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gcc_attribute.c revision 1.8 
      1 /*	$NetBSD: gcc_attribute.c,v 1.8 2021/07/06 18:43:27 rillig Exp $	*/
      2 # 3 "gcc_attribute.c"
      3 
      4 /*
      5  * Tests for the various attributes for functions, types, statements that are
      6  * provided by GCC.
      7  *
      8  * https://gcc.gnu.org/onlinedocs/gcc/Attribute-Syntax.html
      9  */
     10 
     11 void __attribute__((noinline))
     12 do_not_inline(void)
     13 {
     14 }
     15 
     16 /* All pointer arguments must be nonnull. */
     17 void __attribute__((nonnull))
     18 function_nonnull(void *, const void *, int);
     19 
     20 /*
     21  * The documentation suggests that the argument list of nonnull be nonempty,
     22  * but GCC 9.3.0 accepts an empty list as well, treating all parameters as
     23  * nonnull.
     24  */
     25 void __attribute__((nonnull()))
     26 function_nonnull_list(void *, const void *, int);
     27 
     28 /* Arguments 1 and 2 must be nonnull. */
     29 void __attribute__((nonnull(1, 2)))
     30 function_nonnull_list(void *, const void *, int);
     31 
     32 /* expect+1: syntax error 'unknown_attribute' */
     33 void __attribute__((unknown_attribute))
     34 function_with_unknown_attribute(void);
     35 
     36 /*
     37  * There is an attribute called 'pcs', but that attribute must not prevent an
     38  * ordinary variable from being named the same.  Starting with scan.l 1.77
     39  * from 2017-01-07, that variable name generated a syntax error.  Fixed in
     40  * lex.c 1.33 from 2021-05-03.
     41  *
     42  * Seen in yds.c, function yds_allocate_slots.
     43  */
     44 int
     45 local_variable_pcs(void)
     46 {
     47 	int pcs = 3;
     48 	return pcs;
     49 }
     50 
     51 /*
     52  * FIXME: The attributes are handled by different grammar rules even though
     53  *  they occur in the same syntactical position.
     54  *
     55  * Grammar rule abstract_decl_param_list handles the first attribute.
     56  *
     57  * Grammar rule direct_abstract_declarator handles all remaining attributes.
     58  *
     59  * Since abstract_decl_param_list contains type_attribute_opt, this could be
     60  * the source of the many shift/reduce conflicts in the grammar.
     61  */
     62 int
     63 func(
     64     int(int)
     65     __attribute__((__noreturn__))
     66     __attribute__((__noreturn__))
     67 );
     68 
     69 /*
     70  * https://gcc.gnu.org/onlinedocs/gcc/Attribute-Syntax.html says that the
     71  * attribute-list is a "possibly empty comma-separated sequence of
     72  * attributes".
     73  *
     74  * No matter whether this particular example is interpreted as an empty list
     75  * or a list containing a single empty attribute, the result is the same in
     76  * both cases.
     77  */
     78 void one_empty_attribute(void)
     79     __attribute__((/* none */));
     80 
     81 /*
     82  * https://gcc.gnu.org/onlinedocs/gcc/Attribute-Syntax.html further says that
     83  * each individual attribute may be "Empty. Empty attributes are ignored".
     84  */
     85 void two_empty_attributes(void)
     86     __attribute__((/* none */, /* still none */));
     87