Enforce one aconfig_declaration per aconfig package

Bug: b/319121098
Change-Id: Ibe3f1587ed7754f00f464cf385ce51ee9a142412
diff --git a/aconfig/Android.bp b/aconfig/Android.bp
index 3c79f19..402cf16 100644
--- a/aconfig/Android.bp
+++ b/aconfig/Android.bp
@@ -25,6 +25,7 @@
         "aconfig_declarations_test.go",
         "aconfig_values_test.go",
         "aconfig_value_set_test.go",
+        "all_aconfig_declarations_test.go",
     ],
     pluginFor: ["soong_build"],
 }
diff --git a/aconfig/all_aconfig_declarations.go b/aconfig/all_aconfig_declarations.go
index 36bea0e..b6c9023 100644
--- a/aconfig/all_aconfig_declarations.go
+++ b/aconfig/all_aconfig_declarations.go
@@ -16,6 +16,7 @@
 
 import (
 	"android/soong/android"
+	"fmt"
 )
 
 // A singleton module that collects all of the aconfig flags declared in the
@@ -35,6 +36,7 @@
 
 func (this *allAconfigDeclarationsSingleton) GenerateBuildActions(ctx android.SingletonContext) {
 	// Find all of the aconfig_declarations modules
+	var packages = make(map[string]int)
 	var cacheFiles android.Paths
 	ctx.VisitAllModules(func(module android.Module) {
 		decl, ok := android.SingletonModuleProvider(ctx, module, android.AconfigDeclarationsProviderKey)
@@ -42,8 +44,21 @@
 			return
 		}
 		cacheFiles = append(cacheFiles, decl.IntermediateCacheOutputPath)
+		packages[decl.Package]++
 	})
 
+	var numOffendingPkg = 0
+	for pkg, cnt := range packages {
+		if cnt > 1 {
+			fmt.Printf("%d aconfig_declarations found for package %s\n", cnt, pkg)
+			numOffendingPkg++
+		}
+	}
+
+	if numOffendingPkg > 0 {
+		panic(fmt.Errorf("Only one aconfig_declarations allowed for each package."))
+	}
+
 	// Generate build action for aconfig
 	this.intermediatePath = android.PathForIntermediates(ctx, "all_aconfig_declarations.pb")
 	ctx.Build(pctx, android.BuildParams{
diff --git a/aconfig/all_aconfig_declarations_test.go b/aconfig/all_aconfig_declarations_test.go
new file mode 100644
index 0000000..0b2021e
--- /dev/null
+++ b/aconfig/all_aconfig_declarations_test.go
@@ -0,0 +1,48 @@
+// Copyright 2024 Google Inc. All rights reserved.
+//
+// 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.
+
+package aconfig
+
+import (
+	"testing"
+
+	"android/soong/android"
+)
+
+func TestTwoAconfigDeclarationsPerPackage(t *testing.T) {
+	bp := `
+		aconfig_declarations {
+			name: "module_name.foo",
+			package: "com.example.package",
+			container: "com.android.foo",
+			srcs: [
+				"foo.aconfig",
+			],
+		}
+
+		aconfig_declarations {
+			name: "module_name.bar",
+			package: "com.example.package",
+			container: "com.android.foo",
+			srcs: [
+				"bar.aconfig",
+			],
+		}
+	`
+	errMsg := "Only one aconfig_declarations allowed for each package."
+	android.GroupFixturePreparers(
+		PrepareForTestWithAconfigBuildComponents).
+		ExtendWithErrorHandler(android.FixtureExpectsOneErrorPattern(errMsg)).
+		RunTestWithBp(t, bp)
+}
diff --git a/aconfig/codegen/java_aconfig_library_test.go b/aconfig/codegen/java_aconfig_library_test.go
index 8d54b5b..7361d44 100644
--- a/aconfig/codegen/java_aconfig_library_test.go
+++ b/aconfig/codegen/java_aconfig_library_test.go
@@ -34,7 +34,7 @@
 		RunTestWithBp(t, bp+`
 			aconfig_declarations {
 				name: "my_aconfig_declarations_foo",
-				package: "com.example.package",
+				package: "com.example.package.foo",
 				srcs: ["foo.aconfig"],
 			}
 
@@ -45,7 +45,7 @@
 
 			aconfig_declarations {
 				name: "my_aconfig_declarations_bar",
-				package: "com.example.package",
+				package: "com.example.package.bar",
 				srcs: ["bar.aconfig"],
 			}