Add test codifying behavior when two modules reuse the same extension number

settings.gradle.kts

@@ -1,7 +1,7 @@
 buildscript { repositories { gradlePluginPortal() } }
 
 plugins {
-    id("net.vivin.gradle-semantic-build-versioning") version "4.0.0"
+    id("io.alcide.gradle-semantic-build-versioning") version "4.2.2"
 }
 
 rootProject.name = "buf-gradle-plugin"

src/test/kotlin/build/buf/gradle/AbstractBuildTest.kt

@@ -17,6 +17,7 @@ package build.buf.gradle
 import com.google.common.truth.Truth.assertThat
 import org.gradle.testkit.runner.TaskOutcome.SUCCESS
 import org.junit.jupiter.api.Test
+import java.io.File
 import java.nio.file.Paths
 
 abstract class AbstractBuildTest : AbstractBufIntegrationTest() {
@@ -49,6 +50,16 @@ abstract class AbstractBuildTest : AbstractBufIntegrationTest() {
         assertImageGeneration()
     }
 
+    @Test
+    fun `build an image reusing an extension number`() {
+        val result = buildRunner().buildAndFail()
+        val source = listOf("buf", "test", "v1", "test.proto").joinToString(File.separator)
+        assertThat(result.output).contains(
+            "$source:23:14:extension with tag 1072 for message google.protobuf.MessageOptions already defined at " +
+                "validate/validate.proto:17:29",
+        )
+    }
+
     private fun assertImageGeneration() {
         assertThat(buildRunner().build().task(":$BUF_BUILD_TASK_NAME")?.outcome).isEqualTo(SUCCESS)
         val image = Paths.get(projectDir.path, "build", "bufbuild", "image.json").toFile().readText()

src/test/resources/BuildTest/build_an_image_reusing_an_extension_number/buf.lock

@@ -0,0 +1,6 @@
+version: v1
+deps:
+  - remote: buf.build
+    owner: envoyproxy
+    repository: protoc-gen-validate
+    commit: 71881f09a0c5420a9545a07987a86728

src/test/resources/BuildTest/build_an_image_reusing_an_extension_number/buf.yaml

@@ -0,0 +1,3 @@
+version: v1
+deps:
+  - buf.build/envoyproxy/protoc-gen-validate

src/test/resources/BuildTest/build_an_image_reusing_an_extension_number/buf/test/v1/test.proto

@@ -0,0 +1,24 @@
+// Copyright 2023 Buf Technologies, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+syntax = "proto3";
+
+package buf.test.v1;
+
+import "google/protobuf/descriptor.proto";
+import "validate/validate.proto";
+
+extend google.protobuf.MessageOptions {
+  bool foo = 1072;
+}

src/test/resources/BuildTest/build_an_image_reusing_an_extension_number/build.gradle

@@ -0,0 +1,8 @@
+plugins {
+  id 'java'
+  id 'build.buf'
+}
+
+repositories {
+  mavenCentral()
+}

src/test/resources/BuildWithProtobufGradleTest/build_an_image_reusing_an_extension_number/build.gradle

@@ -0,0 +1,19 @@
+plugins {
+  id 'java'
+  id 'com.google.protobuf' version "$protobufGradleVersion"
+  id 'build.buf'
+}
+
+repositories {
+  mavenCentral()
+}
+
+protobuf {
+  protoc {
+    artifact = "com.google.protobuf:protoc:$protobufVersion"
+  }
+}
+
+dependencies {
+  protobuf 'io.envoyproxy.controlplane:api:1.0.41'
+}

src/test/resources/BuildWithProtobufGradleTest/build_an_image_reusing_an_extension_number/src/main/proto/buf/test/v1/test.proto

@@ -0,0 +1,24 @@
+// Copyright 2023 Buf Technologies, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+syntax = "proto3";
+
+package buf.test.v1;
+
+import "google/protobuf/descriptor.proto";
+import "validate/validate.proto";
+
+extend google.protobuf.MessageOptions {
+  bool foo = 1072;
+}

src/test/resources/BuildWithWorkspaceTest/build_an_image_reusing_an_extension_number/buf.work.yaml

@@ -0,0 +1,3 @@
+version: v1
+directories:
+  - workspace

src/test/resources/BuildWithWorkspaceTest/build_an_image_reusing_an_extension_number/build.gradle

@@ -0,0 +1,8 @@
+plugins {
+  id 'java'
+  id 'build.buf'
+}
+
+repositories {
+  mavenCentral()
+}

src/test/resources/BuildWithWorkspaceTest/build_an_image_reusing_an_extension_number/workspace/buf.lock

@@ -0,0 +1,6 @@
+version: v1
+deps:
+  - remote: buf.build
+    owner: envoyproxy
+    repository: protoc-gen-validate
+    commit: 71881f09a0c5420a9545a07987a86728

src/test/resources/BuildWithWorkspaceTest/build_an_image_reusing_an_extension_number/workspace/buf.yaml

@@ -0,0 +1,3 @@
+version: v1
+deps:
+  - buf.build/envoyproxy/protoc-gen-validate

src/test/resources/BuildWithWorkspaceTest/build_an_image_reusing_an_extension_number/workspace/buf/test/v1/test.proto

@@ -0,0 +1,24 @@
+// Copyright 2023 Buf Technologies, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+syntax = "proto3";
+
+package buf.test.v1;
+
+import "google/protobuf/descriptor.proto";
+import "validate/validate.proto";
+
+extend google.protobuf.MessageOptions {
+  bool foo = 1072;
+}