diff --git a/source/dub/internal/configy/Attributes.d b/source/dub/internal/configy/Attributes.d
index 7829064..474d33a 100644
--- a/source/dub/internal/configy/Attributes.d
+++ b/source/dub/internal/configy/Attributes.d
@@ -289,6 +289,19 @@
     return Converter!RType(func);
 }
 
+/*******************************************************************************
+
+    Interface that is passed to `fromYAML` hook
+
+    The `ConfigParser` exposes the raw YAML node (`see `node` method),
+    the path within the file (`path` method), and a simple ability to recurse
+    via `parseAs`.
+
+    Params:
+      T = The type of the structure which defines a `fromYAML` hook
+
+*******************************************************************************/
+
 public interface ConfigParser (T)
 {
     import dub.internal.dyaml.node;
@@ -301,7 +314,20 @@
     /// Returns: current location we are parsing
     public string path () const @safe pure nothrow @nogc;
 
-    ///
+    /***************************************************************************
+
+        Parse this struct as another type
+
+        This allows implementing union-like behavior, where a `struct` which
+        implements `fromYAML` can parse a simple representation as one type,
+        and one more advanced as another type.
+
+        Params:
+          OtherType = The type to parse as
+          defaultValue = The instance to use as a default value for fields
+
+    ***************************************************************************/
+
     public final auto parseAs (OtherType)
         (auto ref OtherType defaultValue = OtherType.init)
     {
diff --git a/source/dub/internal/configy/FieldRef.d b/source/dub/internal/configy/FieldRef.d
index 1af4b67..42bc135 100644
--- a/source/dub/internal/configy/FieldRef.d
+++ b/source/dub/internal/configy/FieldRef.d
@@ -118,7 +118,14 @@
     static assert(FieldRefTuple!(FieldRefTuple!(Config3)[0].Type)[1].Name == "notStr2");
 }
 
-/// A pseudo `FieldRef` used for structs which are not fields (top-level)
+/**
+ * A pseudo `FieldRef` used for structs which are not fields (top-level)
+ *
+ * Params:
+ *   ST = Type for which this pseudo-FieldRef is
+ *   DefaultName = A name to give to this FieldRef, default to `null`,
+ *                 but required to prevent forward references in `parseAs`.
+ */
 package template StructFieldRef (ST, string DefaultName = null)
 {
     ///
diff --git a/source/dub/internal/configy/Read.d b/source/dub/internal/configy/Read.d
index 44afcf1..e23a037 100644
--- a/source/dub/internal/configy/Read.d
+++ b/source/dub/internal/configy/Read.d
@@ -21,14 +21,17 @@
       To mark a field as optional even with its default value,
       use the `Optional` UDA: `@Optional int count = 0;`.
 
-    Converter:
-      Because config structs may contain complex types such as
-      a Phobos type, a user-defined `Amount`, or Vibe.d's `URL`,
-      one may need to apply a converter to a struct's field.
-      Converters are functions that take a YAML `Node` as argument
-      and return a type that is implicitly convertible to the field type
-      (usually just the field type). They offer the most power to users,
-      as they can inspect the YAML structure, but should be used as a last resort.
+    fromYAML:
+      Because config structs may contain complex types outside of the project's
+      control (e.g. a Phobos type, Vibe.d's `URL`, etc...) or one may want
+      the config format to be more dynamic (e.g. by exposing union-like behavior),
+      one may need to apply more custom logic than what Configy does.
+      For this use case, one can define a `fromYAML` static method in the type:
+      `static S fromYAML(scope ConfigParser!S parser)`, where `S` is the type of
+      the enclosing structure. Structs with `fromYAML` will have this method
+      called instead of going through the normal parsing rules.
+      The `ConfigParser` exposes the current path of the field, as well as the
+      raw YAML `Node` itself, allowing for maximum flexibility.
 
     Composite_Types:
       Processing starts from a `struct` at the top level, and recurse into
@@ -400,8 +403,8 @@
                      fullyQualifiedName!T,
                      strict == StrictMode.Warn ?
                        strict.paint(Yellow) : strict.paintIf(!!strict, Green, Red));
-            return node.parseMapping!(StructFieldRef!T)(
-                null, T.init, const(Context)(cmdln, strict), null);
+            return node.parseField!(StructFieldRef!T)(
+                null, T.init, const(Context)(cmdln, strict));
     case NodeID.sequence:
     case NodeID.scalar:
     case NodeID.invalid:
diff --git a/source/dub/internal/configy/Test.d b/source/dub/internal/configy/Test.d
index a334b6d..daa8d5d 100644
--- a/source/dub/internal/configy/Test.d
+++ b/source/dub/internal/configy/Test.d
@@ -692,3 +692,127 @@
     catch (Exception exc)
         assert(exc.toString() == `/dev/null(2:6): data.array[0]: Parsing failed!`);
 }
+
+/// Test for error message: Has to be versioned out, uncomment to check manually
+unittest
+{
+    static struct Nested
+    {
+        int field1;
+
+        private this (string arg) {}
+    }
+
+    static struct Config
+    {
+        Nested nested;
+    }
+
+    static struct Config2
+    {
+        Nested nested;
+        alias nested this;
+    }
+
+    version(none) auto c1 = parseConfigString!Config(null, null);
+    version(none) auto c2 = parseConfigString!Config2(null, null);
+}
+
+/// Test support for `fromYAML` hook
+unittest
+{
+    static struct PackageDef
+    {
+        string name;
+        @Optional string target;
+        int build = 42;
+    }
+
+    static struct Package
+    {
+        string path;
+        PackageDef def;
+
+        public static Package fromYAML (scope ConfigParser!Package parser)
+        {
+            if (parser.node.nodeID == NodeID.mapping)
+                return Package(null, parser.parseAs!PackageDef);
+            else
+                return Package(parser.parseAs!string);
+        }
+    }
+
+    static struct Config
+    {
+        string name;
+        Package[] deps;
+    }
+
+    auto c = parseConfigString!Config(
+`
+name: myPkg
+deps:
+  - /foo/bar
+  - name: foo
+    target: bar
+    build: 24
+  - name: fur
+  - /one/last/path
+`, "/dev/null");
+    assert(c.name == "myPkg");
+    assert(c.deps.length == 4);
+    assert(c.deps[0] == Package("/foo/bar"));
+    assert(c.deps[1] == Package(null, PackageDef("foo", "bar", 24)));
+    assert(c.deps[2] == Package(null, PackageDef("fur", null, 42)));
+    assert(c.deps[3] == Package("/one/last/path"));
+}
+
+/// Test top level hook (fromYAML / fromString)
+unittest
+{
+    static struct Version1 {
+        uint fileVersion;
+        uint value;
+    }
+
+    static struct Version2 {
+        uint fileVersion;
+        string str;
+    }
+
+    static struct Config
+    {
+        uint fileVersion;
+        union {
+            Version1 v1;
+            Version2 v2;
+        }
+        static Config fromYAML (scope ConfigParser!Config parser)
+        {
+            static struct OnlyVersion { uint fileVersion; }
+            auto vers = parseConfig!OnlyVersion(
+                CLIArgs.init, parser.node, StrictMode.Ignore);
+            switch (vers.fileVersion) {
+            case 1:
+                return Config(1, parser.parseAs!Version1);
+            case 2:
+                Config conf = Config(2);
+                conf.v2 = parser.parseAs!Version2;
+                return conf;
+            default:
+                assert(0);
+            }
+        }
+    }
+
+    auto v1 = parseConfigString!Config("fileVersion: 1\nvalue: 42", "/dev/null");
+    auto v2 = parseConfigString!Config("fileVersion: 2\nstr: hello world", "/dev/null");
+
+    assert(v1.fileVersion == 1);
+    assert(v1.v1.fileVersion == 1);
+    assert(v1.v1.value == 42);
+
+    assert(v2.fileVersion == 2);
+    assert(v2.v2.fileVersion == 2);
+    assert(v2.v2.str == "hello world");
+}