tvl-depot/nix/buildGo/default.nix

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# Copyright 2019 Google LLC.
# SPDX-License-Identifier: Apache-2.0
#
# buildGo provides Nix functions to build Go packages in the style of Bazel's
# rules_go.
{ pkgs ? import <nixpkgs> { }
, ...
}:
let
inherit (builtins)
attrNames
baseNameOf
dirOf
elemAt
filter
listToAttrs
map
match
readDir
replaceStrings
toString;
inherit (pkgs) lib runCommand fetchFromGitHub protobuf symlinkJoin;
# TODO: Adapt to Go 1.20 changes
go = pkgs.go_1_19;
# Helpers for low-level Go compiler invocations
spaceOut = lib.concatStringsSep " ";
includeDepSrc = dep: "-I ${dep}";
includeSources = deps: spaceOut (map includeDepSrc deps);
includeDepLib = dep: "-L ${dep}";
includeLibs = deps: spaceOut (map includeDepLib deps);
srcBasename = src: elemAt (match "([a-z0-9]{32}\-)?(.*\.go)" (baseNameOf src)) 1;
srcCopy = path: src: "cp ${src} $out/${path}/${srcBasename src}";
srcList = path: srcs: lib.concatStringsSep "\n" (map (srcCopy path) srcs);
allDeps = deps: lib.unique (lib.flatten (deps ++ (map (d: d.goDeps) deps)));
xFlags = x_defs: spaceOut (map (k: "-X ${k}=${x_defs."${k}"}") (attrNames x_defs));
pathToName = p: replaceStrings [ "/" ] [ "_" ] (toString p);
# Add an `overrideGo` attribute to a function result that works
# similar to `overrideAttrs`, but is used specifically for the
# arguments passed to Go builders.
makeOverridable = f: orig: (f orig) // {
overrideGo = new: makeOverridable f (orig // (new orig));
};
# High-level build functions
# Build a Go program out of the specified files and dependencies.
program = { name, srcs, deps ? [ ], x_defs ? { } }:
let uniqueDeps = allDeps (map (d: d.gopkg) deps);
in runCommand name { } ''
${go}/bin/go tool compile -o ${name}.a -trimpath=$PWD -trimpath=${go} -p main ${includeSources uniqueDeps} ${spaceOut srcs}
mkdir -p $out/bin
export GOROOT_FINAL=go
${go}/bin/go tool link -o $out/bin/${name} -buildid nix ${xFlags x_defs} ${includeLibs uniqueDeps} ${name}.a
'';
# Build a Go library assembled out of the specified files.
#
# This outputs both the sources and compiled binary, as both are
# needed when downstream packages depend on it.
package = { name, srcs, deps ? [ ], path ? name, sfiles ? [ ] }:
let
uniqueDeps = allDeps (map (d: d.gopkg) deps);
# The build steps below need to be executed conditionally for Go
# assembly if the analyser detected any *.s files.
#
# This is required for several popular packages (e.g. x/sys).
ifAsm = do: lib.optionalString (sfiles != [ ]) do;
asmBuild = ifAsm ''
${go}/bin/go tool asm -p ${path} -trimpath $PWD -I $PWD -I ${go}/share/go/pkg/include -D GOOS_linux -D GOARCH_amd64 -gensymabis -o ./symabis ${spaceOut sfiles}
${go}/bin/go tool asm -p ${path} -trimpath $PWD -I $PWD -I ${go}/share/go/pkg/include -D GOOS_linux -D GOARCH_amd64 -o ./asm.o ${spaceOut sfiles}
'';
asmLink = ifAsm "-symabis ./symabis -asmhdr $out/go_asm.h";
asmPack = ifAsm ''
${go}/bin/go tool pack r $out/${path}.a ./asm.o
'';
gopkg = (runCommand "golib-${name}" { } ''
mkdir -p $out/${path}
${srcList path (map (s: "${s}") srcs)}
${asmBuild}
${go}/bin/go tool compile -pack ${asmLink} -o $out/${path}.a -trimpath=$PWD -trimpath=${go} -p ${path} ${includeSources uniqueDeps} ${spaceOut srcs}
${asmPack}
'').overrideAttrs (_: {
passthru = {
inherit gopkg;
goDeps = uniqueDeps;
goImportPath = path;
};
});
in
gopkg;
# Build a tree of Go libraries out of an external Go source
# directory that follows the standard Go layout and was not built
# with buildGo.nix.
#
# The derivation for each actual package will reside in an attribute
# named "gopkg", and an attribute named "gobin" for binaries.
external = import ./external { inherit pkgs program package; };
in
{
# Only the high-level builder functions are exposed, but made
# overrideable.
program = makeOverridable program;
package = makeOverridable package;
external = makeOverridable external;
# re-expose the Go version used
inherit go;
}