parser: add warning for s.$field.name without brackets (#8411)

vlib/v/checker/tests/comptime_field_selector_not_in_for_err.out

@@ -1,7 +1,7 @@
-vlib/v/checker/tests/comptime_field_selector_not_in_for_err.vv:9:5: error: expected selector expression e.g. `$(field.name)`
+vlib/v/checker/tests/comptime_field_selector_not_in_for_err.vv:9:6: error: expected selector expression e.g. `$(field.name)`
     7 |     mut t := T{}
     8 |     name := 'test'
-    9 |     t.$name = '3'
+    9 |     t.$(name) = '3'
       |         ~~~~
    10 | }
    11 |

vlib/v/checker/tests/comptime_field_selector_not_in_for_err.vv

@@ -6,7 +6,7 @@ struct Foo {
 fn test<T>() {
 	mut t := T{}
 	name := 'test'
-	t.$name = '3'
+	t.$(name) = '3'
 }
 
 fn main() {

vlib/v/checker/tests/comptime_field_selector_not_name_err.out

@@ -1,21 +1,21 @@
-vlib/v/checker/tests/comptime_field_selector_not_name_err.vv:10:7: error: expected `string` instead of `FieldData` (e.g. `field.name`)
+vlib/v/checker/tests/comptime_field_selector_not_name_err.vv:10:8: error: expected `string` instead of `FieldData` (e.g. `field.name`)
     8 |     $for f in T.fields {
     9 |         $if f.typ is string {
-   10 |             t.$f = '3'
+   10 |             t.$(f) = '3'
       |                 ^
    11 |             fv := Foo{}
-   12 |             _ = t.$fv.name
+   12 |             _ = t.$(fv.name)
-vlib/v/checker/tests/comptime_field_selector_not_name_err.vv:12:11: error: unknown `$for` variable `fv`
+vlib/v/checker/tests/comptime_field_selector_not_name_err.vv:12:12: error: unknown `$for` variable `fv`
-   10 |             t.$f = '3'
+   10 |             t.$(f) = '3'
    11 |             fv := Foo{}
-   12 |             _ = t.$fv.name
+   12 |             _ = t.$(fv.name)
       |                     ~~
    13 |         }
    14 |     }
-vlib/v/checker/tests/comptime_field_selector_not_name_err.vv:15:9: error: compile time field access can only be used when iterating over `T.fields`
+vlib/v/checker/tests/comptime_field_selector_not_name_err.vv:15:10: error: compile time field access can only be used when iterating over `T.fields`
    13 |         }
    14 |     }
-   15 |     _ = t.$f.name
+   15 |     _ = t.$(f.name)
       |             ^
    16 | }
    17 |

vlib/v/checker/tests/comptime_field_selector_not_name_err.vv

@@ -7,12 +7,12 @@ fn test<T>() {
 	mut t := T{}
 	$for f in T.fields {
 		$if f.typ is string {
-			t.$f = '3'
+			t.$(f) = '3'
 			fv := Foo{}
-			_ = t.$fv.name
+			_ = t.$(fv.name)
 		}
 	}
-	_ = t.$f.name
+	_ = t.$(f.name)
 }
 
 fn main() {

vlib/v/fmt/fmt.v

@@ -1156,8 +1156,7 @@ pub fn (mut f Fmt) comptime_call(node ast.ComptimeCall) {
 }
 
 pub fn (mut f Fmt) comptime_selector(node ast.ComptimeSelector) {
-	field_expr := if node.has_parens { '($node.field_expr)' } else { node.field_expr.str() }
+	f.write('${node.left}.\$($node.field_expr)')
-	f.write('${node.left}.$$field_expr')
 }
 
 pub fn (mut f Fmt) concat_expr(node ast.ConcatExpr) {

vlib/v/fmt/tests/comptime_field_selector_keep.vv

@@ -13,7 +13,7 @@ fn test<T>() {
 	t.name = '2'
 	$for f in T.fields {
 		$if f.typ is string {
-			println(t.$f.name)
+			println(t.$(f.name))
 		}
 	}
 }

vlib/v/parser/comptime.v

@@ -256,17 +256,9 @@ fn (mut p Parser) at() ast.AtExpr {
 
 fn (mut p Parser) comptime_selector(left ast.Expr) ast.Expr {
 	p.check(.dollar)
-	mut has_parens := false
-	if p.tok.kind == .lpar {
-		p.check(.lpar)
-		has_parens = true
-	}
 	if p.peek_tok.kind == .lpar {
 		method_name := p.check_name()
 		// `app.$action()` (`action` is a string)
-		if has_parens {
-			p.check(.rpar)
-		}
 		p.check(.lpar)
 		mut args_var := ''
 		if p.tok.kind == .name {
@@ -279,12 +271,18 @@ fn (mut p Parser) comptime_selector(left ast.Expr) ast.Expr {
 			p.check(.lcbr)
 		}
 		return ast.ComptimeCall{
-			has_parens: has_parens
 			left: left
 			method_name: method_name
 			args_var: args_var
 		}
 	}
+	mut has_parens := false
+	if p.tok.kind == .lpar {
+		p.check(.lpar)
+		has_parens = true
+	} else {
+		p.warn_with_pos('use brackets instead e.g. `s.$(field.name)` - run vfmt', p.tok.position())
+	}
 	expr := p.expr(0)
 	if has_parens {
 		p.check(.rpar)

vlib/v/tests/comptime_field_selector_test.v

@@ -12,7 +12,7 @@ fn comptime_field_selector_read<T>() []string {
 	mut value_list := []string{}
 	$for f in T.fields {
 		$if f.typ is string {
-			value_list << t.$f.name
+			value_list << t.$(f.name)
 		}
 	}
 	return value_list
@@ -26,10 +26,10 @@ fn comptime_field_selector_write<T>() T {
 	mut t := T{}
 	$for f in T.fields {
 		$if f.typ is string {
-			t.$f.name = '1'
+			t.$(f.name) = '1'
 		}
 		$if f.typ is int {
-			t.$f.name = 1
+			t.$(f.name) = 1
 		}
 	}
 	return t