Fix proc_macro dependency handling.

Currently proc_macros don't pull in the correct arch dependencies when
the host arch differs from the target arch.

This fixes how proc_macro dependencies are handled by defining them as
always being host-only and including them as dependencies for
device-modules by using AddFarVariationDependencies.

Bug: 141491501
Test: Example device rust module builds with proc_macro dependency.
Change-Id: Ic037dc406ce90526f8b68c92fffc0d93a498a4ff

rust/builder.go

@@ -43,28 +43,19 @@ func init() {
 }
 
 func TransformSrcToBinary(ctx android.ModuleContext, mainSrc android.Path, deps PathDeps, flags Flags, outputFile android.WritablePath, includeDirs []string) {
-	targetTriple := ctx.(ModuleContext).toolchain().RustTriple()
+	transformSrctoCrate(ctx, mainSrc, deps.RLibs, deps.DyLibs, deps.ProcMacros, deps.StaticLibs, deps.SharedLibs, flags, outputFile, "bin", includeDirs)
-
-	transformSrctoCrate(ctx, mainSrc, deps.RLibs, deps.DyLibs, deps.ProcMacros, deps.StaticLibs, deps.SharedLibs, flags, outputFile, "bin", includeDirs, targetTriple)
 }
 
 func TransformSrctoRlib(ctx android.ModuleContext, mainSrc android.Path, deps PathDeps, flags Flags, outputFile android.WritablePath, includeDirs []string) {
-	targetTriple := ctx.(ModuleContext).toolchain().RustTriple()
+	transformSrctoCrate(ctx, mainSrc, deps.RLibs, deps.DyLibs, deps.ProcMacros, deps.StaticLibs, deps.SharedLibs, flags, outputFile, "rlib", includeDirs)
-
-	transformSrctoCrate(ctx, mainSrc, deps.RLibs, deps.DyLibs, deps.ProcMacros, deps.StaticLibs, deps.SharedLibs, flags, outputFile, "rlib", includeDirs, targetTriple)
 }
 
 func TransformSrctoDylib(ctx android.ModuleContext, mainSrc android.Path, deps PathDeps, flags Flags, outputFile android.WritablePath, includeDirs []string) {
-	targetTriple := ctx.(ModuleContext).toolchain().RustTriple()
+	transformSrctoCrate(ctx, mainSrc, deps.RLibs, deps.DyLibs, deps.ProcMacros, deps.StaticLibs, deps.SharedLibs, flags, outputFile, "dylib", includeDirs)
-
-	transformSrctoCrate(ctx, mainSrc, deps.RLibs, deps.DyLibs, deps.ProcMacros, deps.StaticLibs, deps.SharedLibs, flags, outputFile, "dylib", includeDirs, targetTriple)
 }
 
 func TransformSrctoProcMacro(ctx android.ModuleContext, mainSrc android.Path, deps PathDeps, flags Flags, outputFile android.WritablePath, includeDirs []string) {
-	// Proc macros are compiler plugins, and thus should target the host compiler
+	transformSrctoCrate(ctx, mainSrc, deps.RLibs, deps.DyLibs, deps.ProcMacros, deps.StaticLibs, deps.SharedLibs, flags, outputFile, "proc-macro", includeDirs)
-	targetTriple := ""
-
-	transformSrctoCrate(ctx, mainSrc, deps.RLibs, deps.DyLibs, deps.ProcMacros, deps.StaticLibs, deps.SharedLibs, flags, outputFile, "proc-macro", includeDirs, targetTriple)
 }
 
 func rustLibsToPaths(libs RustLibraries) android.Paths {
@@ -76,12 +67,13 @@ func rustLibsToPaths(libs RustLibraries) android.Paths {
 }
 
 func transformSrctoCrate(ctx android.ModuleContext, main android.Path,
-	rlibs, dylibs, proc_macros RustLibraries, static_libs, shared_libs android.Paths, flags Flags, outputFile android.WritablePath, crate_type string, includeDirs []string, targetTriple string) {
+	rlibs, dylibs, proc_macros RustLibraries, static_libs, shared_libs android.Paths, flags Flags, outputFile android.WritablePath, crate_type string, includeDirs []string) {
 
 	var inputs android.Paths
 	var deps android.Paths
 	var libFlags, rustcFlags []string
 	crate_name := ctx.(ModuleContext).CrateName()
+	targetTriple := ctx.(ModuleContext).toolchain().RustTriple()
 
 	inputs = append(inputs, main)
 

rust/compiler_test.go

@@ -64,7 +64,6 @@ func TestEnforceSingleSourceFile(t *testing.T) {
 		rust_proc_macro {
 			name: "foo-bar-proc-macro",
 			srcs: ["foo.rs", "src/bar.rs"],
-			host_supported: true,
 		}`)
 
 	// Test prebuilts

rust/proc_macro.go

@@ -45,7 +45,7 @@ type procMacroInterface interface {
 var _ compiler = (*procMacroDecorator)(nil)
 
 func ProcMacroFactory() android.Module {
-	module, _ := NewProcMacro(android.HostAndDeviceSupported)
+	module, _ := NewProcMacro(android.HostSupportedNoCross)
 	return module.Init()
 }
 

rust/rust.go

@@ -321,15 +321,6 @@ func (mod *Module) depsToPaths(ctx android.ModuleContext) PathDeps {
 		if rustDep, ok := dep.(*Module); ok {
 			//Handle Rust Modules
 
-			if rustDep.Target().Os != ctx.Os() {
-				ctx.ModuleErrorf("OS mismatch between %q and %q", ctx.ModuleName(), depName)
-				return
-			}
-			if rustDep.Target().Arch.ArchType != ctx.Arch().ArchType {
-				ctx.ModuleErrorf("Arch mismatch between %q and %q", ctx.ModuleName(), depName)
-				return
-			}
-
 			linkFile := rustDep.outputFile
 			if !linkFile.Valid() {
 				ctx.ModuleErrorf("Invalid output file when adding dep %q to %q", depName, ctx.ModuleName())
@@ -361,9 +352,6 @@ func (mod *Module) depsToPaths(ctx android.ModuleContext) PathDeps {
 			if lib, ok := rustDep.compiler.(*libraryDecorator); ok {
 				depPaths.linkDirs = append(depPaths.linkDirs, lib.exportedDirs()...)
 				depPaths.depFlags = append(depPaths.depFlags, lib.exportedDepFlags()...)
-			} else if procMacro, ok := rustDep.compiler.(*libraryDecorator); ok {
-				depPaths.linkDirs = append(depPaths.linkDirs, procMacro.exportedDirs()...)
-				depPaths.depFlags = append(depPaths.depFlags, procMacro.exportedDepFlags()...)
 			}
 
 			// Append this dependencies output to this mod's linkDirs so they can be exported to dependencies
@@ -491,7 +479,9 @@ func (mod *Module) DepsMutator(actx android.BottomUpMutatorContext) {
 	}
 	actx.AddVariationDependencies(append(ccDepVariations, blueprint.Variation{Mutator: "link", Variation: "shared"}), cc.SharedDepTag(), deps.SharedLibs...)
 	actx.AddVariationDependencies(append(ccDepVariations, blueprint.Variation{Mutator: "link", Variation: "static"}), cc.StaticDepTag(), deps.StaticLibs...)
-	actx.AddDependency(mod, procMacroDepTag, deps.ProcMacros...)
+
+	// proc_macros are compiler plugins, and so we need the host arch variant as a dependendcy.
+	actx.AddFarVariationDependencies([]blueprint.Variation{{Mutator: "arch", Variation: ctx.Config().BuildOsVariant}}, procMacroDepTag, deps.ProcMacros...)
 }
 
 func (mod *Module) Name() string {

rust/rust_test.go

@@ -150,7 +150,6 @@ func TestDepsTracking(t *testing.T) {
 		rust_proc_macro {
 			name: "libpm",
 			srcs: ["foo.rs"],
-			host_supported: true,
 		}
 		rust_binary_host {
 			name: "fizz-buzz",