Add aliases property for renaming Rust dependencies.

This is equivalent to specifying a dependency name different to the
package name in cargo, which some external crates do.

Bug: 308790322
Test: Built libgrpcio with aliases for protobuf
Change-Id: I2801222051fdd962460cc7f4900cec357f63b974

rust/compiler.go

@@ -75,6 +75,8 @@ type compiler interface {
 	strippedOutputFilePath() android.OptionalPath
 
 	checkedCrateRootPath() (android.Path, error)
+
+	Aliases() map[string]string
 }
 
 func (compiler *baseCompiler) edition() string {
@@ -140,6 +142,12 @@ type BaseCompilerProperties struct {
 	// flags to pass to the linker
 	Ld_flags []string `android:"arch_variant"`
 
+	// Rust crate dependencies to rename. Each entry should be a string of the form "dependencyname:alias".
+	//
+	// "dependencyname" here should be the name of the crate, not the Android module. This is
+	// equivalent to writing `alias = { package = "dependencyname" }` in a `Cargo.toml`.
+	Aliases []string
+
 	// list of rust rlib crate dependencies
 	Rlibs []string `android:"arch_variant"`
 
@@ -281,6 +289,18 @@ func (compiler *baseCompiler) preferRlib() bool {
 	return Bool(compiler.Properties.Prefer_rlib)
 }
 
+func (compiler *baseCompiler) Aliases() map[string]string {
+	aliases := map[string]string{}
+	for _, entry := range compiler.Properties.Aliases {
+		dep, alias, found := strings.Cut(entry, ":")
+		if !found {
+			panic(fmt.Errorf("invalid aliases entry %q missing ':'", entry))
+		}
+		aliases[dep] = alias
+	}
+	return aliases
+}
+
 func (compiler *baseCompiler) stdLinkage(ctx *depsContext) RustLinkage {
 	// For devices, we always link stdlibs in as dylibs by default.
 	if compiler.preferRlib() {