rust: Only pass "-lstatic" for rlibs.

Passing '-lstatic' for dylib static dependencies results in some
unexpected bloat as the static libraries are included as
whole-archives.

For now, limit this to rlibs while we investigate.

Bug: 175886967
Bug: 179122837
Test: cd system/bt/; mma
Test: Checked size of dylibs.
Change-Id: Id8328e95771e2ca8503bc8df35248b1c39cabc8e

rust/rust.go

@@ -896,6 +896,8 @@ func (mod *Module) depsToPaths(ctx android.ModuleContext) PathDeps {
 			exportDep := false
 			switch {
 			case cc.IsStaticDepTag(depTag):
+				// Only pass -lstatic for rlibs as it results in dylib bloat.
+				if lib, ok := ctx.Module().(*Module).compiler.(libraryInterface); ok && lib.rlib() {
 					// Link cc static libraries using "-lstatic" so rustc can reason about how to handle these
 					// (for example, bundling them into rlibs).
 					//
@@ -905,6 +907,7 @@ func (mod *Module) depsToPaths(ctx android.ModuleContext) PathDeps {
 					if libName, ok := libNameFromFilePath(linkObject.Path()); ok {
 						depPaths.depFlags = append(depPaths.depFlags, "-lstatic="+libName)
 					}
+				}
 
 				// Add this to linkObjects to pass the library directly to the linker as well. This propagates
 				// to dependencies to avoid having to redeclare static libraries for dependents of the dylib variant.

rust/rust_test.go

@@ -213,6 +213,7 @@ func TestDepsTracking(t *testing.T) {
 			name: "librlib",
 			srcs: ["foo.rs"],
 			crate_name: "rlib",
+			static_libs: ["libstatic"],
 		}
 		rust_proc_macro {
 			name: "libpm",
@@ -230,7 +231,7 @@ func TestDepsTracking(t *testing.T) {
 		}
 	`)
 	module := ctx.ModuleForTests("fizz-buzz", "linux_glibc_x86_64").Module().(*Module)
-	rustc := ctx.ModuleForTests("fizz-buzz", "linux_glibc_x86_64").Rule("rustc")
+	rustc := ctx.ModuleForTests("librlib", "linux_glibc_x86_64_rlib_rlib-std").Rule("rustc")
 
 	// Since dependencies are added to AndroidMk* properties, we can check these to see if they've been picked up.
 	if !android.InList("libdylib", module.Properties.AndroidMkDylibs) {