From bac7ee3208209cca6d8c58ade2f25e3f91053848 Mon Sep 17 00:00:00 2001
From: Alex Martens <alex@thinglab.org>
Date: Fri, 7 Oct 2022 07:35:29 -0700
Subject: [PATCH] rustc: fix build for no_std targets

---
 pkgs/build-support/rust/lib/default.nix     | 5 +++++
 pkgs/development/compilers/rust/default.nix | 2 +-
 pkgs/development/compilers/rust/rustc.nix   | 2 ++
 3 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/pkgs/build-support/rust/lib/default.nix b/pkgs/build-support/rust/lib/default.nix
index 2be0c2567879..5eac208cc31c 100644
--- a/pkgs/build-support/rust/lib/default.nix
+++ b/pkgs/build-support/rust/lib/default.nix
@@ -38,4 +38,9 @@ rec {
     if platform ? rustc.platform
     then builtins.toFile (toRustTarget platform + ".json") (builtins.toJSON platform.rustc.platform)
     else toRustTarget platform;
+
+  # Returns true if the target is no_std
+  # https://github.com/rust-lang/rust/blob/2e44c17c12cec45b6a682b1e53a04ac5b5fcc9d2/src/bootstrap/config.rs#L415-L421
+  IsNoStdTarget = platform: let rustTarget = toRustTarget platform; in
+    builtins.any (t: lib.hasInfix t rustTarget) ["-none" "nvptx" "switch" "-uefi"];
 }
diff --git a/pkgs/development/compilers/rust/default.nix b/pkgs/development/compilers/rust/default.nix
index 7c78a784575a..ef01cbf2abc1 100644
--- a/pkgs/development/compilers/rust/default.nix
+++ b/pkgs/development/compilers/rust/default.nix
@@ -28,7 +28,7 @@ in
   lib = lib';
 
   # Backwards compat before `lib` was factored out.
-  inherit (lib') toTargetArch toTargetOs toRustTarget toRustTargetSpec;
+  inherit (lib') toTargetArch toTargetOs toRustTarget toRustTargetSpec IsNoStdTarget;
 
   # This just contains tools for now. But it would conceivably contain
   # libraries too, say if we picked some default/recommended versions from
diff --git a/pkgs/development/compilers/rust/rustc.nix b/pkgs/development/compilers/rust/rustc.nix
index bb5bc1bb1d73..94b7171c02d3 100644
--- a/pkgs/development/compilers/rust/rustc.nix
+++ b/pkgs/development/compilers/rust/rustc.nix
@@ -107,6 +107,8 @@ in stdenv.mkDerivation rec {
     "${setHost}.musl-root=${pkgsBuildHost.targetPackages.stdenv.cc.libc}"
   ] ++ optionals stdenv.targetPlatform.isMusl [
     "${setTarget}.musl-root=${pkgsBuildTarget.targetPackages.stdenv.cc.libc}"
+  ] ++ optionals (rust.IsNoStdTarget stdenv.targetPlatform) [
+    "--disable-docs"
   ];
 
   # The bootstrap.py will generated a Makefile that then executes the build.