fmt: fix inserted empty line before go stmt with anonymus function (#8951)

vlib/v/ast/ast.v

@@ -1340,12 +1340,9 @@ pub fn (stmt Stmt) position() token.Position {
 	match stmt {
 		AssertStmt, AssignStmt, Block, BranchStmt, CompFor, ConstDecl, DeferStmt, EnumDecl, ExprStmt,
 		FnDecl, ForCStmt, ForInStmt, ForStmt, GotoLabel, GotoStmt, Import, Return, StructDecl,
-		GlobalDecl, HashStmt, InterfaceDecl, Module, SqlStmt {
+		GlobalDecl, HashStmt, InterfaceDecl, Module, SqlStmt, GoStmt {
 			return stmt.pos
 		}
-		GoStmt {
-			return stmt.call_expr.pos
-		}
 		TypeDecl {
 			match stmt {
 				AliasTypeDecl, FnTypeDecl, SumTypeDecl { return stmt.pos }

vlib/v/fmt/fmt.v

@@ -310,7 +310,7 @@ pub fn (f Fmt) imp_stmt_str(imp ast.Import) string {
 	return '$imp.mod$imp_alias_suffix'
 }
 
-fn (mut f Fmt) should_insert_newline_before_stmt(stmt ast.Stmt, prev_stmt ast.Stmt) bool {
+fn (f Fmt) should_insert_newline_before_stmt(stmt ast.Stmt, prev_stmt ast.Stmt) bool {
 	prev_line_nr := prev_stmt.position().last_line
 	// No need to insert a newline if there is already one
 	if f.out.last_n(2) == '\n\n' {

vlib/v/fmt/tests/go_stmt_keep.vv

@@ -0,0 +1,9 @@
+import sync
+
+fn go_with_anon_fn() {
+	wg.add(1)
+	go fn (mut wg sync.WaitGroup) {
+		wg.done()
+	}(mut wg)
+	wg.wait()
+}

vlib/v/parser/parser.v

@@ -779,7 +779,7 @@ pub fn (mut p Parser) stmt(is_top_level bool) ast.Stmt {
 			}
 			return ast.GoStmt{
 				call_expr: call_expr
-				pos: spos.extend(p.tok.position())
+				pos: spos.extend(p.prev_tok.position())
 			}
 		}
 		.key_goto {