[rust] Add SourceProviders as crates support.

This allows SourceProvider modules to create rust_library variants so
that generated source can be referenced as an external crate rather than
via an include macro. This is done by including rust_bindgen modules
like any other library, as a dependency in either rlibs, dylibs, or
rustlibs.

This renames the stem and flags properties for rust_bindgen modules to
source_stem and bindgen_flags, respectively. This deconflicts with the
usage in baseCompiler.

This also removes 'subName' from the Module struct and moves it over to
SourceProvider, which was the only user. This allows us to set it in
baseSourceProvider's AndroidMk; setting it in Module's AndroidMk was
causing problems finding NOTICE files for bindgen library variants.

Bug: 159064919
Test: New Soong tests pass.
Test: Local test rust_binary can use rust_bindgen module as a crate.

Change-Id: Ieb2cb614c2dd0b5aa7120541d77f6f822a6a1806

rust/rust.go

@@ -63,7 +63,8 @@ type BaseProperties struct {
 	AndroidMkSharedLibs    []string
 	AndroidMkStaticLibs    []string
 
-	SubName        string `blueprint:"mutated"`
+	SubName string `blueprint:"mutated"`
+
 	PreventInstall bool
 	HideFromMake   bool
 }
@@ -83,9 +84,9 @@ type Module struct {
 	cachedToolchain  config.Toolchain
 	sourceProvider   SourceProvider
 	subAndroidMkOnce map[subAndroidMkProvider]bool
-	outputFile       android.OptionalPath
 
-	subName string
+	outputFile    android.OptionalPath
+	generatedFile android.OptionalPath
 }
 
 func (mod *Module) OutputFiles(tag string) (android.Paths, error) {
@@ -285,6 +286,9 @@ type compiler interface {
 	relativeInstallPath() string
 
 	nativeCoverage() bool
+
+	Disabled() bool
+	SetDisabled()
 }
 
 type exportedFlagsProducer interface {
@@ -667,16 +671,21 @@ func (mod *Module) GenerateAndroidBuildActions(actx android.ModuleContext) {
 		flags, deps = mod.clippy.flags(ctx, flags, deps)
 	}
 
-	if mod.compiler != nil {
+	// SourceProvider needs to call generateSource() before compiler calls compile() so it can provide the source.
+	// TODO(b/162588681) This shouldn't have to run for every variant.
+	if mod.sourceProvider != nil {
+		generatedFile := mod.sourceProvider.generateSource(ctx, deps)
+		mod.generatedFile = android.OptionalPathForPath(generatedFile)
+		mod.sourceProvider.setSubName(ctx.ModuleSubDir())
+	}
+
+	if mod.compiler != nil && !mod.compiler.Disabled() {
 		outputFile := mod.compiler.compile(ctx, flags, deps)
+
 		mod.outputFile = android.OptionalPathForPath(outputFile)
-		if !mod.Properties.PreventInstall {
+		if mod.outputFile.Valid() && !mod.Properties.PreventInstall {
 			mod.compiler.install(ctx, mod.outputFile.Path())
 		}
-	} else if mod.sourceProvider != nil {
-		outputFile := mod.sourceProvider.generateSource(ctx, deps)
-		mod.outputFile = android.OptionalPathForPath(outputFile)
-		mod.subName = ctx.ModuleSubDir()
 	}
 }
 
@@ -685,7 +694,8 @@ func (mod *Module) deps(ctx DepsContext) Deps {
 
 	if mod.compiler != nil {
 		deps = mod.compiler.compilerDeps(ctx, deps)
-	} else if mod.sourceProvider != nil {
+	}
+	if mod.sourceProvider != nil {
 		deps = mod.sourceProvider.sourceProviderDeps(ctx, deps)
 	}
 
@@ -755,11 +765,6 @@ func (mod *Module) depsToPaths(ctx android.ModuleContext) PathDeps {
 		if rustDep, ok := dep.(*Module); ok && !rustDep.CcLibraryInterface() {
 			//Handle Rust Modules
 
-			linkFile := rustDep.outputFile
-			if !linkFile.Valid() {
-				ctx.ModuleErrorf("Invalid output file when adding dep %q to %q", depName, ctx.ModuleName())
-			}
-
 			switch depTag {
 			case dylibDepTag:
 				dylib, ok := rustDep.compiler.(libraryInterface)
@@ -808,6 +813,12 @@ func (mod *Module) depsToPaths(ctx android.ModuleContext) PathDeps {
 			}
 
 			if depTag == dylibDepTag || depTag == rlibDepTag || depTag == procMacroDepTag {
+				linkFile := rustDep.outputFile
+				if !linkFile.Valid() {
+					ctx.ModuleErrorf("Invalid output file when adding dep %q to %q",
+						depName, ctx.ModuleName())
+					return
+				}
 				linkDir := linkPathFromFilePath(linkFile.Path())
 				if lib, ok := mod.compiler.(exportedFlagsProducer); ok {
 					lib.exportLinkDirs(linkDir)
@@ -826,7 +837,6 @@ func (mod *Module) depsToPaths(ctx android.ModuleContext) PathDeps {
 					return
 				}
 			}
-
 			linkFile := ccDep.OutputFile()
 			linkPath := linkPathFromFilePath(linkFile.Path())
 			libName := libNameFromFilePath(linkFile.Path())