How to configure g++ as the default compiler in Mac OS (M1) - c++

So, I wanted to use some header files native to GNU C++:
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
I read that in MacOS, gcc and g++ are both linked to clang. So, we had to install the gcc using homebrew and use that.
But after installing gcc using homebrew. When I run
g++ --version
I get
Apple clang version 12.0.5 (clang-1205.0.22.9)
Target: arm64-apple-darwin22.1.0
Thread model: posix
InstalledDir: /Library/Developer/CommandLineTools/usr/bin
But running g++-12 --version I get:
g++-12 (Homebrew GCC 12.2.0) 12.2.0
Copyright (C) 2022 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
My VSCode runs g++ (Apple One) to compile C/C++ files. For the goal I wanted to accomplish at the start, I read that we need to have the g++ (installed using homebrew) do the compiling.
So, I ran the following commands:
cd /opt/homebrew/bin
ls -s g++-12 g++
But now, even when I compile the following code:
#include <iostream>
int main()
{
std::cout << 1;
}
I get the following error:
In file included from /opt/homebrew/Cellar/gcc/12.2.0/include/c++/12/bits/postypes.h:40,
from /opt/homebrew/Cellar/gcc/12.2.0/include/c++/12/iosfwd:40,
from /opt/homebrew/Cellar/gcc/12.2.0/include/c++/12/ios:38,
from /opt/homebrew/Cellar/gcc/12.2.0/include/c++/12/ostream:38,
from /opt/homebrew/Cellar/gcc/12.2.0/include/c++/12/iostream:39,
from test.cpp:1:
/opt/homebrew/Cellar/gcc/12.2.0/include/c++/12/cwchar:44:10: fatal error: wchar.h: No such file or directory
44 | #include <wchar.h>
| ^~~~~~~~~
compilation terminated.
Now, removing the link using rm g++ reverts back to my original configuration. But that configuration can't run the headers I requested at the start. Is there any way to solve this?
Most of the above have mostly been taken from here. But I didn't find any solution. But, I have seen people using the same and getting successful.
EDIT:
I found a website where there was a solution. It was to compile not using g++. Rather use
g++-12 --sysroot=$(xcrun --show-sdk-path)
When I used this, it solved the problem. Can someone explain why this happened?

The header error likely indicates the g++ you installed via Homebrew may not be compatible with the Apple Xcode version installed in the macos system directories.
The solution is probably to reinstall one or both packages.
EDIT:
g++-12 --sysroot=$(xcrun --show-sdk-path) changes the search path for system header includes from the default (which was probably set when homebrew installed g++) to the one provided by the Xcode SDK currently installed.

Related

Can't cross-compile gdb with MinGW

I'm trying to cross-compile gdb so I could debug my Windows version of program.
My host system is Arch Linux(5.13.4-arch1-1 to be exact).
I'm using MinGW from the official repositories.
$ i686-w64-mingw32-gcc --version
i686-w64-mingw32-gcc (GCC) 11.2.0
Copyright (C) 2021 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
I downloaded the source for gdb from https://ftp.gnu.org/gnu/gdb/ (gdb-10.2.tar.gz).
I unpacked it, cd into dir and ran:
$ ./configure --host=i686-w64-mingw32
$ make
For long it compiled without any errors and then:
CXX source-cache.o
source-cache.c:37:10: fatal error: srchilite/sourcehighlight.h: No such file or directory
37 | #include <srchilite/sourcehighlight.h>
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
compilation terminated.
And also although compiler already compiled gdbserver and other different programs, I can't run them.
Launching gdbserver.exe with wine gives:
$ wine gdbserver.exe
0024:err:module:import_dll Library libgcc_s_dw2-1.dll (which is needed by L"Z:\\home\\udalny\\.local\\build\\gdb\\gdb-10.2\\gdbserver\\gdbserver.exe") not found
0024:err:module:import_dll Library libstdc++-6.dll (which is needed by L"Z:\\home\\udalny\\.local\\build\\gdb\\gdb-10.2\\gdbserver\\gdbserver.exe") not found
0024:err:module:LdrInitializeThunk Importing dlls for L"Z:\\home\\udalny\\.local\\build\\gdb\\gdb-10.2\\gdbserver\\gdbserver.exe" failed, status c0000135
Is it not statically linked?
Does anybody know how to fix it?
You can avoid the problem with the configure flag --disable-source-highlight if you can do without sourxe highlighting.

Cannot cross-compile for arm with c++17

I am trying to cross-compile c++14/c++17 code for my raspberry pi. I am sure it worked on my old PC. However, when I try to compile it on my new pc, it returns me the following error.
$ arm-linux-gnueabihf-g++ main.cpp -std=c++17
arm-linux-gnueabihf-g++: error: unrecognized command line option ‘-std=c++17’
I thought it is the compiler issue, the version of the compiler I am using is:
$ arm-linux-gnueabihf-g++ --version
arm-linux-gnueabihf-g++ (crosstool-NG linaro-1.13.1+bzr2650 - Linaro GCC 2014.03) 4.8.3 20140303 (prerelease)
Copyright (C) 2013 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
I try to get the newest compiler with
sudo apt-get install libc6-armel-cross libc6-dev-armel-cross binutils-arm-linux-gnueabi libncurses5-dev build-essential bison flex libssl-dev bc
Yet, the version is still the same, which can only compile c++11.
How can I update the arm-linux-gnueabi-g++ compiler?? I am pretty sure there is a compiler that works since I used it before, but not sure how I get it.
I found the easiest way to solve this issue is to directly install the newest cross-compiler
sudo apt-get install g++-9-arm-linux-gnueabihf
and use the compiler as (just an example of using c++17)
arm-linux-gnueabihf-g++-9 main.cpp -std=c++17

Clang refuses to compile libstdc++'s <filesystem> header

Consider this minimal example:
#include <filesystem>
#include <iostream>
int main()
{
std::cout << std::filesystem::current_path() << '\n';
}
It works as expected in GCC 9.2, but Clang 8.0.1 refuses to compile the <filesystem> header (from GCC 9.2's libstdc++):
# clang++ 1.cpp -std=c++17
In file included from 1.cpp:1:
In file included from Z:\Lander\msys2\mingw64\include\c++\9.2.0\filesystem:37:
Z:\Lander\msys2\mingw64\include\c++\9.2.0\bits/fs_path.h:636:31: error: invalid use of incomplete
type 'std::filesystem::__cxx11::filesystem_error'
_GLIBCXX_THROW_OR_ABORT(filesystem_error(
^~~~~~~~~~~~~~~~~
Z:\Lander\msys2\mingw64\include\c++\9.2.0\x86_64-w64-mingw32\bits/c++config.h:177:49: note: expanded
from macro '_GLIBCXX_THROW_OR_ABORT'
# define _GLIBCXX_THROW_OR_ABORT(_EXC) (throw (_EXC))
^~~~
Z:\Lander\msys2\mingw64\include\c++\9.2.0\bits/fs_fwd.h:61:9: note: forward declaration of
'std::filesystem::__cxx11::filesystem_error'
class filesystem_error;
^
1 error generated.
Is it a Clang bug, or a libstdc++ bug?
I found this bug report on MSYS2 bug tracker, but there is no useful information in there.
Is there a way to patch <filesystem> header to get rid of this error, while we're waiting for an official fix?
I'm on Windows. I'm using latest GCC & Clang available in MSYS2 packages.
GCC identifies as:
# g++ --version
g++.exe (Rev2, Built by MSYS2 project) 9.2.0
Copyright (C) 2019 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
Clang identifies as:
# clang++ --version
clang version 8.0.1 (tags/RELEASE_801/final)
Target: x86_64-w64-windows-gnu
Thread model: posix
InstalledDir: Z:\Lander\msys2\mingw64\bin
Clang uses libstdc++ that comes with this GCC.
The issue can be fixed by patching <msys2_path>/mingw64/include/c++/9.2.0/bits/fs_path.h.
At lines 666-692, there is a definition of class filesystem_error. It has to be moved up to line 614, to be right above the definition of u8path().
I think it's a libstdc++ bug. I've reported it here.
class filesystem_error is used several times in bits/fs_path.h, and every use of it is below the definition, except for the problematic line 636.
That line is wrapped in #ifdef _GLIBCXX_FILESYSTEM_IS_WINDOWS, so I guess the Clang developers don't run libstdc++ compatibility tests on Windows.
UPD: This is fixed in GCC 9.3.

OS X Yosemite gcc unrecognized command line option 'mdll' after brew install gcc

I installed gcc using brew because I needed to install brew's Fortran package. It seems that the gcc package installed by brew install gcc does not support the mdll flag. How can I install the correct versions of Fortran and gcc?
$ which gcc
/usr/local/bin/gcc
$ gcc --version
gcc (GCC) 4.9.2 20141029 (prerelease)
Copyright (C) 2014 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
$ gcc -mdll
gcc: error: unrecognized command line option ‘-mdll’
gcc: fatal error: no input files
compilation terminated.
According to the gcc(1) manpage:
-mdll
This option is available for Cygwin and MinGW targets. It
specifies that a DLL---a dynamic link library---is to be generated,
enabling the selection of the required runtime startup object and
entry point.
Since OS X isn't either Cygwin or MinGW, it's safe to assume that no version of GCC will enable it on OS X.
If you're trying to build a dynamically linked object ("shared object" in UNIX terminology), check out the -dynamic/-dynamiclib flags. They seem to be the rough equivalent on OS X.

Why doesn't g++ (4.9.2) compile (a very simple program)?

My overall problem is trying to install HEALPix C++ version and, to isolate the problem, I created foo.cpp:
#include <string>
#include <iostream>
I then run
g++ foo.cpp
to which I get the following error message:
foo.cpp:1:18: fatal error: string: No such file or directory
#include <string>
^
compilation terminated.
I am running
g++ (GCC) 4.9.2 20141029 (prerelease)
Copyright (C) 2014 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
downloaded from http://hpc.sourceforge.net/
on OS X Yosemite 10.10
I get the same error message with gcc 5.0 and 4.8 as well. I tried downloading gcc 4.9 from homebrew but this also doesn't work (though with a different error message).
I then try
g++ -I/usr/local/include/c++/4.9.2 foo.cpp
to which I get the error message:
In file included from foo.cpp:1:0:
/usr/local/include/c++/4.9.2/string:38:28: fatal error: bits/c++config.h: No such file
or directory
#include <bits/c++config.h>
^
compilation terminated.
Now, obviously, I don't want to have to find (recursively) the directory of each required header (for my HEALPix installation, this could take forever!) It seems to me that there is a problem with where #include is looking? How can I change this? Also, if the workaround is to specify the directories of required headers, it is not immediately obvious to me how to specify this within my configuration for the HEALPix installation.
Hope someone can suggest a solution!
Thanks