1/*	$NetBSD: c11_generic_expression.c,v 1.19 2023/08/06 19:44:50 rillig Exp $	*/
2# 3 "c11_generic_expression.c"
3
4/* lint1-extra-flags: -X 351 */
5
6/*
7 * C99 added support for type-generic macros, but these were limited to the
8 * header <tgmath.h>.  C11 made this feature generally available.
9 *
10 * The generic selection is typically used with macros, but since lint1 works
11 * on the preprocessed source, the test cases look a bit strange.
12 *
13 * C11 6.5.1.1 "Generic selection"
14 */
15
16/* lint1-extra-flags: -Ac11 */
17
18/*
19 * The type of 'var' is not compatible with any of the types from the
20 * generic-association.  This is a constraint violation that the compiler must
21 * detect, therefore lint doesn't repeat that diagnostic.
22 */
23const char *
24classify_type_without_default(double var)
25{
26	/* expect-2: warning: parameter 'var' unused in function 'classify_type_without_default' [231] */
27
28	return _Generic(var,
29	    long double: "long double",
30	    long long: "long long",
31	    unsigned: "unsigned"
32	);
33	/* expect-1: error: function 'classify_type_without_default' expects to return value [214] */
34}
35
36/*
37 * In this case, the 'default' expression is selected.
38 */
39const char *
40classify_type_with_default(double var)
41{
42	/* expect-2: warning: parameter 'var' unused in function 'classify_type_with_default' [231] */
43
44	return _Generic(var,
45	    long double: "long double",
46	    long long: "long long",
47	    unsigned: "unsigned",
48	    default: "unknown"
49	);
50}
51
52/*
53 * The type of a _Generic expression is the one from the selected association.
54 */
55const char *
56classify_char(char c)
57{
58	/* expect-2: warning: parameter 'c' unused in function 'classify_char' [231] */
59
60	return _Generic(c,
61	    char: "yes",
62	    default: 0.0
63	);
64}
65
66/*
67 * Before cgram.y 1.238 from 2021-06-27, lint accepted a comma-expression,
68 * which looked as if _Generic would accept multiple arguments before the
69 * selection.
70 */
71/* ARGSUSED */
72const int *
73comma_expression(char first, double second)
74{
75	/* expect+1: error: syntax error 'second' [249] */
76	return _Generic(first, second,
77	    char: "first",
78	    double: 2.0
79	);
80	/* expect+1: warning: function 'comma_expression' falls off bottom without returning value [217] */
81}
82
83/*
84 * Ensure that assignment-expressions are accepted by the grammar, as
85 * opposed to comma-expressions.
86 */
87/* ARGSUSED */
88int
89assignment_expression(int first, int second)
90{
91	return _Generic(first = second,
92	    int: second = first
93	);
94}
95
96int
97primary_expression(void)
98{
99	return _Generic(0, int: assignment_expression)(0, 0);
100}
101
102/*
103 * The types don't match, therefore build_generic_selection returns NULL,
104 * which is then silently ignored by init_expr.  This situation is already
105 * covered by the compilers, so there is no need for lint to double-check it.
106 */
107const char *x = _Generic(
108    1ULL + 1.0f,
109    int: 1
110);
111