From 3a9ae518f2c9424251eae13fb23db6ea571cfce1 Mon Sep 17 00:00:00 2001
From: Nikita Shulga <nshulga@fb.com>
Date: Wed, 24 Aug 2022 18:31:25 +0000
Subject: [PATCH] Skip NCCL slimming for cxx11 libtorch builds (#83959)

Fixes https://github.com/pytorch/pytorch/issues/83887

Pull Request resolved: https://github.com/pytorch/pytorch/pull/83959
Approved by: https://github.com/atalman
---
 cmake/External/nccl.cmake | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/cmake/External/nccl.cmake b/cmake/External/nccl.cmake
index fa882d0bfb8..18b39033119 100644
--- a/cmake/External/nccl.cmake
+++ b/cmake/External/nccl.cmake
@@ -42,7 +42,13 @@ if(NOT __NCCL_INCLUDED)
     string(REGEX REPLACE "GNU objcopy .+ ([0-9])\\.([0-9]+).*" "\\1" OBJCOPY_VERSION_MAJOR ${OBJCOPY_VERSION_STR})
     string(REGEX REPLACE "GNU objcopy .+ ([0-9])\\.([0-9]+).*" "\\2" OBJCOPY_VERSION_MINOR ${OBJCOPY_VERSION_STR})
 
-    if((${OBJCOPY_VERSION_MAJOR} GREATER 2) OR ((${OBJCOPY_VERSION_MAJOR} EQUAL 2) AND (${OBJCOPY_VERSION_MINOR} GREATER 27)))
+    # TODO: Replace me with SKIP_NCCL_SLIMMING option (and investigate why it does not work on newer compilers)
+    if("$ENV{BUILD_ENVIRONMENT}" MATCHES ".*-libtorch-cxx11-abi$")
+      # See https://github.com/pytorch/pytorch/issues/83887
+      message(WARNING "Skip NCCL library slimming for cxx11-abi builds")
+      set(__NCCL_LIBRARY_DEP nccl_external)
+      set(NCCL_LIBRARIES ${__NCCL_BUILD_DIR}/lib/libnccl_static.a)
+    elseif((${OBJCOPY_VERSION_MAJOR} GREATER 2) OR ((${OBJCOPY_VERSION_MAJOR} EQUAL 2) AND (${OBJCOPY_VERSION_MINOR} GREATER 27)))
       message(WARNING "Enabling NCCL library slimming")
       add_custom_command(
         OUTPUT "${__NCCL_BUILD_DIR}/lib/libnccl_slim_static.a"