#include <stdio.h>
#include <Block.h>
int main()
{
__block int x = 5;
^{printf("x is %i\n", x);}();
}
When I use clang to compile a c (or c++) program that uses both clang's blocks and the __block type specifier, no compiler warnings are produced, even using -Wall and -Wpedantic. The program also runs as expected. However, if I open the executable using a text editor, I find this block of text (extracted using 'strings' command):
Block_release called upon a stack Block: %p, ignored
_Block_byref_release: Block byref data structure at %p underflowed
Block compiled by obsolete compiler, please recompile source for this Block
descriptor->dispose helper: %p
byref data block %p contents:
^%p (new layout) =
isa?: %p
refcount: %u
invoke: %p
descriptor: %p
descriptor->reserved: %lu
descriptor->size: %lu
descriptor->copy helper: %p
forwarding: %p
flags: 0x%x
size: %d
copy helper: %p
dispose helper: %p
NULL passed to _isa: stack Blockisa: malloc heapisa: GC heap Bloisa: global Blocisa: finalizing
The problem is that I am using the latest version of clang - hardly an 'obsolete' compiler. I am on Linux (musl) and I installed the BlocksRuntime from https://github.com/mackyle/blocksruntime. I also found the piece of code that generates the warning here - https://github.com/mackyle/blocksruntime/blob/master/BlocksRuntime/runtime.c#L629
λ: clang --version
clang version 10.0.0
Target: x86_64-unknown-linux-musl
Thread model: posix
InstalledDir: /bin
λ: uname -a
Linux thinkpad 5.7.9_1 #1 SMP Thu Jul 16 10:02:50 UTC 2020 x86_64 GNU/Linux
Is it safe to ignore this warning? If not, what can I do about it?
