Home | History | Annotate | Line # | Download | only in lint1 
      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  */
     23 const char *
     24 classify_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  */
     39 const char *
     40 classify_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  */
     55 const char *
     56 classify_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 */
     72 const int *
     73 comma_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 */
     88 int
     89 assignment_expression(int first, int second)
     90 {
     91 	return _Generic(first = second,
     92 	    int: second = first
     93 	);
     94 }
     95 
     96 int
     97 primary_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  */
    107 const char *x = _Generic(
    108     1ULL + 1.0f,
    109     int: 1
    110 );
    111