From 6c0e44397ba766e2f5587dc030552adcaedad0b8 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Martin=20Ha=CC=88cker?= <mhaecker@mac.com>
Date: Wed, 4 Dec 2024 10:38:57 +0100
Subject: [PATCH] Add documentation on how to enable compilation of binary
 dependencies.

---
 docs/common-patterns.md | 33 +++++++++++++++++++++++++++++++++
 1 file changed, 33 insertions(+)

diff --git a/docs/common-patterns.md b/docs/common-patterns.md
index b01a55486..a35349301 100644
--- a/docs/common-patterns.md
+++ b/docs/common-patterns.md
@@ -141,3 +141,36 @@ in {
   ];
 }
 ```
+
+### Compile x86 dependencies on ARM Macs via Rosetta
+
+If you want to also compile dependencies for x86, you can add dependencies to `packages`:
+
+```nix
+packages = with rosettaPkgs; [
+    # these are the packages required for pymssql
+    freetds
+    krb5
+    openssl
+];
+```
+
+And switch the compiler to x86:
+
+```nix
+stdenv = rosettaPkgs.stdenv;
+```
+
+Then, in the generated shell, you can compile software for x86, like `pymssql` or `ibm_db`. However some creative DYLD_FALLBACK_LIBRARY_PATH may be required to make some dependency libraries available to the x86 binaries:
+
+```sh
+export DYLD_FALLBACK_LIBRARY_PATH="${rosettaPkgs.lib.makeLibraryPath [ rosettaPkgs.gcc14.cc] }:$DYLD_FALLBACK_LIBRARY_PATH"
+git clone git@github.com:pymssql/pymssql.git
+${rosettaPkgs.python312Full}/bin/python3 -m venv venv
+source venv/bin/activate
+(
+    cd pymssql
+    pip install -e .
+)
+pip install ibm_db
+```