# Const pointer with large array size **URL:** \ **Category:** Help\ **Tags:** language, zig-0-12\ **Created:** [May 12, 2024, 7:04pm UTC](https://ziggit.dev/t/const-pointer-with-large-array-size/4294 "2024-05-12T19:04:47Z")\ **Posts on this page:** 10\ **Page:** 1
**Author:** ![fmamud](https://ziggit.dev/user_avatar/ziggit.dev/fmamud/32/2352_2.png) [@fmamud](https://ziggit.dev/u/fmamud)\ **Post date:** [May 12, 2024, 7:04pm UTC](https://ziggit.dev/t/const-pointer-with-large-array-size/4294/1 "2024-05-12T19:04:47Z")
Hey, please could you help me to understand what is the expected behaviour of code snippet bellow? ```zig const t: *const [1000]u8 = "asdf"; std.debug.print("string: {s}\n", .{t}); ``` I’m using a scaffold build file from `zig init`, and using `zig build && ./zig-out/bin/main` to test it. Compilation is fine with no errors. Should I get a panic instead or it’s expected? I do see different kind of overflow data 😀 depends on release mode. Please see few examples: | Buil type cmd | Output | | --- | --- | | `zig build` | string: asdfinteger overflowattempt to cast negative value to unsigned integerh�Fstring: {s} invalid error codethread {} panic: {s} Panicked during a panic. Aborting. (msg truncated)@memcpy arguments aliasswitch on corrupt valueunable to install segfault handler, maybe adjust have\_segfault\_handling\_support in std/debug.zigreached unreachable codeDeadlock detectedincorrect alignment’noreturn’ function returnedattempt to use null valueinteger cast truncated bitscast causes pointer to be null\_\_TEXT\_\_unwind\_info\_\_eh\_frame{s}:{d}:{d}???:?:?: 0x{x} in {s} ({s}) ^???for loop over objects with non-equal lengths@memcpy arguments have non-equal lengths\_\_DWARF\_\_debug\_info\_\_debug\_abbrev\_\_debug\_str\_\_debug\_str\_offsets\_\_debug\_line\_\_debug\_line\_str\_\_debug\_ranges\_\_debug\_loclists\_\_debug\_rnglists\_\_debug\_addr\_\_debug\_names\_\_debug\_frame\_\_eh\_frame\_h | | `zig build --release=small` | string: asdf00010203040506070809101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899OperationNotSupported 8888@`��0`��04X���� t | | `zig build --release=fast` | string: asdf(msg truncated)failed to set noop SIGPIPE handler: {s}00010203040506070809101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899OperationNotSupportedDiskQuotaFileTooBigInputOutputNoSpaceLeftDeviceBusyInvalidArgumentAccessDeniedBrokenPipeSystemResourcesOperationAbortedNotOpenForWritingLockViolationWouldBlockConnectionResetByPeerUnexpectedOverflowInvalidUtf8Utf8ExpectedContinuationUtf8OverlongEncodingUtf8EncodesSurrogateHalfUtf8CodepointTooLargeUtf8InvalidStartByteTruncatedInputUtf8CannotEncodeSurrogateHalfCodepointTooLargeMissingDebugInfoUnsupportedOperatingSystemInvalidDebugInfoOutOfMemorySharingViolationPathAlreadyExistsFileNotFoundPipeBusyNameTooLongInvalidWtf8BadPathNameNetworkNotFoundAntivirusInterferenceSymLinkLoopProcessFdQuotaExceededSystemFdQuotaExceededNoDeviceIsDirNotDirFileLocksNotSupportedFileBusy | | `zig build --release=safe` | string: asdf\_\_TEXT\_\_unwind\_info\_\_eh\_frame\_\_DWARF\_\_debug\_info\_\_debug\_abbrev\_\_debug\_str\_\_debug\_str\_offsets\_\_debug\_line\_\_debug\_line\_str\_\_debug\_ranges\_\_debug\_loclists\_\_debug\_rnglists\_\_debug\_addr\_\_debug\_names\_\_debug\_frame\_\_eh\_frame\_hdr(msg truncated)failed to set noop SIGPIPE handler: {s}00010203040506070809101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899OperationNotSupportedDiskQuotaFileTooBigInputOutputNoSpaceLeftDeviceBusyInvalidArgumentAccessDeniedBrokenPipeSystemResourcesOperationAbortedNotOpenForWritingLockViolationWouldBlockConnectionResetByPeerUnexpectedMissingDebugInfoUnsupportedOperatingSystemInvalidDebugInfoOutOfMemorySharingViolationPathAlreadyExistsFileNotFoundPipeBusyNameTooLongInvalidUtf8InvalidWtf8BadPathNameNetworkNotFoundAntivirusInterferenceSymLinkLoopProcessFdQuotaExc | Many thanks in advance. Best, Felipe ---
**Author:** ![IntegratedQuantum](https://ziggit.dev/user_avatar/ziggit.dev/integratedquantum/32/782_2.png) [@IntegratedQuantum](https://ziggit.dev/u/IntegratedQuantum)\ **Post date:** [May 12, 2024, 7:50pm UTC](https://ziggit.dev/t/const-pointer-with-large-array-size/4294/2 "2024-05-12T19:50:07Z")
It should give you a compiler error, something like ```zig test.zig:10:29: error: expected type '*const [1000]u8', found '*const [4:0]u8' const t: *const [1000]u8 = "asdf"; ^ ~~~~~ ``` This looks like it could be a compiler bug. What version of zig you are using? ---
**Author:** ![fmamud](https://ziggit.dev/user_avatar/ziggit.dev/fmamud/32/2352_2.png) [@fmamud](https://ziggit.dev/u/fmamud)\ **Post date:** [May 12, 2024, 7:52pm UTC](https://ziggit.dev/t/const-pointer-with-large-array-size/4294/3 "2024-05-12T19:52:06Z")
@IntegratedQuantum I’m using `0.12.0` installed by homebrew. ```zig $ zig version 0.12.0 $ sw_vers ProductName: macOS ProductVersion: 14.4.1 BuildVersion: 23E224 ``` ---
**Author:** ![fmamud](https://ziggit.dev/user_avatar/ziggit.dev/fmamud/32/2352_2.png) [@fmamud](https://ziggit.dev/u/fmamud)\ **Post date:** [May 12, 2024, 7:59pm UTC](https://ziggit.dev/t/const-pointer-with-large-array-size/4294/4 "2024-05-12T19:59:59Z")
btw I was expecting an compiler error like you’ve sent. Currently I’m using on MacOS ARM M1 arch. Have you using same version but diff arch probably? ---
**Author:** ![IntegratedQuantum](https://ziggit.dev/user_avatar/ziggit.dev/integratedquantum/32/782_2.png) [@IntegratedQuantum](https://ziggit.dev/u/IntegratedQuantum)\ **Post date:** [May 12, 2024, 8:02pm UTC](https://ziggit.dev/t/const-pointer-with-large-array-size/4294/5 "2024-05-12T20:02:17Z")
I was using a slightly older version (0.12.0-dev.3518+d2be725e4). I just tried zig 0.12 and I get the same behavior. ---
**Author:** ![IntegratedQuantum](https://ziggit.dev/user_avatar/ziggit.dev/integratedquantum/32/782_2.png) [@IntegratedQuantum](https://ziggit.dev/u/IntegratedQuantum)\ **Post date:** [May 12, 2024, 8:04pm UTC](https://ziggit.dev/t/const-pointer-with-large-array-size/4294/6 "2024-05-12T20:04:18Z")
It’s probably best if you report this on github. ---
**Author:** ![fmamud](https://ziggit.dev/user_avatar/ziggit.dev/fmamud/32/2352_2.png) [@fmamud](https://ziggit.dev/u/fmamud)\ **Post date:** [May 12, 2024, 8:05pm UTC](https://ziggit.dev/t/const-pointer-with-large-array-size/4294/7 "2024-05-12T20:05:06Z")
Yeah, I’m actually doing that right now… afterwards I’ll post the link over here. Many thanks for the confirmation @IntegratedQuantum . ---
**Author:** ![dimdin](https://ziggit.dev/user_avatar/ziggit.dev/dimdin/32/1457_2.png) [@dimdin](https://ziggit.dev/u/dimdin)\ **Post date:** [May 12, 2024, 8:16pm UTC](https://ziggit.dev/t/const-pointer-with-large-array-size/4294/8 "2024-05-12T20:16:55Z")
Yes, it’s a bug. This compiles and panics (since 995 bytes are undefined): ```zig const ts: *const [4:0]u8 = &[4:0]u8{ 'a', 's', 'd', 'f' }; const t: *const [1000]u8 = ts; ``` This does not compile: ```zig const ts: *const [4]u8 = &[4]u8{ 'a', 's', 'd', 'f' }; const t: *const [1000]u8 = ts; ``` error: `expected type '*const [1000]u8', found '*const [4]u8'` ---
**Author:** ![fmamud](https://ziggit.dev/user_avatar/ziggit.dev/fmamud/32/2352_2.png) [@fmamud](https://ziggit.dev/u/fmamud)\ **Post date:** [May 12, 2024, 8:26pm UTC](https://ziggit.dev/t/const-pointer-with-large-array-size/4294/9 "2024-05-12T20:26:28Z")
Many thanks for confirming this @dimdin and to catch it by other example, which doesn’t not compile here as well. ---
**Author:** ![fmamud](https://ziggit.dev/user_avatar/ziggit.dev/fmamud/32/2352_2.png) [@fmamud](https://ziggit.dev/u/fmamud)\ **Post date:** [May 12, 2024, 8:27pm UTC](https://ziggit.dev/t/const-pointer-with-large-array-size/4294/10 "2024-05-12T20:27:11Z")
Bug reported it. > > > \### Zig Version > > 0.12.0 > > \### Steps to Reproduce and Observed Behavior > > I was tes…ting the code snippet bellow and I was expecting a compiler error, but it doesn't happened. > > \`\`\`zig > const t: \*const \[1000\]u8 = "asdf"; > std.debug.print("string: {s}\\n", .{t}); > \`\`\` > > My current targeting is \`arm64\`: > > \`\`\` > $ sw\_vers > ProductName: macOS > ProductVersion: 14.4.1 > BuildVersion: 23E224 > \`\`\` > > I do see different kind of overflow data depending on release mode. Please see few examples: > > | Build type cmd | Output | > |--- | ---| > |\`zig build\` | string: asdfinteger overflowattempt to cast negative value to unsigned integerh�Fstring: {s} invalid error codethread {} panic: {s} Panicked during a panic. Aborting. (msg truncated)@memcpy arguments aliasswitch on corrupt valueunable to install segfault handler, maybe adjust have\_segfault\_handling\_support in std/debug.zigreached unreachable codeDeadlock detectedincorrect alignment'noreturn' function returnedattempt to use null valueinteger cast truncated bitscast causes pointer to be null\_\_TEXT\_\_unwind\_info\_\_eh\_frame{s}:{d}:{d}???:?:?: 0x{x} in {s} ({s}) ^???for loop over objects with non-equal lengths@memcpy arguments have non-equal lengths\_\_DWARF\_\_debug\_info\_\_debug\_abbrev\_\_debug\_str\_\_debug\_str\_offsets\_\_debug\_line\_\_debug\_line\_str\_\_debug\_ranges\_\_debug\_loclists\_\_debug\_rnglists\_\_debug\_addr\_\_debug\_names\_\_debug\_frame\_\_eh\_frame\_h| > |\`zig build --release=small\` | string: asdf00010203040506070809101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899OperationNotSupported 8888@\`��0\`��04X���� t| > |\`zig build --release=fast\` | string: asdf(msg truncated)failed to set noop SIGPIPE handler: {s}00010203040506070809101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899OperationNotSupportedDiskQuotaFileTooBigInputOutputNoSpaceLeftDeviceBusyInvalidArgumentAccessDeniedBrokenPipeSystemResourcesOperationAbortedNotOpenForWritingLockViolationWouldBlockConnectionResetByPeerUnexpectedOverflowInvalidUtf8Utf8ExpectedContinuationUtf8OverlongEncodingUtf8EncodesSurrogateHalfUtf8CodepointTooLargeUtf8InvalidStartByteTruncatedInputUtf8CannotEncodeSurrogateHalfCodepointTooLargeMissingDebugInfoUnsupportedOperatingSystemInvalidDebugInfoOutOfMemorySharingViolationPathAlreadyExistsFileNotFoundPipeBusyNameTooLongInvalidWtf8BadPathNameNetworkNotFoundAntivirusInterferenceSymLinkLoopProcessFdQuotaExceededSystemFdQuotaExceededNoDeviceIsDirNotDirFileLocksNotSupportedFileBusy| > |\`zig build --release=safe\` | string: asdf\_\_TEXT\_\_unwind\_info\_\_eh\_frame\_\_DWARF\_\_debug\_info\_\_debug\_abbrev\_\_debug\_str\_\_debug\_str\_offsets\_\_debug\_line\_\_debug\_line\_str\_\_debug\_ranges\_\_debug\_loclists\_\_debug\_rnglists\_\_debug\_addr\_\_debug\_names\_\_debug\_frame\_\_eh\_frame\_hdr(msg truncated)failed to set noop SIGPIPE handler: {s}00010203040506070809101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899OperationNotSupportedDiskQuotaFileTooBigInputOutputNoSpaceLeftDeviceBusyInvalidArgumentAccessDeniedBrokenPipeSystemResourcesOperationAbortedNotOpenForWritingLockViolationWouldBlockConnectionResetByPeerUnexpectedMissingDebugInfoUnsupportedOperatingSystemInvalidDebugInfoOutOfMemorySharingViolationPathAlreadyExistsFileNotFoundPipeBusyNameTooLongInvalidUtf8InvalidWtf8BadPathNameNetworkNotFoundAntivirusInterferenceSymLinkLoopProcessFdQuotaExc| > > > \### Expected Behavior > > A compiler error, like before on \[slightly older version 0.12.0-dev.3518+d2be725e4\](https://ziggit.dev/t/const-pointer-with-large-array-size/4294/5?u=fmamud). > > \`\`\` > test.zig:10:29: error: expected type '\*const \[1000\]u8', found '\*const \[4:0\]u8' > const t: \*const \[1000\]u8 = "asdf"; > ^ ~~~~~ > \`\`\`