From 0ec0cc0f9592fe9ba716a1567b887ba52e4b75dc Mon Sep 17 00:00:00 2001
From: Mitchell Hashimoto <mitchell.hashimoto@gmail.com>
Date: Tue, 6 Aug 2024 16:04:41 -0700
Subject: [PATCH] build: build proper metallib for iOS builds

---
 build.zig                  | 31 ++++++++++---------------------
 src/build/MetallibStep.zig | 32 ++++++++++++++++++++++++++++++--
 2 files changed, 40 insertions(+), 23 deletions(-)

diff --git a/build.zig b/build.zig
index 9cac8d810..afc97f57f 100644
--- a/build.zig
+++ b/build.zig
@@ -1267,29 +1267,18 @@ fn addDeps(
 /// Generate Metal shader library
 fn addMetallib(
     b: *std.Build,
-    step_: ?*std.Build.Step.Compile,
+    step: *std.Build.Step.Compile,
 ) !void {
-    // Our static state between runs. We memoize so we only compile
-    // the Metal shaders once.
-    const MetalState = struct {
-        var generated: ?std.Build.LazyPath = null;
-    };
+    const metal_step = MetallibStep.create(b, .{
+        .name = "Ghostty",
+        .target = step.root_module.resolved_target.?,
+        .sources = &.{b.path("src/renderer/shaders/cell.metal")},
+    });
 
-    const output = MetalState.generated orelse metal: {
-        const step = MetallibStep.create(b, .{
-            .name = "Ghostty",
-            .sources = &.{b.path("src/renderer/shaders/cell.metal")},
-        });
-
-        break :metal step.output;
-    };
-
-    if (step_) |step| {
-        output.addStepDependencies(&step.step);
-        step.root_module.addAnonymousImport("ghostty_metallib", .{
-            .root_source_file = output,
-        });
-    }
+    metal_step.output.addStepDependencies(&step.step);
+    step.root_module.addAnonymousImport("ghostty_metallib", .{
+        .root_source_file = metal_step.output,
+    });
 }
 
 /// Generate help files
diff --git a/src/build/MetallibStep.zig b/src/build/MetallibStep.zig
index 8d78d0ceb..e576b9c3a 100644
--- a/src/build/MetallibStep.zig
+++ b/src/build/MetallibStep.zig
@@ -11,6 +11,9 @@ pub const Options = struct {
     /// The name of the xcframework to create.
     name: []const u8,
 
+    /// The OS being targeted
+    target: std.Build.ResolvedTarget,
+
     /// The Metal source files.
     sources: []const LazyPath,
 };
@@ -21,20 +24,45 @@ output: LazyPath,
 pub fn create(b: *std.Build, opts: Options) *MetallibStep {
     const self = b.allocator.create(MetallibStep) catch @panic("OOM");
 
+    const sdk = switch (opts.target.result.os.tag) {
+        .macos => "macosx",
+        .ios => "iphoneos",
+        else => @panic("unsupported metallib OS"),
+    };
+
+    const min_version = if (opts.target.query.os_version_min) |v|
+        b.fmt("{}", .{v.semver})
+    else switch (opts.target.result.os.tag) {
+        .macos => "10.14",
+        .ios => "11.0",
+        else => unreachable,
+    };
+
     const run_ir = RunStep.create(
         b,
         b.fmt("metal {s}", .{opts.name}),
     );
-    run_ir.addArgs(&.{ "xcrun", "-sdk", "macosx", "metal", "-o" });
+    run_ir.addArgs(&.{ "xcrun", "-sdk", sdk, "metal", "-o" });
     const output_ir = run_ir.addOutputFileArg(b.fmt("{s}.ir", .{opts.name}));
     run_ir.addArgs(&.{"-c"});
     for (opts.sources) |source| run_ir.addFileArg(source);
+    switch (opts.target.result.os.tag) {
+        .ios => run_ir.addArgs(&.{b.fmt(
+            "-mios-version-min={s}",
+            .{min_version},
+        )}),
+        .macos => run_ir.addArgs(&.{b.fmt(
+            "-mmacos-version-min={s}",
+            .{min_version},
+        )}),
+        else => {},
+    }
 
     const run_lib = RunStep.create(
         b,
         b.fmt("metallib {s}", .{opts.name}),
     );
-    run_lib.addArgs(&.{ "xcrun", "-sdk", "macosx", "metallib", "-o" });
+    run_lib.addArgs(&.{ "xcrun", "-sdk", sdk, "metallib", "-o" });
     const output_lib = run_lib.addOutputFileArg(b.fmt("{s}.metallib", .{opts.name}));
     run_lib.addFileArg(output_ir);
     run_lib.step.dependOn(&run_ir.step);