fix #3624 ALLOW_COERCION_OF_SCALARS allows int->float coercion (#3625)

Author: carterkozak

src/main/java/com/fasterxml/jackson/databind/cfg/CoercionConfigs.java

@@ -217,11 +217,14 @@ public CoercionAction findCoercion(DeserializationConfig config,
         // scalar for this particular purpose
         final boolean baseScalar = _isScalarType(targetType);
 
-        if (baseScalar) {
-            // Default for setting in 2.x is true
-            if (!config.isEnabled(MapperFeature.ALLOW_COERCION_OF_SCALARS)) {
+        if (baseScalar
+                // Default for setting in 2.x is true
+                && !config.isEnabled(MapperFeature.ALLOW_COERCION_OF_SCALARS)
+                // Coercion from integer-shaped data into a floating point type is not banned by the
+                // ALLOW_COERCION_OF_SCALARS feature because '1' is a valid JSON representation of
+                // '1.0' in a way that other types of coercion do not satisfy.
+                && (targetType != LogicalType.Float || inputShape != CoercionInputShape.Integer)) {
                 return CoercionAction.Fail;
-            }
         }
 
         if (inputShape == CoercionInputShape.EmptyString) {

src/test/java/com/fasterxml/jackson/databind/convert/CoerceIntToFloatTest.java

@@ -2,6 +2,7 @@
 
 import com.fasterxml.jackson.core.JsonProcessingException;
 import com.fasterxml.jackson.databind.BaseMapTest;
+import com.fasterxml.jackson.databind.MapperFeature;
 import com.fasterxml.jackson.databind.ObjectMapper;
 import com.fasterxml.jackson.databind.ObjectReader;
 import com.fasterxml.jackson.databind.cfg.CoercionAction;
@@ -34,6 +35,10 @@ public class CoerceIntToFloatTest extends BaseMapTest
                     cfg.setCoercion(CoercionInputShape.Integer, CoercionAction.AsEmpty))
             .build();
 
+    private final ObjectMapper LEGACY_SCALAR_COERCION_FAIL = jsonMapperBuilder()
+            .disable(MapperFeature.ALLOW_COERCION_OF_SCALARS)
+            .build();
+
     public void testDefaultIntToFloatCoercion() throws JsonProcessingException
     {
         assertSuccessfulIntToFloatConversionsWith(DEFAULT_MAPPER);
@@ -115,6 +120,11 @@ public void testCoerceConfigToFail() throws JsonProcessingException
         _verifyCoerceFail(MAPPER_TO_FAIL, BigDecimal.class, "73455342");
     }
 
+    public void testLegacyConfiguration() throws JsonProcessingException
+    {
+        assertSuccessfulIntToFloatConversionsWith(LEGACY_SCALAR_COERCION_FAIL);
+    }
+
     /*
     /********************************************************
     /* Helper methods