parser: disallow indexing on next line at top-level (#8128)

vlib/v/parser/fn.v

@@ -390,7 +390,9 @@ fn (mut p Parser) fn_decl() ast.FnDecl {
 	no_body := p.tok.kind != .lcbr
 	body_start_pos := p.peek_tok.position()
 	if p.tok.kind == .lcbr {
+		p.inside_fn = true
 		stmts = p.parse_block_no_scope(true)
+		p.inside_fn = false
 	}
 	if !no_body && are_args_type_only {
 		p.error_with_pos('functions with type only args can not have bodies', body_start_pos)

vlib/v/parser/parser.v

@@ -41,7 +41,7 @@ mut:
 	inside_ct_if_expr bool
 	inside_or_expr    bool
 	inside_for        bool
-	inside_fn         bool
+	inside_fn         bool // true even with implicit main
 	inside_str_interp bool
 	or_is_handled     bool         // ignore `or` in this expression
 	builtin_mod       bool         // are we in the `builtin` module?
@@ -532,6 +532,7 @@ pub fn (mut p Parser) top_stmt() ast.Stmt {
 				return p.comment_stmt()
 			}
 			else {
+				p.inside_fn = true
 				if p.pref.is_script && !p.pref.is_test {
 					mut stmts := []ast.Stmt{}
 					for p.tok.kind != .eof {

vlib/v/parser/pratt.v

@@ -286,7 +286,7 @@ pub fn (mut p Parser) expr_with_left(left ast.Expr, precedence int, is_stmt_iden
 				return node
 			}
 			p.is_stmt_ident = is_stmt_ident
-		} else if p.tok.kind == .lsbr {
+		} else if p.tok.kind == .lsbr && (p.inside_fn || p.tok.line_nr == p.prev_tok.line_nr) {
 			node = p.index_expr(node)
 			p.is_stmt_ident = is_stmt_ident
 			if p.tok.kind == .lpar && p.tok.line_nr == p.prev_tok.line_nr && node is ast.IndexExpr {

vlib/v/parser/tests/const_index.out

@@ -0,0 +1 @@
+

vlib/v/parser/tests/const_index.vv

@@ -0,0 +1,22 @@
+// must not parse 4[deprecated] as index expression
+const x = 4
+[deprecated]
+fn g() {
+	a := [3]
+	// indexing is currently allowed on next line
+	_ = a
+	[0]
+}
+
+const y = 5
+[deprecated]
+fn h() {}
+
+const z = 6
+[typedef]
+struct C.Foo{}
+
+// test implicit main allows indexing on next line
+a := [3]
+_ := a
+[0]