Include trace for fx.Provide(return fx.Annotated)

This changes error reporting to include a stack trace of the
`fx.Provide()` call site when failing because the user provided a
function that returns an `fx.Annotated` instead of providing an
`fx.Annotated` directly.

annotated_test.go

@@ -24,6 +24,7 @@ import (
 	"testing"
 
 	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
 	"go.uber.org/fx"
 	"go.uber.org/fx/fxtest"
 )
@@ -83,7 +84,20 @@ func TestAnnotatedWrongUsage(t *testing.T) {
 			),
 			fx.Populate(&in),
 		)
-		assert.Contains(t, app.Err().Error(), "fx.Annotated should be passed to fx.Provide directly", "expected error when return types were annotated")
+
+		err := app.Err()
+		require.Error(t, err)
+
+		// Example:
+		// fx.Annotated should be passed to fx.Provide directly, it should not be returned by the constructor: fx.Provide received go.uber.org/fx_test.TestAnnotatedWrongUsage.func2.1() from:
+		// go.uber.org/fx_test.TestAnnotatedWrongUsage.func2
+		//         /.../fx/annotated_test.go:76
+		// testing.tRunner
+		//         /.../go/1.13.3/libexec/src/testing/testing.go:909
+		assert.Contains(t, err.Error(), "fx.Annotated should be passed to fx.Provide directly, it should not be returned by the constructor")
+		assert.Contains(t, err.Error(), "fx.Provide received go.uber.org/fx_test.TestAnnotatedWrongUsage")
+		assert.Contains(t, err.Error(), "go.uber.org/fx_test.TestAnnotatedWrongUsage")
+		assert.Contains(t, err.Error(), "/fx/annotated_test.go")
 	})
 
 	t.Run("Result Type", func(t *testing.T) {

app.go

@@ -615,7 +615,11 @@ func (app *App) provide(p provide) {
 			t := ft.Out(i)
 
 			if t == reflect.TypeOf(Annotated{}) {
-				app.err = fmt.Errorf("fx.Annotated should be passed to fx.Provide directly, it should not be returned by the constructor: fx.Provide received %v", constructor)
+				app.err = fmt.Errorf(
+					"fx.Annotated should be passed to fx.Provide directly, "+
+						"it should not be returned by the constructor: "+
+						"fx.Provide received %v from:\n%+v",
+					fxreflect.FuncName(constructor), p.Stack)
 				return
 			}
 		}