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language.c: bang into shape #102

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zimbatm
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@zimbatm zimbatm commented Mar 6, 2021

A few learning:

ld uses LIBRARY_PATH, not LD_LIBRARY_PATH to find object files. Link to the
libraries directly to minimize rebuilds.

pkgs.gcc doesn't expose the gcov binary. pkgs.gcc is heavily tweaked to
work with the nixpkgs stdenv so use pkgs.gcc-unwrapped instead.

Made pkg-config optional, it's not used all the time.

name = "LD_LIBRARY_PATH";
prefix = "$DEVSHELL_DIR/lib";
name = "LIBRARY_PATH";
value = lib.concatStringsSep ":" (map (x: "${lib.getLib x}/lib") cfg.libraries);
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value = "$DEVSHELL_DIR/lib";

does not work here?

Also how would programs build like this find their libraries at runtime? This is especially a problem when you run outside of devshell.

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@Mic92 Mic92 Mar 7, 2021

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How about setting NIX_LDFLAGS="-rpath $DEVSHELL_DIR/lib";

description = ''
Which C compiler to use.

For gcc, use pkgs.gcc-unwrapped.
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Having a wrapped and a unwrapped version will behave quite differently here. i.e. the wrapped version of clang will set hardening flags that the unwrapped version of gcc won't. This might be surprising for users.

prefix = "$DEVSHELL_DIR/include";
})
++ (lib.optional cfg.pkg-config {
name = "PKG_CONFIG_PATH";
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@Mic92 Mic92 Mar 7, 2021

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You also want to set CC/CXX/LD. Otherwise many buildsystems will default to something like CC = /usr/bin/gcc

libraries = mkOption {
type = types.listOf strOrPackage;
default = [ ];
description = "Use this when another language dependens on a dynamic library";
example = lib.literalExample ''
[ pkgs.glibc ]
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Does glibc in libraries have any effect when a wrapped clang is used?

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Mic92 commented Mar 11, 2021

For testing: https://github.com/Mic92/build-system-koans

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zimbatm commented Dec 13, 2021

I'm a bit overwhelmed by the complexity of this work and don't think I can do a good job at it. If somebody wants to take over, I would be happy.

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Mic92 commented Dec 13, 2021

I'm a bit overwhelmed by the complexity of this work and don't think I can do a good job at it. If somebody wants to take over, I would be happy.

Maybe we can talk about this next year.

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