queries.c revision 1.26
1 /* $NetBSD: queries.c,v 1.26 2024/03/30 17:23:13 rillig Exp $ */ 2 # 3 "queries.c" 3 4 /* 5 * Demonstrate the case-by-case queries. Unlike warnings, queries do not 6 * point to questionable code but rather to code that may be interesting to 7 * inspect manually on a case-by-case basis. 8 * 9 * Possible use cases are: 10 * 11 * Understanding how C works internally, by making the usual arithmetic 12 * conversions visible. 13 * 14 * Finding code that intentionally suppresses a regular lint warning, 15 * such as casts between arithmetic types. 16 */ 17 18 /* lint1-extra-flags: -q 1,2,3,4,5,6,7,8,9,10 */ 19 /* lint1-extra-flags: -q 11,12,13,14,15,16,17,18,19 */ 20 /* lint1-extra-flags: -X 351 */ 21 22 typedef unsigned char u8_t; 23 typedef unsigned short u16_t; 24 typedef unsigned int u32_t; 25 typedef unsigned long long u64_t; 26 typedef signed char s8_t; 27 typedef signed short s16_t; 28 typedef signed int s32_t; 29 typedef signed long long s64_t; 30 31 typedef float f32_t; 32 typedef double f64_t; 33 typedef float _Complex c32_t; 34 typedef double _Complex c64_t; 35 36 typedef char *str_t; 37 typedef const char *cstr_t; 38 typedef volatile char *vstr_t; 39 typedef typeof(sizeof 0) size_t; 40 41 _Bool cond; 42 43 u8_t u8; 44 u16_t u16; 45 u32_t u32; 46 u64_t u64; 47 48 s8_t s8; 49 s16_t s16; 50 s32_t s32; 51 s64_t s64; 52 53 struct { 54 unsigned u8:8; 55 unsigned u9:9; 56 unsigned u10:10; 57 unsigned u32:32; 58 int s8:8; 59 int s9:9; 60 int s10:10; 61 int s32:32; 62 } bits; 63 64 f32_t f32; 65 f64_t f64; 66 67 c32_t c32; 68 c64_t c64; 69 70 char *str; 71 const char *cstr; 72 volatile char *vstr; 73 74 int 75 Q1(double dbl) 76 { 77 /* expect+1: implicit conversion from floating point 'double' to integer 'int' [Q1] */ 78 return dbl; 79 } 80 81 int 82 Q2(double dbl) 83 { 84 /* expect+1: cast from floating point 'double' to integer 'int' [Q2] */ 85 return (int)dbl; 86 } 87 88 // The Q3 query triggers so often that it also occurs outside this function. 89 void 90 Q3(int i, unsigned u) 91 { 92 /* expect+1: implicit conversion changes sign from 'int' to 'unsigned int' [Q3] */ 93 u = i; 94 95 /* expect+1: implicit conversion changes sign from 'unsigned int' to 'int' [Q3] */ 96 i = u; 97 98 /* expect+2: implicit conversion changes sign from 'unsigned char' to 'int' [Q3] */ 99 /* expect+1: implicit conversion changes sign from 'int' to 'unsigned short' [Q3] */ 100 u16 += u8; 101 /* expect+2: implicit conversion changes sign from 'unsigned short' to 'int' [Q3] */ 102 /* expect+1: implicit conversion changes sign from 'int' to 'unsigned int' [Q3] */ 103 u32 += u16; 104 } 105 106 unsigned long long 107 Q4(signed char *ptr, int i, unsigned long long ull, size_t sz) 108 { 109 110 /* 111 * For constants, the usual arithmetic conversions are usually not 112 * interesting, so omit them. 113 */ 114 u32 = u32 & 0xff; 115 u32 &= 0xff; 116 117 /* expect+2: usual arithmetic conversion for '&' from 'int' to 'unsigned int' [Q4] */ 118 /* expect+1: implicit conversion changes sign from 'int' to 'unsigned int' [Q3] */ 119 u32 = u32 & s32; 120 /* 121 * XXX: C99 5.6.16.2 says that the usual arithmetic conversions 122 * happen for compound assignments as well. 123 */ 124 /* expect+1: implicit conversion changes sign from 'int' to 'unsigned int' [Q3] */ 125 u32 &= s32; 126 127 /* expect+3: implicit conversion changes sign from 'unsigned char' to 'int' [Q3] */ 128 /* expect+2: usual arithmetic conversion for '&' from 'int' to 'unsigned int' [Q4] */ 129 /* expect+1: implicit conversion changes sign from 'int' to 'unsigned int' [Q3] */ 130 u32 = u32 & u8; 131 132 s8 = ptr[sz]; 133 134 /* 135 * The conversion from 'signed char' to 'int' is done by the integer 136 * promotions (C11 6.3.1.1p2), not by the usual arithmetic 137 * conversions (C11 6.3.1.8p1). 138 */ 139 /* expect+2: usual arithmetic conversion for '+' from 'int' to 'unsigned long long' [Q4] */ 140 /* expect+1: implicit conversion changes sign from 'int' to 'unsigned long long' [Q3] */ 141 return ptr[0] + ptr[1] + i + ull; 142 } 143 144 void 145 Q5(signed char *ptr, int i) 146 { 147 if (ptr + i > ptr) 148 return; 149 150 /* expect+1: pointer addition has integer on the left-hand side [Q5] */ 151 if (i + ptr > ptr) 152 return; 153 154 if (ptr[i] != '\0') 155 return; 156 157 /* expect+1: pointer addition has integer on the left-hand side [Q5] */ 158 if (i[ptr] != '\0') 159 return; 160 } 161 162 void 163 Q6(int i) 164 { 165 /* expect+1: no-op cast from 'int' to 'int' [Q6] */ 166 i = (int)4; 167 168 /* expect+1: no-op cast from 'int' to 'int' [Q6] */ 169 i = (int)i + 1; 170 } 171 172 void *allocate(void); 173 174 void 175 Q7(void) 176 { 177 178 /* expect+2: no-op cast from '_Bool' to '_Bool' [Q6] */ 179 /* expect+1: redundant cast from '_Bool' to '_Bool' before assignment [Q7] */ 180 cond = (_Bool)cond; 181 cond = (_Bool)u8; 182 u8 = (u8_t)cond; 183 184 /* expect+2: no-op cast from 'unsigned char' to 'unsigned char' [Q6] */ 185 /* expect+1: redundant cast from 'unsigned char' to 'unsigned char' before assignment [Q7] */ 186 u8 = (u8_t)u8; 187 u8 = (u8_t)u16; 188 u8 = (u16_t)u8; 189 /* expect+1: no-op cast from 'unsigned short' to 'unsigned short' [Q6] */ 190 u8 = (u16_t)u16; 191 /* expect+1: no-op cast from 'unsigned char' to 'unsigned char' [Q6] */ 192 u16 = (u8_t)u8; 193 u16 = (u8_t)u16; 194 /* expect+1: redundant cast from 'unsigned char' to 'unsigned short' before assignment [Q7] */ 195 u16 = (u16_t)u8; 196 /* expect+2: no-op cast from 'unsigned short' to 'unsigned short' [Q6] */ 197 /* expect+1: redundant cast from 'unsigned short' to 'unsigned short' before assignment [Q7] */ 198 u16 = (u16_t)u16; 199 200 /* Mixing signed and unsigned types. */ 201 u8 = (u8_t)s8; 202 s8 = (s8_t)u8; 203 /* expect+1: redundant cast from 'unsigned char' to 'short' before assignment [Q7] */ 204 s16 = (s16_t)u8; 205 /* expect+1: redundant cast from 'signed char' to 'short' before assignment [Q7] */ 206 s16 = (s16_t)s8; 207 208 209 /* 210 * Neither GCC nor Clang accept typeof(bit-field), as that would add 211 * unnecessary complexity. Lint accepts it but silently discards the 212 * bit-field portion from the type; see dcs_add_type. 213 */ 214 /* expect+1: redundant cast from 'unsigned char' to 'unsigned int' before assignment [Q7] */ 215 bits.u9 = (typeof(bits.u9))u8; 216 217 218 /* expect+2: no-op cast from 'float' to 'float' [Q6] */ 219 /* expect+1: redundant cast from 'float' to 'float' before assignment [Q7] */ 220 f32 = (f32_t)f32; 221 f32 = (f32_t)f64; 222 f32 = (f64_t)f32; 223 /* expect+1: no-op cast from 'double' to 'double' [Q6] */ 224 f32 = (f64_t)f64; 225 /* expect+1: no-op cast from 'float' to 'float' [Q6] */ 226 f64 = (f32_t)f32; 227 f64 = (f32_t)f64; 228 /* expect+1: redundant cast from 'float' to 'double' before assignment [Q7] */ 229 f64 = (f64_t)f32; 230 /* expect+2: no-op cast from 'double' to 'double' [Q6] */ 231 /* expect+1: redundant cast from 'double' to 'double' before assignment [Q7] */ 232 f64 = (f64_t)f64; 233 234 235 /* expect+2: no-op cast from 'float _Complex' to 'float _Complex' [Q6] */ 236 /* expect+1: redundant cast from 'float _Complex' to 'float _Complex' before assignment [Q7] */ 237 c32 = (c32_t)c32; 238 c32 = (c32_t)c64; 239 c32 = (c64_t)c32; 240 /* expect+1: no-op cast from 'double _Complex' to 'double _Complex' [Q6] */ 241 c32 = (c64_t)c64; 242 /* expect+1: no-op cast from 'float _Complex' to 'float _Complex' [Q6] */ 243 c64 = (c32_t)c32; 244 c64 = (c32_t)c64; 245 /* expect+1: redundant cast from 'float _Complex' to 'double _Complex' before assignment [Q7] */ 246 c64 = (c64_t)c32; 247 /* expect+2: no-op cast from 'double _Complex' to 'double _Complex' [Q6] */ 248 /* expect+1: redundant cast from 'double _Complex' to 'double _Complex' before assignment [Q7] */ 249 c64 = (c64_t)c64; 250 251 252 /* Mixing real and complex floating point types. */ 253 /* expect+1: no-op cast from 'float' to 'float' [Q6] */ 254 c32 = (f32_t)f32; 255 c32 = (c32_t)f32; 256 /* expect+1: no-op cast from 'float' to 'float' [Q6] */ 257 c64 = (f32_t)f32; 258 c64 = (f64_t)f32; 259 c64 = (c32_t)f32; 260 c64 = (c64_t)f32; 261 262 263 /* 264 * Converting a void pointer type to an object pointer type requires 265 * an explicit cast in C++, as it is a narrowing conversion. In C, 266 * that conversion is done implicitly. 267 */ 268 269 /* expect+1: redundant cast from 'pointer to void' to 'pointer to char' before assignment [Q7] */ 270 str = (char *)allocate(); 271 /* expect+1: redundant cast from 'pointer to void' to 'pointer to const char' before assignment [Q7] */ 272 cstr = (const char *)allocate(); 273 cstr = (char *)allocate(); 274 275 /* expect+2: no-op cast from 'pointer to char' to 'pointer to char' [Q6] */ 276 /* expect+1: redundant cast from 'pointer to char' to 'pointer to char' before assignment [Q7] */ 277 str = (str_t)str; 278 str = (str_t)cstr; 279 /* expect+1: warning: operands of '=' have incompatible pointer types to 'char' and 'const char' [128] */ 280 str = (cstr_t)str; 281 /* expect+2: no-op cast from 'pointer to const char' to 'pointer to const char' [Q6] */ 282 /* expect+1: warning: operands of '=' have incompatible pointer types to 'char' and 'const char' [128] */ 283 str = (cstr_t)cstr; 284 /* expect+1: no-op cast from 'pointer to char' to 'pointer to char' [Q6] */ 285 cstr = (str_t)str; 286 cstr = (str_t)cstr; 287 cstr = (cstr_t)str; 288 /* expect+2: no-op cast from 'pointer to const char' to 'pointer to const char' [Q6] */ 289 /* expect+1: redundant cast from 'pointer to const char' to 'pointer to const char' before assignment [Q7] */ 290 cstr = (cstr_t)cstr; 291 292 /* expect+2: no-op cast from 'pointer to char' to 'pointer to char' [Q6] */ 293 /* expect+1: redundant cast from 'pointer to char' to 'pointer to char' before assignment [Q7] */ 294 str = (str_t)str; 295 str = (str_t)vstr; 296 /* expect+1: warning: operands of '=' have incompatible pointer types to 'char' and 'volatile char' [128] */ 297 str = (vstr_t)str; 298 /* expect+2: no-op cast from 'pointer to volatile char' to 'pointer to volatile char' [Q6] */ 299 /* expect+1: warning: operands of '=' have incompatible pointer types to 'char' and 'volatile char' [128] */ 300 str = (vstr_t)vstr; 301 /* expect+1: no-op cast from 'pointer to char' to 'pointer to char' [Q6] */ 302 vstr = (str_t)str; 303 vstr = (str_t)vstr; 304 vstr = (vstr_t)str; 305 /* expect+2: no-op cast from 'pointer to volatile char' to 'pointer to volatile char' [Q6] */ 306 /* expect+1: redundant cast from 'pointer to volatile char' to 'pointer to volatile char' before assignment [Q7] */ 307 vstr = (vstr_t)vstr; 308 } 309 310 /* 311 * Octal numbers were common in the 1970s, especially on 36-bit machines. 312 * 50 years later, they are still used in numeric file permissions. 313 */ 314 void 315 Q8(void) 316 { 317 318 u16 = 0; 319 u16 = 000000; 320 /* expect+1: octal number '0644' [Q8] */ 321 u16 = 0644; 322 /* expect+1: octal number '0000644' [Q8] */ 323 u16 = 0000644; 324 } 325 326 int 327 Q9(int x) 328 { 329 switch (x) { 330 case 0: 331 return 0; 332 case 1: 333 /* expect+1: parenthesized return value [Q9] */ 334 return (0); 335 case 2: 336 return +(0); 337 case 3: 338 return -(13); 339 case 4: 340 /* expect+2: comma operator with types 'int' and 'int' [Q12] */ 341 /* expect+1: parenthesized return value [Q9] */ 342 return (0), (1); 343 case 5: 344 /* expect+2: comma operator with types 'int' and 'int' [Q12] */ 345 /* expect+1: parenthesized return value [Q9] */ 346 return (0, 1); 347 case 6: 348 /* expect+1: comma operator with types 'int' and 'int' [Q12] */ 349 return 0, 1; 350 case 7: 351 /* expect+1: implicit conversion from floating point 'double' to integer 'int' [Q1] */ 352 return 0.0; 353 case 8: 354 /* expect+2: parenthesized return value [Q9] */ 355 /* expect+1: implicit conversion from floating point 'double' to integer 'int' [Q1] */ 356 return (0.0); 357 case 9: 358 return 359 # 360 "queries.c" 3 4 360 ((void *)0) 361 # 362 "queries.c" 362 /* expect+1: warning: illegal combination of integer 'int' and pointer 'pointer to void' [183] */ 363 ; 364 case 10: 365 /* expect+1: warning: illegal combination of integer 'int' and pointer 'pointer to void' [183] */ 366 return (void *)(0); 367 default: 368 return 0; 369 } 370 } 371 372 void 373 Q10(void) 374 { 375 int a, b, c; 376 377 /* expect+2: chained assignment with '=' and '=' [Q10] */ 378 /* expect+1: chained assignment with '=' and '=' [Q10] */ 379 a = b = c = 0; 380 381 /* expect+2: chained assignment with '*=' and '-=' [Q10] */ 382 /* expect+1: chained assignment with '+=' and '*=' [Q10] */ 383 a += b *= c -= 0; 384 } 385 386 void 387 Q11(void) 388 { 389 /* expect+1: static variable 'static_var_no_init' in function [Q11] */ 390 static int static_var_no_init; 391 /* expect+1: static variable 'static_var_init' in function [Q11] */ 392 static int static_var_init = 1; 393 394 static_var_no_init++; 395 static_var_init++; 396 } 397 398 void 399 Q12(void) 400 { 401 /* expect+1: comma operator with types 'void' and '_Bool' [Q12] */ 402 if (Q11(), cond) 403 return; 404 405 /* expect+5: implicit conversion changes sign from 'unsigned char' to 'int' [Q3] */ 406 /* expect+4: implicit conversion changes sign from 'int' to 'unsigned short' [Q3] */ 407 /* expect+3: implicit conversion changes sign from 'unsigned short' to 'int' [Q3] */ 408 /* expect+2: implicit conversion changes sign from 'int' to 'unsigned int' [Q3] */ 409 /* expect+1: comma operator with types 'unsigned short' and 'unsigned int' [Q12] */ 410 u16 += u8, u32 += u16; 411 } 412 413 /* expect+1: redundant 'extern' in function declaration of 'extern_Q13' [Q13] */ 414 extern void extern_Q13(void); 415 void extern_Q13(void); 416 /* expect+1: redundant 'extern' in function declaration of 'extern_Q13' [Q13] */ 417 extern void extern_Q13(void), *extern_ptr; 418 419 int 420 Q14(signed char sc, unsigned char uc, int wc) 421 { 422 // Plain 'char' is platform-dependent, see queries-{schar,uchar}.c. 423 424 if (sc == 'c' || sc == L'w' || sc == 92 || sc == 0) 425 return 2; 426 /* expect+4: implicit conversion changes sign from 'unsigned char' to 'int' [Q3] */ 427 /* expect+3: implicit conversion changes sign from 'unsigned char' to 'int' [Q3] */ 428 /* expect+2: implicit conversion changes sign from 'unsigned char' to 'int' [Q3] */ 429 /* expect+1: implicit conversion changes sign from 'unsigned char' to 'int' [Q3] */ 430 if (uc == 'c' || uc == L'w' || uc == 92 || uc == 0) 431 return 3; 432 if (wc == 'c' || wc == L'w' || wc == 92 || wc == 0) 433 return 4; 434 return 5; 435 } 436 437 void * 438 Q15(void) 439 { 440 /* expect+1: implicit conversion from integer 0 to pointer 'pointer to void' [Q15] */ 441 void *ptr_from_int = 0; 442 /* expect+1: implicit conversion from integer 0 to pointer 'pointer to void' [Q15] */ 443 void *ptr_from_uint = 0U; 444 /* expect+1: implicit conversion from integer 0 to pointer 'pointer to void' [Q15] */ 445 void *ptr_from_long = 0L; 446 447 ptr_from_int = &ptr_from_int; 448 ptr_from_uint = &ptr_from_uint; 449 ptr_from_long = &ptr_from_long; 450 451 /* expect+1: implicit conversion from integer 0 to pointer 'pointer to void' [Q15] */ 452 return 0; 453 } 454 455 /* 456 * Even though C99 6.2.2p4 allows a 'static' declaration followed by a 457 * non-'static' declaration, it may look confusing. 458 */ 459 static void Q16(void); 460 /* expect+3: 'Q16' was declared 'static', now non-'static' [Q16] */ 461 /* expect+2: warning: static function 'Q16' unused [236] */ 462 void 463 Q16(void) 464 { 465 } 466 467 /* expect+1: invisible character U+0009 in character constant [Q17] */ 468 char Q17_char[] = { ' ', '\0', ' ' }; 469 /* expect+1: invisible character U+0009 in string literal [Q17] */ 470 char Q17_char_string[] = " \0 "; 471 /* expect+1: invisible character U+0009 in character constant [Q17] */ 472 int Q17_wide[] = { L' ', L'\0', L' ' }; 473 /* expect+1: invisible character U+0009 in string literal [Q17] */ 474 int Q17_wide_string[] = L" \0 "; 475 476 /* For Q18, see queries_schar.c and queries_uchar.c. */ 477 478 void 479 convert_from_integer_to_floating(void) 480 { 481 /* expect+1: implicit conversion from integer 'unsigned int' to floating point 'float' [Q19] */ 482 f32 = 0xffff0000; 483 /* expect+1: implicit conversion from integer 'unsigned int' to floating point 'float' [Q19] */ 484 f32 = 0xffffffff; 485 /* expect+1: implicit conversion from integer 'int' to floating point 'float' [Q19] */ 486 f32 = s32; 487 /* expect+1: implicit conversion from integer 'unsigned int' to floating point 'float' [Q19] */ 488 f32 = u32; 489 /* expect+1: implicit conversion from integer 'int' to floating point 'double' [Q19] */ 490 f64 = s32; 491 /* expect+1: implicit conversion from integer 'unsigned int' to floating point 'double' [Q19] */ 492 f64 = u32; 493 /* expect+1: implicit conversion from integer 'long long' to floating point 'double' [Q19] */ 494 f64 = s64; 495 /* expect+1: implicit conversion from integer 'unsigned long long' to floating point 'double' [Q19] */ 496 f64 = u64; 497 498 f32 = 0.0F; 499 f32 = 0.0; 500 f64 = 0.0; 501 } 502 503 /* 504 * Since queries do not affect the exit status, force a warning to make this 505 * test conform to the general expectation that a test that produces output 506 * exits non-successfully. 507 */ 508 /* expect+1: warning: static variable 'unused' unused [226] */ 509 static int unused; 510
Indexes created Tue Sep 23 07:09:52 GMT 2025