From 4dd58fbf2e2b737564450007d67384ddc28f6a67 Mon Sep 17 00:00:00 2001
From: "Shota Kudo (chaploud)" <shota.508@studist.jp>
Date: Mon, 27 Apr 2026 03:09:14 +0900
Subject: [PATCH] fix(build): link libc to cljw / cache_gen / test module

The Zig 0.16.0 migration switched several runtime helpers
(runtime/lifecycle, lang/builtins/system, lang/interop/classes/file,
engine/vm/jit, runtime/io_default) to call std.c.{getcwd, getenv,
realpath, write, mprotect} directly because the corresponding
std.posix.* surface was removed. build.zig was never updated to
link libc explicitly, so the references resolved only on macOS
native targets where libc is auto-linked. Linux native builds and
all *-macos-none / *-linux-gnu cross-compile targets failed with
"dependency on libc must be explicitly specified" (cache_gen
ReleaseSafe + zig build test on Linux + every cross-compile job).

Set link_libc = true on the test module, the cache_gen module, and
the cljw exe module to match the post-migration source-level
dependency. F146 still tracks the eventual removal once std.c
usages get pure-Zig equivalents.
---
 build.zig | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/build.zig b/build.zig
index 6884efb1..a36d0e32 100644
--- a/build.zig
+++ b/build.zig
@@ -36,9 +36,13 @@ pub fn build(b: *std.Build) void {
     } else null;
 
     // Library module (test root)
+    // link_libc: std.c.{getcwd,getenv,realpath,mprotect,write} are used by
+    // runtime/lifecycle, lang/builtins/system, lang/interop/classes/file,
+    // engine/vm/jit, runtime/io_default. Tracked for removal in F146.
     const mod = b.addModule("ClojureWasm", .{
         .root_source_file = b.path("src/root.zig"),
         .target = target,
+        .link_libc = true,
     });
     mod.addImport("build_options", options_module);
     if (zwasm_mod) |m| mod.addImport("zwasm", m);
@@ -53,6 +57,7 @@ pub fn build(b: *std.Build) void {
             .root_source_file = b.path("src/cache_gen.zig"),
             .target = b.resolveTargetQuery(.{}),
             .optimize = .ReleaseSafe,
+            .link_libc = true,
         }),
     });
     cache_gen.root_module.addImport("build_options", options_module);
@@ -78,6 +83,7 @@ pub fn build(b: *std.Build) void {
             .root_source_file = b.path("src/main.zig"),
             .target = target,
             .optimize = optimize,
+            .link_libc = true,
         }),
     });
     exe.root_module.addImport("build_options", options_module);