From 69cdfaf6a649c55e3379a906b6aae751803ea3c0 Mon Sep 17 00:00:00 2001
From: Connor Baker <ConnorBaker01@gmail.com>
Date: Tue, 28 Oct 2025 11:22:02 -0700
Subject: [PATCH] cudaPackages.nccl: 2.27.6-1 -> 2.28.7-1; support earlier CUDA
 releases

Signed-off-by: Connor Baker <ConnorBaker01@gmail.com>
---
 .../cuda-modules/packages/nccl.nix            | 56 ++++++++++++++-----
 1 file changed, 43 insertions(+), 13 deletions(-)

diff --git a/pkgs/development/cuda-modules/packages/nccl.nix b/pkgs/development/cuda-modules/packages/nccl.nix
index 07f0ba06a067..ea3d1f3d2cb0 100644
--- a/pkgs/development/cuda-modules/packages/nccl.nix
+++ b/pkgs/development/cuda-modules/packages/nccl.nix
@@ -1,12 +1,10 @@
-# NOTE: Though NCCL is called within the cudaPackages package set, we avoid passing in
-# the names of dependencies from that package set directly to avoid evaluation errors
-# in the case redistributable packages are not available.
 {
   _cuda,
   backendStdenv,
   cuda_cccl,
   cuda_cudart,
   cuda_nvcc,
+  cudaAtLeast,
   cudaNamePrefix,
   fetchFromGitHub,
   flags,
@@ -19,11 +17,19 @@
 let
   inherit (_cuda.lib) _mkMetaBadPlatforms;
   inherit (backendStdenv) hasJetsonCudaCapability requestedJetsonCudaCapabilities;
-  inherit (lib) licenses maintainers teams;
-  inherit (lib.attrsets)
+  inherit (lib)
+    all
+    flip
+    getAttr
     getBin
+    getInclude
     getLib
-    getOutput
+    licenses
+    maintainers
+    optionalString
+    teams
+    versionAtLeast
+    versionOlder
     ;
 in
 backendStdenv.mkDerivation (finalAttrs: {
@@ -33,13 +39,28 @@ backendStdenv.mkDerivation (finalAttrs: {
   # NOTE: Depends on the CUDA package set, so use cudaNamePrefix.
   name = "${cudaNamePrefix}-${finalAttrs.pname}-${finalAttrs.version}";
   pname = "nccl";
-  version = "2.27.6-1";
+
+  # NOTE:
+  #   Compilation errors resulting from newer versions of NCCL on older releases of CUDA seem to be caused (mostly)
+  #   by differences in assumed version of CCCL: using a newer CCCL with an older release of CUDA can (sometimes) allow
+  #   newer versions of NCCL than what we provide here.
+  version =
+    if cudaAtLeast "11.7" then
+      "2.28.7-1"
+    else if cudaAtLeast "11.6" then
+      "2.26.6-1"
+    else
+      "2.25.1-1";
 
   src = fetchFromGitHub {
     owner = "NVIDIA";
     repo = "nccl";
     tag = "v${finalAttrs.version}";
-    hash = "sha256-/BiLSZaBbVIqOfd8nQlgUJub0YR3SR4B93x2vZpkeiU=";
+    hash = getAttr finalAttrs.version {
+      "2.28.7-1" = "sha256-NM19OiBBGmv3cGoVoRLKSh9Y59hiDoei9NIrRnTqWeA=";
+      "2.26.6-1" = "sha256-vkWMGXCy+dIpYCecdafmOAGlnfRxIQ5Y2ZQuMjinraI=";
+      "2.25.1-1" = "sha256-3snh0xdL9I5BYqdbqdl+noizJoI38mZRVOJChgEE1I8=";
+    };
   };
 
   outputs = [
@@ -55,7 +76,7 @@ backendStdenv.mkDerivation (finalAttrs: {
   ];
 
   buildInputs = [
-    (getOutput "include" cuda_nvcc)
+    (getInclude cuda_nvcc)
     cuda_cccl
     cuda_cudart
   ];
@@ -71,12 +92,21 @@ backendStdenv.mkDerivation (finalAttrs: {
       --replace-fail \
         '-ccbin $(CXX)' \
         ""
+  ''
+  # 2.27.3-1 was the first to introuce CXXSTD
+  + optionalString (versionOlder finalAttrs.version "2.27.3-1") ''
+    nixLog "patching $PWD/makefiles/common.mk to remove NVIDIA's std hardcoding"
+    substituteInPlace ./makefiles/common.mk \
+      --replace-fail \
+        '-std=c++11' \
+        '$(CXXSTD)'
   '';
 
   # TODO: This would likely break under cross; need to delineate between build and host packages.
   makeFlags = [
+    "CXXSTD=-std=c++17"
     "CUDA_HOME=${getBin cuda_nvcc}"
-    "CUDA_INC=${getOutput "include" cuda_cudart}/include"
+    "CUDA_INC=${getInclude cuda_cudart}/include"
     "CUDA_LIB=${getLib cuda_cudart}/lib"
     "NVCC_GENCODE=${flags.gencodeString}"
     "PREFIX=$(out)"
@@ -85,7 +115,8 @@ backendStdenv.mkDerivation (finalAttrs: {
   enableParallelBuilding = true;
 
   postFixup = ''
-    moveToOutput lib/libnccl_static.a "$static"
+    _overrideFirst outputStatic "static" "lib" "out"
+    moveToOutput lib/libnccl_static.a "''${!outputStatic:?}"
   '';
 
   passthru = {
@@ -93,8 +124,7 @@ backendStdenv.mkDerivation (finalAttrs: {
       {
         message = "Pre-Thor Jetson devices (CUDA capabilities < 10.1) are not supported by NCCL";
         assertion =
-          !hasJetsonCudaCapability
-          || lib.all (lib.flip lib.versionAtLeast "10.1") requestedJetsonCudaCapabilities;
+          !hasJetsonCudaCapability || all (flip versionAtLeast "10.1") requestedJetsonCudaCapabilities;
       }
     ];