Xiaohuba's blog

Homebrew GCC may not work properly on Apple M1 devices
By Xiaohuba, history, 19 months ago, In English

These days I'm trying to compile the following c++ code:

#include<vector>

const int MAXN=1e5+5;
std::vector<int> factor[MAXN];

signed main() {return 0;}

This code works while I'm using g++ 11.3.0. However, if I use g++ 13.1.0 or 12.1.0, I'll receive a compile error:

/var/folders/v7/yk8tz4j54cl2lhp1f80nyz700000gn/T//cc2HpyzP.s:371:29: error: unexpected token in '.section' directive
        .section .data.rel.ro.local

Reinstalling the compiler doesn't works. What should I do?

Note I use Apple M1 with MacOS 13.2.1 (22D68).

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19 months ago, # |
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Have you tried updating your Xcode command line tools? It worked for me. This might help: updating command line tools

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19 months ago, # |
  Vote: I like it +8 Vote: I do not like it

Try compiling with -O2.

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    19 months ago, # ^ |
      Vote: I like it +18 Vote: I do not like it

    Even if this worked, it'd still be a bug, or it could be sneaking in hidden bugs. You don't always want to compile with -O2.

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      19 months ago, # ^ |
        Vote: I like it +8 Vote: I do not like it

      Yeah, it's certainly not a great fix, but it's the only one I've found so far. Before, I used to just decrease MAXN, but I've lost track of how many bugs I've gotten by forgetting to revert MAXN before submitting :/

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    19 months ago, # ^ |
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    For me, it doesn't work. :(

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19 months ago, # |
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Same Error Here. It has to do with MAXN. If you set it small enough, it will work. Also, if you use the default Clang Apple provides, it works normally. See here for some discussion.

I have also tried increasing the stack size, but it too doesn't work.

Is anybody here on Apple Silicon who uses gcc who fixed this problem? Thanks

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19 months ago, # |
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Since decreasing MAXN has been suggested, try comparing the assembly for sufficiently small and too large MAXN. How do they differ?

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19 months ago, # |
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I am using g++ 12.2.0 and it's working for me as for your concern you should run it on custom test if it's working then it may be an internal problem of your system.

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19 months ago, # |
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Can i know how ur able to use g++ compiler with mac? Whenever i type g++ [filename] it always compiles with clang. How do I make it compile with g++?

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    19 months ago, # ^ |
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    In Mac, g++ is an alias for Clang. Use the g++ inside Homebrew folder, for me it is /opt/homebrew/bin/g++-13

    See here

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      19 months ago, # ^ |
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      Ohh tysm. Ive been struggling with this for a while and just decided to deal with it and use clang lol. Appreciate it.

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19 months ago, # |
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GCC has never officially supported macos, so you either revert to past versions or wait for proper fixes. One possible workaround is to use clang/llvm with libstdc++ instead of libc++.

For instance, if your gcc installation lies in /opt/homebrew/Cellar/gcc/12.1.0 (which is the default path for aarch64 homebrew gcc), the compilation command would be

clang++ \
    -stdlib=libstdc++ \
    -stdlib++-isystem \
    /opt/homebrew/Cellar/gcc/12.1.0/include/c++/12 \
    -cxx-isystem \
    /opt/homebrew/Cellar/gcc/12.1.0/include/c++/12/aarch64-apple-darwin22 \
    -L/opt/homebrew/Cellar/gcc/12.1.0/lib/gcc/12 \
    -std=c++17 \
    -o main main.cpp
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    19 months ago, # ^ |
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    Does this provide access to gnu pbds? I have been trying to find a way to use pbds without gcc, because gcc does not support sanitizers on my computer

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      19 months ago, # ^ |
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      Yes, if libstdc++ in your system provides gnu pbds.

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    19 months ago, # ^ |
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    I'm trying your recommendation. Seems the most all around. But I'm facing strange errors in code execution:

    A simple hello world program causes a segfault. And other codes not prints output when executed.

    Compilation:

    clang++ -stdlib=libstdc++ -stdlib++-isystem /opt/homebrew/Cellar/gcc/13.1.0/include/c++/13 -cxx-isystem /opt/homebrew/Cellar/gcc/13.1.0/include/c++/13/aarch64-apple-darwin22 -L /opt/homebrew/Cellar/gcc/13.1.0/lib/gcc/13 -std=c++17 -o a hello.cpp

    Any thoughts?

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    19 months ago, # ^ |
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    As Duds pointed out, this solution may cause mysterious segmentation fault. How to work out this problem?

    P.S. When I tried to compile a single hello world, it looked normal. 

    #include <iostream>

int main() {
  std::cout << "Hello World!" << std::endl;
  return 0;
}

    But when I executed the program, the sanitizer gave me the following information:

    AddressSanitizer:DEADLYSIGNAL
=================================================================
==9741==ERROR: AddressSanitizer: SEGV on unknown address 0xffffffffffffffe8 (pc 0x000102a151d0 bp 0x00016d86a7a0 sp 0x00016d86a7a0 T0)
==9741==The signal is caused by a READ memory access.
    #0 0x102a151d0 in std::ostream::sentry::sentry(std::ostream&)+0x20 (libstdc++.6.dylib:arm64+0x991d0) (BuildId: 151c02a14b16389887c4edd68fe8a80832000000200000000100000000000d00)
    #1 0x102a15c50 in std::basic_ostream<char, std::char_traits<char>>& std::__ostream_insert<char, std::char_traits<char>>(std::basic_ostream<char, std::char_traits<char>>&, char const*, long)+0x30 (libstdc++.6.dylib:arm64+0x99c50) (BuildId: 151c02a14b16389887c4edd68fe8a80832000000200000000100000000000d00)
    #2 0x102a160b0 in std::basic_ostream<char, std::char_traits<char>>& std::operator<<<std::char_traits<char>>(std::basic_ostream<char, std::char_traits<char>>&, char const*)+0x2c (libstdc++.6.dylib:arm64+0x9a0b0) (BuildId: 151c02a14b16389887c4edd68fe8a80832000000200000000100000000000d00)
    #3 0x102597cdc in main tmp.cpp:4
    #4 0x1aaacff24  (<unknown module>)
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      19 months ago, # ^ |
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      GCC 11 works just fine for me, so you may want to install that particular version.

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19 months ago, # |
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Not a permanent fix but using -std=gnu++20 made the error go away for me (14/17 both have the bug it seems). The -O2 flag didn't work for me.

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19 months ago, # |
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Did you find any fix? Have you tried downgrading the compiler? I am also facing the same problem actually, so wanted to check if anyone had any progress with this

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    19 months ago, # ^ |
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    You can either downgrade the compiler to 11.x.x or use clang with libstdc++.

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18 months ago, # |
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I am also facing the same problem.

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9 months ago, # |
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if anyone still facing the same issue i fixed it by upgrading to gcc version 13.2.0 (Homebrew GCC 13.2.0)

write these steps in your terminal:

step 1: brew update

step 2: brew upgrade gcc

step 3: g++ -v

it'll show apple clang version, in my case it was Apple clang version 15.0.0 (clang-1500.1.0.2.5)

step 4: sudo rm g++

remove already existing g++ file by typing your sudo password

step 5:

ln -s g++-13 g++

step 6:

g++ -v

it'll switch to g++ version from apple clang version and in my case it shows gcc version 13.2.0 (Homebrew GCC 13.2.0)

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