Reject unsupported inline pointer schemas safely

schema_test.go

@@ -1,6 +1,7 @@
 package configkit
 
 import (
+	"errors"
 	"reflect"
 	"testing"
 	"time"
@@ -302,3 +303,40 @@ func mustPath(t *testing.T, pointer string) Path {
 	}
 	return path
 }
+
+func TestInlineMapPointersFailBeforeDefaults(t *testing.T) {
+	type cfg struct {
+		Extra *map[string]int `yaml:",inline"`
+	}
+	for _, nonNil := range []bool{false, true} {
+		called := false
+		_, err := Load(NoSource(), Options[cfg]{Definition: Definition[cfg]{Defaults: func() cfg {
+			called = true
+			if nonNil {
+				m := map[string]int{"value": 1}
+				return cfg{Extra: &m}
+			}
+			return cfg{}
+		}}})
+		var loadErr *LoadError
+		if !errors.As(err, &loadErr) || called {
+			t.Fatalf("invalid inline schema reached defaults: called=%v error=%v", called, err)
+		}
+		if len(loadErr.Diagnostics()) != 1 || loadErr.Diagnostics()[0].Code != CodeSchemaInline {
+			t.Fatal("missing inline schema diagnostic")
+		}
+	}
+	type pointer *pointer
+	type recursive struct {
+		Extra pointer `yaml:",inline"`
+	}
+	if _, err := Load[recursive](NoSource()); err == nil {
+		t.Fatal("recursive inline pointer was accepted")
+	}
+	type double struct {
+		Extra **map[string]int `yaml:",inline"`
+	}
+	if _, err := Load[double](NoSource()); err == nil {
+		t.Fatal("double inline map pointer was accepted")
+	}
+}