gcc_typeof.c revision 1.2 
1/*	$NetBSD: gcc_typeof.c,v 1.2 2021/07/25 11:19:51 rillig Exp $	*/
2# 3 "gcc_typeof.c"
3
4/*
5 * Tests for the GCC extension 'typeof'.
6 *
7 * https://gcc.gnu.org/onlinedocs/gcc/Typeof.html
8 */
9
10void take_double(typeof(0.0));
11
12void take_function_double_returning_double(
13    /*
14     * FIXME: lint's grammar uses 'typeof cast_expression', while GCC's
15     *  c_parser_typeof_specifier uses 'typeof ( expression )'.  The crucial
16     *  difference is that lint parses the following expression as 'typeof
17     *  ((0.0)(typeof(0.0))', that is, it tries to call the function 0.0,
18     *  which of course is nonsense.
19     */
20    typeof(0.0)(
21	/* FIXME: GCC can parse this */
22	/* expect+1: error: syntax error 'typeof' [249] */
23	typeof(0.0)
24    )
25);
26
27void
28cast(double(*fn)(double))
29{
30	take_double(0.0);
31
32	/* expect+1: warning: passing 'pointer to function(double) returning double' to incompatible 'double', arg #1 [155] */
33	take_double(fn);
34
35	/* XXX: oops; GCC detects this type mismatch. probably due to the parse error. */
36	take_function_double_returning_double(0.0);
37
38	take_function_double_returning_double(fn);
39
40	/* identity cast */
41	take_function_double_returning_double((double (*)(double))fn);
42}
43