checker: add support for deprecation messages for structs and struct …

…fields (#21017)

vlib/v/checker/struct.v

@@ -483,10 +483,20 @@ fn (mut c Checker) struct_init(mut node ast.StructInit, is_field_zero_struct_ini
 		&& type_sym.mod != 'builtin')) && !is_field_zero_struct_init {
 		c.error('type `${type_sym.name}` is private', node.pos)
 	}
-	if type_sym.info is ast.Struct && type_sym.mod != c.mod
-		&& type_sym.info.attrs.contains('noinit') {
-		c.error('struct `${type_sym.name}` is declared with a `@[noinit]` attribute, so ' +
-			'it cannot be initialized with `${type_sym.name}{}`', node.pos)
+	if type_sym.info is ast.Struct && type_sym.mod != c.mod {
+		for attr in type_sym.info.attrs {
+			match attr.name {
+				'noinit' {
+					c.error(
+						'struct `${type_sym.name}` is declared with a `@[noinit]` attribute, so ' +
+						'it cannot be initialized with `${type_sym.name}{}`', node.pos)
+				}
+				'deprecated' {
+					c.deprecate('struct', type_sym.name, type_sym.info.attrs, node.pos)
+				}
+				else {}
+			}
+		}
 	}
 	if type_sym.name.len == 1 && c.table.cur_fn != unsafe { nil }
 		&& c.table.cur_fn.generic_names.len == 0 {
@@ -506,9 +516,20 @@ fn (mut c Checker) struct_init(mut node ast.StructInit, is_field_zero_struct_ini
 			}
 			sym := c.table.sym(c.unwrap_generic(node.typ))
 			if sym.info is ast.Struct {
-				if sym.mod != c.mod && sym.info.attrs.contains('noinit') {
-					c.error('struct `${sym.name}` is declared with a `@[noinit]` attribute, so ' +
-						'it cannot be initialized with `${sym.name}{}`', node.pos)
+				if sym.mod != c.mod {
+					for attr in sym.info.attrs {
+						match attr.name {
+							'noinit' {
+								c.error(
+									'struct `${sym.name}` is declared with a `@[noinit]` attribute, so ' +
+									'it cannot be initialized with `${sym.name}{}`', node.pos)
+							}
+							'deprecated' {
+								c.deprecate('struct', sym.name, sym.info.attrs, node.pos)
+							}
+							else {}
+						}
+					}
 				}
 				if node.no_keys && node.init_fields.len != sym.info.fields.len {
 					fname := if sym.info.fields.len != 1 { 'fields' } else { 'field' }
@@ -742,6 +763,14 @@ or use an explicit `unsafe{ a[..] }`, if you do not want a copy of the slice.',
 
 			for i, mut field in fields {
 				if field.name in inited_fields {
+					if c.mod != type_sym.mod && field.is_deprecated {
+						for init_field in node.init_fields {
+							if field.name == init_field.name {
+								c.deprecate('field', field.name, field.attrs, init_field.pos)
+								break
+							}
+						}
+					}
 					continue
 				}
 				sym := c.table.sym(field.typ)

vlib/v/checker/tests/.gitignore

@@ -1,5 +1,2 @@
-*.v
-*.c
 require_or_block_sumtype_map.err
 !*_test.v
-!modules/**/*.v

vlib/v/checker/tests/field_deprecations.vv

@@ -1,4 +1,4 @@
-import v.checker.tests.module_with_structs_with_deprecated_fields as m
+import v.checker.tests.module_with_deprecated_structs as m
 
 struct Abc {
 mut:

vlib/v/checker/tests/module_with_structs_with_deprecated_fields/fields.v → vlib/v/checker/tests/module_with_deprecated_structs/module.v

@@ -1,4 +1,4 @@
-module module_with_structs_with_deprecated_fields
+module module_with_deprecated_structs
 
 pub struct Xyz {
 pub mut:
@@ -8,14 +8,26 @@ pub mut:
 	d int @[deprecated: 'd use Xyz.a instead'; deprecated_after: '2999-03-01']
 }
 
+@[deprecated: 'use New instead']
+@[deprecated_after: '2021-03-01']
+pub struct Old {}
+
+@[deprecated: 'use Future instead']
+@[deprecated_after: '2999-03-01']
+pub struct Present {}
+
 fn some_internal_function() {
 	mut x := Xyz{} // initialisation; no error
+	mut o := Old{}
+	mut p := Present{}
 
 	// reads:
 	dump(x.a) // no error
 	dump(x.b) // no error internally
 	dump(x.c) // no error internally
 	dump(x.d) // no error internally
+	dump(o) // no error internally
+	dump(p) // no error internally
 
 	// writes:
 	x.a = 1 // no error

vlib/v/checker/tests/struct_init_deprecations.out

@@ -0,0 +1,35 @@
+vlib/v/checker/tests/struct_init_deprecations.vv:5:9: notice: struct `v.checker.tests.module_with_deprecated_structs.Present` will be deprecated after 2999-03-01, and will become an error after 2999-08-28; use Future instead
+    3 | fn init_deprecated_structs() {
+    4 |     o := m.Old{}
+    5 |     p := m.Present{}
+      |            ~~~~~~~~~
+    6 |     dump(o)
+    7 |     dump(p)
+vlib/v/checker/tests/struct_init_deprecations.vv:15:3: notice: field `d` will be deprecated after 2999-03-01, and will become an error after 2999-08-28; d use Xyz.a instead
+   13 |         b: 1
+   14 |         c: 2
+   15 |         d: 3
+      |         ~~~~
+   16 |     }
+   17 |     dump(x)
+vlib/v/checker/tests/struct_init_deprecations.vv:13:3: warning: field `b` has been deprecated
+   11 |     x := m.Xyz{
+   12 |         a: 0
+   13 |         b: 1
+      |         ~~~~
+   14 |         c: 2
+   15 |         d: 3
+vlib/v/checker/tests/struct_init_deprecations.vv:4:9: error: struct `v.checker.tests.module_with_deprecated_structs.Old` has been deprecated since 2021-03-01; use New instead
+    2 | 
+    3 | fn init_deprecated_structs() {
+    4 |     o := m.Old{}
+      |            ~~~~~
+    5 |     p := m.Present{}
+    6 |     dump(o)
+vlib/v/checker/tests/struct_init_deprecations.vv:14:3: error: field `c` has been deprecated since 2021-03-01; c use Xyz.a instead
+   12 |         a: 0
+   13 |         b: 1
+   14 |         c: 2
+      |         ~~~~
+   15 |         d: 3
+   16 |     }

vlib/v/checker/tests/struct_init_deprecations.vv

@@ -0,0 +1,23 @@
+import v.checker.tests.module_with_deprecated_structs as m
+
+fn init_deprecated_structs() {
+	o := m.Old{}
+	p := m.Present{}
+	dump(o)
+	dump(p)
+}
+
+fn init_deprecated_fields() {
+	x := m.Xyz{
+		a: 0
+		b: 1
+		c: 2
+		d: 3
+	}
+	dump(x)
+}
+
+fn main() {
+	init_deprecated_structs()
+	init_deprecated_fields()
+}