minimal-zig: update for Zig 0.13.0

examples/minimal-zig/build.zig

@@ -1,6 +1,9 @@
 const std = @import("std");
 
-pub fn build(b: *std.build.Builder) void {
+// Although this function looks imperative, note that its job is to
+// declaratively construct a build graph that will be executed by an external
+// runner.
+pub fn build(b: *std.Build) void {
     // Standard target options allows the person running `zig build` to choose
     // what target to build for. Here we do not override the defaults, which
     // means any target is allowed, and the default is native. Other options
@@ -9,36 +12,68 @@ pub fn build(b: *std.build.Builder) void {
 
     // Standard release options allow the person running `zig build` to select
     // between Debug, ReleaseSafe, ReleaseFast, and ReleaseSmall.
-    const mode = b.standardReleaseOptions();
-
-    const exe = b.addExecutable("minimal-zig", "src/main.zig");
-    exe.setTarget(target);
-    exe.setBuildMode(mode);
-    exe.addIncludePath("src");
-    exe.addCSourceFile("src/fenster.c", &[_][]const u8{});
-    if (exe.target.isDarwin()) {
-        exe.linkFramework("Cocoa");
-    } else if (exe.target.isWindows()) {
-        exe.linkSystemLibrary("gdi32");
-    } else {
-        exe.linkSystemLibrary("X11");
+    const optimize = b.standardOptimizeOption(.{});
+
+    const exe = b.addExecutable(.{
+        .name = "minimal-zig",
+        .root_source_file = b.path("src/main.zig"),
+        .target = target,
+        .optimize = optimize,
+    });
+
+    exe.addIncludePath(b.path("src"));
+    exe.addCSourceFile(.{ .file = b.path("src/fenster.c"), .flags = &[_][]const u8{} });
+
+    switch (target.result.os.tag) {
+        .macos => exe.linkFramework("Cocoa"),
+        .windows => exe.linkSystemLibrary("gdi32"),
+        .linux => exe.linkSystemLibrary("X11"),
+        else => {},
     }
-    exe.linkSystemLibrary("c");
-    exe.install();
 
-    const run_cmd = exe.run();
+    exe.linkLibC();
+
+    // This declares intent for the executable to be installed into the
+    // standard location when the user invokes the "install" step (the default
+    // step when running `zig build`).
+    b.installArtifact(exe);
+
+    // This *creates* a Run step in the build graph, to be executed when another
+    // step is evaluated that depends on it. The next line below will establish
+    // such a dependency.
+    const run_cmd = b.addRunArtifact(exe);
+
+    // By making the run step depend on the install step, it will be run from the
+    // installation directory rather than directly from within the cache directory.
+    // This is not necessary, however, if the application depends on other installed
+    // files, this ensures they will be present and in the expected location.
     run_cmd.step.dependOn(b.getInstallStep());
+
+    // This allows the user to pass arguments to the application in the build
+    // command itself, like this: `zig build run -- arg1 arg2 etc`
     if (b.args) |args| {
         run_cmd.addArgs(args);
     }
 
+    // This creates a build step. It will be visible in the `zig build --help` menu,
+    // and can be selected like this: `zig build run`
+    // This will evaluate the `run` step rather than the default, which is "install".
     const run_step = b.step("run", "Run the app");
     run_step.dependOn(&run_cmd.step);
 
-    const exe_tests = b.addTest("src/main.zig");
-    exe_tests.setTarget(target);
-    exe_tests.setBuildMode(mode);
+    // Creates a step for unit testing. This only builds the test executable
+    // but does not run it.
+    const unit_tests = b.addTest(.{
+        .root_source_file = b.path("src/main.zig"),
+        .target = target,
+        .optimize = optimize,
+    });
+
+    const run_unit_tests = b.addRunArtifact(unit_tests);
 
+    // Similar to creating the run step earlier, this exposes a `test` step to
+    // the `zig build --help` menu, providing a way for the user to request
+    // running the unit tests.
     const test_step = b.step("test", "Run unit tests");
-    test_step.dependOn(&exe_tests.step);
+    test_step.dependOn(&run_unit_tests.step);
 }

examples/minimal-zig/src/fenster.zig

@@ -7,7 +7,7 @@ pub const Fenster = struct {
 };
 
 pub fn new(comptime w: i32, comptime h: i32, title: [:0]const u8) type {
-    var buf: [w*h]u32 = undefined;
+    var buf: [w * h]u32 = undefined;
     const f = .{
         .width = w,
         .height = h,

examples/minimal-zig/src/main.zig

@@ -21,12 +21,12 @@ pub fn main() void {
             break;
         }
         // Render x^y^t pattern
-        for (buf) |_, i| {
-            buf[i] = @intCast(u32, i % 320) ^ @intCast(u32, i / 240) ^ t;
+        for (buf, 0..) |_, i| {
+            buf[i] = @as(u32, @intCast(i % 320)) ^ @as(u32, @intCast(i / 240)) ^ t;
         }
         t +%= 1;
         // Keep ~60 FPS
-        var diff: i64 = 1000 / 60 - (c.fenster_time() - now);
+        const diff: i64 = 1000 / 60 - (c.fenster_time() - now);
         if (diff > 0) {
             c.fenster_sleep(diff);
         }