From 04226193ccb69f50936e47804be56bd1bdc316d9 Mon Sep 17 00:00:00 2001
From: Matthew Lugg <mlugg@mlugg.co.uk>
Date: Sat, 3 Jan 2026 14:52:17 +0000
Subject: [PATCH] Revert "Use `mmap` `std.heap.page_allocator` impl when
 compiling for Wasm + libc"

This reverts commit c9fa8e46df21cdf66b291fb3dfdcef1b6a1d3cab.

This commit was failing CI checks. This failure was unfortunately not
noticed before merge, due in part to the build runner bug fixed in the
last commit.
---
 lib/std/c.zig             | 15 ++-------------
 lib/std/heap.zig          |  2 +-
 lib/std/os/emscripten.zig |  9 +++++++++
 3 files changed, 12 insertions(+), 14 deletions(-)

diff --git a/lib/std/c.zig b/lib/std/c.zig
index 77ea235f53761c59d699905e607ce7fd54ba112a..e9810aeb0912015c015dd68f1259cde477b1a60a 100644
--- a/lib/std/c.zig
+++ b/lib/std/c.zig
@@ -1885,16 +1885,7 @@ pub const POLL = switch (native_os) {
 /// Basic memory protection flags
 pub const PROT = switch (native_os) {
     .linux => linux.PROT,
-    // https://github.com/emscripten-core/emscripten/blob/08e2de1031913e4ba7963b1c56f35f036a7d4d56/system/lib/libc/musl/include/sys/mman.h#L57-L62
-    // lib/libc/include/wasm-wasi-musl/sys/mman.h
-    .emscripten, .wasi => struct {
-        pub const NONE = 0;
-        pub const READ = 1;
-        pub const WRITE = 2;
-        pub const EXEC = 4;
-        pub const GROWSDOWN = 0x01000000;
-        pub const GROWSUP = 0x02000000;
-    },
+    .emscripten => emscripten.PROT,
     // https://github.com/SerenityOS/serenity/blob/6d59d4d3d9e76e39112842ec487840828f1c9bfe/Kernel/API/POSIX/sys/mman.h#L28-L31
     .openbsd, .haiku, .dragonfly, .netbsd, .illumos, .freebsd, .windows, .serenity => struct {
         /// page can not be accessed
@@ -8649,9 +8640,7 @@ pub const O = switch (native_os) {
 
 pub const MAP = switch (native_os) {
     .linux => linux.MAP,
-    // https://github.com/emscripten-core/emscripten/blob/08e2de1031913e4ba7963b1c56f35f036a7d4d56/system/lib/libc/musl/include/sys/mman.h#L21-L39
-    // lib/libc/include/wasm-wasi-musl/sys/mman.h
-    .emscripten, .wasi => packed struct(u32) {
+    .emscripten => packed struct(u32) {
         TYPE: enum(u4) {
             SHARED = 0x01,
             PRIVATE = 0x02,
diff --git a/lib/std/heap.zig b/lib/std/heap.zig
index 3da8a063ed762ee01bd89c8b825db401d358902d..f584e3f72e46241728ba1448ae2c7a766401b348 100644
--- a/lib/std/heap.zig
+++ b/lib/std/heap.zig
@@ -352,7 +352,7 @@ pub const page_allocator: Allocator = if (@hasDecl(root, "os") and
     @hasDecl(root.os, "heap") and
     @hasDecl(root.os.heap, "page_allocator"))
     root.os.heap.page_allocator
-else if (builtin.target.cpu.arch.isWasm() and !builtin.link_libc) .{
+else if (builtin.target.cpu.arch.isWasm()) .{
     .ptr = undefined,
     .vtable = &WasmAllocator.vtable,
 } else if (builtin.target.os.tag == .plan9) .{
diff --git a/lib/std/os/emscripten.zig b/lib/std/os/emscripten.zig
index 8dbf90dad9bcebb118b130b55e2e6023b63a6b85..cb444b360dd00e0375a6e02e0d95936fce90b2b5 100644
--- a/lib/std/os/emscripten.zig
+++ b/lib/std/os/emscripten.zig
@@ -331,6 +331,15 @@ pub const POLL = struct {
     pub const RDBAND = 0x080;
 };
 
+pub const PROT = struct {
+    pub const NONE = 0x0;
+    pub const READ = 0x1;
+    pub const WRITE = 0x2;
+    pub const EXEC = 0x4;
+    pub const GROWSDOWN = 0x01000000;
+    pub const GROWSUP = 0x02000000;
+};
+
 pub const rlim_t = u64;
 
 pub const RLIM = struct {
-- 
2.54.0