diff --git a/rust/builder.go b/rust/builder.go
index 162d1aa..c855cfb 100644
--- a/rust/builder.go
+++ b/rust/builder.go
@@ -196,7 +196,7 @@
 	}
 
 	if len(deps.SrcDeps) > 0 {
-		moduleGenDir := ctx.RustModule().compiler.CargoOutDir()
+		moduleGenDir := ctx.RustModule().compiler.cargoOutDir()
 		// We must calculate an absolute path for OUT_DIR since Rust's include! macro (which normally consumes this)
 		// assumes that paths are relative to the source file.
 		var outDirPrefix string
@@ -215,13 +215,13 @@
 
 	envVars = append(envVars, "ANDROID_RUST_VERSION="+config.GetRustVersion(ctx))
 
-	if ctx.RustModule().compiler.CargoEnvCompat() {
+	if ctx.RustModule().compiler.cargoEnvCompat() {
 		if bin, ok := ctx.RustModule().compiler.(*binaryDecorator); ok {
 			envVars = append(envVars, "CARGO_BIN_NAME="+bin.getStem(ctx))
 		}
 		envVars = append(envVars, "CARGO_CRATE_NAME="+ctx.RustModule().CrateName())
 		envVars = append(envVars, "CARGO_PKG_NAME="+ctx.RustModule().CrateName())
-		pkgVersion := ctx.RustModule().compiler.CargoPkgVersion()
+		pkgVersion := ctx.RustModule().compiler.cargoPkgVersion()
 		if pkgVersion != "" {
 			envVars = append(envVars, "CARGO_PKG_VERSION="+pkgVersion)
 
@@ -327,7 +327,7 @@
 	orderOnly = append(orderOnly, deps.SharedLibs...)
 
 	if len(deps.SrcDeps) > 0 {
-		moduleGenDir := ctx.RustModule().compiler.CargoOutDir()
+		moduleGenDir := ctx.RustModule().compiler.cargoOutDir()
 		var outputs android.WritablePaths
 
 		for _, genSrc := range deps.SrcDeps {
diff --git a/rust/compiler.go b/rust/compiler.go
index 3c9f6d4..9666ce2 100644
--- a/rust/compiler.go
+++ b/rust/compiler.go
@@ -47,13 +47,13 @@
 
 	// Output directory in which source-generated code from dependencies is
 	// copied. This is equivalent to Cargo's OUT_DIR variable.
-	CargoOutDir() android.OptionalPath
+	cargoOutDir() android.OptionalPath
 
-	// CargoPkgVersion returns the value of the Cargo_pkg_version property.
-	CargoPkgVersion() string
+	// cargoPkgVersion returns the value of the Cargo_pkg_version property.
+	cargoPkgVersion() string
 
-	// CargoEnvCompat returns whether Cargo environment variables should be used.
-	CargoEnvCompat() bool
+	// cargoEnvCompat returns whether Cargo environment variables should be used.
+	cargoEnvCompat() bool
 
 	inData() bool
 	install(ctx ModuleContext)
@@ -242,7 +242,10 @@
 
 	// 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
+	// This is stored internally because it may not be available during
+	// singleton-generation passes like rustdoc/rust_project.json, but should
+	// be stashed during initial generation.
+	cachedCargoOutDir android.ModuleOutPath
 }
 
 func (compiler *baseCompiler) Disabled() bool {
@@ -393,18 +396,18 @@
 }
 
 func (compiler *baseCompiler) initialize(ctx ModuleContext) {
-	compiler.cargoOutDir = android.PathForModuleOut(ctx, genSubDir)
+	compiler.cachedCargoOutDir = android.PathForModuleOut(ctx, genSubDir)
 }
 
-func (compiler *baseCompiler) CargoOutDir() android.OptionalPath {
-	return android.OptionalPathForPath(compiler.cargoOutDir)
+func (compiler *baseCompiler) cargoOutDir() android.OptionalPath {
+	return android.OptionalPathForPath(compiler.cachedCargoOutDir)
 }
 
-func (compiler *baseCompiler) CargoEnvCompat() bool {
+func (compiler *baseCompiler) cargoEnvCompat() bool {
 	return Bool(compiler.Properties.Cargo_env_compat)
 }
 
-func (compiler *baseCompiler) CargoPkgVersion() string {
+func (compiler *baseCompiler) cargoPkgVersion() string {
 	return String(compiler.Properties.Cargo_pkg_version)
 }
 
diff --git a/rust/project_json.go b/rust/project_json.go
index 40aa7c7..9a9c600 100644
--- a/rust/project_json.go
+++ b/rust/project_json.go
@@ -241,8 +241,8 @@
 		ProcMacro:   procMacro,
 	}
 
-	if comp.CargoOutDir().Valid() {
-		crate.Env["OUT_DIR"] = comp.CargoOutDir().String()
+	if comp.cargoOutDir().Valid() {
+		crate.Env["OUT_DIR"] = comp.cargoOutDir().String()
 	}
 
 	for _, feature := range comp.Properties.Features {