fmt: fix removal of Abc in import mod { Abc }, where Abc is used in a x as Abc expression #10306

vlib/v/fmt/fmt.v

@@ -1561,6 +1561,7 @@ fn should_decrease_arr_penalty(e ast.Expr) bool {
 }
 
 pub fn (mut f Fmt) as_cast(node ast.AsCast) {
+	f.mark_types_import_as_used(node.typ)
 	type_str := f.table.type_to_str_using_aliases(node.typ, f.mod2alias)
 	f.expr(node.expr)
 	f.write(' as $type_str')

vlib/v/fmt/tests/cast_expected.vv

@@ -1,4 +1,4 @@
-import v.ast
+import v.ast { InfixExpr }
 import v.table
 
 fn test_as() {

vlib/v/fmt/tests/import_selective_expected.vv

@@ -11,6 +11,7 @@ import mod {
 	InterfaceField,
 	InterfaceMethodArg,
 	InterfaceMethodRet,
+	RightOfAs,
 	RightOfIs,
 	StructEmbed,
 	StructField,
@@ -37,6 +38,7 @@ interface Interface {
 fn f(v FnArg) FnRet {
 	if v is RightOfIs {
 	}
+	_ = v as RightOfAs
 
 	return {}
 }

vlib/v/fmt/tests/import_selective_input.vv

@@ -21,6 +21,7 @@ import mod {
 	FnRet,
 
 	RightOfIs,
+	RightOfAs,
 }
 
 struct Struct {
@@ -40,6 +41,7 @@ interface Interface {
 
 fn f(v FnArg) FnRet {
 	if v is RightOfIs {}
+	_ = v as RightOfAs
 
 	return {}
 }