env: allow compiling code outside llgo directory

internal/build/build.go

@@ -37,10 +37,11 @@ import (
 	"golang.org/x/tools/go/ssa"
 
 	"github.com/goplus/llgo/cl"
+	"github.com/goplus/llgo/internal/env"
 	"github.com/goplus/llgo/internal/packages"
 	"github.com/goplus/llgo/internal/typepatch"
 	"github.com/goplus/llgo/ssa/abi"
-	"github.com/goplus/llgo/xtool/env"
+	xenv "github.com/goplus/llgo/xtool/env"
 	"github.com/goplus/llgo/xtool/env/llvm"
 
 	llssa "github.com/goplus/llgo/ssa"
@@ -175,6 +176,7 @@ func Do(args []string, conf *Config) ([]Package, error) {
 	}
 
 	altPkgPaths := altPkgs(initial, llssa.PkgRuntime)
+	cfg.Dir = env.LLGoROOT()
 	altPkgs, err := packages.LoadEx(dedup, sizes, cfg, altPkgPaths...)
 	check(err)
 
@@ -316,7 +318,7 @@ func buildAllPkgs(ctx *context, initial []*packages.Package, verbose bool) (pkgs
 				for _, param := range altParts {
 					param = strings.TrimSpace(param)
 					if strings.ContainsRune(param, '$') {
-						expdArgs = append(expdArgs, env.ExpandEnvToArgs(param)...)
+						expdArgs = append(expdArgs, xenv.ExpandEnvToArgs(param)...)
 						ctx.nLibdir++
 					} else {
 						fields := strings.Fields(param)
@@ -748,7 +750,7 @@ func clFiles(ctx *context, files string, pkg *packages.Package, procFile func(li
 	args := make([]string, 0, 16)
 	if strings.HasPrefix(files, "$") { // has cflags
 		if pos := strings.IndexByte(files, ':'); pos > 0 {
-			cflags := env.ExpandEnvToArgs(files[:pos])
+			cflags := xenv.ExpandEnvToArgs(files[:pos])
 			files = files[pos+1:]
 			args = append(args, cflags...)
 		}

internal/env/env.go

@@ -0,0 +1,58 @@
+package env
+
+import (
+	"os"
+	"path/filepath"
+	"strings"
+)
+
+const (
+	LLGoCompilerPkg = "github.com/goplus/llgo"
+)
+
+func LLGoROOT() string {
+	if root, ok := isLLGoRoot(os.Getenv("LLGO_ROOT")); ok {
+		return root
+	}
+	// Get executable path
+	exe, err := os.Executable()
+	if err != nil {
+		return ""
+	}
+	// Resolve any symlinks
+	exe, err = filepath.EvalSymlinks(exe)
+	if err != nil {
+		return ""
+	}
+	// Check if parent directory is bin
+	dir := filepath.Dir(exe)
+	if filepath.Base(dir) != "bin" {
+		return ""
+	}
+	// Get parent directory of bin
+	root := filepath.Dir(dir)
+	if root, ok := isLLGoRoot(root); ok {
+		return root
+	}
+	return ""
+}
+
+func isLLGoRoot(root string) (string, bool) {
+	if root == "" {
+		return "", false
+	}
+	root, err := filepath.Abs(root)
+	if err != nil {
+		return "", false
+	}
+	// Check for go.mod
+	data, err := os.ReadFile(filepath.Join(root, "go.mod"))
+	if err != nil {
+		return "", false
+	}
+	// Check module name
+	if !strings.Contains(string(data), "module "+LLGoCompilerPkg+"\n") {
+		return "", false
+	}
+	return root, true
+}