Make @JsonAlias be respected by polymorphic deduction for deserialization

src/main/java/com/fasterxml/jackson/databind/jsontype/impl/AsDeductionTypeDeserializer.java

@@ -2,11 +2,14 @@
 
 import java.io.IOException;
 import java.util.*;
+import java.util.stream.Collectors;
 
 import com.fasterxml.jackson.core.JsonParser;
 import com.fasterxml.jackson.core.JsonToken;
 
 import com.fasterxml.jackson.databind.*;
+import com.fasterxml.jackson.databind.introspect.AnnotatedField;
+import com.fasterxml.jackson.databind.introspect.AnnotatedMethod;
 import com.fasterxml.jackson.databind.introspect.BeanPropertyDefinition;
 import com.fasterxml.jackson.databind.jsontype.NamedType;
 import com.fasterxml.jackson.databind.jsontype.TypeDeserializer;
@@ -79,6 +82,12 @@ protected Map<BitSet, String> buildFingerprints(DeserializationConfig config, Co
                     bitIndex = nextField;
                     fieldBitIndex.put(name, nextField++);
                 }
+                // [databind#4327] 2.17 @JsonAlias should be respected by polymorphic deduction
+                List<String> aliases = _findAliases(config, property);
+                for (String alias : aliases) {
+                    if (ignoreCase) alias = alias.toLowerCase();
+                    fieldBitIndex.put(alias, bitIndex);
+                }
                 fingerprint.set(bitIndex);
             }
 
@@ -94,6 +103,37 @@ protected Map<BitSet, String> buildFingerprints(DeserializationConfig config, Co
         return fingerprints;
     }
 
+    private List<String> _findAliases(DeserializationConfig config, BeanPropertyDefinition property)
+    {
+        AnnotationIntrospector ai = config.getAnnotationIntrospector();
+        List<PropertyName> aliases = new ArrayList<>();
+        AnnotatedField field = property.getField();
+        AnnotatedMethod setter = property.getSetter();
+        AnnotatedMethod getter = property.getGetter();
+
+        if (setter != null) {
+            List<PropertyName> names = ai.findPropertyAliases(setter);
+            if (names != null) {
+                aliases.addAll(names);
+            }
+        }
+        if (getter != null) {
+            List<PropertyName> names = ai.findPropertyAliases(getter);
+            if (names != null) {
+                aliases.addAll(names);
+            }
+        }
+        if (field != null) {
+            List<PropertyName> names = ai.findPropertyAliases(field);
+            if (names != null) {
+                aliases.addAll(names);
+            }
+        }
+        return aliases.stream()
+            .map(PropertyName::getSimpleName)
+            .collect(Collectors.toList());
+    }
+
     @Override
     public Object deserializeTypedFromObject(JsonParser p, DeserializationContext ctxt) throws IOException {
 

src/test-jdk17/java/com/fasterxml/jackson/databind/records/JsonAliasWithDeduction4327RecordTest.java

@@ -0,0 +1,44 @@
+package com.fasterxml.jackson.databind.records;
+
+import com.fasterxml.jackson.annotation.JsonAlias;
+import com.fasterxml.jackson.annotation.JsonSubTypes;
+import com.fasterxml.jackson.annotation.JsonTypeInfo;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.ValueSource;
+
+import com.fasterxml.jackson.databind.ObjectMapper;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+
+import static com.fasterxml.jackson.databind.testutil.DatabindTestUtil.a2q;
+import static com.fasterxml.jackson.databind.testutil.DatabindTestUtil.jsonMapperBuilder;
+
+// [databind#4327] JsonAlias should respsect with Polymorphic Deduction
+public class JsonAliasWithDeduction4327RecordTest
+{
+    @JsonTypeInfo(use = JsonTypeInfo.Id.DEDUCTION)
+    @JsonSubTypes({
+        @JsonSubTypes.Type(value = DeductionBean1.class),
+        @JsonSubTypes.Type(value = DeductionBean2.class)
+    })
+    interface Deduction { }
+
+    record DeductionBean1(int x) implements Deduction { }
+
+    record DeductionBean2(
+        @JsonAlias(value = {"Y", "yy", "ff", "X"}) int y
+    ) implements Deduction { }
+
+
+    private final ObjectMapper mapper = jsonMapperBuilder().build();
+
+    @ParameterizedTest
+    @ValueSource(strings = {"Y", "yy", "ff", "X"})
+    public void testAliasWithPolymorphicDeduction(String field) throws Exception {
+        String json = a2q(String.format("{'%s': 2 }", field));
+        Deduction value = mapper.readValue(json, Deduction.class);
+        assertNotNull(value);
+        assertEquals(2, ((DeductionBean2) value).y());
+    }
+}

src/test/java/com/fasterxml/jackson/databind/jsontype/JsonAliasWithDeduction4327Test.java

@@ -0,0 +1,47 @@
+package com.fasterxml.jackson.databind.jsontype;
+
+import com.fasterxml.jackson.annotation.JsonAlias;
+import com.fasterxml.jackson.annotation.JsonSubTypes;
+import com.fasterxml.jackson.annotation.JsonTypeInfo;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.ValueSource;
+
+import com.fasterxml.jackson.databind.ObjectMapper;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+
+import static com.fasterxml.jackson.databind.testutil.DatabindTestUtil.a2q;
+import static com.fasterxml.jackson.databind.testutil.DatabindTestUtil.jsonMapperBuilder;
+
+// [databind#4327] JsonAlias should respsect with Polymorphic Deduction
+public class JsonAliasWithDeduction4327Test
+{
+    @JsonTypeInfo(use = JsonTypeInfo.Id.DEDUCTION)
+    @JsonSubTypes({
+        @JsonSubTypes.Type(value = DeductionBean1.class),
+        @JsonSubTypes.Type(value = DeductionBean2.class)
+    })
+    interface Deduction { }
+
+    static class DeductionBean1 implements Deduction {
+        public int x;
+    }
+
+    static class DeductionBean2 implements Deduction {
+        @JsonAlias(value = {"Y", "yy", "ff", "X"})
+        public int y;
+    }
+
+
+    private final ObjectMapper mapper = jsonMapperBuilder().build();
+
+    @ParameterizedTest
+    @ValueSource(strings = {"Y", "yy", "ff", "X"})
+    public void testAliasWithPolymorphicDeduction(String field) throws Exception {
+        String json = a2q(String.format("{'%s': 2 }", field));
+        Deduction value = mapper.readValue(json, Deduction.class);
+        assertNotNull(value);
+        assertEquals(2, ((DeductionBean2) value).y);
+    }
+}