Default values usage require explicit enabling (changed default setting)

README.md

@@ -111,6 +111,11 @@ sbt makeSite
 
 HTML Documentation should be generated at `target/sphinx/html/index.html`.
 
+Alternatively use Docker:
+
+```bash
+docker run --rm -v ./docs:/docs sphinxdoc/sphinx:3.2.1 bash -c "pip install sphinx-rtd-theme && make html"
+```
 
 ## Thanks
 

chimney/src/main/scala/io/scalaland/chimney/dsl/FlagsDsl.scala

@@ -23,16 +23,16 @@ trait FlagsDsl[UpdateFlag[_ <: TransformerFlags], Flags <: TransformerFlags] {
 
   /** Enable fallback to default case class values in `To` type.
     *
-    * @see [[https://scalalandio.github.io/chimney/transformers/default-values.html#disabling-default-values-in-generated-transformer]] for more details
+    * By default in such case derivation will fail. By enabling this flag, derivation will fallback to default value.
+    *
+    * @see [[https://scalalandio.github.io/chimney/transformers/default-values.html#enabling-default-values-in-generated-transformer]] for more details
     */
   def enableDefaultValues: UpdateFlag[Enable[DefaultValues, Flags]] =
     enableFlag[DefaultValues]
 
   /** Fail derivation if `From` type is missing field even if `To` has default value for it.
     *
-    * By default in such case derivation will fallback to default values.
-    *
-    * @see [[https://scalalandio.github.io/chimney/transformers/default-values.html#disabling-default-values-in-generated-transformer]] for more details
+    * @see [[https://scalalandio.github.io/chimney/transformers/default-values.html#enabling-default-values-in-generated-transformer]] for more details
     */
   def disableDefaultValues: UpdateFlag[Disable[DefaultValues, Flags]] =
     disableFlag[DefaultValues]

chimney/src/main/scala/io/scalaland/chimney/internal/macros/TransformerConfigSupport.scala

@@ -174,7 +174,7 @@ trait TransformerConfigSupport extends MacroUtils {
 
   case class TransformerFlags(
       methodAccessors: Boolean = false,
-      processDefaultValues: Boolean = true,
+      processDefaultValues: Boolean = false,
       beanSetters: Boolean = false,
       beanGetters: Boolean = false,
       optionDefaultsToNone: Boolean = false,

chimney/src/test/scala/io/scalaland/chimney/DslSpec.scala

@@ -114,8 +114,11 @@ object DslSpec extends TestSuite {
           }
 
           "not use None as default when other default value is set" - {
-            SomeFoo("foo").into[Foobar2].transform ==> Foobar2("foo", Some(42))
-            SomeFoo("foo").into[Foobar2].enableOptionDefaultsToNone.transform ==> Foobar2("foo", Some(42))
+            SomeFoo("foo").into[Foobar2].enableDefaultValues.transform ==> Foobar2("foo", Some(42))
+            SomeFoo("foo").into[Foobar2].enableDefaultValues.enableOptionDefaultsToNone.transform ==> Foobar2(
+              "foo",
+              Some(42)
+            )
           }
 
           "not compile if default value is missing and no .enableOptionDefaultsToNone" - {
@@ -199,6 +202,7 @@ object DslSpec extends TestSuite {
       case class Baahr(x: Int, y: Bar)
 
       "use default parameter value" - {
+        implicit val cfg = TransformerConfiguration.default.enableDefaultValues
 
         "field does not exists - the source" - {
           Foo(10).transformInto[Bar] ==> Bar(10, 30L)

docs/source/transformers/default-values.rst

@@ -1,14 +1,20 @@
 Default values support
 ======================
 
-Chimney respects case classes' default values as a possible target
+Chimney allows case classes' default values as a possible target
 field value source.
 
-Automatic value provision
--------------------------
+Enabling default values in generated transformer
+------------------------------------------------
 
-Field's default value is automatically used as a target value when constructing
-target object.
+.. warning::
+
+  Prior to version 0.7.0 fallback to default values was automatically enabled
+  and required explicit disabling.
+
+Field's default value can be enabled as a target value when constructing
+target object. The support for them has to be explicitly enabled to avoid
+accidents.
 
 .. code-block:: scala
 
@@ -17,42 +23,30 @@ target object.
 
   val stevie = Catterpillar(5, "Steve")
 
-  val steve = stevie.transformInto[Butterfly]
+  //val steve = stevie.transformInto[Butterfly] // fails with
+  // error: Chimney can't derive transformation from Catterpillar to Butterfly
+  //
+  // Butterfly
+  //   wingsColor: String - no field named wingsColor in source type Catterpillar
+  //
+  // Consult https://scalalandio.github.io/chimney for usage examples.
+  //
+  //            .transform
+  //            ^
+  val steve = stevie.into[Butterfly].enableDefaultValues.transform
   // Butterfly(5, "Steve", "purple")
 
 Providing the value manually has always a priority over the default.
 
 .. code-block:: scala
 
   val steve = stevie.into[Butterfly]
+    .enableDefaultValues
     .withFieldConst(_.wingsColor, "yellow")
     .transform
   // Butterfly(5, "Steve", "yellow")
 
 
-Disabling default values in generated transformer
--------------------------------------------------
-
-Using ``.disableDefaultValues`` operation it's possible to disable
-lookup for default values and require them always to be passed explicitly.
-
-.. code-block:: scala
-
-  val steve = stevie
-    .into[Butterfly]
-    .disableDefaultValues
-    .transform
-  // error: Chimney can't derive transformation from Catterpillar to Butterfly
-  //
-  // Butterfly
-  //   wingsColor: String - no field named wingsColor in source type Catterpillar
-  //
-  // Consult https://scalalandio.github.io/chimney for usage examples.
-  //
-  //            .transform
-  //            ^
-
-
 Default values for ``Option`` fields
 ------------------------------------