feat(libfetchers): add zig build

src/libfetchers/build.zig

@@ -0,0 +1,157 @@
+const std = @import("std");
+
+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 fsys_libstore = b.systemIntegrationOption("nix-store", .{});
+    const use_meson_libs = std.mem.eql(u8, b.graph.env_map.get("USE_MESON_LIBS") orelse "0", "1");
+
+    const libfetchers = std.Build.Step.Compile.create(b, .{
+        .name = "nixfetchers",
+        .kind = .lib,
+        .linkage = linkage,
+        .root_module = b.createModule(.{
+            .target = target,
+            .optimize = optimize,
+            .link_libc = true,
+            .link_libcpp = true,
+        }),
+    });
+
+    libfetchers.root_module.addCMacro("SYSTEM", b.fmt("\"{s}-{s}\"", .{
+        @tagName(target.result.cpu.arch),
+        @tagName(target.result.os.tag),
+    }));
+
+    libfetchers.addIncludePath(b.path("."));
+
+    libfetchers.addCSourceFiles(.{
+        .files = &.{
+            "attrs.cc",
+            "cache.cc",
+            "fetch-settings.cc",
+            "fetch-to-store.cc",
+            "fetchers.cc",
+            "filtering-source-accessor.cc",
+            "git-lfs-fetch.cc",
+            "git-utils.cc",
+            "git.cc",
+            "github.cc",
+            "indirect.cc",
+            "mercurial.cc",
+            "path.cc",
+            "registry.cc",
+            "store-path-accessor.cc",
+            "tarball.cc",
+        },
+        .flags = &.{
+            "--std=c++2a",
+            b.fmt("-I{s}", .{std.mem.trimRight(u8, b.run(&.{ "pkg-config", "--variable=includedir", "boost" }), "\n")}),
+        },
+    });
+
+    libfetchers.linkSystemLibrary("nlohmann_json");
+    libfetchers.linkSystemLibrary("libgit2");
+
+    if (fsys_libutil) {
+        if (use_meson_libs) {
+            libfetchers.linkSystemLibrary("nixutil");
+
+            for (b.search_prefixes.items) |prefix| {
+                const path = b.pathJoin(&.{ prefix, "include", "nix" });
+
+                var dir = std.fs.cwd().openDir(path, .{}) catch continue;
+                defer dir.close();
+
+                libfetchers.root_module.addSystemIncludePath(.{ .cwd_relative = path });
+            }
+
+            libfetchers.linkSystemLibrary("libarchive");
+            libfetchers.linkSystemLibrary("boost");
+            libfetchers.linkSystemLibrary("nlohmann_json");
+        } else {
+            libfetchers.linkSystemLibrary("nix-util");
+        }
+    } else {
+        const libutil = b.dependency("nix-util", .{
+            .target = target,
+            .optimize = optimize,
+            .linkage = linkage orelse .static,
+        });
+
+        libfetchers.linkLibrary(libutil.artifact("nixutil"));
+
+        for (libutil.artifact("nixutil").root_module.include_dirs.items) |hdr| {
+            libfetchers.root_module.include_dirs.append(b.allocator, hdr) catch @panic("OOM");
+        }
+
+        libfetchers.linkSystemLibrary("libarchive");
+        libfetchers.linkSystemLibrary("boost");
+        libfetchers.linkSystemLibrary("nlohmann_json");
+    }
+
+    if (fsys_libstore) {
+        if (use_meson_libs) {
+            libfetchers.linkSystemLibrary("nixstore");
+
+            for (b.search_prefixes.items) |prefix| {
+                const path = b.pathJoin(&.{ prefix, "include", "nix" });
+
+                var dir = std.fs.cwd().openDir(path, .{}) catch continue;
+                defer dir.close();
+
+                libfetchers.root_module.addSystemIncludePath(.{ .cwd_relative = path });
+            }
+        } else {
+            libfetchers.linkSystemLibrary("nix-store");
+        }
+    } else {
+        const libstore = b.dependency("nix-store", .{
+            .target = target,
+            .optimize = optimize,
+            .linkage = linkage orelse .static,
+        });
+
+        libfetchers.linkLibrary(libstore.artifact("nixstore"));
+
+        for (libstore.artifact("nixstore").root_module.include_dirs.items) |hdr| {
+            libfetchers.root_module.include_dirs.append(b.allocator, hdr) catch @panic("OOM");
+        }
+    }
+
+    inline for (&.{
+        "attrs.hh",
+        "cache.hh",
+        "fetch-settings.hh",
+        "fetch-to-store.hh",
+        "fetchers.hh",
+        "filtering-source-accessor.hh",
+        "git-lfs-fetch.hh",
+        "git-utils.hh",
+        "registry.hh",
+        "store-path-accessor.hh",
+        "tarball.hh",
+    }) |hdr| {
+        libfetchers.installHeader(b.path(hdr), "nix/" ++ hdr);
+    }
+
+    b.installArtifact(libfetchers);
+
+    b.getInstallStep().dependOn(&b.addInstallFileWithDir(b.addWriteFile("nix-fetchers.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}} -lnixfetchers
+    , .{
+        b.getInstallPath(.prefix, ""),
+        b.getInstallPath(.lib, ""),
+        b.getInstallPath(.header, ""),
+    })).getDirectory().path(b, "nix-fetchers.pc"), .lib, "pkgconfig/nix-fetchers.pc").step);
+}

src/libfetchers/build.zig.zon

@@ -0,0 +1,13 @@
+.{
+    .name = "nix-fetchers",
+    .version = "0.1.0",
+    .paths = .{"."},
+    .dependencies = .{
+        .@"nix-util" = .{
+            .path = "../libutil",
+        },
+        .@"nix-store" = .{
+            .path = "../libstore",
+        },
+    },
+}

src/libfetchers/meson.build

@@ -1,7 +1,6 @@
-project('nix-fetchers', 'cpp',
+project('nix-fetchers',
   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
@@ -10,82 +9,58 @@ project('nix-fetchers', 'cpp',
   license : 'LGPL-2.1-or-later',
 )
 
-cxx = meson.get_compiler('cpp')
+fs = import('fs')
 
-subdir('nix-meson-build-support/deps-lists')
+subdir('nix-meson-build-support/zig')
 
-configuration_data()
+zig_prefix = meson.current_build_dir() / 'zig-out'
 
-deps_private_maybe_subproject = [
-]
-deps_public_maybe_subproject = [
-  dependency('nix-util'),
-  dependency('nix-store'),
-]
-subdir('nix-meson-build-support/subprojects')
+deps = []
 
-nlohmann_json = dependency('nlohmann_json', version : '>= 3.9')
-deps_public += nlohmann_json
+libutil = dependency('nix-util', required: false)
+if libutil.found()
+  deps += libutil
+  zig_build_args += [
+    '-fsys=nix-util',
+    '--search-prefix', libutil.get_variable('prefix'),
+    '--search-prefix', fs.parent(libutil.get_variable('includedir')),
+    '--search-prefix', fs.parent(libutil.get_variable('libdir')),
+  ]
+endif
 
-libgit2 = dependency('libgit2')
-deps_private += libgit2
+libstore = dependency('nix-store', required: false)
+if libstore.found()
+  deps += libstore
+  zig_build_args += [
+    '-fsys=nix-store',
+    '--search-prefix', libstore.get_variable('prefix'),
+    '--search-prefix', fs.parent(libstore.get_variable('includedir')),
+    '--search-prefix', fs.parent(libstore.get_variable('libdir')),
+  ]
+endif
 
-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.
-  '-include', 'config-util.hh',
-  '-include', 'config-store.hh',
-  # '-include', 'config-fetchers.h',
-  language : 'cpp',
+zig_target = custom_target('zig build',
+  output: ['zig-out'],
+  command: [zig, 'build', zig_build_args, '--prefix', zig_prefix, '--build-file', meson.project_source_root() / 'build.zig'],
+  env: {
+    'USE_MESON_LIBS': '1',
+  },
 )
 
-subdir('nix-meson-build-support/common')
+includedir = zig_prefix / 'include' / 'nix'
+compile_args = ['-I' + includedir]
 
-sources = files(
-  'attrs.cc',
-  'cache.cc',
-  'fetch-settings.cc',
-  'fetch-to-store.cc',
-  'fetchers.cc',
-  'filtering-source-accessor.cc',
-  'git-lfs-fetch.cc',
-  'git-utils.cc',
-  'git.cc',
-  'github.cc',
-  'indirect.cc',
-  'mercurial.cc',
-  'path.cc',
-  'registry.cc',
-  'store-path-accessor.cc',
-  'tarball.cc',
-)
-
-include_dirs = [include_directories('.')]
-
-headers = files(
-  'attrs.hh',
-  'cache.hh',
-  'fetch-settings.hh',
-  'fetch-to-store.hh',
-  'fetchers.hh',
-  'filtering-source-accessor.hh',
-  'git-lfs-fetch.hh',
-  'git-utils.hh',
-  'registry.hh',
-  'store-path-accessor.hh',
-  'tarball.hh',
-)
-
-this_library = library(
-  'nixfetchers',
-  sources,
-  dependencies : deps_public + deps_private + deps_other,
-  prelink : true, # For C++ static initializers
-  install : true,
-)
-
-install_headers(headers, subdir : 'nix', preserve_path : true)
-
-libraries_private = []
+install_subdir(zig_prefix / 'lib', install_dir: get_option('libdir'), strip_directory: true)
+install_subdir(zig_prefix / 'include', install_dir: get_option('includedir'), strip_directory: true)
 
-subdir('nix-meson-build-support/export')
+meson.override_dependency('nix-fetchers', declare_dependency(
+  compile_args: compile_args,
+  link_args: ['-L' + zig_prefix / 'lib', '-lnixfetchers'],
+  sources: [zig_target],
+  dependencies: deps,
+  variables: {
+    'prefix': zig_prefix,
+    'includedir': zig_prefix / 'include',
+    'libdir': zig_prefix / 'lib'
+  }
+))

src/libfetchers/package.nix

@@ -1,6 +1,6 @@
 {
   lib,
-  mkMesonLibrary,
+  mkZigLibrary,
 
   nix-util,
   nix-store,
@@ -17,12 +17,14 @@ let
   inherit (lib) fileset;
 in
 
-mkMesonLibrary (finalAttrs: {
+mkZigLibrary (finalAttrs: {
   pname = "zix-fetchers";
   inherit version nixVersion;
 
   workDir = ./.;
   fileset = fileset.unions [
+    ../libutil
+    ../libstore
     ../../nix-meson-build-support
     ./nix-meson-build-support
     ../../.version
@@ -33,6 +35,8 @@ mkMesonLibrary (finalAttrs: {
     ./meson.options
     (fileset.fileFilter (file: file.hasExt "cc") ./.)
     (fileset.fileFilter (file: file.hasExt "hh") ./.)
+    (fileset.fileFilter (file: file.hasExt "zig") ./.)
+    (fileset.fileFilter (file: file.hasExt "zon") ./.)
   ];
 
   buildInputs = [
@@ -45,6 +49,16 @@ mkMesonLibrary (finalAttrs: {
     nlohmann_json
   ];
 
+  zigBuildFlags = [
+    "-fsys=nix-util"
+    "-fsys=nix-store"
+  ];
+
+  postInstall = ''
+    substituteInPlace $out/lib/pkgconfig/nix-fetchers.pc \
+      --replace-fail "includedir=$out" "includedir=$dev"
+  '';
+
   meta = {
     platforms = lib.platforms.unix ++ lib.platforms.windows;
   };