Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Jump to bottom

Improper translate-c of pointer cast #12110

Closed
jfo opened this issue Jul 13, 2022 · 6 comments · Fixed by #12336
Closed

Improper translate-c of pointer cast #12110

jfo opened this issue Jul 13, 2022 · 6 comments · Fixed by #12336
Labels
bug Observed behavior contradicts documented or intended behavior contributor friendly This issue is limited in scope and/or knowledge of Zig internals. translate-c C to Zig source translation feature (@cImport)
Milestone
0.10.0

Comments

@jfo
Copy link
Contributor

jfo commented Jul 13, 2022 •
edited
Loading

Zig Version

0.9.1

Steps to Reproduce

Consider

// main.c
void* wat() {
   int x = 123;
   return &x;
}

int main() {
   int** x  = (int **) wat();
}

And ignore that I'm taking the address of a stack variable.

The full resulting zig code from `zig translate-c main.c > main.zig` 
pub const __builtin_bswap16 = @import("std").zig.c_builtins.__builtin_bswap16;
pub const __builtin_bswap32 = @import("std").zig.c_builtins.__builtin_bswap32;
pub const __builtin_bswap64 = @import("std").zig.c_builtins.__builtin_bswap64;
pub const __builtin_signbit = @import("std").zig.c_builtins.__builtin_signbit;
pub const __builtin_signbitf = @import("std").zig.c_builtins.__builtin_signbitf;
pub const __builtin_popcount = @import("std").zig.c_builtins.__builtin_popcount;
pub const __builtin_ctz = @import("std").zig.c_builtins.__builtin_ctz;
pub const __builtin_clz = @import("std").zig.c_builtins.__builtin_clz;
pub const __builtin_sqrt = @import("std").zig.c_builtins.__builtin_sqrt;
pub const __builtin_sqrtf = @import("std").zig.c_builtins.__builtin_sqrtf;
pub const __builtin_sin = @import("std").zig.c_builtins.__builtin_sin;
pub const __builtin_sinf = @import("std").zig.c_builtins.__builtin_sinf;
pub const __builtin_cos = @import("std").zig.c_builtins.__builtin_cos;
pub const __builtin_cosf = @import("std").zig.c_builtins.__builtin_cosf;
pub const __builtin_exp = @import("std").zig.c_builtins.__builtin_exp;
pub const __builtin_expf = @import("std").zig.c_builtins.__builtin_expf;
pub const __builtin_exp2 = @import("std").zig.c_builtins.__builtin_exp2;
pub const __builtin_exp2f = @import("std").zig.c_builtins.__builtin_exp2f;
pub const __builtin_log = @import("std").zig.c_builtins.__builtin_log;
pub const __builtin_logf = @import("std").zig.c_builtins.__builtin_logf;
pub const __builtin_log2 = @import("std").zig.c_builtins.__builtin_log2;
pub const __builtin_log2f = @import("std").zig.c_builtins.__builtin_log2f;
pub const __builtin_log10 = @import("std").zig.c_builtins.__builtin_log10;
pub const __builtin_log10f = @import("std").zig.c_builtins.__builtin_log10f;
pub const __builtin_abs = @import("std").zig.c_builtins.__builtin_abs;
pub const __builtin_fabs = @import("std").zig.c_builtins.__builtin_fabs;
pub const __builtin_fabsf = @import("std").zig.c_builtins.__builtin_fabsf;
pub const __builtin_floor = @import("std").zig.c_builtins.__builtin_floor;
pub const __builtin_floorf = @import("std").zig.c_builtins.__builtin_floorf;
pub const __builtin_ceil = @import("std").zig.c_builtins.__builtin_ceil;
pub const __builtin_ceilf = @import("std").zig.c_builtins.__builtin_ceilf;
pub const __builtin_trunc = @import("std").zig.c_builtins.__builtin_trunc;
pub const __builtin_truncf = @import("std").zig.c_builtins.__builtin_truncf;
pub const __builtin_round = @import("std").zig.c_builtins.__builtin_round;
pub const __builtin_roundf = @import("std").zig.c_builtins.__builtin_roundf;
pub const __builtin_strlen = @import("std").zig.c_builtins.__builtin_strlen;
pub const __builtin_strcmp = @import("std").zig.c_builtins.__builtin_strcmp;
pub const __builtin_object_size = @import("std").zig.c_builtins.__builtin_object_size;
pub const __builtin___memset_chk = @import("std").zig.c_builtins.__builtin___memset_chk;
pub const __builtin_memset = @import("std").zig.c_builtins.__builtin_memset;
pub const __builtin___memcpy_chk = @import("std").zig.c_builtins.__builtin___memcpy_chk;
pub const __builtin_memcpy = @import("std").zig.c_builtins.__builtin_memcpy;
pub const __builtin_expect = @import("std").zig.c_builtins.__builtin_expect;
pub const __builtin_nanf = @import("std").zig.c_builtins.__builtin_nanf;
pub const __builtin_huge_valf = @import("std").zig.c_builtins.__builtin_huge_valf;
pub const __builtin_inff = @import("std").zig.c_builtins.__builtin_inff;
pub const __builtin_isnan = @import("std").zig.c_builtins.__builtin_isnan;
pub const __builtin_isinf = @import("std").zig.c_builtins.__builtin_isinf;
pub const __builtin_isinf_sign = @import("std").zig.c_builtins.__builtin_isinf_sign;
pub export fn wat() ?*anyopaque {
    var x: c_int = 123;
    return @ptrCast(?*anyopaque, &x);
}
pub export fn main() c_int {
    var x: [*c][*c]c_int = @ptrCast([*c][*c]c_int, @alignCast(@import("std").meta.alignment([*c]c_int), wat()));
    _ = x;
    return 0;
}
pub const __block = @compileError("unable to translate macro: undefined identifier `__attribute__`"); // (no file):27:9
pub const __INTMAX_C_SUFFIX__ = @compileError("unable to translate macro: undefined identifier `L`"); // (no file):69:9
pub const __UINTMAX_C_SUFFIX__ = @compileError("unable to translate macro: undefined identifier `UL`"); // (no file):75:9
pub const __INT64_C_SUFFIX__ = @compileError("unable to translate macro: undefined identifier `LL`"); // (no file):165:9
pub const __UINT32_C_SUFFIX__ = @compileError("unable to translate macro: undefined identifier `U`"); // (no file):187:9
pub const __UINT64_C_SUFFIX__ = @compileError("unable to translate macro: undefined identifier `ULL`"); // (no file):195:9
pub const __USER_LABEL_PREFIX__ = @compileError("unable to translate macro: undefined identifier `_`"); // (no file):278:9
pub const __nonnull = @compileError("unable to translate macro: undefined identifier `_Nonnull`"); // (no file):308:9
pub const __null_unspecified = @compileError("unable to translate macro: undefined identifier `_Null_unspecified`"); // (no file):309:9
pub const __nullable = @compileError("unable to translate macro: undefined identifier `_Nullable`"); // (no file):310:9
pub const __seg_gs = @compileError("unable to translate macro: undefined identifier `__attribute__`"); // (no file):319:9
pub const __seg_fs = @compileError("unable to translate macro: undefined identifier `__attribute__`"); // (no file):320:9
pub const __weak = @compileError("unable to translate macro: undefined identifier `__attribute__`"); // (no file):368:9
pub const __llvm__ = @as(c_int, 1);
pub const __clang__ = @as(c_int, 1);
pub const __clang_major__ = @as(c_int, 13);
pub const __clang_minor__ = @as(c_int, 0);
pub const __clang_patchlevel__ = @as(c_int, 1);
pub const __clang_version__ = "13.0.1 ";
pub const __GNUC__ = @as(c_int, 4);
pub const __GNUC_MINOR__ = @as(c_int, 2);
pub const __GNUC_PATCHLEVEL__ = @as(c_int, 1);
pub const __GXX_ABI_VERSION = @as(c_int, 1002);
pub const __ATOMIC_RELAXED = @as(c_int, 0);
pub const __ATOMIC_CONSUME = @as(c_int, 1);
pub const __ATOMIC_ACQUIRE = @as(c_int, 2);
pub const __ATOMIC_RELEASE = @as(c_int, 3);
pub const __ATOMIC_ACQ_REL = @as(c_int, 4);
pub const __ATOMIC_SEQ_CST = @as(c_int, 5);
pub const __OPENCL_MEMORY_SCOPE_WORK_ITEM = @as(c_int, 0);
pub const __OPENCL_MEMORY_SCOPE_WORK_GROUP = @as(c_int, 1);
pub const __OPENCL_MEMORY_SCOPE_DEVICE = @as(c_int, 2);
pub const __OPENCL_MEMORY_SCOPE_ALL_SVM_DEVICES = @as(c_int, 3);
pub const __OPENCL_MEMORY_SCOPE_SUB_GROUP = @as(c_int, 4);
pub const __PRAGMA_REDEFINE_EXTNAME = @as(c_int, 1);
pub const __VERSION__ = "Homebrew Clang 13.0.1";
pub const __OBJC_BOOL_IS_BOOL = @as(c_int, 0);
pub const __CONSTANT_CFSTRINGS__ = @as(c_int, 1);
pub const __BLOCKS__ = @as(c_int, 1);
pub const __clang_literal_encoding__ = "UTF-8";
pub const __clang_wide_literal_encoding__ = "UTF-32";
pub const __OPTIMIZE__ = @as(c_int, 1);
pub const __ORDER_LITTLE_ENDIAN__ = @as(c_int, 1234);
pub const __ORDER_BIG_ENDIAN__ = @as(c_int, 4321);
pub const __ORDER_PDP_ENDIAN__ = @as(c_int, 3412);
pub const __BYTE_ORDER__ = __ORDER_LITTLE_ENDIAN__;
pub const __LITTLE_ENDIAN__ = @as(c_int, 1);
pub const _LP64 = @as(c_int, 1);
pub const __LP64__ = @as(c_int, 1);
pub const __CHAR_BIT__ = @as(c_int, 8);
pub const __SCHAR_MAX__ = @as(c_int, 127);
pub const __SHRT_MAX__ = @as(c_int, 32767);
pub const __INT_MAX__ = @import("std").zig.c_translation.promoteIntLiteral(c_int, 2147483647, .decimal);
pub const __LONG_MAX__ = @import("std").zig.c_translation.promoteIntLiteral(c_long, 9223372036854775807, .decimal);
pub const __LONG_LONG_MAX__ = @as(c_longlong, 9223372036854775807);
pub const __WCHAR_MAX__ = @import("std").zig.c_translation.promoteIntLiteral(c_int, 2147483647, .decimal);
pub const __WINT_MAX__ = @import("std").zig.c_translation.promoteIntLiteral(c_int, 2147483647, .decimal);
pub const __INTMAX_MAX__ = @import("std").zig.c_translation.promoteIntLiteral(c_long, 9223372036854775807, .decimal);
pub const __SIZE_MAX__ = @import("std").zig.c_translation.promoteIntLiteral(c_ulong, 18446744073709551615, .decimal);
pub const __UINTMAX_MAX__ = @import("std").zig.c_translation.promoteIntLiteral(c_ulong, 18446744073709551615, .decimal);
pub const __PTRDIFF_MAX__ = @import("std").zig.c_translation.promoteIntLiteral(c_long, 9223372036854775807, .decimal);
pub const __INTPTR_MAX__ = @import("std").zig.c_translation.promoteIntLiteral(c_long, 9223372036854775807, .decimal);
pub const __UINTPTR_MAX__ = @import("std").zig.c_translation.promoteIntLiteral(c_ulong, 18446744073709551615, .decimal);
pub const __SIZEOF_DOUBLE__ = @as(c_int, 8);
pub const __SIZEOF_FLOAT__ = @as(c_int, 4);
pub const __SIZEOF_INT__ = @as(c_int, 4);
pub const __SIZEOF_LONG__ = @as(c_int, 8);
pub const __SIZEOF_LONG_DOUBLE__ = @as(c_int, 16);
pub const __SIZEOF_LONG_LONG__ = @as(c_int, 8);
pub const __SIZEOF_POINTER__ = @as(c_int, 8);
pub const __SIZEOF_SHORT__ = @as(c_int, 2);
pub const __SIZEOF_PTRDIFF_T__ = @as(c_int, 8);
pub const __SIZEOF_SIZE_T__ = @as(c_int, 8);
pub const __SIZEOF_WCHAR_T__ = @as(c_int, 4);
pub const __SIZEOF_WINT_T__ = @as(c_int, 4);
pub const __SIZEOF_INT128__ = @as(c_int, 16);
pub const __INTMAX_TYPE__ = c_long;
pub const __INTMAX_FMTd__ = "ld";
pub const __INTMAX_FMTi__ = "li";
pub const __UINTMAX_TYPE__ = c_ulong;
pub const __UINTMAX_FMTo__ = "lo";
pub const __UINTMAX_FMTu__ = "lu";
pub const __UINTMAX_FMTx__ = "lx";
pub const __UINTMAX_FMTX__ = "lX";
pub const __INTMAX_WIDTH__ = @as(c_int, 64);
pub const __PTRDIFF_TYPE__ = c_long;
pub const __PTRDIFF_FMTd__ = "ld";
pub const __PTRDIFF_FMTi__ = "li";
pub const __PTRDIFF_WIDTH__ = @as(c_int, 64);
pub const __INTPTR_TYPE__ = c_long;
pub const __INTPTR_FMTd__ = "ld";
pub const __INTPTR_FMTi__ = "li";
pub const __INTPTR_WIDTH__ = @as(c_int, 64);
pub const __SIZE_TYPE__ = c_ulong;
pub const __SIZE_FMTo__ = "lo";
pub const __SIZE_FMTu__ = "lu";
pub const __SIZE_FMTx__ = "lx";
pub const __SIZE_FMTX__ = "lX";
pub const __SIZE_WIDTH__ = @as(c_int, 64);
pub const __WCHAR_TYPE__ = c_int;
pub const __WCHAR_WIDTH__ = @as(c_int, 32);
pub const __WINT_TYPE__ = c_int;
pub const __WINT_WIDTH__ = @as(c_int, 32);
pub const __SIG_ATOMIC_WIDTH__ = @as(c_int, 32);
pub const __SIG_ATOMIC_MAX__ = @import("std").zig.c_translation.promoteIntLiteral(c_int, 2147483647, .decimal);
pub const __CHAR16_TYPE__ = c_ushort;
pub const __CHAR32_TYPE__ = c_uint;
pub const __UINTMAX_WIDTH__ = @as(c_int, 64);
pub const __UINTPTR_TYPE__ = c_ulong;
pub const __UINTPTR_FMTo__ = "lo";
pub const __UINTPTR_FMTu__ = "lu";
pub const __UINTPTR_FMTx__ = "lx";
pub const __UINTPTR_FMTX__ = "lX";
pub const __UINTPTR_WIDTH__ = @as(c_int, 64);
pub const __FLT_DENORM_MIN__ = @as(f32, 1.40129846e-45);
pub const __FLT_HAS_DENORM__ = @as(c_int, 1);
pub const __FLT_DIG__ = @as(c_int, 6);
pub const __FLT_DECIMAL_DIG__ = @as(c_int, 9);
pub const __FLT_EPSILON__ = @as(f32, 1.19209290e-7);
pub const __FLT_HAS_INFINITY__ = @as(c_int, 1);
pub const __FLT_HAS_QUIET_NAN__ = @as(c_int, 1);
pub const __FLT_MANT_DIG__ = @as(c_int, 24);
pub const __FLT_MAX_10_EXP__ = @as(c_int, 38);
pub const __FLT_MAX_EXP__ = @as(c_int, 128);
pub const __FLT_MAX__ = @as(f32, 3.40282347e+38);
pub const __FLT_MIN_10_EXP__ = -@as(c_int, 37);
pub const __FLT_MIN_EXP__ = -@as(c_int, 125);
pub const __FLT_MIN__ = @as(f32, 1.17549435e-38);
pub const __DBL_DENORM_MIN__ = 4.9406564584124654e-324;
pub const __DBL_HAS_DENORM__ = @as(c_int, 1);
pub const __DBL_DIG__ = @as(c_int, 15);
pub const __DBL_DECIMAL_DIG__ = @as(c_int, 17);
pub const __DBL_EPSILON__ = 2.2204460492503131e-16;
pub const __DBL_HAS_INFINITY__ = @as(c_int, 1);
pub const __DBL_HAS_QUIET_NAN__ = @as(c_int, 1);
pub const __DBL_MANT_DIG__ = @as(c_int, 53);
pub const __DBL_MAX_10_EXP__ = @as(c_int, 308);
pub const __DBL_MAX_EXP__ = @as(c_int, 1024);
pub const __DBL_MAX__ = 1.7976931348623157e+308;
pub const __DBL_MIN_10_EXP__ = -@as(c_int, 307);
pub const __DBL_MIN_EXP__ = -@as(c_int, 1021);
pub const __DBL_MIN__ = 2.2250738585072014e-308;
pub const __LDBL_DENORM_MIN__ = @as(c_longdouble, 3.64519953188247460253e-4951);
pub const __LDBL_HAS_DENORM__ = @as(c_int, 1);
pub const __LDBL_DIG__ = @as(c_int, 18);
pub const __LDBL_DECIMAL_DIG__ = @as(c_int, 21);
pub const __LDBL_EPSILON__ = @as(c_longdouble, 1.08420217248550443401e-19);
pub const __LDBL_HAS_INFINITY__ = @as(c_int, 1);
pub const __LDBL_HAS_QUIET_NAN__ = @as(c_int, 1);
pub const __LDBL_MANT_DIG__ = @as(c_int, 64);
pub const __LDBL_MAX_10_EXP__ = @as(c_int, 4932);
pub const __LDBL_MAX_EXP__ = @as(c_int, 16384);
pub const __LDBL_MAX__ = @as(c_longdouble, 1.18973149535723176502e+4932);
pub const __LDBL_MIN_10_EXP__ = -@as(c_int, 4931);
pub const __LDBL_MIN_EXP__ = -@as(c_int, 16381);
pub const __LDBL_MIN__ = @as(c_longdouble, 3.36210314311209350626e-4932);
pub const __POINTER_WIDTH__ = @as(c_int, 64);
pub const __BIGGEST_ALIGNMENT__ = @as(c_int, 16);
pub const __INT8_TYPE__ = i8;
pub const __INT8_FMTd__ = "hhd";
pub const __INT8_FMTi__ = "hhi";
pub const __INT8_C_SUFFIX__ = "";
pub const __INT16_TYPE__ = c_short;
pub const __INT16_FMTd__ = "hd";
pub const __INT16_FMTi__ = "hi";
pub const __INT16_C_SUFFIX__ = "";
pub const __INT32_TYPE__ = c_int;
pub const __INT32_FMTd__ = "d";
pub const __INT32_FMTi__ = "i";
pub const __INT32_C_SUFFIX__ = "";
pub const __INT64_TYPE__ = c_longlong;
pub const __INT64_FMTd__ = "lld";
pub const __INT64_FMTi__ = "lli";
pub const __UINT8_TYPE__ = u8;
pub const __UINT8_FMTo__ = "hho";
pub const __UINT8_FMTu__ = "hhu";
pub const __UINT8_FMTx__ = "hhx";
pub const __UINT8_FMTX__ = "hhX";
pub const __UINT8_C_SUFFIX__ = "";
pub const __UINT8_MAX__ = @as(c_int, 255);
pub const __INT8_MAX__ = @as(c_int, 127);
pub const __UINT16_TYPE__ = c_ushort;
pub const __UINT16_FMTo__ = "ho";
pub const __UINT16_FMTu__ = "hu";
pub const __UINT16_FMTx__ = "hx";
pub const __UINT16_FMTX__ = "hX";
pub const __UINT16_C_SUFFIX__ = "";
pub const __UINT16_MAX__ = @import("std").zig.c_translation.promoteIntLiteral(c_int, 65535, .decimal);
pub const __INT16_MAX__ = @as(c_int, 32767);
pub const __UINT32_TYPE__ = c_uint;
pub const __UINT32_FMTo__ = "o";
pub const __UINT32_FMTu__ = "u";
pub const __UINT32_FMTx__ = "x";
pub const __UINT32_FMTX__ = "X";
pub const __UINT32_MAX__ = @import("std").zig.c_translation.promoteIntLiteral(c_uint, 4294967295, .decimal);
pub const __INT32_MAX__ = @import("std").zig.c_translation.promoteIntLiteral(c_int, 2147483647, .decimal);
pub const __UINT64_TYPE__ = c_ulonglong;
pub const __UINT64_FMTo__ = "llo";
pub const __UINT64_FMTu__ = "llu";
pub const __UINT64_FMTx__ = "llx";
pub const __UINT64_FMTX__ = "llX";
pub const __UINT64_MAX__ = @as(c_ulonglong, 18446744073709551615);
pub const __INT64_MAX__ = @as(c_longlong, 9223372036854775807);
pub const __INT_LEAST8_TYPE__ = i8;
pub const __INT_LEAST8_MAX__ = @as(c_int, 127);
pub const __INT_LEAST8_FMTd__ = "hhd";
pub const __INT_LEAST8_FMTi__ = "hhi";
pub const __UINT_LEAST8_TYPE__ = u8;
pub const __UINT_LEAST8_MAX__ = @as(c_int, 255);
pub const __UINT_LEAST8_FMTo__ = "hho";
pub const __UINT_LEAST8_FMTu__ = "hhu";
pub const __UINT_LEAST8_FMTx__ = "hhx";
pub const __UINT_LEAST8_FMTX__ = "hhX";
pub const __INT_LEAST16_TYPE__ = c_short;
pub const __INT_LEAST16_MAX__ = @as(c_int, 32767);
pub const __INT_LEAST16_FMTd__ = "hd";
pub const __INT_LEAST16_FMTi__ = "hi";
pub const __UINT_LEAST16_TYPE__ = c_ushort;
pub const __UINT_LEAST16_MAX__ = @import("std").zig.c_translation.promoteIntLiteral(c_int, 65535, .decimal);
pub const __UINT_LEAST16_FMTo__ = "ho";
pub const __UINT_LEAST16_FMTu__ = "hu";
pub const __UINT_LEAST16_FMTx__ = "hx";
pub const __UINT_LEAST16_FMTX__ = "hX";
pub const __INT_LEAST32_TYPE__ = c_int;
pub const __INT_LEAST32_MAX__ = @import("std").zig.c_translation.promoteIntLiteral(c_int, 2147483647, .decimal);
pub const __INT_LEAST32_FMTd__ = "d";
pub const __INT_LEAST32_FMTi__ = "i";
pub const __UINT_LEAST32_TYPE__ = c_uint;
pub const __UINT_LEAST32_MAX__ = @import("std").zig.c_translation.promoteIntLiteral(c_uint, 4294967295, .decimal);
pub const __UINT_LEAST32_FMTo__ = "o";
pub const __UINT_LEAST32_FMTu__ = "u";
pub const __UINT_LEAST32_FMTx__ = "x";
pub const __UINT_LEAST32_FMTX__ = "X";
pub const __INT_LEAST64_TYPE__ = c_longlong;
pub const __INT_LEAST64_MAX__ = @as(c_longlong, 9223372036854775807);
pub const __INT_LEAST64_FMTd__ = "lld";
pub const __INT_LEAST64_FMTi__ = "lli";
pub const __UINT_LEAST64_TYPE__ = c_ulonglong;
pub const __UINT_LEAST64_MAX__ = @as(c_ulonglong, 18446744073709551615);
pub const __UINT_LEAST64_FMTo__ = "llo";
pub const __UINT_LEAST64_FMTu__ = "llu";
pub const __UINT_LEAST64_FMTx__ = "llx";
pub const __UINT_LEAST64_FMTX__ = "llX";
pub const __INT_FAST8_TYPE__ = i8;
pub const __INT_FAST8_MAX__ = @as(c_int, 127);
pub const __INT_FAST8_FMTd__ = "hhd";
pub const __INT_FAST8_FMTi__ = "hhi";
pub const __UINT_FAST8_TYPE__ = u8;
pub const __UINT_FAST8_MAX__ = @as(c_int, 255);
pub const __UINT_FAST8_FMTo__ = "hho";
pub const __UINT_FAST8_FMTu__ = "hhu";
pub const __UINT_FAST8_FMTx__ = "hhx";
pub const __UINT_FAST8_FMTX__ = "hhX";
pub const __INT_FAST16_TYPE__ = c_short;
pub const __INT_FAST16_MAX__ = @as(c_int, 32767);
pub const __INT_FAST16_FMTd__ = "hd";
pub const __INT_FAST16_FMTi__ = "hi";
pub const __UINT_FAST16_TYPE__ = c_ushort;
pub const __UINT_FAST16_MAX__ = @import("std").zig.c_translation.promoteIntLiteral(c_int, 65535, .decimal);
pub const __UINT_FAST16_FMTo__ = "ho";
pub const __UINT_FAST16_FMTu__ = "hu";
pub const __UINT_FAST16_FMTx__ = "hx";
pub const __UINT_FAST16_FMTX__ = "hX";
pub const __INT_FAST32_TYPE__ = c_int;
pub const __INT_FAST32_MAX__ = @import("std").zig.c_translation.promoteIntLiteral(c_int, 2147483647, .decimal);
pub const __INT_FAST32_FMTd__ = "d";
pub const __INT_FAST32_FMTi__ = "i";
pub const __UINT_FAST32_TYPE__ = c_uint;
pub const __UINT_FAST32_MAX__ = @import("std").zig.c_translation.promoteIntLiteral(c_uint, 4294967295, .decimal);
pub const __UINT_FAST32_FMTo__ = "o";
pub const __UINT_FAST32_FMTu__ = "u";
pub const __UINT_FAST32_FMTx__ = "x";
pub const __UINT_FAST32_FMTX__ = "X";
pub const __INT_FAST64_TYPE__ = c_longlong;
pub const __INT_FAST64_MAX__ = @as(c_longlong, 9223372036854775807);
pub const __INT_FAST64_FMTd__ = "lld";
pub const __INT_FAST64_FMTi__ = "lli";
pub const __UINT_FAST64_TYPE__ = c_ulonglong;
pub const __UINT_FAST64_MAX__ = @as(c_ulonglong, 18446744073709551615);
pub const __UINT_FAST64_FMTo__ = "llo";
pub const __UINT_FAST64_FMTu__ = "llu";
pub const __UINT_FAST64_FMTx__ = "llx";
pub const __UINT_FAST64_FMTX__ = "llX";
pub const __FINITE_MATH_ONLY__ = @as(c_int, 0);
pub const __GNUC_STDC_INLINE__ = @as(c_int, 1);
pub const __GCC_ATOMIC_TEST_AND_SET_TRUEVAL = @as(c_int, 1);
pub const __CLANG_ATOMIC_BOOL_LOCK_FREE = @as(c_int, 2);
pub const __CLANG_ATOMIC_CHAR_LOCK_FREE = @as(c_int, 2);
pub const __CLANG_ATOMIC_CHAR16_T_LOCK_FREE = @as(c_int, 2);
pub const __CLANG_ATOMIC_CHAR32_T_LOCK_FREE = @as(c_int, 2);
pub const __CLANG_ATOMIC_WCHAR_T_LOCK_FREE = @as(c_int, 2);
pub const __CLANG_ATOMIC_SHORT_LOCK_FREE = @as(c_int, 2);
pub const __CLANG_ATOMIC_INT_LOCK_FREE = @as(c_int, 2);
pub const __CLANG_ATOMIC_LONG_LOCK_FREE = @as(c_int, 2);
pub const __CLANG_ATOMIC_LLONG_LOCK_FREE = @as(c_int, 2);
pub const __CLANG_ATOMIC_POINTER_LOCK_FREE = @as(c_int, 2);
pub const __GCC_ATOMIC_BOOL_LOCK_FREE = @as(c_int, 2);
pub const __GCC_ATOMIC_CHAR_LOCK_FREE = @as(c_int, 2);
pub const __GCC_ATOMIC_CHAR16_T_LOCK_FREE = @as(c_int, 2);
pub const __GCC_ATOMIC_CHAR32_T_LOCK_FREE = @as(c_int, 2);
pub const __GCC_ATOMIC_WCHAR_T_LOCK_FREE = @as(c_int, 2);
pub const __GCC_ATOMIC_SHORT_LOCK_FREE = @as(c_int, 2);
pub const __GCC_ATOMIC_INT_LOCK_FREE = @as(c_int, 2);
pub const __GCC_ATOMIC_LONG_LOCK_FREE = @as(c_int, 2);
pub const __GCC_ATOMIC_LLONG_LOCK_FREE = @as(c_int, 2);
pub const __GCC_ATOMIC_POINTER_LOCK_FREE = @as(c_int, 2);
pub const __PIC__ = @as(c_int, 2);
pub const __pic__ = @as(c_int, 2);
pub const __FLT_EVAL_METHOD__ = @as(c_int, 0);
pub const __FLT_RADIX__ = @as(c_int, 2);
pub const __DECIMAL_DIG__ = __LDBL_DECIMAL_DIG__;
pub const __SSP_STRONG__ = @as(c_int, 2);
pub const __GCC_ASM_FLAG_OUTPUTS__ = @as(c_int, 1);
pub const __code_model_small__ = @as(c_int, 1);
pub const __amd64__ = @as(c_int, 1);
pub const __amd64 = @as(c_int, 1);
pub const __x86_64 = @as(c_int, 1);
pub const __x86_64__ = @as(c_int, 1);
pub const __SEG_GS = @as(c_int, 1);
pub const __SEG_FS = @as(c_int, 1);
pub const __corei7 = @as(c_int, 1);
pub const __corei7__ = @as(c_int, 1);
pub const __tune_corei7__ = @as(c_int, 1);
pub const __REGISTER_PREFIX__ = "";
pub const __NO_MATH_INLINES = @as(c_int, 1);
pub const __AES__ = @as(c_int, 1);
pub const __PCLMUL__ = @as(c_int, 1);
pub const __LAHF_SAHF__ = @as(c_int, 1);
pub const __LZCNT__ = @as(c_int, 1);
pub const __RDRND__ = @as(c_int, 1);
pub const __FSGSBASE__ = @as(c_int, 1);
pub const __BMI__ = @as(c_int, 1);
pub const __BMI2__ = @as(c_int, 1);
pub const __POPCNT__ = @as(c_int, 1);
pub const __PRFCHW__ = @as(c_int, 1);
pub const __RDSEED__ = @as(c_int, 1);
pub const __ADX__ = @as(c_int, 1);
pub const __MOVBE__ = @as(c_int, 1);
pub const __FMA__ = @as(c_int, 1);
pub const __F16C__ = @as(c_int, 1);
pub const __FXSR__ = @as(c_int, 1);
pub const __XSAVE__ = @as(c_int, 1);
pub const __XSAVEOPT__ = @as(c_int, 1);
pub const __XSAVEC__ = @as(c_int, 1);
pub const __XSAVES__ = @as(c_int, 1);
pub const __CLFLUSHOPT__ = @as(c_int, 1);
pub const __SGX__ = @as(c_int, 1);
pub const __INVPCID__ = @as(c_int, 1);
pub const __AVX2__ = @as(c_int, 1);
pub const __AVX__ = @as(c_int, 1);
pub const __SSE4_2__ = @as(c_int, 1);
pub const __SSE4_1__ = @as(c_int, 1);
pub const __SSSE3__ = @as(c_int, 1);
pub const __SSE3__ = @as(c_int, 1);
pub const __SSE2__ = @as(c_int, 1);
pub const __SSE2_MATH__ = @as(c_int, 1);
pub const __SSE__ = @as(c_int, 1);
pub const __SSE_MATH__ = @as(c_int, 1);
pub const __MMX__ = @as(c_int, 1);
pub const __GCC_HAVE_SYNC_COMPARE_AND_SWAP_1 = @as(c_int, 1);
pub const __GCC_HAVE_SYNC_COMPARE_AND_SWAP_2 = @as(c_int, 1);
pub const __GCC_HAVE_SYNC_COMPARE_AND_SWAP_4 = @as(c_int, 1);
pub const __GCC_HAVE_SYNC_COMPARE_AND_SWAP_8 = @as(c_int, 1);
pub const __GCC_HAVE_SYNC_COMPARE_AND_SWAP_16 = @as(c_int, 1);
pub const __APPLE_CC__ = @as(c_int, 6000);
pub const __APPLE__ = @as(c_int, 1);
pub const __STDC_NO_THREADS__ = @as(c_int, 1);
pub const __strong = "";
pub const __unsafe_unretained = "";
pub const __DYNAMIC__ = @as(c_int, 1);
pub const __ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__ = @import("std").zig.c_translation.promoteIntLiteral(c_int, 120100, .decimal);
pub const __MACH__ = @as(c_int, 1);
pub const __STDC__ = @as(c_int, 1);
pub const __STDC_HOSTED__ = @as(c_int, 1);
pub const __STDC_VERSION__ = @as(c_long, 201710);
pub const __STDC_UTF_16__ = @as(c_int, 1);
pub const __STDC_UTF_32__ = @as(c_int, 1);
pub const _DEBUG = @as(c_int, 1);
pub const __GCC_HAVE_DWARF2_CFI_ASM = @as(c_int, 1);

But specifically note:

    var x: [*c][*c]c_int = @ptrCast([*c][*c]c_int, @alignCast(@import("std").meta.alignment([*c]c_int), wat()));

And then zig build-exe main.zig

./main.zig:55:28: error: cast increases pointer alignment
    var x: [*c][*c]c_int = @ptrCast([*c][*c]c_int, @alignCast(@import("std").meta.alignment([*c]c_int), wat()));
                           ^
./main.zig:55:52: note: '?*align(4) anyopaque' has alignment 4
    var x: [*c][*c]c_int = @ptrCast([*c][*c]c_int, @alignCast(@import("std").meta.alignment([*c]c_int), wat()));
                                                   ^
./main.zig:55:37: note: '[*c][*c]c_int' has alignment 8
    var x: [*c][*c]c_int = @ptrCast([*c][*c]c_int, @alignCast(@import("std").meta.alignment([*c]c_int), wat()));
                                    ^

But manually edited

    var x: [*c][*c]c_int = @ptrCast([*c][*c]c_int, @alignCast(@import("std").meta.alignment([*c][*c]c_int), wat()));

Compiles and executes fine. This has been observed with malloc return values being cast as well, but wanted to not include any lib code for repro hence the stack variable address taking.

Expected Behavior

The output of translate-c to be compilable without errors.

Actual Behavior

Gots errs.
@jfo jfo added the bug Observed behavior contradicts documented or intended behavior label Jul 13, 2022
@SpexGuy
Copy link
Contributor

SpexGuy commented Jul 13, 2022

This is a bug, but the problem is slightly different from what you've pointed out. char ** from C is correctly translated to [*c][*c]u8. The problem is that std.meta.alignment([*c]u8) is used instead of std.meta.alignment([*c][*c]u8).

@SpexGuy SpexGuy added contributor friendly This issue is limited in scope and/or knowledge of Zig internals. translate-c C to Zig source translation feature (@cImport) labels Jul 13, 2022
@jfo
Copy link
Contributor Author

jfo commented Jul 14, 2022

Yes, actually sorry you are right. In the "in the wild" example that is how we fixed it, in my minimum case I introduced a pointer cast that doesn't align correctly when the bug case is fixed, I will edit the comment above to better illustrate the point.

@Vexu Vexu added this to the 0.11.0 milestone Jul 29, 2022
@em-dash
Copy link
Contributor

em-dash commented Jul 31, 2022

i'll have a go at this, hopefully i'm not biting off too too much.

@em-dash
Copy link
Contributor

em-dash commented Aug 1, 2022

ok i think this is too much for me at the moment, i'll step aside and let someone else take it on. apologies.

@SpexGuy
Copy link
Contributor

SpexGuy commented Aug 4, 2022

@em-dash if you want a hint, the relevant code is here:

zig/src/translate_c.zig

Lines 3974 to 4011 in 616f65d

fn transCPtrCast(
c: *Context,
scope: *Scope,
loc: clang.SourceLocation,
dst_type: clang.QualType,
src_type: clang.QualType,
expr: Node,
) !Node {
const ty = dst_type.getTypePtr();
const child_type = ty.getPointeeType();
const src_ty = src_type.getTypePtr();
const src_child_type = src_ty.getPointeeType();
const dst_type_node = try transType(c, scope, ty, loc);
if (!src_ty.isArrayType() and ((src_child_type.isConstQualified() and
!child_type.isConstQualified()) or
(src_child_type.isVolatileQualified() and
!child_type.isVolatileQualified())))
{
return removeCVQualifiers(c, dst_type_node, expr);
} else {
// Implicit downcasting from higher to lower alignment values is forbidden,
// use @alignCast to side-step this problem
const rhs = if (qualTypeCanon(child_type).isVoidType())
// void has 1-byte alignment, so @alignCast is not needed
expr
else if (typeIsOpaque(c, qualTypeCanon(child_type), loc))
// For opaque types a ptrCast is enough
expr
else blk: {
const child_type_node = try transQualType(c, scope, child_type, loc);
const alignof = try Tag.std_meta_alignment.create(c.arena, child_type_node);
const align_cast = try Tag.align_cast.create(c.arena, .{ .lhs = alignof, .rhs = expr });
break :blk align_cast;
};
return Tag.ptr_cast.create(c.arena, .{ .lhs = dst_type_node, .rhs = rhs });
}
}

The std_meta_alignment tag is the one that generates this call, and the problem is that it's operating on the child type instead of the actual pointer type.

@em-dash
Copy link
Contributor

em-dash commented Aug 5, 2022

@SpexGuy thanks for the hint, i think i've got it now.

@em-dash em-dash mentioned this issue Aug 5, 2022
Merged
@Vexu Vexu modified the milestones: 0.11.0, 0.10.0 Aug 5, 2022
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
Assignees
No one assigned
Labels
bug Observed behavior contradicts documented or intended behavior contributor friendly This issue is limited in scope and/or knowledge of Zig internals. translate-c C to Zig source translation feature (@cImport)
Projects
None yet
Milestone
0.10.0
Development

Successfully merging a pull request may close this issue.

Fix translate-c pointer cast #12110 em-dash/zig
4 participants
@SpexGuy @jfo @Vexu @em-dash