g++: as fails to determine which assembler to run

Question

Today I wanted to recompile one of my projects. Compiling this project had already worked on my machine, but this time an error occured.

The compiler output goes:

fatal error: as: unknown host architecture (can't determine which assembler to run)`

for the line:

g++ -c -pipe -O2 -Wall -W -D_REENTRANT -DQT_NO_DEBUG -DQT_GUI_LIB -DQT_CORE_LIB -DQT_SHARED -I/usr/share/qt4/mkspecs/linux-g++ -I../../.vscode -I/usr/include/qt4/QtCore -I/usr/include/qt4/QtGui -I/usr/include/qt4 -I. -I../../.vscode -I. -o Main.o ../../Main.cpp

I tried to compile some other projects, but realized, that I wouldn't be able to compile anything using any c++ compiler, so I looked it up.

The only fitting thread I found was this one but the solution 'reinstalling binutils' didn't work for me (tried sudo apt-get install --reinstall binutils as well as --reinstall gcc, g++ and build-essential)

One possible reason for this problem that comes to my mind is the iOS-toolchain I installed yesterday - I had to install some different clang versions - but I actually didn't change anything on the system's assembler...

If someone's got an idea; any help would be appreciated :)

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Additional info:

Ubuntu 16.04 LTS 64bit

AMD FX(tm)-6300 Six-Core Processor × 6

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uname -m

returns x86_64

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 gcc -march=native -v -E - 2>&1 <<<'' | grep "cc1" | egrep -o -e $'-m(arch|tune)=[^ "\']+'

returns -march=bdver2 and -mtune=bdver2

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already tried gcc [...] -march with bdver2 and other architectures

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g++ -v -c HelloWorld.cpp gives me: http://pastebin.com/Ks2be0hL

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type -a as says:

as is /usr/local/bin/as
as is /usr/bin/as

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as --version sadly just show's me the error again, but info as tells me it's binutils-2.26.1-system from 2016-08-07

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dpkg -S /usr/bin/as prints: binutils: /usr/bin/as

Answer 1

type -a as says as is /usr/local/bin/as. This is what gcc is running, not /usr/bin/as, because /usr/local/bin/as is found first in your $PATH search order. This is why re-installing packages and so on is having no effect: something else you installed (probably manually) installed a non-standard as.

Have a look at /usr/local/bin/as and figure out where it came from, and what to do with it. For now you can just rename it to as.unknown or something, and then everything will use the normal system assembler (/usr/bin/as).

Answer 2

Remove binutils and reinstall it using the following steps:

Create an installation directory /opt/cross, and make sure you have write permission to .

sudo mkdir -p /opt/cross
sudo chown user /opt/cross
export PATH=/opt/cross/bin:$PATH

Download and install

wget http://mirrors.muzzy.it/gnu/binutils/binutils-2.9.tar.gz
tar xvf binutils-2.9.tar.gz
cd binutils-2.9
linux32 ./configure --prefix=/opt/cross --target=aarch64-linux --disable-multilib

If dosn't work remove --target=aarch64-linux, the --disable-multilib option means that we only want our Binutils installation to work with programs and libraries using the aarch64 instruction set, and not any related instruction sets such as aarch32, run:

linux32 ./configure --prefix=/opt/cross --disable-multilib
linux32 make
linux32 make install