = new ArrayList<>(0);
+        } else {
+            messages = unlints.stream().filter(
+                new DefectMissing(this.existing(unlints, xmir), this.excluded)::apply
+            ).flatMap(
                 unlint -> new Xnav(xmir.inner()).path(
                     String.format(
                         "object/metas/meta[head='unlint' and tail=%s]/@line",
@@ -76,6 +86,8 @@ public Collection<Defect> defects(final XML xmir) throws IOException {
                     )
                 )
             ).collect(Collectors.toList());
+        }
+        return messages;
     }
 
     @Override
@@ -105,20 +117,31 @@ private static String quoted(final String value) {
         return result;
     }
 
-    private Map<String, List<Integer>> existingDefects(final XML xmir) {
-        return StreamSupport.stream(this.lints.spliterator(), false).flatMap(
-            lint -> {
-                try {
-                    return lint.defects(xmir).stream();
-                } catch (final IOException exception) {
-                    throw new IllegalStateException(exception);
+    /**
+     * Build a map of existing defects, checking only lints referenced by
+     * <code>+unlint</code> metas.
+     * @param unlints Tails of all <code>+unlint</code> metas in the document
+     * @param xmir The XMIR document
+     * @return Existing defects grouped by rule and line
+     */
+    private Map<String, List<Integer>> existing(final List<String> unlints, final XML xmir) {
+        final Set<String> names = unlints.stream()
+            .map(unlint -> unlint.split(":", -1)[0])
+            .collect(Collectors.toSet());
+        return StreamSupport.stream(this.lints.spliterator(), false)
+            .filter(lint -> names.contains(lint.name())).flatMap(
+                lint -> {
+                    try {
+                        return lint.defects(xmir).stream();
+                    } catch (final IOException exception) {
+                        throw new IllegalStateException(exception);
+                    }
                 }
-            }
-        ).collect(
-            Collectors.groupingBy(
-                Defect::rule,
-                Collectors.mapping(Defect::line, Collectors.toList())
-            )
-        );
+            ).collect(
+                Collectors.groupingBy(
+                    Defect::rule,
+                    Collectors.mapping(Defect::line, Collectors.toList())
+                )
+            );
     }
 }
diff --git a/src/test/java/org/eolang/lints/LtUnlintNonExistingDefectTest.java b/src/test/java/org/eolang/lints/LtUnlintNonExistingDefectTest.java
index 7c1ea63c5..456835855 100644
--- a/src/test/java/org/eolang/lints/LtUnlintNonExistingDefectTest.java
+++ b/src/test/java/org/eolang/lints/LtUnlintNonExistingDefectTest.java
@@ -4,8 +4,10 @@
  */
 package org.eolang.lints;
 
+import com.jcabi.xml.XML;
 import fixtures.EoProgram;
 import java.io.IOException;
+import java.util.Collection;
 import java.util.stream.Collectors;
 import org.cactoos.list.ListOf;
 import org.hamcrest.MatcherAssert;
@@ -187,4 +189,62 @@ void catchesUnlintWithApostrophe() throws IOException {
             Matchers.iterableWithSize(1)
         );
     }
+
+    @Test
+    void doesNotRunLintsWithoutUnlints() throws IOException {
+        MatcherAssert.assertThat(
+            "Lints should not be executed when there are no +unlint metas",
+            new LtUnlintNonExistingDefect(
+                new ListOf<>(new LtUnlintNonExistingDefectTest.Boom()),
+                new ListOf<>()
+            ).defects(
+                new EoProgram("org/eolang/lints/non-ascii-bar.eo").parse()
+            ),
+            Matchers.emptyIterable()
+        );
+    }
+
+    @Test
+    void doesNotInvokeUnreferencedLint() throws IOException {
+        MatcherAssert.assertThat(
+            "Only the referenced lint should be executed",
+            new LtUnlintNonExistingDefect(
+                new ListOf<>(
+                    new LtAsciiOnly(),
+                    new LtUnlintNonExistingDefectTest.Boom()
+                ),
+                new ListOf<>()
+            ).defects(
+                new EoProgram("org/eolang/lints/unlint-ascii-only-no-defect.eo").parse()
+            ),
+            Matchers.hasSize(Matchers.greaterThan(0))
+        );
+    }
+
+    /**
+     * Fake lint that explodes when invoked.
+     * @since 0.0.40
+     */
+    private static final class Boom implements Lint {
+
+        @Override
+        public String name() {
+            return "boom";
+        }
+
+        @Override
+        public Collection<Defect> defects(final XML xmir) {
+            throw new IllegalStateException("this lint must not be executed");
+        }
+
+        @Override
+        public String motive() {
+            return "";
+        }
+
+        @Override
+        public Fix fix() {
+            return new FxEmpty();
+        }
+    }
 }