cgen: fix comptime ref argument passing (#21335)

vlib/v/gen/c/fn.v

@@ -1282,6 +1282,14 @@ fn (mut g Gen) resolve_comptime_args(func ast.Fn, mut node_ ast.CallExpr, concre
 					if param_typ.nr_muls() > 0 && comptime_args[k].nr_muls() > 0 {
 						comptime_args[k] = comptime_args[k].set_nr_muls(0)
 					}
+				} else if mut call_arg.expr.right is ast.Ident {
+					mut ctyp := g.comptime.get_comptime_var_type(call_arg.expr.right)
+					if ctyp != ast.void_type {
+						comptime_args[k] = ctyp
+						if param_typ.nr_muls() > 0 && comptime_args[k].nr_muls() > 0 {
+							comptime_args[k] = comptime_args[k].set_nr_muls(0)
+						}
+					}
 				}
 			} else if mut call_arg.expr is ast.ComptimeSelector {
 				comptime_args[k] = g.comptime.comptime_for_field_type

vlib/v/tests/comptime_ref_arg_test.v

@@ -0,0 +1,101 @@
+// Declare structures covering a subset of a HAR file
+
+struct HarContent {
+	size      i64
+	mime_type string @[json: 'mimeType']
+}
+
+struct HarResponse {
+	content HarContent
+}
+
+struct HarEntry {
+	response HarResponse
+}
+
+pub struct HarLog {
+	entries []HarEntry
+}
+
+struct Har {
+	log HarLog
+}
+
+// Declare function printing object contents using generics
+
+fn show[T](val T) {
+	$if T is string {
+		show_string(val)
+	} $else $if T is $array {
+		show_array(val)
+	} $else $if T is $struct {
+		show_struct(&val)
+	} $else {
+		print('primitive: ${val.str()}')
+	}
+}
+
+fn show_array[T](array []T) {
+	println('array []${T.name}')
+	for i, item in array {
+		println('item ${i}')
+		show(item)
+		println('')
+	}
+}
+
+fn show_struct[T](object &T) {
+	println('struct ${T.name}')
+	$for field in T.fields {
+		mut json_name := field.name
+		for attr in field.attrs {
+			if attr.starts_with('json: ') {
+				json_name = attr[6..]
+			}
+		}
+
+		print('key: ')
+		show_string(json_name)
+		println('')
+
+		println('value ${T.name}.${field.name} (json: ${json_name}), field.typ: ${field.typ}')
+		$if field.typ is string {
+			print('string: ')
+			show_string(object.$(field.name))
+		} $else $if field.is_array {
+			show_array(object.$(field.name))
+		} $else $if field.is_struct {
+			item := object.$(field.name)
+			show_struct(&item)
+		} $else {
+			print('primitive: ')
+			print(object.$(field.name).str())
+		}
+		println('')
+	}
+}
+
+fn show_string(s string) {
+	print(`"`)
+	print(s)
+	print(`"`)
+}
+
+fn test_main() {
+	har := Har{
+		log: HarLog{
+			entries: [
+				HarEntry{
+					response: HarResponse{
+						content: HarContent{
+							size: 48752
+							mime_type: 'text/html'
+						}
+					}
+				},
+			]
+		}
+	}
+	show(har)
+	assert true
+}