gnm (binutils) fails on Mojave (and breaks gcc-8)

[ggouaillardet]

When the binutils formula is not installed, gcc-8 works just fine

KA15-002: gilles$ cat conftest.c 
int main(int argc, char *argv[]) {
    return 0;
}
KA15-002:ompi-master-gcc8 gilles$ gcc-8 conftest.c 
KA15-002:ompi-master-gcc8 gilles$ gnm a.out 
-bash: gnm: command not found

now, after installing binutils, the same command fails

KA15-002: gilles$ brew install binutils
==> Downloading https://homebrew.bintray.com/bottles/binutils-2.31.1.mojave.bottle.tar.gz
######################################################################## 100.0%
==> Pouring binutils-2.31.1.mojave.bottle.tar.gz
🍺  /usr/local/Cellar/binutils/2.31.1: 114 files, 170.8MB
KA15-002: gilles$ gcc-8 conftest.c 
collect2: fatal error: /usr/local/bin/gnm returned 1 exit status
compilation terminated

Here is the error generated by manually invoking gnm

KA15-002: gilles$ /usr/local/bin/gnm a.out 
/usr/local/bin/gnm: a.out: unknown load command 0x32
/usr/local/bin/gnm: a.out: unknown load command 0x32
/usr/local/bin/gnm: a.out: unknown load command 0x32
/usr/local/bin/gnm: a.out: file format not recognized

Unsurprisingly, removing the binutils formula solves the issue.

KA15-002: gilles$ brew uninstall binutils
Uninstalling /usr/local/Cellar/binutils/2.31.1... (114 files, 170.8MB)
KA15-002:ompi-master-gcc8 gilles$ gcc-8 conftest.c 

I initially thought something was wrong with my system (I recently upgraded OS X from High Sierra to Mojave) so uninstalled brew and made a fresh install with just a few packages, and am still able to reproduce the very same issue.

[fxcoudert]

Indeed, it appears that binutils' gnm cannot read MachO files:

bli /tmp $ cat a.c
int main (void) { return 0; }
bli /tmp $ clang -c a.c 
bli /tmp $ file a.o    
a.o: Mach-O 64-bit object x86_64
bli /tmp $ gnm a.o
gnm: a.o: unknown load command 0x32
gnm: a.o: unknown load command 0x32
gnm: a.o: unknown load command 0x32
gnm: a.o: file format not recognized
bli /tmp $ gnm --version
GNU nm (GNU Binutils) 2.31.1
Copyright (C) 2018 Free Software Foundation, Inc.
This program is free software; you may redistribute it under the terms of
the GNU General Public License version 3 or (at your option) any later version.
This program has absolutely no warranty.

Could you report this bug to the binutils project? It does not appear to be specific to Homebrew.

[ggouaillardet]

done

the bug report is available at https://sourceware.org/bugzilla/show_bug.cgi?id=23728

Meanwhile, should something been done for Mojave (such as not installing /usr/local/bin/gnm) in order not to break gcc-8 ?

[ggouaillardet]

@dmarinescu your trolling is very unwelcome here, good speed.

[wukefe]

Hi @ggouaillardet, I have the same problem with Xcode 10, the latest version. (I don't think it is caused by the new OS Mojave because gcc works nicely with old Xcode 7 on Mojave.)

A temporary solution is to set nm to gnm as follows

mv /usr/local/bin/gnm /usr/local/bin/gnm-backup
ln -s /usr/bin/nm /usr/local/bin/gnm

[fxcoudert]

We could introduce a conflict between the two packages, but in general that's not true. It's a case of bug in binutils, so I would suggest to simply uninstall the binutils until it is fixed in a new version.

[ggouaillardet]

@fxcoudert I was something in between. For example, we could install nm in /usr/local/bin/gnm-binutils on Mojave/XCode 10

The benefits (to be tested) are :

• gcc-8 works out of the box regardless binutils is installed or not
• some other utils provided by binutils that might not be broken are available

[zbeekman]

I'm going to open a PR to make binutils keg_only since it's so incredibly broken/janky on macOS.

[roolebo]

Patch series to address the issue has been sent upstream: https://sourceware.org/ml/binutils/2018-11/msg00031.html

[mistydemeo]

This now-upstreamed patch fixes it: https://sourceware.org/bugzilla/show_bug.cgi?id=23728

I've added it in Homebrew/formula-patches#256