From 050df1a7e6391db584d5bb88da6a845c26f19375 Mon Sep 17 00:00:00 2001
From: Daniel Nagy <danielnagy@posteo.de>
Date: Wed, 29 May 2024 00:45:00 +0200
Subject: [PATCH] go: Support WASI platform

With this change it is now possible to build simple Go packages into
WebAssembly and WASI. For example, it is now possible to build
`wazero` to wasm:

```sh
$ file $(nix-build -A pkgsCross.wasi32.wazero --no-out-link)/bin/wazero
/nix/store/pzzzsnmyjjrxi8gmadksn99rgfbxqrp2-wazero-static-wasm32-unknown-wasi-1.7.2/bin/wazero: WebAssembly (wasm) binary module version 0x1 (MVP)
```

https://go.dev/blog/wasi
---
 pkgs/development/compilers/go/1.22.nix | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/pkgs/development/compilers/go/1.22.nix b/pkgs/development/compilers/go/1.22.nix
index c0103090b331..aad242c88606 100644
--- a/pkgs/development/compilers/go/1.22.nix
+++ b/pkgs/development/compilers/go/1.22.nix
@@ -37,6 +37,7 @@ let
     "riscv64" = "riscv64";
     "s390x" = "s390x";
     "x86_64" = "amd64";
+    "wasm32" = "wasm";
   }.${platform.parsed.cpu.name} or (throw "Unsupported system: ${platform.parsed.cpu.name}");
 
   # We need a target compiler which is still runnable at build time,
@@ -90,7 +91,7 @@ stdenv.mkDerivation (finalAttrs: {
     ./go_no_vendor_checks-1.22.patch
   ];
 
-  GOOS = stdenv.targetPlatform.parsed.kernel.name;
+  GOOS = if stdenv.targetPlatform.isWasi then "wasip1" else stdenv.targetPlatform.parsed.kernel.name;
   GOARCH = goarch stdenv.targetPlatform;
   # GOHOSTOS/GOHOSTARCH must match the building system, not the host system.
   # Go will nevertheless build a for host system that we will copy over in
@@ -113,7 +114,8 @@ stdenv.mkDerivation (finalAttrs: {
 
   GOARM = toString (lib.intersectLists [ (stdenv.hostPlatform.parsed.cpu.version or "") ] [ "5" "6" "7" ]);
   GO386 = "softfloat"; # from Arch: don't assume sse2 on i686
-  CGO_ENABLED = 1;
+  # Wasi does not support CGO
+  CGO_ENABLED = if stdenv.targetPlatform.isWasi then 0 else 1;
 
   GOROOT_BOOTSTRAP = if useGccGoBootstrap then goBootstrap else "${goBootstrap}/share/go";
 
@@ -184,7 +186,7 @@ stdenv.mkDerivation (finalAttrs: {
     homepage = "https://go.dev/";
     license = licenses.bsd3;
     maintainers = teams.golang.members;
-    platforms = platforms.darwin ++ platforms.linux;
+    platforms = platforms.darwin ++ platforms.linux ++ platforms.wasi;
     mainProgram = "go";
   };
 })