Prepare recovery tools for the host target

internal/gotool/recovery.go

@@ -43,10 +43,16 @@ func TemporaryExecutable(path string) bool {
 	return err == nil
 }
 
-// RecoveryTool returns module-selected Go arguments for a later invocation.
-// An empty result means this module does not select ReleaseKit. API-only modules
+// RecoveryInvocation describes a module-selected Go tool invocation.
+type RecoveryInvocation struct {
+	Directory string
+	Args      []string
+}
+
+// RecoveryTool returns a module-selected Go invocation for later use.
+// A nil result means this module does not select ReleaseKit. API-only modules
 // receive a private module root that outlives launcher-owned bootstraps.
-func RecoveryTool(ctx context.Context, moduleDir, recordDir string) ([]string, error) {
+func RecoveryTool(ctx context.Context, moduleDir, recordDir string) (*RecoveryInvocation, error) {
 	path := filepath.Join(moduleDir, "go.mod")
 	data, err := os.ReadFile(path)
 	if err != nil {
@@ -58,7 +64,7 @@ func RecoveryTool(ctx context.Context, moduleDir, recordDir string) ([]string, e
 	}
 	for _, tool := range module.Tool {
 		if tool.Path == releaseKitCommand {
-			return []string{"-C", moduleDir, "tool", "-modfile=", releaseKitCommand}, nil
+			return &RecoveryInvocation{Directory: moduleDir, Args: []string{"tool", "-modfile=", releaseKitCommand}}, nil
 		}
 	}
 	// Ask Go about the selected module graph, including transitive dependencies.
@@ -140,15 +146,31 @@ func RecoveryTool(ctx context.Context, moduleDir, recordDir string) ([]string, e
 		return nil, err
 	}
 	// Prepare the private graph and sums before the later tool invocation.
+	environment := map[string]string{"GOWORK": "off", "GOTOOLCHAIN": "local"}
+	hostJSON, err := discover(ctx, directory, environment, "go", "env", "-json", "GOHOSTOS", "GOHOSTARCH")
+	if err != nil {
+		return nil, fmt.Errorf("prepare recovery tool: %w", err)
+	}
+	var host struct {
+		GOHOSTOS   string
+		GOHOSTARCH string
+	}
+	if err := json.Unmarshal(hostJSON, &host); err != nil {
+		return nil, fmt.Errorf("prepare recovery tool: decode host target: %w", err)
+	}
+	if host.GOHOSTOS == "" || host.GOHOSTARCH == "" {
+		return nil, fmt.Errorf("prepare recovery tool: missing host target")
+	}
+	environment["GOOS"], environment["GOARCH"] = host.GOHOSTOS, host.GOHOSTARCH
 	captured := &combinedWriter{mode: captureStatus}
 	err = process.Run(ctx, process.Invocation{
 		Args: []string{"go", "list", "-mod=mod", "-modfile=", "-deps", releaseKitCommand},
-		Dir:  directory, Env: map[string]string{"GOWORK": "off", "GOTOOLCHAIN": "local"},
+		Dir:  directory, Env: environment,
 		Stdout: captured, Stderr: captured,
 	})
 	if err != nil {
 		return nil, fmt.Errorf("prepare recovery tool: %w: %s", err, diagnosticText(captured.take(), captured.omitted()))
 	}
 	complete = true
-	return []string{"-C", directory, "tool", "-modfile=", releaseKitCommand}, nil
+	return &RecoveryInvocation{Directory: directory, Args: []string{"tool", "-modfile=", releaseKitCommand}}, nil
 }