From 226b6db57ff61340bc359d2347486b0bc7ac5211 Mon Sep 17 00:00:00 2001
From: Carlos O'Ryan <coryan@google.com>
Date: Sat, 18 Jan 2025 14:53:05 -0500
Subject: [PATCH] fix(generator): mixins may enable streaming features

---
 generator/internal/language/rust.go | 24 +++++++++++++++++++-----
 1 file changed, 19 insertions(+), 5 deletions(-)

diff --git a/generator/internal/language/rust.go b/generator/internal/language/rust.go
index 30e52bc5a..46fbd6458 100644
--- a/generator/internal/language/rust.go
+++ b/generator/internal/language/rust.go
@@ -1216,14 +1216,28 @@ func rustValidate(api *api.API, sourceSpecificationPackageName string) error {
 	return nil
 }
 
-func rustAddStreamingFeature(data *RustTemplateData, api *api.API, extraPackages []*rustPackage) {
-	var hasStreamingRPC bool
-	for _, m := range api.Messages {
+func rustHasStreamingRPC(model *api.API) bool {
+	for _, m := range model.Messages {
 		if m.IsPageableResponse {
-			hasStreamingRPC = true
-			break
+			return true
 		}
 	}
+	// Sometimes the method with a pageable message is using an imported message
+	// or is part of a mixin.
+	for _, s := range model.Services {
+		for _, m := range s.Methods {
+			if output, ok := model.State.MessageByID[m.OutputTypeID]; ok {
+				if output.IsPageableResponse {
+					return true
+				}
+			}
+		}
+	}
+	return false
+}
+
+func rustAddStreamingFeature(data *RustTemplateData, api *api.API, extraPackages []*rustPackage) {
+	hasStreamingRPC := rustHasStreamingRPC(api)
 	if !hasStreamingRPC {
 		return
 	}