feat(libutil-c): add zig build

src/libutil-c/build.zig

@@ -0,0 +1,88 @@
+const std = @import("std");
+
+fn readFile(b: *std.Build, path: []const u8) []const u8 {
+    var file = b.build_root.handle.openFile(path, .{}) catch |err| std.debug.panic("Failed to open {s}: {}", .{ path, err });
+    defer file.close();
+
+    const meta = file.metadata() catch |err| std.debug.panic("Failed to get metadata for {s}: {}", .{ path, err });
+
+    return file.readToEndAlloc(b.allocator, meta.size()) catch @panic("OOM");
+}
+
+pub fn build(b: *std.Build) void {
+    const optimize = b.standardOptimizeOption(.{});
+    const target = b.standardTargetOptions(.{});
+    const linkage = b.option(std.builtin.LinkMode, "linkage", "The link mode of binaries");
+    const fsys_libutil = b.systemIntegrationOption("nix-util", .{});
+
+    const config = b.addConfigHeader(.{
+        .include_path = "config-util.h",
+    }, .{
+        .PACKAGE_VERSION_NIX = std.mem.trimRight(u8, readFile(b, ".version"), "\n"),
+        .PACKAGE_VERSION_ZIX = std.mem.trimRight(u8, readFile(b, ".zix-version"), "\n"),
+    });
+
+    const libutilc = std.Build.Step.Compile.create(b, .{
+        .name = "nixutilc",
+        .kind = .lib,
+        .linkage = linkage,
+        .root_module = b.createModule(.{
+            .target = target,
+            .optimize = optimize,
+            .link_libc = true,
+            .link_libcpp = true,
+        }),
+    });
+
+    libutilc.addConfigHeader(config);
+
+    libutilc.addIncludePath(b.path("."));
+
+    libutilc.addCSourceFiles(.{
+        .files = &.{
+            "nix_api_util.cc",
+        },
+        .flags = &.{
+            "--std=c++2a",
+        },
+    });
+
+    libutilc.installHeader(config.getOutput(), "nix/config-util.h");
+
+    if (fsys_libutil) {
+        libutilc.linkSystemLibrary("nix-util");
+    } else {
+        const libutil = b.dependency("nix-util", .{
+            .target = target,
+            .optimize = optimize,
+            .linkage = linkage orelse .static,
+        });
+
+        libutilc.linkLibrary(libutil.artifact("nixutil"));
+    }
+
+    inline for (&.{
+        "nix_api_util.h",
+        "nix_api_util_internal.h",
+    }) |hdr| {
+        libutilc.installHeader(b.path(hdr), "nix/" ++ hdr);
+    }
+
+    b.installArtifact(libutilc);
+
+    b.getInstallStep().dependOn(&b.addInstallFileWithDir(b.addWriteFile("nix-util-c.pc", b.fmt(
+        \\prefix={s}
+        \\libdir={s}
+        \\includedir={s}
+        \\
+        \\Name: Nix
+        \\Description: Nix Package Manager
+        \\Version: 0.1.0
+        \\Cflags: -I${{includedir}}/nix -std=c++2a
+        \\Libs: -L${{libdir}} -lnixutil -lnixutilc
+    , .{
+        b.getInstallPath(.prefix, ""),
+        b.getInstallPath(.lib, ""),
+        b.getInstallPath(.header, ""),
+    })).getDirectory().path(b, "nix-util-c.pc"), .lib, "pkgconfig/nix-util-c.pc").step);
+}

src/libutil-c/build.zig.zon

@@ -0,0 +1,10 @@
+.{
+    .name = "nix-util-c",
+    .version = "0.1.0",
+    .paths = .{"."},
+    .dependencies = .{
+        .@"nix-util" = .{
+            .path = "../libutil",
+        },
+    },
+}

src/libutil-c/meson.build

@@ -1,7 +1,6 @@
-project('nix-util-c', 'cpp',
+project('nix-util-c',
   version : files('.zix-version'),
   default_options : [
-    'cpp_std=c++2a',
     # TODO(Qyriad): increase the warning level
     'warning_level=1',
     'errorlogs=true', # Please print logs for tests that fail
@@ -10,72 +9,21 @@ project('nix-util-c', 'cpp',
   license : 'LGPL-2.1-or-later',
 )
 
-fs = import('fs')
 
-cxx = meson.get_compiler('cpp')
+subdir('nix-meson-build-support/zig')
 
-subdir('nix-meson-build-support/deps-lists')
-
-configdata = configuration_data()
-
-deps_private_maybe_subproject = [
-  dependency('nix-util'),
-]
-deps_public_maybe_subproject = [
-]
-subdir('nix-meson-build-support/subprojects')
-
-# TODO rename, because it will conflict with downstream projects
-configdata.set_quoted('PACKAGE_VERSION_ZIX', meson.project_version())
-configdata.set_quoted('PACKAGE_VERSION_NIX', fs.read('.version').strip().split('\n')[0])
-
-config_h = configure_file(
-  configuration : configdata,
-  output : 'config-util.h',
-)
-
-add_project_arguments(
-  # TODO(Qyriad): Yes this is how the autoconf+Make system did it.
-  # It would be nice for our headers to be idempotent instead.
-
-  # From C++ libraries, only for internals
-  '-include', 'config-util.hh',
-
-  # From C libraries, for our public, installed headers too
-  '-include', 'config-util.h',
-  language : 'cpp',
-)
-
-subdir('nix-meson-build-support/common')
-
-sources = files(
-  'nix_api_util.cc',
-)
-
-include_dirs = [include_directories('.')]
-
-headers = [config_h] + files(
-  'nix_api_util.h',
-)
-
-# TODO don't install this once tests don't use it.
-headers += files('nix_api_util_internal.h')
-
-subdir('nix-meson-build-support/export-all-symbols')
-subdir('nix-meson-build-support/windows-version')
-
-this_library = library(
-  'nixutilc',
-  sources,
-  dependencies : deps_public + deps_private + deps_other,
-  include_directories : include_dirs,
-  link_args: linker_export_flags,
-  prelink : true, # For C++ static initializers
-  install : true,
+zig_target = custom_target('zig build',
+  output: ['zig-out'],
+  command: [zig, 'build', zig_build_args, '--prefix', meson.current_build_dir() / 'zig-out', '--build-file', meson.project_source_root() / 'build.zig'],
 )
 
-install_headers(headers, subdir : 'nix', preserve_path : true)
+include_dirs = ['zig-out' / 'include' / 'nix']
 
-libraries_private = []
+install_subdir(meson.current_build_dir() / 'zig-out' / 'lib', install_dir: get_option('libdir'), strip_directory: true)
+install_subdir(meson.current_build_dir() / 'zig-out' / 'include', install_dir: get_option('includedir'), strip_directory: true)
 
-subdir('nix-meson-build-support/export')
+meson.override_dependency('nix-util-c', declare_dependency(
+  include_directories: include_dirs,
+  link_args: ['-L' + meson.current_build_dir() / 'zig-out' / 'lib', '-lnixutilc'],
+  sources: [zig_target],
+))

src/libutil-c/nix_api_util.cc

@@ -1,5 +1,6 @@
 #include "nix_api_util.h"
 #include "config-global.hh"
+#include "config-util.h"
 #include "error.hh"
 #include "nix_api_util_internal.h"
 #include "util.hh"

src/libutil-c/package.nix

@@ -1,6 +1,6 @@
 {
   lib,
-  mkMesonLibrary,
+  mkZigLibrary,
 
   nix-util,
 
@@ -14,12 +14,13 @@ let
   inherit (lib) fileset;
 in
 
-mkMesonLibrary (finalAttrs: {
+mkZigLibrary (finalAttrs: {
   pname = "zix-util-c";
   inherit version nixVersion;
 
   workDir = ./.;
   fileset = fileset.unions [
+    ../libutil
     ../../nix-meson-build-support
     ./nix-meson-build-support
     ../../.version
@@ -31,15 +32,23 @@ mkMesonLibrary (finalAttrs: {
     (fileset.fileFilter (file: file.hasExt "cc") ./.)
     (fileset.fileFilter (file: file.hasExt "hh") ./.)
     (fileset.fileFilter (file: file.hasExt "h") ./.)
+    (fileset.fileFilter (file: file.hasExt "zig") ./.)
+    (fileset.fileFilter (file: file.hasExt "zon") ./.)
   ];
 
   propagatedBuildInputs = [
     nix-util
   ];
 
-  mesonFlags = [
+  zigBuildFlags = [
+    "-fsys=nix-util"
   ];
 
+  postInstall = ''
+    substituteInPlace $out/lib/pkgconfig/nix-util-c.pc \
+      --replace-fail "includedir=$out" "includedir=$dev"
+  '';
+
   meta = {
     platforms = lib.platforms.unix ++ lib.platforms.windows;
   };