1 /* $NetBSD: gcc_attribute.c,v 1.10 2021/07/15 21:00:05 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 88 /* 89 * Ensure that __attribute__ can be specified everywhere in a declaration. 90 * This is the simplest possible requirement that covers all valid code. 91 * It accepts invalid code as well, but these cases are covered by GCC and 92 * Clang already. 93 * 94 * Since lint only parses the attributes but doesn't really relate them to 95 * identifiers or other entities, ensuring that valid code can be parsed is 96 * enough for now. 97 * 98 * To really associate __attribute__ with the corresponding entity, the 99 * grammar needs to be rewritten, see the example with __noreturn__ above. 100 */ 101 __attribute__((deprecated("d1"))) 102 const 103 __attribute__((deprecated("d2"))) 104 int 105 __attribute__((deprecated("d3"))) 106 * 107 // The below line would produce a syntax error. 108 // __attribute__((deprecated("d3"))) 109 const 110 __attribute__((deprecated("d4"))) 111 identifier 112 __attribute__((deprecated("d5"))) 113 ( 114 __attribute__((deprecated("d6"))) 115 void 116 __attribute__((deprecated("d7"))) 117 ) 118 __attribute__((deprecated("d8"))) 119 ; 120 121 /* 122 * The attribute 'const' provides stronger guarantees than 'pure', and 123 * 'volatile' is not defined. To keep the grammar simple, any T_QUAL is 124 * allowed at this point, but only syntactically. 125 */ 126 int const_function(int) __attribute__((const)); 127 /* cover 'gcc_attribute_spec: T_QUAL' */ 128 /* expect+1: syntax error 'volatile' [249] */ 129 int volatile_function(int) __attribute__((volatile)); 130