checker: add a deprecation warning for const () groups (an error af…

…ter 2025-01-01) (#22019)

cmd/tools/vcreate/project_model_web.v

@@ -355,9 +355,7 @@ import vweb
 import databases
 import os
 
-const (
-	port = 8082
-)
+const port = 8082
 
 struct App {
 	vweb.Context

vlib/regex/regex_test.v

@@ -17,8 +17,7 @@ struct TestItem {
 }
 
 // vfmt off
-const(
-match_test_suite = [
+const match_test_suite = [
 	// minus in CC
 	TestItem{"d.def",r"abc.\.[\w\-]{,100}",-1,0},
 	TestItem{"abc12345.asd",r"abc.\.[\w\-]{,100}",-1,4},
@@ -203,10 +202,8 @@ match_test_suite = [
     TestItem{"abcAAxyz", r"^abc\X4141xyz$", 0,8},
     TestItem{"abcALxyz", r"^abc\X414cxyz$", 0,8},
     TestItem{"abcALxyz", r"^abc\X414Cxyz$", 0,8},
-    TestItem{"abcBxyz", r"^abc\x41+xyz$", -1,3},
-
+    TestItem{"abcBxyz", r"^abc\x41+xyz$", -1,3},    
 ]
-)
 
 struct TestItemRe {
 	src string
@@ -215,8 +212,7 @@ struct TestItemRe {
 	r   string
 }
 
-const (
-match_test_suite_replace = [
+const match_test_suite_replace = [
 	// replace tests
 	TestItemRe{
 		"oggi pibao è andato a casa di pbababao ed ha trovato pibabababao",
@@ -250,7 +246,7 @@ match_test_suite_replace = [
 	},
 ]
 
-match_test_suite_replace_simple = [
+const match_test_suite_replace_simple = [
 	// replace tests
 	TestItemRe{
 		"oggi pibao è andato a casa di pbababao ed ha trovato pibabababao",
@@ -265,7 +261,6 @@ match_test_suite_replace_simple = [
 		"CIAO is a good day and CIAO will be for sure."
 	},
 ]
-)
 
 struct TestItemCGroup {
 	src string
@@ -276,8 +271,7 @@ struct TestItemCGroup {
 	cgn map[string]int
 }
 
-const (
-cgroups_test_suite = [
+const cgroups_test_suite = [
 	TestItemCGroup{
 		"http://www.ciao.mondo/hello/pippo12_/pera.html",
 		r"(?P<format>https?)|(?:ftps?)://(?P<token>[\w_]+[\.|/])+",0,42,
@@ -316,7 +310,6 @@ cgroups_test_suite = [
 		map[string]int{}
 	},
 ]
-)
 
 struct Test_find_all {
 	src     string
@@ -325,8 +318,7 @@ struct Test_find_all {
 	res_str []string // ['find0','find1'...]
 }
 
-const (
-find_all_test_suite = [
+const find_all_test_suite = [
 	Test_find_all{
 		"abcd 1234 efgh 1234 ghkl1234 ab34546df",
 		r"\d+",
@@ -417,18 +409,16 @@ find_all_test_suite = [
 		[0, 2],
 		['ab']
 	}
-
 ]
-)
+
 
 struct Test_split {
 	src string
 	q   string
 	res []string // ['abc','def',...]
 }
 
-const (
-	split_test_suite = [
+const split_test_suite = [
 		Test_split{'abcd 1234 efgh 1234 ghkl1234 ab34546df', r'\d+', ['abcd ', ' efgh ', ' ghkl',
 			' ab', 'df']},
 		Test_split{'abcd 1234 efgh 1234 ghkl1234 ab34546df', r'\a+', ['', ' 1234 ', ' 1234 ', '1234 ',
@@ -457,7 +447,6 @@ const (
 		Test_split{'a-', r'-', ['a', '']},
 		Test_split{'-a', r'-', ['', 'a']},
 	]
-)
 // vfmt on
 
 fn test_regex() {

vlib/v/ast/str.v

@@ -756,8 +756,7 @@ pub fn (node Stmt) str() string {
 			return node.str()
 		}
 		ConstDecl {
-			fields := node.fields.map(field_to_string)
-			return 'const (${fields.join(' ')})'
+			return node.fields.map(field_to_string).join('')
 		}
 		DeferStmt {
 			mut res := ''
@@ -870,7 +869,7 @@ pub fn (node Stmt) str() string {
 
 fn field_to_string(f ConstField) string {
 	x := f.name.trim_string_left(f.mod + '.')
-	return '${x} = ${f.expr}'
+	return 'const ${x} = ${f.expr};'
 }
 
 pub fn (e ComptimeForKind) str() string {

vlib/v/checker/checker.v

@@ -1753,6 +1753,10 @@ fn (mut c Checker) const_decl(mut node ast.ConstDecl) {
 	if node.fields.len == 0 {
 		c.warn('const block must have at least 1 declaration', node.pos)
 	}
+	if node.is_block {
+		c.warn('const () groups will be an error after 2025-01-01 (`v fmt -w source.v` will fix that for you)',
+			node.pos)
+	}
 	for mut field in node.fields {
 		if checker.reserved_type_names_chk.matches(util.no_cur_mod(field.name, c.mod)) {
 			c.error('invalid use of reserved type `${field.name}` as a const name', field.pos)

vlib/v/checker/tests/const_decl_multi_return_err.out

@@ -1,7 +1,7 @@
-vlib/v/checker/tests/const_decl_multi_return_err.vv:6:6: error: const declarations do not support multiple return values yet
-    4 |
-    5 | const (
-    6 |     a = foo()
-      |         ~~~~~
-    7 | )
-    8 |
+vlib/v/checker/tests/const_decl_multi_return_err.vv:5:11: error: const declarations do not support multiple return values yet
+    3 | }
+    4 | 
+    5 | const a = foo()
+      |           ~~~~~
+    6 | 
+    7 | fn main() {

vlib/v/checker/tests/const_decl_multi_return_err.vv

@@ -2,11 +2,8 @@ fn foo() (int, int, int) {
 	return 1, 2, 3
 }
 
-const (
-	a = foo()
-)
-
+const a = foo()
 
 fn main() {
-	println("$a")
+	println('${a}')
 }

vlib/v/checker/tests/const_define_in_function_err.out

@@ -1,6 +1,6 @@
 vlib/v/checker/tests/const_define_in_function_err.vv:2:2: error: const can only be defined at the top level (outside of functions)
     1 | fn main() {
-    2 |     const (a = 1)
+    2 |     const a = 1
       |     ~~~~~
     3 |     println(a)
     4 | }

vlib/v/checker/tests/const_define_in_function_err.vv

@@ -1,4 +1,4 @@
 fn main() {
-	const (a = 1)
+	const a = 1
 	println(a)
 }

vlib/v/checker/tests/const_field_add_err.out

@@ -1,6 +1,6 @@
-vlib/v/checker/tests/const_field_add_err.vv:6:2: error: cannot modify constant `a`
-    4 | 
-    5 | fn main() {
-    6 |     a += 1
+vlib/v/checker/tests/const_field_add_err.vv:4:2: error: cannot modify constant `a`
+    2 | 
+    3 | fn main() {
+    4 |     a += 1
       |     ^
-    7 | }
+    5 | }

vlib/v/checker/tests/const_field_add_err.vv

@@ -1,6 +1,4 @@
-const (
-	a = 1
-)
+const a = 1
 
 fn main() {
 	a += 1

vlib/v/checker/tests/const_field_dec_err.out

@@ -1,6 +1,6 @@
-vlib/v/checker/tests/const_field_dec_err.vv:6:2: error: cannot modify constant `a`
-    4 | 
-    5 | fn main() {
-    6 |     a--
+vlib/v/checker/tests/const_field_dec_err.vv:4:2: error: cannot modify constant `a`
+    2 | 
+    3 | fn main() {
+    4 |     a--
       |     ^
-    7 | }
+    5 | }

vlib/v/checker/tests/const_field_dec_err.vv

@@ -1,6 +1,4 @@
-const (
-	a = 1
-)
+const a = 1
 
 fn main() {
 	a--

vlib/v/checker/tests/const_field_inc_err.out

@@ -1,6 +1,6 @@
-vlib/v/checker/tests/const_field_inc_err.vv:6:2: error: cannot modify constant `a` 
-    4 | 
-    5 | fn main() {
-    6 |     a++
+vlib/v/checker/tests/const_field_inc_err.vv:4:2: error: cannot modify constant `a`
+    2 | 
+    3 | fn main() {
+    4 |     a++
       |     ^
-    7 | }
+    5 | }

vlib/v/checker/tests/const_field_inc_err.vv

@@ -1,6 +1,4 @@
-const (
-	a = 1
-)
+const a = 1
 
 fn main() {
 	a++

vlib/v/checker/tests/const_field_name_duplicate_err.out

@@ -1,7 +1,6 @@
-vlib/v/checker/tests/const_field_name_duplicate_err.vv:3:2: error: duplicate const `aaa`
-    1 | const (
-    2 |     aaa = 1
-    3 |     aaa = 2
-      |     ~~~
-    4 | )
-    5 | fn main() {
+vlib/v/checker/tests/const_field_name_duplicate_err.vv:2:1: error: unexpected name `cosnt`
+    1 | const aaa = 1
+    2 | cosnt aaa = 2
+      | ~~~~~
+    3 | 
+    4 | fn main() {

vlib/v/checker/tests/const_field_name_duplicate_err.vv

@@ -1,7 +1,6 @@
-const (
-	aaa = 1
-	aaa = 2
-)
+const aaa = 1
+cosnt aaa = 2
+
 fn main() {
 	println(aaa)
 }

vlib/v/checker/tests/const_field_name_snake_case.out

@@ -1,6 +1,5 @@
-vlib/v/checker/tests/const_field_name_snake_case.vv:2:2: error: const names cannot contain uppercase letters, use snake_case instead
-    1 | const (
-    2 |     Red = 1
-      |     ~~~
-    3 | )
-    4 | fn main() { println(Red) }
+vlib/v/checker/tests/const_field_name_snake_case.vv:1:7: error: const names cannot contain uppercase letters, use snake_case instead
+    1 | const Red = 1
+      |       ~~~
+    2 | 
+    3 | fn main() { println(Red) }

vlib/v/checker/tests/const_field_name_snake_case.vv

@@ -1,4 +1,3 @@
-const (
-	Red = 1
-)
+const Red = 1
+
 fn main() { println(Red) }

vlib/v/checker/tests/const_field_sub_err.out

@@ -1,6 +1,6 @@
-vlib/v/checker/tests/const_field_sub_err.vv:6:2: error: cannot modify constant `a`
-    4 | 
-    5 | fn main() {
-    6 |     a -= 1
+vlib/v/checker/tests/const_field_sub_err.vv:4:2: error: cannot modify constant `a`
+    2 | 
+    3 | fn main() {
+    4 |     a -= 1
       |     ^
-    7 | }
+    5 | }

vlib/v/checker/tests/const_field_sub_err.vv

@@ -1,6 +1,4 @@
-const (
-	a = 1
-)
+const a = 1
 
 fn main() {
 	a -= 1

vlib/v/checker/tests/globals/name_conflict_with_const.out

@@ -1,6 +1,5 @@
-vlib/v/checker/tests/globals/name_conflict_with_const.vv:6:2: error: duplicate global and const `foo`
-    4 | 
-    5 | __global (
-    6 |     foo = 123
-      |     ~~~
-    7 | )
+vlib/v/checker/tests/globals/name_conflict_with_const.vv:3:10: error: duplicate global and const `foo`
+    1 | const foo = 'abc'
+    2 | 
+    3 | __global foo = 123
+      |          ~~~

vlib/v/checker/tests/globals/name_conflict_with_const.vv

@@ -1,7 +1,3 @@
-const (
-	foo = 'abc'
-)
+const foo = 'abc'
 
-__global (
-	foo = 123
-)
+__global foo = 123

vlib/v/checker/tests/if_diff_expected_type_err.out

@@ -1,7 +1,7 @@
-vlib/v/checker/tests/if_diff_expected_type_err.vv:7:11: error: mismatched types `&[]rune` and `[]rune`
-    5 | 
-    6 | fn main() {
-    7 |     runes := if true { &some_runes } else { some_other_runes }
+vlib/v/checker/tests/if_diff_expected_type_err.vv:5:11: error: mismatched types `&[]rune` and `[]rune`
+    3 | 
+    4 | fn main() {
+    5 |     runes := if true { &some_runes } else { some_other_runes }
       |              ~~
-    8 |     println(runes)
-    9 | }
+    6 |     println(runes)
+    7 | }

vlib/v/checker/tests/if_diff_expected_type_err.vv

@@ -1,9 +1,7 @@
-const (
-	some_runes       = [`a`, `b`, `c`]
-	some_other_runes = [`c`, `b`, `a`]
-)
+const some_runes = [`a`, `b`, `c`]
+const some_other_runes = [`c`, `b`, `a`]
 
 fn main() {
 	runes := if true { &some_runes } else { some_other_runes }
 	println(runes)
-}
+}

vlib/v/checker/tests/incorrect_name_const.vv

@@ -1,3 +1 @@
-const (
-	_my_const = 0
-)
+const _my_const = 0

vlib/v/checker/tests/lock_const.out

@@ -1,7 +1,7 @@
-vlib/v/checker/tests/lock_const.vv:7:8: error: `a` must be declared as `shared` variable to be locked
-    5 | fn main() {
-    6 |     mut c := 0
-    7 |     rlock a {
+vlib/v/checker/tests/lock_const.vv:5:8: error: `a` must be declared as `shared` variable to be locked
+    3 | fn main() {
+    4 |     mut c := 0
+    5 |     rlock a {
       |           ^
-    8 |         c = a
-    9 |     }
+    6 |         c = a
+    7 |     }

vlib/v/checker/tests/lock_const.vv

@@ -1,6 +1,4 @@
-const (
-	a = 5
-)
+const a = 5
 
 fn main() {
 	mut c := 0