expand template vars in targets config

internal/crosscompile/crosscompile.go

@@ -44,6 +44,83 @@ func cacheDir() string {
 	return filepath.Join(env.LLGoCacheDir(), "crosscompile")
 }
 
+// expandEnv expands template variables in a string
+// Supports variables like {port}, {hex}, {bin}, {root}, {tmpDir}, etc.
+// Special case: {} expands to the first available file variable (hex, bin, img, zip)
+func expandEnv(template string, envs map[string]string) string {
+	return expandEnvWithDefault(template, envs)
+}
+
+// expandEnvWithDefault expands template variables with optional default for {}
+func expandEnvWithDefault(template string, envs map[string]string, defaultValue ...string) string {
+	if template == "" {
+		return ""
+	}
+
+	result := template
+
+	// Handle special case of {} - use provided default or first available file variable
+	if strings.Contains(result, "{}") {
+		defaultVal := ""
+		if len(defaultValue) > 0 && defaultValue[0] != "" {
+			defaultVal = defaultValue[0]
+		} else {
+			// Priority order: hex, bin, img, zip
+			for _, key := range []string{"hex", "bin", "img", "zip"} {
+				if value, exists := envs[key]; exists && value != "" {
+					defaultVal = value
+					break
+				}
+			}
+		}
+		result = strings.ReplaceAll(result, "{}", defaultVal)
+	}
+
+	// Replace named variables
+	for key, value := range envs {
+		if key != "" { // Skip empty key used for {} default
+			result = strings.ReplaceAll(result, "{"+key+"}", value)
+		}
+	}
+	return result
+}
+
+// expandEnvSlice expands template variables in a slice of strings
+func expandEnvSlice(templates []string, envs map[string]string) []string {
+	return expandEnvSliceWithDefault(templates, envs)
+}
+
+// expandEnvSliceWithDefault expands template variables in a slice with optional default for {}
+func expandEnvSliceWithDefault(templates []string, envs map[string]string, defaultValue ...string) []string {
+	if len(templates) == 0 {
+		return templates
+	}
+
+	result := make([]string, len(templates))
+	for i, template := range templates {
+		result[i] = expandEnvWithDefault(template, envs, defaultValue...)
+	}
+	return result
+}
+
+// buildEnvMap creates a map of template variables for the current context
+func buildEnvMap(llgoRoot string) map[string]string {
+	envs := make(map[string]string)
+
+	// Basic paths
+	envs["root"] = llgoRoot
+	envs["tmpDir"] = os.TempDir()
+
+	// These will typically be set by calling code when actual values are known
+	// envs["port"] = ""     // Serial port (e.g., "/dev/ttyUSB0", "COM3")
+	// envs["hex"] = ""      // Path to hex file
+	// envs["bin"] = ""      // Path to binary file
+	// envs["img"] = ""      // Path to image file
+	// envs["zip"] = ""      // Path to zip file
+
+	return envs
+}
+
 // getMacOSSysroot returns the macOS SDK path using xcrun
 func getMacOSSysroot() (string, error) {
 	cmd := exec.Command("xcrun", "--sdk", "macosx", "--show-sdk-path")
@@ -347,6 +424,9 @@ func useTarget(targetName string) (export Export, err error) {
 	export.GOOS = config.GOOS
 	export.GOARCH = config.GOARCH
 
+	// Build environment map for template variable expansion
+	envs := buildEnvMap(env.LLGoROOT())
+
 	// Convert LLVMTarget, CPU, Features to CCFLAGS/LDFLAGS
 	var ccflags []string
 	var ldflags []string
@@ -361,7 +441,9 @@ func useTarget(targetName string) (export Export, err error) {
 		cflags = append(cflags, "--target="+config.LLVMTarget)
 		ccflags = append(ccflags, "--target="+config.LLVMTarget)
 	}
-	cflags = append(cflags, config.CFlags...)
+	// Expand template variables in cflags
+	expandedCFlags := expandEnvSlice(config.CFlags, envs)
+	cflags = append(cflags, expandedCFlags...)
 
 	// Inspired by tinygo
 	cpu := config.CPU
@@ -394,10 +476,11 @@ func useTarget(targetName string) (export Export, err error) {
 	}
 	ldflags = append(ldflags, "-L", env.LLGoROOT()) // search targets/*.ld
 
-	// Combine with config flags
+	// Combine with config flags and expand template variables
 	export.CFLAGS = cflags
 	export.CCFLAGS = ccflags
-	export.LDFLAGS = append(ldflags, config.LDFlags...)
+	expandedLDFlags := expandEnvSlice(config.LDFlags, envs)
+	export.LDFLAGS = append(ldflags, expandedLDFlags...)
 
 	return export, nil
 }