From 55dc880c2f813637c5a35cdc7fcae39f30c2c71e Mon Sep 17 00:00:00 2001
From: Junjie Qi <jqi@meta.com>
Date: Wed, 27 Mar 2024 10:53:49 -0700
Subject: [PATCH] Change cmake to build googletest from source (#3319)

Summary:
In the https://github.com/facebookresearch/faiss/pull/3278, we to find_package to link to GTest. However, it needs to have googletest to build independently. Not everyone builds their googletest locally first. In this diff, we still try to build googletest from source and combine find_package together.

Pull Request resolved: https://github.com/facebookresearch/faiss/pull/3319

Test Plan:
STEP 1: Install deps
```
conda install -y -q python=3.11 cmake make swig=4.0.2 mkl=2023 mkl-devel=2023 numpy scipy pytest gxx_linux-64 sysroot_linux-64
```

STEP2: Compile

```
cmake -B build \
      -DBUILD_TESTING=ON \
      -DBUILD_SHARED_LIBS=ON \
      -DFAISS_ENABLE_GPU=OFF \
      -DFAISS_ENABLE_RAFT=OFF \
      -DFAISS_OPT_LEVEL=avx2 \
      -DFAISS_ENABLE_C_API=ON \
      -DPYTHON_EXECUTABLE=$(which python) \
      -DCMAKE_BUILD_TYPE=Release \
      -DBLA_VENDOR=Intel10_64_dyn \
      -DCMAKE_CUDA_FLAGS="-gencode arch=compute_75,code=sm_75" \
      .
```

Reviewed By: algoriddle

Differential Revision: D55358059

Pulled By: junjieqi

fbshipit-source-id: 95ad4a745238b88b438728de64173f99d3d50dbe
---
 tests/CMakeLists.txt | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)

diff --git a/tests/CMakeLists.txt b/tests/CMakeLists.txt
index 0cb8219096..66ec9f74a5 100644
--- a/tests/CMakeLists.txt
+++ b/tests/CMakeLists.txt
@@ -59,6 +59,34 @@ if(FAISS_OPT_LEVEL STREQUAL "avx512")
   target_link_libraries(faiss_test PRIVATE faiss_avx512)
 endif()
 
+include(FetchContent)
+FetchContent_Declare(
+  googletest
+  GIT_REPOSITORY https://github.com/google/googletest.git
+  GIT_TAG 58d77fa8070e8cec2dc1ed015d66b454c8d78850 # release-1.12.1
+  OVERRIDE_FIND_PACKAGE)
+set(BUILD_GMOCK CACHE BOOL OFF)
+set(INSTALL_GTEST CACHE BOOL OFF)
+FetchContent_MakeAvailable(googletest)
+
+if(NOT EXISTS ${CMAKE_FIND_PACKAGE_REDIRECTS_DIR}/gtest-config.cmake
+   AND NOT EXISTS ${CMAKE_FIND_PACKAGE_REDIRECTS_DIR}/GTestConfig.cmake)
+  file(
+    WRITE ${CMAKE_FIND_PACKAGE_REDIRECTS_DIR}/gtest-config.cmake
+    [=[
+include(CMakeFindDependencyMacro)
+find_dependency(googletest)
+if(NOT TARGET GTest::GTest)
+  add_library(GTest::GTest INTERFACE IMPORTED)
+  target_link_libraries(GTest::GTest INTERFACE GTest::gtest)
+endif()
+if(NOT TARGET GTest::Main)
+  add_library(GTest::Main INTERFACE IMPORTED)
+  target_link_libraries(GTest::Main INTERFACE GTest::gtest_main)
+endif()
+]=])
+endif()
+
 find_package(OpenMP REQUIRED)
 find_package(GTest CONFIG REQUIRED)