Extract Vala compilation step to individual file I was trying to configure unit testing for Vala, but it was too repetitive writing same "addSystemCommand" step. This struct style is much cleaner and self-descriptiveto.

Changes

3 changed files (+173/-94)

• build.zig
  • @@ -22,6 +22,8 @@ //! https://ziglang.org/learn/build-system/
    const std = @import("std"); + const CompileVala = @import("./build/CompileVala.zig"); + const BuildError = error{ NonValaSourceInSourceListError, };
  • @@ -92,26 +94,6 @@
    break :zig_lib obj; }; - // Vala source codes to compile. - const vala_sources: [][]const u8 = vala_sources: { - var list = std.ArrayList([]const u8).init(b.allocator); - - var dir = try std.fs.cwd().openDir("src", .{ .iterate = true }); - defer dir.close(); - - var walker = try dir.walk(b.allocator); - defer walker.deinit(); - - while (try walker.next()) |entry| { - const ext = std.fs.path.extension(entry.basename); - if (std.mem.eql(u8, ".vala", ext)) { - try list.append(b.dupe(entry.path)); - } - } - - break :vala_sources try list.toOwnedSlice(); - }; - // System libraries to link. const system_libraries = [_][]const u8{ "gtk4",
  • @@ -123,68 +105,42 @@ "gee-0.8",
    "libsoup-3.0", }; - // A directory containing C source files compiled from Vala source code. - // If you use this LazyPath in your artifact, the artifact automatically depends on - // this Vala to C complication step. You don't have to manually `a.dependOn()`. - const vala_cdir = vala: { - const valac = b.addSystemCommand(&.{"valac"}); + const vala_main = vala_main: { + var compile = try CompileVala.init(b, .{ + .src = b.path("src"), + .includeTestFiles = false, + // Vala's GTK binding incorrectly mark `Gtk.StyleContext` as deprecated, even though + // its static method `add_provider_for_display` is the only future proof way to add + // CSS. As Vala compiler has no CLI flag or magic comment to suppress specific use of + // "deprecated" API, I resorted to suppress entire deprecation warnings. This has risk + // of accidentally using deprecated API. It's still better than getting used to see + // warnings on build and starting to ignore warnings. + .suppressDeprecationWarning = true, + }); - // Tell Vala compiler to emit C rather than compile using system C compiler. - valac.addArg("--ccode"); + // System libraries to link. + compile.addPackages(&.{ + "gtk4", + "libadwaita-1", + // Neither GTK4 nor Libadwaita provides SVG rendering. We need to use librsvg for + // that purpose, whilst undocumented. + "librsvg-2.0", + "gee-0.8", + "libsoup-3.0", + }); - // Vala's GTK binding incorrectly mark `Gtk.StyleContext` as deprecated, even though - // its static method `add_provider_for_display` is the only future proof way to add - // CSS. As Vala compiler has no CLI flag or magic comment to suppress specific use of - // "deprecated" API, I resorted to suppress entire deprecation warnings. This has risk - // of accidentally using deprecated API. It's still better than getting used to see - // warnings on build and starting to ignore warnings. - valac.addArg("--enable-deprecated"); + compile.addPackage("posix"); + compile.addPackages(&.{ "plac", "libsood" }); - // Vala compiler uses GResource XML to statically check attributes. - valac.addArg("--gresources"); - valac.addFileArg(b.path("data/gresource.xml")); + compile.addGResourceXML(b.path("data/gresource.xml")); - valac.addArg("--vapidir"); - valac.addDirectoryArg(b.path("src/core")); - - valac.addArg("--vapidir"); - valac.addDirectoryArg(b.path("src")); - valac.addFileInput(b.path("src/libsood.vapi")); - - // Tell Vala what system libraries to use. Perhaps type checking things? - for (system_libraries) |lib| { - valac.addArgs(&.{ "--pkg", lib }); - } - - valac.addArgs(&.{ "--pkg", "posix" }); - valac.addArgs(&.{ "--pkg", "plac" }); - valac.addArgs(&.{ "--pkg", "libsood" }); - - // Tell Vala to emit C source files under the output directory. - // The directory usually is Zig cache directory (like ".zig-cache/o/xxx"). - // For example, when there is "src/Foo.vala", this step produces - // ".zig-cache/o/hash-or-something-idk/vala/src/Foo.c" - valac.addArg("--directory"); - const dir = valac.addOutputDirectoryArg("vala"); - - // Let valac emit C source code without "src/" prefix. - valac.addArg("--basedir"); - valac.addDirectoryArg(b.path("src")); + compile.addVapi(b.path("src/core/plac.vapi")); + compile.addVapi(b.path("src/libsood.vapi")); - // Vala compiler takes a list of Vala source files, then process them all. - for (vala_sources) |src| { - valac.addFileArg(b.path(b.pathJoin(&.{ "src", src }))); - } - - const t = b.addInstallDirectory(.{ - .source_dir = dir, - .install_dir = .{ .custom = "src" }, - .install_subdir = "", - }); const step = b.step("valac", "Compile C source code from Vala files for debugging purpose"); - step.dependOn(&t.step); + step.dependOn(compile.step); - break :vala dir; + break :vala_main compile; }; const gresouce_c = gresource: {
  • @@ -244,25 +200,8 @@ exe.root_module.linkLibrary(libsood);
    exe.addCSourceFile(.{ .file = gresouce_c }); - // At this point, build does not run yet—we can't enumerate C source - // directory. Since we already have a list of Vala source code, we can - // build a list of paths of to-be-generated C source file. - for (vala_sources) |src| { - // Basically unreachable. Don't put non Vala source into `vala_sources`. - if (!std.mem.endsWith(u8, src, ".vala")) { - return BuildError.NonValaSourceInSourceListError; - } - - // Looks fragile but it works. Even if it produced incorrect paths, - // filesystem and Zig compiler will tell us a file is missing. - const rel_path = b.fmt("{s}.c", .{src[0..(src.len - 5)]}); - - // src = "src/Foo.vala" - // rel_path = "src/Foo.c" - // file = "(step cache directory)/vala/src/Foo.c" - exe.addCSourceFile(.{ - .file = try vala_cdir.join(b.allocator, rel_path), - }); + for (vala_main.compiled_c_files) |file| { + exe.addCSourceFile(.{ .file = file }); } break :exe exe;
• build/CompileVala.zig (new)
  • @@ -0,0 +1,139 @@
    + // Copyright 2025 Shota FUJI + // + // Licensed under the Apache License, Version 2.0 (the "License"); + // you may not use this file except in compliance with the License. + // You may obtain a copy of the License at + // + // http://www.apache.org/licenses/LICENSE-2.0 + // + // Unless required by applicable law or agreed to in writing, software + // distributed under the License is distributed on an "AS IS" BASIS, + // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + // See the License for the specific language governing permissions and + // limitations under the License. + // + // SPDX-License-Identifier: Apache-2.0 + + const CompileVala = @This(); + + const std = @import("std"); + + step: *std.Build.Step, + compiled_c_directory: std.Build.LazyPath, + compiled_c_files: []std.Build.LazyPath, + + valac: *std.Build.Step.Run, + + pub const Options = struct { + /// This must be an existing path. + src: std.Build.LazyPath, + + includeTestFiles: bool = false, + suppressDeprecationWarning: bool = false, + }; + + pub fn init(b: *std.Build, opts: Options) !CompileVala { + const valac = b.addSystemCommand(&.{"valac"}); + + // Vala source codes to compile. + const vala_sources: [][]const u8 = vala_sources: { + var list = std.ArrayList([]const u8).init(b.allocator); + + var dir = try opts.src.getPath3(b, &valac.step).openDir("", .{ .iterate = true }); + defer dir.close(); + + var walker = try dir.walk(b.allocator); + defer walker.deinit(); + + while (try walker.next()) |entry| { + const ext = std.fs.path.extension(entry.basename); + if (std.mem.eql(u8, ".vala", ext)) { + if (!opts.includeTestFiles and std.mem.endsWith(u8, entry.basename, ".test.vala")) { + continue; + } + + try list.append(b.dupe(entry.path)); + } + } + + break :vala_sources try list.toOwnedSlice(); + }; + + // Tell Vala compiler to emit C rather than compile using system C compiler. + valac.addArg("--ccode"); + + if (opts.suppressDeprecationWarning) { + valac.addArg("--enable-deprecated"); + } + + // Tell Vala to emit C source files under the output directory. + // The directory usually is Zig cache directory (like ".zig-cache/o/xxx"). + // For example, when there is "src/Foo.vala", this step produces + // ".zig-cache/o/hash-or-something-idk/vala/Foo.c" + valac.addArg("--directory"); + const dir = valac.addOutputDirectoryArg("vala"); + + // Let valac emit C source code without prefixing using directory. + valac.addArg("--basedir"); + valac.addDirectoryArg(opts.src); + + // Vala compiler takes a list of Vala source files, then process them all. + for (vala_sources) |src| { + valac.addFileArg(try opts.src.join(b.allocator, src)); + } + + const t = b.addInstallDirectory(.{ + .source_dir = dir, + .install_dir = .{ .custom = "src" }, + .install_subdir = "", + }); + + const compiled_c_files = try b.allocator.alloc(std.Build.LazyPath, vala_sources.len); + for (vala_sources, 0..) |src, i| { + // Looks fragile but it works. Even if it produced incorrect paths, + // filesystem and Zig compiler will tell us a file is missing. + const rel_path = b.fmt("{s}.c", .{src[0..(src.len - 5)]}); + + // src = "src/Foo.vala" + // rel_path = "Foo.c" + // file = "(step cache directory)/vala/Foo.c" + compiled_c_files[i] = try dir.join(b.allocator, rel_path); + } + + return .{ + .step = &t.step, + .compiled_c_directory = dir, + .compiled_c_files = compiled_c_files, + .valac = valac, + }; + } + + pub fn addPackage(self: *CompileVala, pkg: []const u8) void { + self.valac.addArg("--pkg"); + self.valac.addArg(pkg); + } + + pub fn addPackages(self: *CompileVala, pkgs: []const []const u8) void { + for (pkgs) |pkg| { + self.addPackage(pkg); + } + } + + pub fn addVapi(self: *CompileVala, file: std.Build.LazyPath) void { + self.valac.addArg("--vapidir"); + self.valac.addDirectoryArg(file.dirname()); + self.valac.addFileInput(file); + } + + pub fn addGResourceXML(self: *CompileVala, path: std.Build.LazyPath) void { + self.valac.addArg("--gresources"); + self.valac.addFileArg(path); + } + + pub fn getCompiledCDirectory(self: CompileVala) std.Build.LazyPath { + return self.compiled_c_directory; + } + + pub fn getCompiledCFiles(self: CompileVala) []std.Build.LazyPath { + return self.compiled_c_files; + }
• nix/package.nix
  • @@ -40,6 +40,7 @@ root = ../.;
    fileset = unions [ ../src ../data + ../build ../build.zig ../build.zig.zon ];