checker: warn for deprecated methods too (#8861)

vlib/v/checker/checker.v

@@ -1562,6 +1562,15 @@ pub fn (mut c Checker) call_method(mut call_expr ast.CallExpr) table.Type {
 			c.warn('method `${left_type_sym.name}.$method_name` must be called from an `unsafe` block',
 				call_expr.pos)
 		}
+		if !c.cur_fn.is_deprecated && method.is_deprecated {
+			mut deprecation_message := 'method `${left_type_sym.name}.$method.name` has been deprecated'
+			for attr in method.attrs {
+				if attr.name == 'deprecated' && attr.arg != '' {
+					deprecation_message += '; $attr.arg'
+				}
+			}
+			c.warn(deprecation_message, call_expr.pos)
+		}
 		// TODO: typ optimize.. this node can get processed more than once
 		if call_expr.expected_arg_types.len == 0 {
 			for i in 1 .. method.params.len {
@@ -1783,7 +1792,7 @@ pub fn (mut c Checker) call_fn(mut call_expr ast.CallExpr) table.Type {
 		c.error('function `$f.name` is private, so you can not import it in module `$c.mod`',
 			call_expr.pos)
 	}
-	if f.is_deprecated {
+	if !c.cur_fn.is_deprecated && f.is_deprecated {
 		mut deprecation_message := 'function `$f.name` has been deprecated'
 		for d in f.attrs {
 			if d.name == 'deprecated' && d.arg != '' {

vlib/v/checker/tests/use_deprecated_function_warning.out

@@ -11,3 +11,10 @@ vlib/v/checker/tests/use_deprecated_function_warning.vv:13:2: error: function `a
    13 |     abc()
       |     ~~~~~
    14 | }
+   15 |
+vlib/v/checker/tests/use_deprecated_function_warning.vv:23:4: error: method `S1.m` has been deprecated; use bar instead
+   21 | fn method() {
+   22 |     s := S1{}
+   23 |     s.m()
+      |       ~~~
+   24 | }

vlib/v/checker/tests/use_deprecated_function_warning.vv

@@ -12,3 +12,13 @@ fn main() {
 	xyz()
 	abc()
 }
+
+struct S1 {}
+
+[deprecated: 'use bar instead']
+fn (s S1) m() {}
+
+fn method() {
+	s := S1{}
+	s.m()
+}