why did you embed the c++ code in the .nix file?

just to have everything in one file? how to show how to do it with nix?

because it seem simpler to have a separate C++ file, and a simple shell script or makefile to compile it.

e.g. although I could figure out roughly what the .nix file does, many more people would know plain unix shell than nix.

and where is $out defined in the .nix file?

▲ AnthOlei 6 months ago | parent | next [-]

The nix file is besides the point - it gives you a totally hermetic build environment. Not OP, but it’s the only way I know how to get gcc to use a static glibc. All you should pay attention to is that it’s using a static glibc.

$out is a magic variable in nix that means the output of the derivation - the directory that nix moves to its final destination

▲ JoshTriplett 6 months ago | parent | next [-]

> Not OP, but it’s the only way I know how to get gcc to use a static glibc.

    /tmp$ gcc -O3 test.c -o test
    /tmp$ ldd test
     linux-vdso.so.1 (0x00007f3d9fbfe000)
     libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f3d9f9e8000)
     /lib64/ld-linux-x86-64.so.2 (0x00007f3d9fc00000)
    /tmp$ gcc -static -O3 test.c -o test
    /tmp$ ldd test
     not a dynamic executable

▲

fuzztester 6 months ago | parent | next [-]

>> Not OP, but it’s the only way I know how to get gcc to use a static glibc.

> /tmp$ gcc -static -O3 test.c -o test /tmp$ ldd test not a dynamic executable

yes, that last line above means it's a statically linked executable.

yes, i had a doubt about what the GP said, about their nix way being the only way to create a statically linked executable.

but I didn't remember all the details, because it's been a while since I worked with C in depth (moved to Java, Ruby, Python, etc.)(though I did a lot of that earlier, even in pre-Linux years), so I didn't say anything else. thanks, Josh Triplett for clarifying.

but one thing I do remember, is that static linking was the only option in the beginning, at least on Unix, and dynamic linking came only some time later.

when I started working on UNIX and C, there was no dynamic linking at all, IIRC.

https://en.m.wikipedia.org/wiki/Static_library

("dynamic linking" topic in above page links to the below page in Wikipedia: )

https://en.m.wikipedia.org/wiki/Dynamic_linker

▲

3836293648 6 months ago | parent | prev [-]

I thought glibc had some hacks in it to prevent it from working fully when statically linked? Is this just a myth or outdated or only affects C/C++ or what?

	▲	JoshTriplett 6 months ago \| parent [-]
		The issue is that some features of glibc want to dlopen additional libraries, most notably NSS. If you call `gethostbyname`, even a static glibc will try to dlopen NSS libraries based on /etc/nsswitch.conf, and if the dynamic NSS libraries are incompatible with your statically linked glibc, you'll have problems. musl, by contrast, doesn't support NSS at all, only /etc/hosts and DNS servers listed in /etc/resolv.conf, so whether you statically or dynamically link musl, you just won't have any support for (for instance) mDNS, or dynamic users, or local containers, or various other bits of name resolution users may expect to Just Work.

▲ fuzztester 6 months ago | parent | prev | next [-]

thanks.

▲ fuzztester 6 months ago | parent | prev [-]

[flagged]

▲ fuzztester 6 months ago | parent | prev [-]

and by the way, ignorant mindlessly downvoting dudes who don't even bother to check if a comment is right or not, can shove it up, and take a flying leap into Lake Titicaca. they'll meet a lot of their brothers there, like giant frogs.

from a Google search:

>Overview Lake Titicaca, straddling the border between Peru and Bolivia in the Andes Mountains, is one of South America's largest lakes and the world’s highest navigable body of water. Said to be the birthplace of the Incas, it’s home to numerous ruins. Its waters are famously still and brightly reflective. Around it is Titicaca National Reserve, sheltering rare aquatic wildlife such as giant frogs.