Export OUT_DIR variable to rust-project.json

This variable is required by rust-analyzer to correctly process crates
that uses the include!(concat!(env!("OUT_DIR"), ...)) pattern.

Adds an initialize method to baseCompiler to save the computed path for
this directory. It is not possible to use the BeginMutator as the
BaseModuleContext does not contain enough information to use
PathForModuleOut.

Bug: 175004835
Test: SOONG_GEN_RUST_PROJECT=1 m nothing; inspect rust-project.json
Change-Id: If47b3832d3cca5712ae87773c174a61f5ee27bf8

1 files changed, 13 insertions, 0 deletions

diff --git a/rust/compiler.go b/rust/compiler.go
index c26f208ee..98ad7ad1b 100644
--- a/rust/compiler.go
+++ b/rust/compiler.go
@@ -60,6 +60,7 @@ const (
 	InstallInData                   = iota
 
 	incorrectSourcesError = "srcs can only contain one path for a rust file and source providers prefixed by \":\""
+	genSubDir             = "out/"
 )
 
 type BaseCompilerProperties struct {
@@ -154,6 +155,10 @@ type baseCompiler struct {
 	distFile android.OptionalPath
 	// Stripped output file. If Valid(), this file will be installed instead of outputFile.
 	strippedOutputFile android.OptionalPath
+
+	// If a crate has a source-generated dependency, a copy of the source file
+	// will be available in cargoOutDir (equivalent to Cargo OUT_DIR).
+	cargoOutDir android.ModuleOutPath
 }
 
 func (compiler *baseCompiler) Disabled() bool {
@@ -243,6 +248,14 @@ func (compiler *baseCompiler) compile(ctx ModuleContext, flags Flags, deps PathD
 	panic(fmt.Errorf("baseCrater doesn't know how to crate things!"))
 }
 
+func (compiler *baseCompiler) initialize(ctx ModuleContext) {
+	compiler.cargoOutDir = android.PathForModuleOut(ctx, genSubDir)
+}
+
+func (compiler *baseCompiler) CargoOutDir() android.OptionalPath {
+	return android.OptionalPathForPath(compiler.cargoOutDir)
+}
+
 func (compiler *baseCompiler) isDependencyRoot() bool {
 	return false
 }