gnu / gcc / ab810952eb7c061e37054ddd1dfe0aa033365131 / . / gcc / testsuite / gcc.dg / c99-const-expr-11.c

/* Test for constant expressions: cases involving VLAs. */ | |

/* Origin: Joseph Myers <joseph@codesourcery.com> */ | |

/* { dg-do compile } */ | |

/* { dg-options "-std=iso9899:1999 -pedantic-errors" } */ | |

/* It appears address constants may contain casts to variably modified | |

types. Whether they should be permitted was discussed in | |

<http://groups.google.com/group/comp.std.c/msg/923eee5ab690fd98> | |

<LV7g2Vy3ARF$Ew9Q@romana.davros.org>; since static pointers to VLAs | |

are definitely permitted within functions and may be initialized | |

and such initialization involves implicit conversion to a variably | |

modified type, allowing explicit casts seems appropriate. Thus, | |

GCC allows them as long as the "evaluated" size expressions do not | |

contain the various operators not permitted to be evaluated in a | |

constant expression, and as long as the result is genuinely | |

constant (meaning that pointer arithmetic using the size of the VLA | |

is generally not permitted). */ | |

static int sa[100]; | |

volatile int nv; | |

int | |

f (int m, int n) | |

{ | |

static int (*a1)[n] = &sa; | |

static int (*a2)[n] = (int (*)[n])sa; | |

static int (*a3)[n] = (int (*)[(int){n}])sa; | |

static int (*a4)[n] = (int (*)[(int){m++}])sa; /* { dg-error "constant" } */ | |

static int (*a5)[n] = (int (*)[(int){++m}])sa; /* { dg-error "constant" } */ | |

static int (*a6)[n] = (int (*)[(int){m--}])sa; /* { dg-error "constant" } */ | |

static int (*a7)[n] = (int (*)[(int){--m}])sa; /* { dg-error "constant" } */ | |

static int (*a8)[n] = (int (*)[(m=n)])sa; /* { dg-error "constant" } */ | |

static int (*a9)[n] = (int (*)[(m+=n)])sa; /* { dg-error "constant" } */ | |

static int (*a10)[n] = (int (*)[f(m,n)])sa; /* { dg-error "constant" } */ | |

static int (*a11)[n] = (int (*)[(m,n)])sa; /* { dg-error "constant" } */ | |

static int (*a12)[n] = (int (*)[sizeof(int[n])])sa; | |

static int (*a13)[n] = (int (*)[sizeof(int[m++])])sa; /* { dg-error "constant" } */ | |

static int (*a14)[n] = (int (*)[sizeof(*a1)])sa; | |

static int (*a15)[n] = (int (*)[sizeof(*(int (*)[n])sa)])sa; | |

static int (*a16)[n] = (int (*)[sizeof(*(int (*)[m++])sa)])sa; /* { dg-error "constant" } */ | |

static int (*a17)[n] = (int (*)[nv])sa; | |

typedef int (*vmt)[m++]; | |

static int (*a18)[n] = (vmt)sa; | |

return n; | |

} |