From 1c3a571312f94180884ea4deaf4d64cd2a694158 Mon Sep 17 00:00:00 2001
From: Mitchell Hashimoto <m@mitchellh.com>
Date: Fri, 24 Apr 2026 09:26:12 -0700
Subject: [PATCH] pkg/highway: always linkLibC

---
 pkg/highway/build.zig    | 7 +++----
 pkg/simdutf/build.zig    | 9 ++++++---
 src/build/SharedDeps.zig | 1 -
 3 files changed, 9 insertions(+), 8 deletions(-)

diff --git a/pkg/highway/build.zig b/pkg/highway/build.zig
index 57ed667d7..e23abb399 100644
--- a/pkg/highway/build.zig
+++ b/pkg/highway/build.zig
@@ -3,7 +3,6 @@ const std = @import("std");
 pub fn build(b: *std.Build) !void {
     const target = b.standardTargetOptions(.{});
     const optimize = b.standardOptimizeOption(.{});
-    const no_libc = b.option(bool, "no_libc", "Avoid linking libc when embedding Highway into no-libc builds") orelse false;
 
     const upstream_ = b.lazyDependency("highway", .{});
 
@@ -23,9 +22,9 @@ pub fn build(b: *std.Build) !void {
         .linkage = .static,
     });
 
-    // Our highway package is free of libc at runtime, so only libc-backed
-    // consumers should request it explicitly.
-    if (!no_libc) lib.linkLibC();
+    // We don't use libc at runtime but we do need the headers at
+    // compile time.
+    lib.linkLibC();
 
     lib.addIncludePath(b.path("src/cpp"));
     if (upstream_) |upstream| {
diff --git a/pkg/simdutf/build.zig b/pkg/simdutf/build.zig
index 4078c78ba..72387a06f 100644
--- a/pkg/simdutf/build.zig
+++ b/pkg/simdutf/build.zig
@@ -29,15 +29,18 @@ pub fn build(b: *std.Build) !void {
         .linkage = .static,
     });
     lib.addIncludePath(b.path("vendor"));
-    if (!no_libc) lib.linkLibC();
-    libcpp: {
+    libc: {
+        // We always link libc because we require the headers even with
+        // no_libc set.
+        lib.linkLibC();
+
         if (target.result.abi == .msvc) {
             // On MSVC, we must not use linkLibCpp because Zig unconditionally
             // passes -nostdinc++ and then adds its bundled libc++/libc++abi
             // include paths, which conflict with MSVC's own C++ runtime headers.
             // The MSVC SDK include directories (added via linkLibC) contain
             // both C and C++ headers, so linkLibCpp is not needed.
-            break :libcpp;
+            break :libc;
         }
 
         // We link libcpp even with no_libcxx because simdutf requires
diff --git a/src/build/SharedDeps.zig b/src/build/SharedDeps.zig
index 65c6405a1..2d6dce1c2 100644
--- a/src/build/SharedDeps.zig
+++ b/src/build/SharedDeps.zig
@@ -802,7 +802,6 @@ pub fn addSimd(
     } else if (b.lazyDependency("highway", .{
         .target = target,
         .optimize = optimize,
-        .no_libc = simd_libc == .no_libc,
     })) |highway_dep| lib: {
         const lib = highway_dep.artifact("highway");
         if (simd_libc == .no_libc) {