clang/test/Sema/format-strings.c

   1 // RUN: %clang_cc1 -fblocks -fsyntax-only -verify -Wformat-nonliteral -isystem %S/Inputs %s
   2 // RUN: %clang_cc1 -fblocks -fsyntax-only -verify -Wformat-nonliteral -isystem %S/Inputs -fno-signed-char %s
   3 // RUN: %clang_cc1 -fblocks -fsyntax-only -verify -Wformat-nonliteral -isystem %S/Inputs -triple=x86_64-unknown-fuchsia %s
   4 // RUN: %clang_cc1 -fblocks -fsyntax-only -verify -Wformat-nonliteral -isystem %S/Inputs -triple=x86_64-linux-android %s
   5
   6 #include <stdarg.h>
   7 #include <stddef.h>
   8 #define __need_wint_t
   9 #include <stddef.h> // For wint_t and wchar_t
  10
  11 typedef struct _FILE FILE;
  12 int fprintf(FILE *, const char *restrict, ...);
  13 int printf(const char *restrict, ...); // expected-note{{passing argument to parameter here}}
  14 int snprintf(char *restrict, size_t, const char *restrict, ...);
  15 int sprintf(char *restrict, const char *restrict, ...);
  16 int vasprintf(char **, const char *, va_list);
  17 int asprintf(char **, const char *, ...);
  18 int vfprintf(FILE *, const char *restrict, va_list);
  19 int vprintf(const char *restrict, va_list);
  20 int vsnprintf(char *, size_t, const char *, va_list);
  21 int vsprintf(char *restrict, const char *restrict, va_list); // expected-note{{passing argument to parameter here}}
  22
  23 int vscanf(const char *restrict format, va_list arg);
  24
  25 char * global_fmt;
  26
  27 void check_string_literal( FILE* fp, const char* s, char *buf, ... ) {
  28
  29   char * b;
  30   va_list ap;
  31   va_start(ap,buf);
  32
  33   printf(s); // expected-warning {{format string is not a string literal}}
  34   // expected-note@-1{{treat the string as an argument to avoid this}}
  35   vprintf(s,ap); // expected-warning {{format string is not a string literal}}
  36   fprintf(fp,s); // expected-warning {{format string is not a string literal}}
  37   // expected-note@-1{{treat the string as an argument to avoid this}}
  38   vfprintf(fp,s,ap); // expected-warning {{format string is not a string literal}}
  39   asprintf(&b,s); // expected-warning {{format string is not a string lit}}
  40   // expected-note@-1{{treat the string as an argument to avoid this}}
  41   vasprintf(&b,s,ap); // expected-warning {{format string is not a string literal}}
  42   sprintf(buf,s); // expected-warning {{format string is not a string literal}}
  43   // expected-note@-1{{treat the string as an argument to avoid this}}
  44   snprintf(buf,2,s); // expected-warning {{format string is not a string lit}}
  45   // expected-note@-1{{treat the string as an argument to avoid this}}
  46   __builtin___sprintf_chk(buf,0,-1,s); // expected-warning {{format string is not a string literal}}
  47   // expected-note@-1{{treat the string as an argument to avoid this}}
  48   __builtin___snprintf_chk(buf,2,0,-1,s); // expected-warning {{format string is not a string lit}}
  49   // expected-note@-1{{treat the string as an argument to avoid this}}
  50   vsprintf(buf,s,ap); // expected-warning {{format string is not a string lit}}
  51   vsnprintf(buf,2,s,ap); // expected-warning {{format string is not a string lit}}
  52   vsnprintf(buf,2,global_fmt,ap); // expected-warning {{format string is not a string literal}}
  53   __builtin___vsnprintf_chk(buf,2,0,-1,s,ap); // expected-warning {{format string is not a string lit}}
  54   __builtin___vsnprintf_chk(buf,2,0,-1,global_fmt,ap); // expected-warning {{format string is not a string literal}}
  55
  56   vscanf(s, ap); // expected-warning {{format string is not a string literal}}
  57
  58   const char *const fmt = "%d"; // FIXME -- defined here
  59   printf(fmt, 1, 2); // expected-warning{{data argument not used}}
  60
  61   printf("abc"
  62          "%*d", 1, 1); // no-warning
  63   printf("abc\
  64 def"
  65          "%*d", 1, 1); // no-warning
  66
  67   // Allow 'unsigned' (instead of 'int') to be used for both the field width
  68   // and precision. This deviates from C99, but is reasonably safe and is also
  69   // accepted by GCC.
  70   printf("%*d", (unsigned) 1, 1); // no-warning
  71 }
  72
  73 // When calling a non-variadic format function (vprintf, vscanf, NSLogv, ...),
  74 // warn only if the format string argument is a parameter that is not itself
  75 // declared as a format string with compatible format.
  76 __attribute__((__format__ (__printf__, 2, 4)))
  77 void check_string_literal2( FILE* fp, const char* s, char *buf, ... ) {
  78   char * b;
  79   va_list ap;
  80   va_start(ap,buf);
  81
  82   printf(s); // expected-warning {{format string is not a string literal}}
  83   // expected-note@-1{{treat the string as an argument to avoid this}}
  84   vprintf(s,ap); // no-warning
  85   fprintf(fp,s); // expected-warning {{format string is not a string literal}}
  86   // expected-note@-1{{treat the string as an argument to avoid this}}
  87   vfprintf(fp,s,ap); // no-warning
  88   asprintf(&b,s); // expected-warning {{format string is not a string lit}}
  89   // expected-note@-1{{treat the string as an argument to avoid this}}
  90   vasprintf(&b,s,ap); // no-warning
  91   sprintf(buf,s); // expected-warning {{format string is not a string literal}}
  92   // expected-note@-1{{treat the string as an argument to avoid this}}
  93   snprintf(buf,2,s); // expected-warning {{format string is not a string lit}}
  94   // expected-note@-1{{treat the string as an argument to avoid this}}
  95   __builtin___vsnprintf_chk(buf,2,0,-1,s,ap); // no-warning
  96
  97   vscanf(s, ap); // expected-warning {{format string is not a string literal}}
  98 }
  99
 100 void check_conditional_literal(const char* s, int i) {
 101   printf(i == 1 ? "yes" : "no"); // no-warning
 102   printf(i == 0 ? (i == 1 ? "yes" : "no") : "dont know"); // no-warning
 103   printf(i == 0 ? (i == 1 ? s : "no") : "dont know"); // expected-warning{{format string is not a string literal}}
 104   // expected-note@-1{{treat the string as an argument to avoid this}}
 105   printf("yes" ?: "no %d", 1); // expected-warning{{data argument not used by format string}}
 106   printf(0 ? "yes %s" : "no %d", 1); // no-warning
 107   printf(0 ? "yes %d" : "no %s", 1); // expected-warning{{format specifies type 'char *'}}
 108
 109   printf(0 ? "yes" : "no %d", 1); // no-warning
 110   printf(0 ? "yes %d" : "no", 1); // expected-warning{{data argument not used by format string}}
 111   printf(1 ? "yes" : "no %d", 1); // expected-warning{{data argument not used by format string}}
 112   printf(1 ? "yes %d" : "no", 1); // no-warning
 113   printf(i ? "yes" : "no %d", 1); // no-warning
 114   printf(i ? "yes %s" : "no %d", 1); // expected-warning{{format specifies type 'char *'}}
 115   printf(i ? "yes" : "no %d", 1, 2); // expected-warning{{data argument not used by format string}}
 116
 117   printf(i ? "%*s" : "-", i, s); // no-warning
 118   printf(i ? "yes" : 0 ? "no %*d" : "dont know %d", 1, 2); // expected-warning{{data argument not used by format string}}
 119   printf(i ? "%i\n" : "%i %s %s\n", i, s); // expected-warning{{more '%' conversions than data arguments}}
 120 }
 121
 122 #if !defined(__ANDROID__) && !defined(__Fuchsia__)
 123
 124 void check_writeback_specifier(void)
 125 {
 126   int x;
 127   char *b;
 128   printf("%n", b); // expected-warning{{format specifies type 'int *' but the argument has type 'char *'}}
 129   printf("%n", &x); // no-warning
 130
 131   printf("%hhn", (signed char*)0); // no-warning
 132   printf("%hhn", (char*)0); // no-warning
 133   printf("%hhn", (unsigned char*)0); // no-warning
 134   printf("%hhn", (int*)0); // expected-warning{{format specifies type 'signed char *' but the argument has type 'int *'}}
 135
 136   printf("%hn", (short*)0); // no-warning
 137   printf("%hn", (unsigned short*)0); // no-warning
 138   printf("%hn", (int*)0); // expected-warning{{format specifies type 'short *' but the argument has type 'int *'}}
 139
 140   printf("%n", (int*)0); // no-warning
 141   printf("%n", (unsigned int*)0); // no-warning
 142   printf("%n", (char*)0); // expected-warning{{format specifies type 'int *' but the argument has type 'char *'}}
 143
 144   printf("%ln", (long*)0); // no-warning
 145   printf("%ln", (unsigned long*)0); // no-warning
 146   printf("%ln", (int*)0); // expected-warning{{format specifies type 'long *' but the argument has type 'int *'}}
 147
 148   printf("%lln", (long long*)0); // no-warning
 149   printf("%lln", (unsigned long long*)0); // no-warning
 150   printf("%lln", (int*)0); // expected-warning{{format specifies type 'long long *' but the argument has type 'int *'}}
 151
 152   printf("%qn", (long long*)0); // no-warning
 153   printf("%qn", (unsigned long long*)0); // no-warning
 154   printf("%qn", (int*)0); // expected-warning{{format specifies type 'long long *' but the argument has type 'int *'}}
 155
 156   printf("%Ln", 0); // expected-warning{{length modifier 'L' results in undefined behavior or no effect with 'n' conversion specifier}}
 157   // expected-note@-1{{did you mean to use 'll'?}}
 158 }
 159
 160 #else
 161
 162 void check_writeback_specifier(void)
 163 {
 164   int x;
 165   printf("%n", &x); // expected-warning{{'%n' specifier not supported on this platform}}
 166
 167   printf("%hhn", (signed char*)0); // expected-warning{{'%n' specifier not supported on this platform}}
 168   printf("%hhn", (char*)0); // expected-warning{{'%n' specifier not supported on this platform}}
 169   printf("%hhn", (unsigned char*)0); // expected-warning{{'%n' specifier not supported on this platform}}
 170   printf("%hhn", (int*)0); // expected-warning{{format specifies type 'signed char *' but the argument has type 'int *'}}
 171   // expected-warning@-1 {{'%n' specifier not supported on this platform}}
 172
 173   printf("%hn", (short*)0); // expected-warning{{'%n' specifier not supported on this platform}}
 174   printf("%hn", (unsigned short*)0); // expected-warning{{'%n' specifier not supported on this platform}}
 175   printf("%hn", (int*)0); // expected-warning{{format specifies type 'short *' but the argument has type 'int *'}}
 176   // expected-warning@-1 {{'%n' specifier not supported on this platform}}
 177
 178   printf("%n", (int*)0); // expected-warning{{'%n' specifier not supported on this platform}}
 179   printf("%n", (unsigned int*)0); // expected-warning{{'%n' specifier not supported on this platform}}
 180   printf("%n", (char*)0); // expected-warning{{format specifies type 'int *' but the argument has type 'char *'}}
 181   // expected-warning@-1 {{'%n' specifier not supported on this platform}}
 182
 183   printf("%ln", (long*)0); // expected-warning{{'%n' specifier not supported on this platform}}
 184   printf("%ln", (unsigned long*)0); // expected-warning{{'%n' specifier not supported on this platform}}
 185   printf("%ln", (int*)0); // expected-warning{{format specifies type 'long *' but the argument has type 'int *'}}
 186   // expected-warning@-1 {{'%n' specifier not supported on this platform}}
 187
 188   printf("%lln", (long long*)0); // expected-warning{{'%n' specifier not supported on this platform}}
 189   printf("%lln", (unsigned long long*)0); // expected-warning{{'%n' specifier not supported on this platform}}
 190   printf("%lln", (int*)0); // expected-warning{{format specifies type 'long long *' but the argument has type 'int *'}}
 191   // expected-warning@-1 {{'%n' specifier not supported on this platform}}
 192
 193   printf("%qn", (long long*)0); // expected-warning{{'%n' specifier not supported on this platform}}
 194   printf("%qn", (unsigned long long*)0); // expected-warning{{'%n' specifier not supported on this platform}}
 195 }
 196
 197 #endif // !defined(__ANDROID__) && !defined(__Fuchsia__)
 198
 199 void check_invalid_specifier(FILE* fp, char *buf)
 200 {
 201   printf("%s%lv%d","unix",10,20); // expected-warning {{invalid conversion specifier 'v'}} expected-warning {{data argument not used by format string}}
 202   fprintf(fp,"%%%l"); // expected-warning {{incomplete format specifier}}
 203   sprintf(buf,"%%%%%ld%d%d", 1, 2, 3); // expected-warning{{format specifies type 'long' but the argument has type 'int'}}
 204   snprintf(buf, 2, "%%%%%ld%;%d", 1, 2, 3); // expected-warning{{format specifies type 'long' but the argument has type 'int'}} expected-warning {{invalid conversion specifier ';'}} expected-warning {{data argument not used by format string}} \
 205                                             // expected-warning{{'snprintf' will always be truncated; specified size is 2, but format string expands to at least 7}}
 206 }
 207
 208 void check_null_char_string(char* b)
 209 {
 210   printf("\0this is bogus%d",1); // expected-warning {{string contains '\0'}}
 211   snprintf(b,10,"%%%%%d\0%d",1,2); // expected-warning {{string contains '\0'}}
 212   printf("%\0d",1); // expected-warning {{string contains '\0'}}
 213 }
 214
 215 void check_empty_format_string(char* buf, ...)
 216 {
 217   va_list ap;
 218   va_start(ap,buf);
 219   vprintf("",ap); // expected-warning {{format string is empty}}
 220   sprintf(buf, "", 1); // expected-warning {{format string is empty}}
 221
 222   // Don't warn about empty format strings when there are no data arguments.
 223   // This can arise from macro expansions and non-standard format string
 224   // functions.
 225   sprintf(buf, ""); // no-warning
 226 }
 227
 228 void check_wide_string(char* b, ...)
 229 {
 230   va_list ap;
 231   va_start(ap,b);
 232
 233   printf(L"foo %d",2); // expected-warning {{incompatible pointer types}}, expected-warning {{should not be a wide string}}
 234   vsprintf(b,L"bar %d",ap); // expected-warning {{incompatible pointer types}}, expected-warning {{should not be a wide string}}
 235 }
 236
 237 void check_asterisk_precision_width(int x) {
 238   printf("%*d"); // expected-warning {{'*' specified field width is missing a matching 'int' argument}}
 239   printf("%.*d"); // expected-warning {{'.*' specified field precision is missing a matching 'int' argument}}
 240   printf("%*d",12,x); // no-warning
 241   printf("%*d","foo",x); // expected-warning {{field width should have type 'int', but argument has type 'char *'}}
 242   printf("%.*d","foo",x); // expected-warning {{field precision should have type 'int', but argument has type 'char *'}}
 243 }
 244
 245 void __attribute__((format(printf,1,3))) myprintf(const char*, int blah, ...);
 246
 247 void test_myprintf(void) {
 248   myprintf("%d", 17, 18); // okay
 249 }
 250
 251 void test_constant_bindings(void) {
 252   const char * const s1 = "hello";
 253   const char s2[] = "hello";
 254   const char *s3 = "hello";
 255   char * const s4 = "hello";
 256   extern const char s5[];
 257
 258   printf(s1); // no-warning
 259   printf(s2); // no-warning
 260   printf(s3); // expected-warning{{not a string literal}}
 261   // expected-note@-1{{treat the string as an argument to avoid this}}
 262   printf(s4); // expected-warning{{not a string literal}}
 263   // expected-note@-1{{treat the string as an argument to avoid this}}
 264   printf(s5); // expected-warning{{not a string literal}}
 265   // expected-note@-1{{treat the string as an argument to avoid this}}
 266 }
 267
 268
 269 // Test what happens when -Wformat-security only.
 270 #pragma GCC diagnostic ignored "-Wformat-nonliteral"
 271 #pragma GCC diagnostic warning "-Wformat-security"
 272
 273 void test9(char *P) {
 274   int x;
 275   printf(P);   // expected-warning {{format string is not a string literal (potentially insecure)}}
 276   // expected-note@-1{{treat the string as an argument to avoid this}}
 277   printf(P, 42);
 278 }
 279
 280 void torture(va_list v8) {
 281   vprintf ("%*.*d", v8);  // no-warning
 282
 283 }
 284
 285 void test10(int x, float f, int i, long long lli) {
 286   printf("%s"); // expected-warning{{more '%' conversions than data arguments}}
 287   printf("%@", 12); // expected-warning{{invalid conversion specifier '@'}}
 288   printf("\0"); // expected-warning{{format string contains '\0' within the string body}}
 289   printf("xs\0"); // expected-warning{{format string contains '\0' within the string body}}
 290   printf("%*d\n"); // expected-warning{{'*' specified field width is missing a matching 'int' argument}}
 291   printf("%*.*d\n", x); // expected-warning{{'.*' specified field precision is missing a matching 'int' argument}}
 292   printf("%*d\n", f, x); // expected-warning{{field width should have type 'int', but argument has type 'double'}}
 293   printf("%*.*d\n", x, f, x); // expected-warning{{field precision should have type 'int', but argument has type 'double'}}
 294   printf("%**\n"); // expected-warning{{invalid conversion specifier '*'}}
 295   printf("%d%d\n", x); // expected-warning{{more '%' conversions than data arguments}}
 296   printf("%d\n", x, x); // expected-warning{{data argument not used by format string}}
 297   printf("%W%d\n", x, x); // expected-warning{{invalid conversion specifier 'W'}}  expected-warning {{data argument not used by format string}}
 298   printf("%"); // expected-warning{{incomplete format specifier}}
 299   printf("%.d", x); // no-warning
 300   printf("%.", x);  // expected-warning{{incomplete format specifier}}
 301   printf("%f", 4); // expected-warning{{format specifies type 'double' but the argument has type 'int'}}
 302   printf("%qd", lli); // no-warning
 303   printf("%qd", x); // expected-warning{{format specifies type 'long long' but the argument has type 'int'}}
 304   printf("%qp", (void *)0); // expected-warning{{length modifier 'q' results in undefined behavior or no effect with 'p' conversion specifier}}
 305   printf("hhX %hhX", (unsigned char)10); // no-warning
 306   printf("llX %llX", (long long) 10); // no-warning
 307   printf("%lb %lB", (long) 10, (long) 10); // no-warning
 308   printf("%llb %llB", (long long) 10, (long long) 10); // no-warning
 309   // This is fine, because there is an implicit conversion to an int.
 310   printf("%d", (unsigned char) 10); // no-warning
 311   printf("%d", (long long) 10); // expected-warning{{format specifies type 'int' but the argument has type 'long long'}}
 312   printf("%Lf\n", (long double) 1.0); // no-warning
 313   printf("%f\n", (long double) 1.0); // expected-warning{{format specifies type 'double' but the argument has type 'long double'}}
 314   // The man page says that a zero precision is okay.
 315   printf("%.0Lf", (long double) 1.0); // no-warning
 316   printf("%c\n", "x"); // expected-warning{{format specifies type 'int' but the argument has type 'char *'}}
 317   printf("%c\n", 1.23); // expected-warning{{format specifies type 'int' but the argument has type 'double'}}
 318   printf("Format %d, is %! %f", 1, 4.4); // expected-warning{{invalid conversion specifier '!'}}
 319 }
 320
 321 typedef unsigned char uint8_t;
 322
 323 void should_understand_small_integers(void) {
 324   printf("%hhu", (short) 10); // expected-warning{{format specifies type 'unsigned char' but the argument has type 'short'}}
 325   printf("%hu\n", (unsigned char)1); // warning with -Wformat-pedantic only
 326   printf("%hu\n", (uint8_t)1);       // warning with -Wformat-pedantic only
 327 }
 328
 329 void test11(void *p, char *s) {
 330   printf("%p", p); // no-warning
 331   printf("%p", 123); // expected-warning{{format specifies type 'void *' but the argument has type 'int'}}
 332   printf("%.4p", p); // expected-warning{{precision used with 'p' conversion specifier, resulting in undefined behavior}}
 333   printf("%+p", p); // expected-warning{{flag '+' results in undefined behavior with 'p' conversion specifier}}
 334   printf("% p", p); // expected-warning{{flag ' ' results in undefined behavior with 'p' conversion specifier}}
 335   printf("%0p", p); // expected-warning{{flag '0' results in undefined behavior with 'p' conversion specifier}}
 336   printf("%s", s); // no-warning
 337   printf("%+s", p); // expected-warning{{flag '+' results in undefined behavior with 's' conversion specifier}}
 338                     // expected-warning@-1 {{format specifies type 'char *' but the argument has type 'void *'}}
 339   printf("% s", p); // expected-warning{{flag ' ' results in undefined behavior with 's' conversion specifier}}
 340                     // expected-warning@-1 {{format specifies type 'char *' but the argument has type 'void *'}}
 341   printf("%0s", p); // expected-warning{{flag '0' results in undefined behavior with 's' conversion specifier}}
 342                     // expected-warning@-1 {{format specifies type 'char *' but the argument has type 'void *'}}
 343 }
 344
 345 void test12(char *b) {
 346   unsigned char buf[4];
 347   printf ("%.4s\n", buf); // no-warning
 348   printf ("%.4s\n", &buf); // expected-warning{{format specifies type 'char *' but the argument has type 'unsigned char (*)[4]'}}
 349
 350   // Verify that we are checking asprintf
 351   asprintf(&b, "%d", "asprintf"); // expected-warning{{format specifies type 'int' but the argument has type 'char *'}}
 352 }
 353
 354 void test13(short x) {
 355   char bel = 007;
 356   printf("bel: '0%hhd'\n", bel); // no-warning
 357   printf("x: '0%hhd'\n", x); // expected-warning {{format specifies type 'char' but the argument has type 'short'}}
 358 }
 359
 360 typedef struct __aslclient *aslclient;
 361 typedef struct __aslmsg *aslmsg;
 362 int asl_log(aslclient asl, aslmsg msg, int level, const char *format, ...) __attribute__((__format__ (__printf__, 4, 5)));
 363 void test_asl(aslclient asl) {
 364   asl_log(asl, 0, 3, "Error: %m"); // no-warning
 365   asl_log(asl, 0, 3, "Error: %W"); // expected-warning{{invalid conversion specifier 'W'}}
 366 }
 367
 368 typedef enum { A } int_t;
 369 void f0(int_t x) { printf("%d\n", x); }
 370
 371 // Unicode test cases.  These are possibly specific to Mac OS X.  If so, they should
 372 // eventually be moved into a separate test.
 373
 374 void test_unicode_conversions(wchar_t *s) {
 375   printf("%S", s); // no-warning
 376   printf("%s", s); // expected-warning{{format specifies type 'char *' but the argument has type 'wchar_t *'}}
 377   printf("%C", s[0]); // no-warning
 378 #if defined(__sun) && !defined(__LP64__)
 379   printf("%c", s[0]); // expected-warning{{format specifies type 'int' but the argument has type 'wchar_t' (aka 'long')}}
 380 #else
 381   printf("%c", s[0]);
 382 #endif
 383   // FIXME: This test reports inconsistent results. On Windows, '%C' expects
 384   // 'unsigned short'.
 385   // printf("%C", 10);
 386   printf("%S", "hello"); // expected-warning{{but the argument has type 'char *'}}
 387 }
 388
 389 // Mac OS X supports positional arguments in format strings.
 390 // This is an IEEE extension (IEEE Std 1003.1).
 391 // FIXME: This is probably not portable everywhere.
 392 void test_positional_arguments(void) {
 393   printf("%0$", (int)2); // expected-warning{{position arguments in format strings start counting at 1 (not 0)}}
 394   printf("%1$*0$d", (int) 2); // expected-warning{{position arguments in format strings start counting at 1 (not 0)}}
 395   printf("%1$d", (int) 2); // no-warning
 396   printf("%1$d", (int) 2, 2); // expected-warning{{data argument not used by format string}}
 397   printf("%1$d%1$f", (int) 2); // expected-warning{{format specifies type 'double' but the argument has type 'int'}}
 398   printf("%1$2.2d", (int) 2); // no-warning
 399   printf("%2$*1$.2d", (int) 2, (int) 3); // no-warning
 400   printf("%2$*8$d", (int) 2, (int) 3); // expected-warning{{specified field width is missing a matching 'int' argument}}
 401   printf("%%%1$d", (int) 2); // no-warning
 402   printf("%1$d%%", (int) 2); // no-warning
 403 }
 404
 405 // PR 6697 - Handle format strings where the data argument is not adjacent to the format string
 406 void myprintf_PR_6697(const char *format, int x, ...) __attribute__((__format__(printf,1, 3)));
 407 void test_pr_6697(void) {
 408   myprintf_PR_6697("%s\n", 1, "foo"); // no-warning
 409   myprintf_PR_6697("%s\n", 1, (int)0); // expected-warning{{format specifies type 'char *' but the argument has type 'int'}}
 410   // FIXME: Not everything should clearly support positional arguments,
 411   // but we need a way to identify those cases.
 412   myprintf_PR_6697("%1$s\n", 1, "foo"); // no-warning
 413   myprintf_PR_6697("%2$s\n", 1, "foo"); // expected-warning{{data argument position '2' exceeds the number of data arguments (1)}}
 414   myprintf_PR_6697("%18$s\n", 1, "foo"); // expected-warning{{data argument position '18' exceeds the number of data arguments (1)}}
 415   myprintf_PR_6697("%1$s\n", 1, (int) 0); // expected-warning{{format specifies type 'char *' but the argument has type 'int'}}
 416 }
 417
 418 void rdar8026030(FILE *fp) {
 419   fprintf(fp, "\%"); // expected-warning{{incomplete format specifier}}
 420 }
 421
 422 void bug7377_bad_length_mod_usage(void) {
 423   // Bad length modifiers
 424   printf("%hhs", "foo"); // expected-warning{{length modifier 'hh' results in undefined behavior or no effect with 's' conversion specifier}}
 425   printf("%1$zp", (void *)0); // expected-warning{{length modifier 'z' results in undefined behavior or no effect with 'p' conversion specifier}}
 426   printf("%ls", L"foo"); // no-warning
 427   printf("%#.2Lf", (long double)1.234); // no-warning
 428
 429   // Bad flag usage
 430   printf("%#p", (void *) 0); // expected-warning{{flag '#' results in undefined behavior with 'p' conversion specifier}}
 431   printf("%0d", -1); // no-warning
 432   printf("%0b%0B", -1u, -1u); // no-warning
 433   printf("%-p", (void *) 0); // no-warning
 434 #if !defined(__ANDROID__) && !defined(__Fuchsia__)
 435   printf("%#n", (int *) 0); // expected-warning{{flag '#' results in undefined behavior with 'n' conversion specifier}}
 436   printf("%-n", (int *) 0); // expected-warning{{flag '-' results in undefined behavior with 'n' conversion specifier}}
 437 #else
 438   printf("%#n", (int *) 0); // expected-warning{{flag '#' results in undefined behavior with 'n' conversion specifier}}
 439   // expected-warning@-1 {{'%n' specifier not supported on this platform}}
 440   printf("%-n", (int *) 0); // expected-warning{{flag '-' results in undefined behavior with 'n' conversion specifier}}
 441   // expected-warning@-1 {{'%n' specifier not supported on this platform}}
 442 #endif // !defined(__ANDROID__) && !defined(__Fuchsia__)
 443
 444   // Bad optional amount use
 445   printf("%.2c", 'a'); // expected-warning{{precision used with 'c' conversion specifier, resulting in undefined behavior}}
 446 #if !defined(__ANDROID__) && !defined(__Fuchsia__)
 447   printf("%1n", (int *) 0); // expected-warning{{field width used with 'n' conversion specifier, resulting in undefined behavior}}
 448   printf("%.9n", (int *) 0); // expected-warning{{precision used with 'n' conversion specifier, resulting in undefined behavior}}
 449 #else
 450   printf("%1n", (int *) 0); // expected-warning{{field width used with 'n' conversion specifier, resulting in undefined behavior}}
 451   // expected-warning@-1 {{'%n' specifier not supported on this platform}}
 452   printf("%.9n", (int *) 0); // expected-warning{{precision used with 'n' conversion specifier, resulting in undefined behavior}}
 453   // expected-warning@-1 {{'%n' specifier not supported on this platform}}
 454 #endif // #if !defined(__ANDROID__) && !defined(__Fuchsia__)
 455
 456   // Ignored flags
 457   printf("% +f", 1.23); // expected-warning{{flag ' ' is ignored when flag '+' is present}}
 458   printf("%+ f", 1.23); // expected-warning{{flag ' ' is ignored when flag '+' is present}}
 459   printf("%0-f", 1.23); // expected-warning{{flag '0' is ignored when flag '-' is present}}
 460   printf("%-0f", 1.23); // expected-warning{{flag '0' is ignored when flag '-' is present}}
 461   printf("%-+f", 1.23); // no-warning
 462 }
 463
 464 // PR 7981 - handle '%lc' (wint_t)
 465
 466 void pr7981(wint_t c, wchar_t c2) {
 467   printf("%lc", c); // no-warning
 468   printf("%lc", 1.0); // expected-warning{{the argument has type 'double'}}
 469 #if __WINT_WIDTH__ == 32 && !(defined(__sun) && !defined(__LP64__))
 470   printf("%lc", (char) 1); // no-warning
 471 #else
 472   printf("%lc", (char) 1); // expected-warning{{the argument has type 'char'}}
 473 #endif
 474   printf("%lc", &c); // expected-warning{{the argument has type 'wint_t *'}}
 475   // If wint_t and wchar_t are the same width and wint_t is signed where
 476   // wchar_t is unsigned, an implicit conversion isn't possible.
 477 #if defined(__WINT_UNSIGNED__) || !defined(__WCHAR_UNSIGNED__) ||   \
 478   __WINT_WIDTH__ > __WCHAR_WIDTH__
 479   printf("%lc", c2); // no-warning
 480 #endif
 481 }
 482
 483 // -Wformat-security says NULL is not a string literal
 484 void rdar8269537(void) {
 485   // This is likely to crash in most cases, but -Wformat-nonliteral technically
 486   // doesn't warn in this case.
 487   printf(0); // no-warning
 488 }
 489
 490 // Handle functions with multiple format attributes.
 491 extern void rdar8332221_vprintf_scanf(const char *, va_list, const char *, ...)
 492      __attribute__((__format__(__printf__, 1, 0)))
 493      __attribute__((__format__(__scanf__, 3, 4)));
 494
 495 void rdar8332221(va_list ap, int *x, long *y) {
 496   rdar8332221_vprintf_scanf("%", ap, "%d", x); // expected-warning{{incomplete format specifier}}
 497 }
 498
 499 // PR8641
 500 void pr8641(void) {
 501   printf("%#x\n", 10);
 502   printf("%#X\n", 10);
 503   printf("%#b %#15.8B\n", 10, 10u);
 504 }
 505
 506 void posix_extensions(void) {
 507   // Test %'d, "thousands grouping".
 508   printf("%'d\n", 123456789); // no-warning
 509   printf("%'i\n", 123456789); // no-warning
 510   printf("%'f\n", (float) 1.0); // no-warning
 511   printf("%'p\n", (void*) 0); // expected-warning{{results in undefined behavior with 'p' conversion specifier}}
 512   printf("%'b\n", 123456789); // expected-warning{{results in undefined behavior with 'b' conversion specifier}}
 513   printf("%'B\n", 123456789); // expected-warning{{results in undefined behavior with 'B' conversion specifier}}
 514 }
 515
 516 // PR8486
 517 //
 518 // Test what happens when -Wformat is on, but -Wformat-security is off.
 519 #pragma GCC diagnostic warning "-Wformat"
 520 #pragma GCC diagnostic ignored "-Wformat-security"
 521
 522 void pr8486(void) {
 523   printf("%s", 1); // expected-warning{{format specifies type 'char *' but the argument has type 'int'}}
 524 }
 525
 526 // PR9314
 527 // Don't warn about string literals that are PreDefinedExprs, e.g. __func__.
 528 void pr9314(void) {
 529   printf(__PRETTY_FUNCTION__); // no-warning
 530   printf(__func__); // no-warning
 531 }
 532
 533 int printf(const char * restrict, ...) __attribute__((__format__ (__printf__, 1, 2)));
 534
 535 void rdar9612060(void) {
 536   printf("%s", 2); // expected-warning{{format specifies type 'char *' but the argument has type 'int'}}
 537 }
 538
 539 void check_char(unsigned char x, signed char y) {
 540   printf("%c", y); // no-warning
 541   printf("%hhu", x); // no-warning
 542   printf("%hhi", y); // no-warning
 543   printf("%hhi", x); // no-warning
 544   printf("%c", x); // no-warning
 545   printf("%hhu", y); // no-warning
 546   printf("%hhb %hhB", x, x); // no-warning
 547 }
 548
 549 // Test suppression of individual warnings.
 550
 551 void test_suppress_invalid_specifier(void) {
 552 #pragma clang diagnostic push
 553 #pragma clang diagnostic ignored "-Wformat-invalid-specifier"
 554   printf("%@", 12); // no-warning
 555 #pragma clang diagnostic pop
 556 }
 557
 558 // Make sure warnings are on for next test.
 559 #pragma GCC diagnostic warning "-Wformat"
 560 #pragma GCC diagnostic warning "-Wformat-security"
 561
 562 // Test that the printf call site is where the warning is attached.  If the
 563 // format string is somewhere else, point to it in a note.
 564 void pr9751(void) {
 565   const char kFormat1[] = "%d %d \n"; // expected-note{{format string is defined here}}}
 566   printf(kFormat1, 0); // expected-warning{{more '%' conversions than data arguments}}
 567   printf("%d %s\n", 0); // expected-warning{{more '%' conversions than data arguments}}
 568
 569   const char kFormat2[] = "%18$s\n"; // expected-note{{format string is defined here}}
 570   printf(kFormat2, 1, "foo"); // expected-warning{{data argument position '18' exceeds the number of data arguments (2)}}
 571   printf("%18$s\n", 1, "foo"); // expected-warning{{data argument position '18' exceeds the number of data arguments (2)}}
 572
 573   const char kFormat4[] = "%y"; // expected-note{{format string is defined here}}
 574   printf(kFormat4, 5); // expected-warning{{invalid conversion specifier 'y'}}
 575   printf("%y", 5); // expected-warning{{invalid conversion specifier 'y'}}
 576
 577   const char kFormat5[] = "%."; // expected-note{{format string is defined here}}
 578   printf(kFormat5, 5); // expected-warning{{incomplete format specifier}}
 579   printf("%.", 5); // expected-warning{{incomplete format specifier}}
 580
 581   const char kFormat6[] = "%s"; // expected-note{{format string is defined here}}
 582   printf(kFormat6, 5); // expected-warning{{format specifies type 'char *' but the argument has type 'int'}}
 583   printf("%s", 5); // expected-warning{{format specifies type 'char *' but the argument has type 'int'}}
 584
 585   const char kFormat7[] = "%0$"; // expected-note{{format string is defined here}}
 586   printf(kFormat7, 5); // expected-warning{{position arguments in format strings start counting at 1 (not 0)}}
 587   printf("%0$", 5); // expected-warning{{position arguments in format strings start counting at 1 (not 0)}}
 588
 589   const char kFormat8[] = "%1$d %d"; // expected-note{{format string is defined here}}
 590   printf(kFormat8, 4, 4); // expected-warning{{cannot mix positional and non-positional arguments in format string}}
 591   printf("%1$d %d", 4, 4); // expected-warning{{cannot mix positional and non-positional arguments in format string}}
 592
 593   const char kFormat9[] = ""; // expected-note{{format string is defined here}}
 594   printf(kFormat9, 4, 4); // expected-warning{{format string is empty}}
 595   printf("", 4, 4); // expected-warning{{format string is empty}}
 596
 597   const char kFormat10[] = "\0%d"; // expected-note{{format string is defined here}}
 598   printf(kFormat10, 4); // expected-warning{{format string contains '\0' within the string body}}
 599   printf("\0%d", 4); // expected-warning{{format string contains '\0' within the string body}}
 600
 601   const char kFormat11[] = "%*d"; // expected-note{{format string is defined here}}
 602   printf(kFormat11); // expected-warning{{'*' specified field width is missing a matching 'int' argument}}
 603   printf("%*d"); // expected-warning{{'*' specified field width is missing a matching 'int' argument}}
 604
 605   const char kFormat12[] = "%*d"; // expected-note{{format string is defined here}}
 606   printf(kFormat12, 4.4); // expected-warning{{field width should have type 'int', but argument has type 'double'}}
 607   printf("%*d", 4.4); // expected-warning{{field width should have type 'int', but argument has type 'double'}}
 608
 609   const char kFormat13[] = "%.3p"; // expected-note{{format string is defined here}}
 610   void *p;
 611   printf(kFormat13, p); // expected-warning{{precision used with 'p' conversion specifier, resulting in undefined behavior}}
 612   printf("%.3p", p); // expected-warning{{precision used with 'p' conversion specifier, resulting in undefined behavior}}
 613
 614   const char kFormat14[] = "%0s"; // expected-note{{format string is defined here}}
 615   printf(kFormat14, "a"); // expected-warning{{flag '0' results in undefined behavior with 's' conversion specifier}}
 616   printf("%0s", "a"); // expected-warning{{flag '0' results in undefined behavior with 's' conversion specifier}}
 617
 618   const char kFormat15[] = "%hhs"; // expected-note{{format string is defined here}}
 619   printf(kFormat15, "a"); // expected-warning{{length modifier 'hh' results in undefined behavior or no effect with 's' conversion specifier}}
 620   printf("%hhs", "a"); // expected-warning{{length modifier 'hh' results in undefined behavior or no effect with 's' conversion specifier}}
 621
 622   const char kFormat16[] = "%-0d"; // expected-note{{format string is defined here}}
 623   printf(kFormat16, 5); // expected-warning{{flag '0' is ignored when flag '-' is present}}
 624   printf("%-0d", 5); // expected-warning{{flag '0' is ignored when flag '-' is present}}
 625
 626   // Make sure that the "format string is defined here" note is not emitted
 627   // when the original string is within the argument expression.
 628   printf(1 ? "yes %d" : "no %d"); // expected-warning{{more '%' conversions than data arguments}}
 629
 630   const char kFormat17[] = "%hu"; // expected-note{{format string is defined here}}}
 631   printf(kFormat17, (int[]){0}); // expected-warning{{format specifies type 'unsigned short' but the argument}}
 632
 633   printf("%a", (long double)0); // expected-warning{{format specifies type 'double' but the argument has type 'long double'}}
 634
 635   // Test braced char[] initializers.
 636   const char kFormat18[] = { "%lld" }; // expected-note{{format string is defined here}}
 637   printf(kFormat18, 0); // expected-warning{{format specifies type}}
 638
 639   // Make sure we point at the offending argument rather than the format string.
 640   const char kFormat19[] = "%d";  // expected-note{{format string is defined here}}
 641   printf(kFormat19,
 642          0.0); // expected-warning{{format specifies}}
 643 }
 644
 645 void pr18905(void) {
 646   const char s1[] = "s\0%s"; // expected-note{{format string is defined here}}
 647   const char s2[1] = "s"; // expected-note{{format string is defined here}}
 648   const char s3[2] = "s\0%s"; // expected-warning{{initializer-string for char array is too long}}
 649   const char s4[10] = "s";
 650   const char s5[0] = "%s"; // expected-warning{{initializer-string for char array is too long}}
 651                            // expected-note@-1{{format string is defined here}}
 652
 653   printf(s1); // expected-warning{{format string contains '\0' within the string body}}
 654   printf(s2); // expected-warning{{format string is not null-terminated}}
 655   printf(s3); // no-warning
 656   printf(s4); // no-warning
 657   printf(s5); // expected-warning{{format string is not null-terminated}}
 658 }
 659
 660 void __attribute__((format(strfmon,1,2))) monformat(const char *fmt, ...);
 661 void __attribute__((format(strftime,1,0))) dateformat(const char *fmt);
 662
 663 // Other formats
 664 void test_other_formats(void) {
 665   char *str = "";
 666   monformat("", 1); // expected-warning{{format string is empty}}
 667   monformat(str); // expected-warning{{format string is not a string literal (potentially insecure)}}
 668   dateformat(""); // expected-warning{{format string is empty}}
 669   dateformat(str); // no-warning (using strftime non-literal is not unsafe)
 670 }
 671
 672 // Do not warn about unused arguments coming from system headers.
 673 #include <format-unused-system-args.h>
 674 void test_unused_system_args(int x) {
 675   PRINT1("%d\n", x); // no-warning{{extra argument is system header is OK}}
 676 }
 677
 678 void pr12761(char c) {
 679   // This should not warn even with -fno-signed-char.
 680   printf("%hhx", c);
 681 }
 682
 683 void test_opencl_vector_format(int x) {
 684   printf("%v4d", x); // expected-warning{{invalid conversion specifier 'v'}}
 685   printf("%vd", x); // expected-warning{{invalid conversion specifier 'v'}}
 686   printf("%0vd", x); // expected-warning{{invalid conversion specifier 'v'}}
 687   printf("%hlf", x); // expected-warning{{invalid conversion specifier 'l'}}
 688   printf("%hld", x); // expected-warning{{invalid conversion specifier 'l'}}
 689 }
 690
 691 // Test that we correctly merge the format in both orders.
 692 extern void test14_foo(const char *, const char *, ...)
 693      __attribute__((__format__(__printf__, 1, 3)));
 694 extern void test14_foo(const char *, const char *, ...)
 695      __attribute__((__format__(__scanf__, 2, 3)));
 696
 697 extern void test14_bar(const char *, const char *, ...)
 698      __attribute__((__format__(__scanf__, 2, 3)));
 699 extern void test14_bar(const char *, const char *, ...)
 700      __attribute__((__format__(__printf__, 1, 3)));
 701
 702 void test14_zed(int *p) {
 703   test14_foo("%", "%d", p); // expected-warning{{incomplete format specifier}}
 704   test14_bar("%", "%d", p); // expected-warning{{incomplete format specifier}}
 705 }
 706
 707 #if !defined(__ANDROID__) && !defined(__Fuchsia__)
 708
 709 void test_qualifiers(volatile int *vip, const int *cip,
 710                      const volatile int *cvip) {
 711   printf("%n", cip); // expected-warning{{format specifies type 'int *' but the argument has type 'const int *'}}
 712   printf("%n", cvip); // expected-warning{{format specifies type 'int *' but the argument has type 'const volatile int *'}}
 713
 714   printf("%n", vip); // No warning.
 715   printf("%p", cip); // No warning.
 716   printf("%p", cvip); // No warning.
 717
 718
 719   typedef int* ip_t;
 720   typedef const int* cip_t;
 721   printf("%n", (ip_t)0); // No warning.
 722   printf("%n", (cip_t)0); // expected-warning{{format specifies type 'int *' but the argument has type 'cip_t' (aka 'const int *')}}
 723 }
 724
 725 #else
 726
 727 void test_qualifiers(volatile int *vip, const int *cip,
 728                      const volatile int *cvip) {
 729   printf("%n", cip); // expected-warning{{format specifies type 'int *' but the argument has type 'const int *'}}
 730   // expected-warning@-1 {{'%n' specifier not supported on this platform}}
 731   printf("%n", cvip); // expected-warning{{format specifies type 'int *' but the argument has type 'const volatile int *'}}
 732   // expected-warning@-1 {{'%n' specifier not supported on this platform}}
 733
 734   printf("%n", vip); // expected-warning{{'%n' specifier not supported on this platform}}
 735   printf("%p", cip); // No warning.
 736   printf("%p", cvip); // No warning.
 737
 738
 739   typedef int* ip_t;
 740   typedef const int* cip_t;
 741   printf("%n", (ip_t)0); // expected-warning{{'%n' specifier not supported on this platform}}
 742   printf("%n", (cip_t)0); // expected-warning{{format specifies type 'int *' but the argument has type 'cip_t' (aka 'const int *')}}
 743   // expected-warning@-1 {{'%n' specifier not supported on this platform}}
 744 }
 745
 746 #endif // #if !defined(__ANDROID__) && !defined(__Fuchsia__)
 747
 748 #pragma GCC diagnostic ignored "-Wformat-nonliteral"
 749 #pragma GCC diagnostic warning "-Wformat-security"
 750 extern void test_format_security_extra_args(const char*, int, ...)
 751     __attribute__((__format__(__printf__, 1, 3)));
 752 void test_format_security_pos(char* string) {
 753   test_format_security_extra_args(string, 5); // expected-warning {{format string is not a string literal (potentially insecure)}}
 754   // expected-note@-1{{treat the string as an argument to avoid this}}
 755 }
 756 #pragma GCC diagnostic warning "-Wformat-nonliteral"
 757
 758 void test_char_pointer_arithmetic(int b) {
 759   const char s1[] = "string";
 760   const char s2[] = "%s string";
 761
 762   printf(s1 - 1);  // expected-warning {{format string is not a string literal (potentially insecure)}}
 763   // expected-note@-1{{treat the string as an argument to avoid this}}
 764
 765   printf(s1 + 2);  // no-warning
 766   printf(s2 + 2);  // no-warning
 767
 768   const char s3[] = "%s string";
 769   printf((s3 + 2) - 2);  // expected-warning{{more '%' conversions than data arguments}}
 770   // expected-note@-2{{format string is defined here}}
 771   printf(2 + s2);             // no-warning
 772   printf(6 + s2 - 2);         // no-warning
 773   printf(2 + (b ? s1 : s2));  // no-warning
 774
 775   const char s5[] = "string %s";
 776   printf(2 + (b ? s2 : s5));  // expected-warning{{more '%' conversions than data arguments}}
 777   // expected-note@-2{{format string is defined here}}
 778   printf(2 + (b ? s2 : s5), "");      // no-warning
 779   printf(2 + (b ? s1 : s2 - 2), "");  // no-warning
 780
 781   const char s6[] = "%s string";
 782   printf(2 + (b ? s1 : s6 - 2));  // expected-warning{{more '%' conversions than data arguments}}
 783   // expected-note@-2{{format string is defined here}}
 784   printf(1 ? s2 + 2 : s2);  // no-warning
 785   printf(0 ? s2 : s2 + 2);  // no-warning
 786   printf(2 + s2 + 5 * 3 - 16, "");  // expected-warning{{data argument not used}}
 787
 788   const char s7[] = "%s string %s %s";
 789   printf(s7 + 3, "");  // expected-warning{{more '%' conversions than data arguments}}
 790   // expected-note@-2{{format string is defined here}}
 791 }
 792
 793 void PR30481(void) {
 794   // This caused crashes due to invalid casts.
 795   printf(1 > 0); // expected-warning{{format string is not a string literal}} expected-error{{incompatible integer to pointer conversion}} expected-note@format-strings.c:*{{passing argument to parameter here}} expected-note{{to avoid this}}
 796 }
 797
 798 void test_printf_opaque_ptr(void *op) {
 799   printf("%s", op); // expected-warning{{format specifies type 'char *' but the argument has type 'void *'}}
 800 }
 801
 802 void test_block(void) {
 803   void __attribute__((__format__(__printf__, 1, 2))) (^printf_arg1)(
 804       const char *, ...) =
 805       ^(const char *fmt, ...) __attribute__((__format__(__printf__, 1, 2))) {
 806     va_list ap;
 807     va_start(ap, fmt);
 808     vprintf(fmt, ap);
 809     va_end(ap);
 810   };
 811
 812   printf_arg1("%s string %i\n", "aaa", 123);
 813   printf_arg1("%s string\n", 123); // expected-warning{{format specifies type 'char *' but the argument has type 'int'}}
 814
 815   void __attribute__((__format__(__printf__, 2, 3))) (^printf_arg2)(
 816       const char *, const char *, ...) =
 817       ^(const char *not_fmt, const char *fmt, ...)
 818           __attribute__((__format__(__printf__, 2, 3))) {
 819     va_list ap;
 820     va_start(ap, fmt);
 821     vprintf(fmt, ap);
 822     vprintf(not_fmt, ap); // expected-warning{{format string is not a string literal}}
 823     va_end(ap);
 824   };
 825
 826   printf_arg2("foo", "%s string %i\n", "aaa", 123);
 827   printf_arg2("%s string\n", "foo", "bar"); // expected-warning{{data argument not used by format string}}
 828 }
 829
 830 void test_promotion(void) {
 831   // Default argument promotions for *printf in N2562
 832   // https://github.com/llvm/llvm-project/issues/57102
 833   // N2562: https://www.open-std.org/jtc1/sc22/wg14/www/docs/n2562.pdf
 834   int i;
 835   signed char sc;
 836   unsigned char uc;
 837   char c;
 838   short ss;
 839   unsigned short us;
 840
 841   printf("%hhd %hd %d %hhd %hd %d", i, i, i, sc, sc, sc); // no-warning
 842   printf("%hhd %hd %d %hhd %hd %d", uc, uc, uc, c, c, c); // no-warning
 843
 844   // %ld %lld %llx
 845   printf("%ld", i); // expected-warning{{format specifies type 'long' but the argument has type 'int'}}
 846   printf("%lld", i); // expected-warning{{format specifies type 'long long' but the argument has type 'int'}}
 847   printf("%ld", sc); // expected-warning{{format specifies type 'long' but the argument has type 'signed char'}}
 848   printf("%lld", sc); // expected-warning{{format specifies type 'long long' but the argument has type 'signed char'}}
 849   printf("%ld", uc); // expected-warning{{format specifies type 'long' but the argument has type 'unsigned char'}}
 850   printf("%lld", uc); // expected-warning{{format specifies type 'long long' but the argument has type 'unsigned char'}}
 851   printf("%llx", i); // expected-warning{{format specifies type 'unsigned long long' but the argument has type 'int'}}
 852
 853   // ill formed spec for floats
 854   printf("%hf", // expected-warning{{length modifier 'h' results in undefined behavior or no effect with 'f' conversion specifier}}
 855   sc); // expected-warning{{format specifies type 'double' but the argument has type 'signed char'}}
 856
 857   // for %hhd and `short` they are compatible by promotions but more likely misuse
 858   printf("%hd", ss); // no-warning
 859   printf("%hhd", ss); // expected-warning{{format specifies type 'char' but the argument has type 'short'}}
 860   printf("%hu", us); // no-warning
 861   printf("%hhu", ss); // expected-warning{{format specifies type 'unsigned char' but the argument has type 'short'}}
 862
 863   // floats & integers are not compatible
 864   printf("%f", i); // expected-warning{{format specifies type 'double' but the argument has type 'int'}}
 865   printf("%f", sc); // expected-warning{{format specifies type 'double' but the argument has type 'signed char'}}
 866   printf("%f", uc); // expected-warning{{format specifies type 'double' but the argument has type 'unsigned char'}}
 867   printf("%f", c); // expected-warning{{format specifies type 'double' but the argument has type 'char'}}
 868   printf("%f", ss); // expected-warning{{format specifies type 'double' but the argument has type 'short'}}
 869   printf("%f", us); // expected-warning{{format specifies type 'double' but the argument has type 'unsigned short'}}
 870
 871   // character literals
 872   // In C language engineering practice, printing a character literal with %hhd or %d is common, but %hd may be misuse.
 873   printf("%hhu", 'a'); // no-warning
 874   printf("%hhd", 'a'); // no-warning
 875   printf("%hd", 'a'); // expected-warning{{format specifies type 'short' but the argument has type 'char'}}
 876   printf("%hu", 'a'); // expected-warning{{format specifies type 'unsigned short' but the argument has type 'char'}}
 877   printf("%d", 'a'); // no-warning
 878   printf("%u", 'a'); // no-warning
 879
 880   // pointers
 881   printf("%s", i); // expected-warning{{format specifies type 'char *' but the argument has type 'int'}}
 882 }