Support generating module_info.json in Soong

Generate module_info.json for some Soong modules in Soong in order to
pass fewer properties to Kati, which can prevent Kati reanalysis when
some Android.bp changes are made.

Soong modules can export a ModuleInfoJSONProvider containing the
data that should be included in module-info.json.  During the androidmk
singleton the providers are collected and written to a single JSON
file.  Make then merges the Soong modules into its own modules.

For now, to keep the result as similar as possible to the
module-info.json currently being generated by Make, only modules that
are exported to Make are written to the Soong module-info.json.

Bug: 309006256
Test: Compare module-info.json
Change-Id: I996520eb48e04743d43ac11c9aba0f3ada7745de
diff --git a/cmd/merge_module_info_json/Android.bp b/cmd/merge_module_info_json/Android.bp
new file mode 100644
index 0000000..1ae6a47
--- /dev/null
+++ b/cmd/merge_module_info_json/Android.bp
@@ -0,0 +1,30 @@
+// Copyright 2021 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 {
+    default_applicable_licenses: ["Android-Apache-2.0"],
+}
+
+blueprint_go_binary {
+    name: "merge_module_info_json",
+    srcs: [
+        "merge_module_info_json.go",
+    ],
+    deps: [
+        "soong-response",
+    ],
+    testSrcs: [
+        "merge_module_info_json_test.go",
+    ],
+}
diff --git a/cmd/merge_module_info_json/merge_module_info_json.go b/cmd/merge_module_info_json/merge_module_info_json.go
new file mode 100644
index 0000000..0143984
--- /dev/null
+++ b/cmd/merge_module_info_json/merge_module_info_json.go
@@ -0,0 +1,223 @@
+// Copyright 2021 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.
+
+// merge_module_info_json is a utility that merges module_info.json files generated by
+// Soong and Make.
+
+package main
+
+import (
+	"android/soong/response"
+	"cmp"
+	"encoding/json"
+	"flag"
+	"fmt"
+	"os"
+	"slices"
+)
+
+var (
+	out      = flag.String("o", "", "output file")
+	listFile = flag.String("l", "", "input file list file")
+)
+
+func usage() {
+	fmt.Fprintf(os.Stderr, "usage: %s -o <output file> <input files>\n", os.Args[0])
+	flag.PrintDefaults()
+	fmt.Fprintln(os.Stderr, "merge_module_info_json reads input files that each contain an array of json objects")
+	fmt.Fprintln(os.Stderr, "and writes them out as a single json array to the output file.")
+
+	os.Exit(2)
+}
+
+func main() {
+	flag.Usage = usage
+	flag.Parse()
+
+	if *out == "" {
+		fmt.Fprintf(os.Stderr, "%s: error: -o is required\n", os.Args[0])
+		usage()
+	}
+
+	inputs := flag.Args()
+	if *listFile != "" {
+		listFileInputs, err := readListFile(*listFile)
+		if err != nil {
+			fmt.Fprintf(os.Stderr, "failed to read list file %s: %s", *listFile, err)
+			os.Exit(1)
+		}
+		inputs = append(inputs, listFileInputs...)
+	}
+
+	err := mergeJsonObjects(*out, inputs)
+
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "%s: error: %s\n", os.Args[0], err.Error())
+		os.Exit(1)
+	}
+}
+
+func readListFile(file string) ([]string, error) {
+	f, err := os.Open(*listFile)
+	if err != nil {
+		return nil, err
+	}
+	return response.ReadRspFile(f)
+}
+
+func mergeJsonObjects(output string, inputs []string) error {
+	combined := make(map[string]any)
+	for _, input := range inputs {
+		objects, err := decodeObjectFromJson(input)
+		if err != nil {
+			return err
+		}
+
+		for _, object := range objects {
+			for k, v := range object {
+				if old, exists := combined[k]; exists {
+					v = combine(old, v)
+				}
+				combined[k] = v
+			}
+		}
+	}
+
+	f, err := os.Create(output)
+	if err != nil {
+		return fmt.Errorf("failed to open output file: %w", err)
+	}
+	encoder := json.NewEncoder(f)
+	encoder.SetIndent("", "  ")
+	err = encoder.Encode(combined)
+	if err != nil {
+		return fmt.Errorf("failed to encode to output file: %w", err)
+	}
+
+	return nil
+}
+
+func decodeObjectFromJson(input string) ([]map[string]any, error) {
+	f, err := os.Open(input)
+	if err != nil {
+		return nil, fmt.Errorf("failed to open input file: %w", err)
+	}
+
+	decoder := json.NewDecoder(f)
+	var object any
+	err = decoder.Decode(&object)
+	if err != nil {
+		return nil, fmt.Errorf("failed to parse input file %q: %w", input, err)
+	}
+
+	switch o := object.(type) {
+	case []any:
+		var ret []map[string]any
+		for _, arrayElement := range o {
+			if m, ok := arrayElement.(map[string]any); ok {
+				ret = append(ret, m)
+			} else {
+				return nil, fmt.Errorf("unknown JSON type in array %T", arrayElement)
+			}
+		}
+		return ret, nil
+
+	case map[string]any:
+		return []map[string]any{o}, nil
+	}
+
+	return nil, fmt.Errorf("unknown JSON type %T", object)
+}
+
+func combine(old, new any) any {
+	//	fmt.Printf("%#v %#v\n", old, new)
+	switch oldTyped := old.(type) {
+	case map[string]any:
+		if newObject, ok := new.(map[string]any); ok {
+			return combineObjects(oldTyped, newObject)
+		} else {
+			panic(fmt.Errorf("expected map[string]any, got %#v", new))
+		}
+	case []any:
+		if newArray, ok := new.([]any); ok {
+			return combineArrays(oldTyped, newArray)
+		} else {
+			panic(fmt.Errorf("expected []any, got %#v", new))
+		}
+	case string:
+		if newString, ok := new.(string); ok {
+			if oldTyped != newString {
+				panic(fmt.Errorf("strings %q and %q don't match", oldTyped, newString))
+			}
+			return oldTyped
+		} else {
+			panic(fmt.Errorf("expected []any, got %#v", new))
+		}
+	default:
+		panic(fmt.Errorf("can't combine type %T", old))
+	}
+}
+
+func combineObjects(old, new map[string]any) map[string]any {
+	for k, newField := range new {
+		// HACK: Don't merge "test_config" field.  This matches the behavior in base_rules.mk that overwrites
+		// instead of appending ALL_MODULES.$(my_register_name).TEST_CONFIG, keeping the
+		if k == "test_config" {
+			old[k] = newField
+			continue
+		}
+		if oldField, exists := old[k]; exists {
+			oldField = combine(oldField, newField)
+			old[k] = oldField
+		} else {
+			old[k] = newField
+		}
+	}
+
+	return old
+}
+
+func combineArrays(old, new []any) []any {
+	containsNonStrings := false
+	for _, oldElement := range old {
+		switch oldElement.(type) {
+		case string:
+		default:
+			containsNonStrings = true
+		}
+	}
+	for _, newElement := range new {
+		found := false
+		for _, oldElement := range old {
+			if oldElement == newElement {
+				found = true
+				break
+			}
+		}
+		if !found {
+			switch newElement.(type) {
+			case string:
+			default:
+				containsNonStrings = true
+			}
+			old = append(old, newElement)
+		}
+	}
+	if !containsNonStrings {
+		slices.SortFunc(old, func(a, b any) int {
+			return cmp.Compare(a.(string), b.(string))
+		})
+	}
+	return old
+}
diff --git a/cmd/merge_module_info_json/merge_module_info_json_test.go b/cmd/merge_module_info_json/merge_module_info_json_test.go
new file mode 100644
index 0000000..dbf1aa1
--- /dev/null
+++ b/cmd/merge_module_info_json/merge_module_info_json_test.go
@@ -0,0 +1,58 @@
+// Copyright 2021 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 main
+
+import (
+	"reflect"
+	"testing"
+)
+
+func Test_combine(t *testing.T) {
+	tests := []struct {
+		name string
+		old  any
+		new  any
+		want any
+	}{
+		{
+			name: "objects",
+			old: map[string]any{
+				"foo": "bar",
+				"baz": []any{"a"},
+			},
+			new: map[string]any{
+				"foo": "bar",
+				"baz": []any{"b"},
+			},
+			want: map[string]any{
+				"foo": "bar",
+				"baz": []any{"a", "b"},
+			},
+		},
+		{
+			name: "arrays",
+			old:  []any{"foo", "bar"},
+			new:  []any{"foo", "baz"},
+			want: []any{"bar", "baz", "foo"},
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := combine(tt.old, tt.new); !reflect.DeepEqual(got, tt.want) {
+				t.Errorf("combine() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}