Add rust-project.json generator
Because we are not relying on Cargo.toml for our crate dependencies,
we need to provide a structured file to rust-analyzer which describes
the locations of the crates. Add a generator for that purpose, similarly
to cc/compdb and cc/ccdeps.
Bug: 156395307
Test: SOONG_GEN_RUST_PROJECT=1 m nothing && \
cat ${ANDROID_BUILD_TOP}/out/soong/rust-project.json
Change-Id: I46efe0adeddae281eaf86707504c3aa15b5e80b8
diff --git a/rust/project_json.go b/rust/project_json.go
new file mode 100644
index 0000000..909aebc
--- /dev/null
+++ b/rust/project_json.go
@@ -0,0 +1,161 @@
+// Copyright 2020 Google Inc. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package rust
+
+import (
+ "encoding/json"
+ "fmt"
+ "path"
+
+ "android/soong/android"
+)
+
+// This singleton collects Rust crate definitions and generates a JSON file
+// (${OUT_DIR}/soong/rust-project.json) which can be use by external tools,
+// such as rust-analyzer. It does so when either make, mm, mma, mmm or mmma is
+// called. This singleton is enabled only if SOONG_GEN_RUST_PROJECT is set.
+// For example,
+//
+// $ SOONG_GEN_RUST_PROJECT=1 m nothing
+
+func init() {
+ android.RegisterSingletonType("rust_project_generator", rustProjectGeneratorSingleton)
+}
+
+func rustProjectGeneratorSingleton() android.Singleton {
+ return &projectGeneratorSingleton{}
+}
+
+type projectGeneratorSingleton struct{}
+
+const (
+ // Environment variables used to control the behavior of this singleton.
+ envVariableCollectRustDeps = "SOONG_GEN_RUST_PROJECT"
+ rustProjectJsonFileName = "rust-project.json"
+)
+
+// The format of rust-project.json is not yet finalized. A current description is available at:
+// https://github.com/rust-analyzer/rust-analyzer/blob/master/docs/user/manual.adoc#non-cargo-based-projects
+type rustProjectDep struct {
+ Crate int `json:"crate"`
+ Name string `json:"name"`
+}
+
+type rustProjectCrate struct {
+ RootModule string `json:"root_module"`
+ Edition string `json:"edition,omitempty"`
+ Deps []rustProjectDep `json:"deps"`
+ Cfgs []string `json:"cfgs"`
+}
+
+type rustProjectJson struct {
+ Roots []string `json:"roots"`
+ Crates []rustProjectCrate `json:"crates"`
+}
+
+// crateInfo is used during the processing to keep track of the known crates.
+type crateInfo struct {
+ ID int
+ Deps map[string]int
+}
+
+func mergeDependencies(ctx android.SingletonContext, project *rustProjectJson,
+ knownCrates map[string]crateInfo, module android.Module,
+ crate *rustProjectCrate, deps map[string]int) {
+
+ //TODO(tweek): The stdlib dependencies do not appear here. We need to manually add them.
+ ctx.VisitDirectDeps(module, func(child android.Module) {
+ childId, childName, ok := appendLibraryAndDeps(ctx, project, knownCrates, child)
+ if !ok {
+ return
+ }
+ if _, ok = deps[childName]; ok {
+ return
+ }
+ crate.Deps = append(crate.Deps, rustProjectDep{Crate: childId, Name: childName})
+ deps[childName] = childId
+ })
+}
+
+// appendLibraryAndDeps creates a rustProjectCrate for the module argument and
+// appends it to the rustProjectJson struct. It visits the dependencies of the
+// module depth-first. If the current module is already in knownCrates, its
+// its dependencies are merged. Returns a tuple (id, crate_name, ok).
+func appendLibraryAndDeps(ctx android.SingletonContext, project *rustProjectJson,
+ knownCrates map[string]crateInfo, module android.Module) (int, string, bool) {
+ rModule, ok := module.(*Module)
+ if !ok {
+ return 0, "", false
+ }
+ if rModule.compiler == nil {
+ return 0, "", false
+ }
+ rustLib, ok := rModule.compiler.(*libraryDecorator)
+ if !ok {
+ return 0, "", false
+ }
+ crateName := rModule.CrateName()
+ if cInfo, ok := knownCrates[crateName]; ok {
+ // We have seen this crate already; merge any new dependencies.
+ crate := project.Crates[cInfo.ID]
+ mergeDependencies(ctx, project, knownCrates, module, &crate, cInfo.Deps)
+ return cInfo.ID, crateName, true
+ }
+ crate := rustProjectCrate{Deps: make([]rustProjectDep, 0), Cfgs: make([]string, 0)}
+ src := rustLib.Properties.Srcs[0]
+ crate.RootModule = path.Join(ctx.ModuleDir(rModule), src)
+ crate.Edition = getEdition(rustLib.baseCompiler)
+
+ deps := make(map[string]int)
+ mergeDependencies(ctx, project, knownCrates, module, &crate, deps)
+
+ id := len(project.Crates)
+ knownCrates[crateName] = crateInfo{ID: id, Deps: deps}
+ project.Crates = append(project.Crates, crate)
+ // rust-analyzer requires that all crates belong to at least one root:
+ // https://github.com/rust-analyzer/rust-analyzer/issues/4735.
+ project.Roots = append(project.Roots, path.Dir(crate.RootModule))
+ return id, crateName, true
+}
+
+func (r *projectGeneratorSingleton) GenerateBuildActions(ctx android.SingletonContext) {
+ if !ctx.Config().IsEnvTrue(envVariableCollectRustDeps) {
+ return
+ }
+
+ project := rustProjectJson{}
+ knownCrates := make(map[string]crateInfo)
+ ctx.VisitAllModules(func(module android.Module) {
+ appendLibraryAndDeps(ctx, &project, knownCrates, module)
+ })
+
+ path := android.PathForOutput(ctx, rustProjectJsonFileName)
+ err := createJsonFile(project, path)
+ if err != nil {
+ ctx.Errorf(err.Error())
+ }
+}
+
+func createJsonFile(project rustProjectJson, rustProjectPath android.WritablePath) error {
+ buf, err := json.MarshalIndent(project, "", " ")
+ if err != nil {
+ return fmt.Errorf("JSON marshal of rustProjectJson failed: %s", err)
+ }
+ err = android.WriteFileToOutputDir(rustProjectPath, buf, 0666)
+ if err != nil {
+ return fmt.Errorf("Writing rust-project to %s failed: %s", rustProjectPath.String(), err)
+ }
+ return nil
+}