feat: support external types with type widening

fixes #1296

.gitignore

@@ -24,7 +24,7 @@ testdata/**/go.work.sum
 # Leaving old _ftl for now to avoid old stuff getting checked in
 **/testdata/**/_ftl
 **/examples/**/_ftl
-**/examples/**/types.ftl.go
+**/types.ftl.go
 **/testdata/**/.ftl
 **/examples/**/.ftl
 /.ftl

backend/controller/ingress/ingress_integration_test.go

@@ -122,5 +122,10 @@ func TestHttpIngress(t *testing.T) {
 			assert.Equal(t, []string{"application/json; charset=utf-8"}, resp.Headers["Content-Type"])
 			assert.Equal(t, in.JsonData(t, in.Obj{"name": "A", "value": "hello"}), resp.BodyBytes)
 		}),
+		in.HttpCall(http.MethodGet, "/external", in.JsonData(t, in.Obj{"message": "hello"}), func(t testing.TB, resp *in.HTTPResponse) {
+			assert.Equal(t, 200, resp.Status)
+			assert.Equal(t, []string{"application/json; charset=utf-8"}, resp.Headers["Content-Type"])
+			assert.Equal(t, in.JsonData(t, in.Obj{"message": "hello"}), resp.BodyBytes)
+		}),
 	)
 }

backend/controller/ingress/testdata/go/httpingress/httpingress.go

@@ -6,6 +6,7 @@ import (
 
 	"ftl/builtin"
 
+	lib "github.com/TBD54566975/ftl/go-runtime/compile/testdata"
 	"github.com/TBD54566975/ftl/go-runtime/ftl" // Import the FTL SDK.
 )
 
@@ -178,3 +179,10 @@ func ArrayData(ctx context.Context, req builtin.HttpRequest[[]ArrayType]) (built
 func TypeEnum(ctx context.Context, req builtin.HttpRequest[SumType]) (builtin.HttpResponse[SumType, string], error) {
 	return builtin.HttpResponse[SumType, string]{Body: ftl.Some(req.Body)}, nil
 }
+
+type ExternalAlias lib.NonFTLType
+
+//ftl:ingress http GET /external
+func External(ctx context.Context, req builtin.HttpRequest[ExternalAlias]) (builtin.HttpResponse[ExternalAlias, string], error) {
+	return builtin.HttpResponse[ExternalAlias, string]{Body: ftl.Some(req.Body)}, nil
+}