build: make llgen, cltest, gentests call build.Do

internal/build/build.go

@@ -53,6 +53,7 @@ const (
 	ModeInstall
 	ModeRun
 	ModeCmpTest
+	ModeGen
 )
 
 const (
@@ -119,7 +120,7 @@ const (
 	loadSyntax  = loadTypes | packages.NeedSyntax | packages.NeedTypesInfo
 )
 
-func Do(args []string, conf *Config) {
+func Do(args []string, conf *Config) ([]Package, error) {
 	flags, patterns, verbose := ParseArgs(args, buildFlags)
 	cl.EnableDebugSymbols(IsDebugEnabled())
 	flags = append(flags, "-tags", "llgo")
@@ -159,7 +160,6 @@ func Do(args []string, conf *Config) {
 	}
 	initial, err := packages.LoadEx(dedup, sizes, cfg, patterns...)
 	check(err)
-
 	mode := conf.Mode
 	if len(initial) == 1 && len(initial[0].CompiledGoFiles) > 0 {
 		if mode == ModeBuild {
@@ -167,11 +167,10 @@ func Do(args []string, conf *Config) {
 		}
 	} else if mode == ModeRun {
 		if len(initial) > 1 {
-			fmt.Fprintln(os.Stderr, "cannot run multiple packages")
+			return nil, fmt.Errorf("cannot run multiple packages")
 		} else {
-			fmt.Fprintln(os.Stderr, "no Go files in matched packages")
+			return nil, fmt.Errorf("no Go files in matched packages")
 		}
-		return
 	}
 
 	altPkgPaths := altPkgs(initial, llssa.PkgRuntime)
@@ -203,12 +202,21 @@ func Do(args []string, conf *Config) {
 
 	ctx := &context{env, cfg, progSSA, prog, dedup, patches, make(map[string]none), initial, mode, 0}
 	pkgs := buildAllPkgs(ctx, initial, verbose)
+	if mode == ModeGen {
+		for _, pkg := range pkgs {
+			if pkg.Package == initial[0] {
+				return []*aPackage{pkg}, nil
+			}
+		}
+		return nil, fmt.Errorf("initial package not found")
+	}
 
 	dpkg := buildAllPkgs(ctx, altPkgs[noRt:], verbose)
 	var linkArgs []string
 	for _, pkg := range dpkg {
 		linkArgs = append(linkArgs, pkg.LinkArgs...)
 	}
+
 	if mode != ModeBuild {
 		nErr := 0
 		for _, pkg := range initial {
@@ -220,6 +228,7 @@ func Do(args []string, conf *Config) {
 			os.Exit(nErr)
 		}
 	}
+	return dpkg, nil
 }
 
 func setNeedRuntimeOrPyInit(pkg *packages.Package, needRuntime, needPyInit bool) {
@@ -571,6 +580,8 @@ type aPackage struct {
 	LinkArgs []string
 }
 
+type Package = *aPackage
+
 func allPkgs(ctx *context, initial []*packages.Package, verbose bool) (all []*aPackage, errs []*packages.Package) {
 	prog := ctx.progSSA
 	built := ctx.built