Use FetchContent to download, unpack and configure in-tree dependencies

FetchContent is available since CMake 3.11, and does all the heavy lifting that `http_archive` did.

NOTE: `FetchContent_MakeAvailable` is only available >= 3.14, so for now we must use `add_subdirectory`.
PiperOrigin-RevId: 527204754

3 files changed, 31 insertions, 84 deletions

diff --git a/cmake/HttpArchive.cmake b/cmake/HttpArchive.cmake
index d13a10398..75fd0d3a6 100644
--- a/cmake/HttpArchive.cmake
+++ b/cmake/HttpArchive.cmake
@@ -12,21 +12,19 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-include(ExternalProject)
+include(FetchContent)
 include(CMakeParseArguments)
 
-if (NOT DEFINED TINK_THIRD_PARTY_DIR)
-  set(TINK_THIRD_PARTY_DIR "${CMAKE_CURRENT_BINARY_DIR}/__third_party")
-endif()
-
 # Download, unpack and configure a dependency.
 #
 # The project is added as a subdirectory of Tink, unless DATA_ONLY is
 # specified. This makes all target defined by it available as dependencies.
 #
-# This rule also defines a <NAME>_SOURCE_DIR variable, which points to the
-# root directory of the downloaded package and can be used to reference data in
-# tests, or append extra include/link paths in the Workspace file.
+# This rule also defines two variables:
+#   - <NAME>_SOURCE_DIR points to the root directory of the downloaded package;
+#     it can be used to reference data in tests, or append extra include/link
+#     paths in the Workspace file.
+#   - <NAME>_BINARY_DIR points to the build directory.
 #
 # Parameters:
 #   NAME name of the dependency.
@@ -49,40 +47,29 @@ function(http_archive)
     "NAME;URL;SHA256;CMAKE_SUBDIR"
     "CMAKE_ARGS"
   )
-
+  FetchContent_Declare(
+    ${http_archive_NAME}
+    URL       ${http_archive_URL}
+    URL_HASH  SHA256=${http_archive_SHA256}
+  )
   message(STATUS "Fetching ${http_archive_NAME}")
-
-  set(http_archive_PREFIX "${TINK_THIRD_PARTY_DIR}/${http_archive_NAME}")
-  set(http_archive_SOURCE_DIR "${http_archive_PREFIX}/src")
-  set(http_archive_BINARY_DIR "${http_archive_PREFIX}/build")
-
-  configure_file(
-    cmake/HttpArchiveDownloader.cmake.in
-    "${http_archive_PREFIX}/CMakeLists.txt")
-
-  execute_process(
-    COMMAND ${CMAKE_COMMAND} -G "${CMAKE_GENERATOR}" .
-    RESULT_VARIABLE errors
-    WORKING_DIRECTORY "${http_archive_PREFIX}")
-
-  if (errors)
-    message(FATAL_ERROR "While configuring ${http_archive_NAME}: ${errors}")
-  endif()
-
-  set(${http_archive_NAME}_SOURCE_DIR "${http_archive_SOURCE_DIR}" PARENT_SCOPE)
-
-  execute_process(
-    COMMAND ${CMAKE_COMMAND} --build .
-    RESULT_VARIABLE errors
-    WORKING_DIRECTORY "${http_archive_PREFIX}")
-
-  if (errors)
-    message(FATAL_ERROR "While fetching ${http_archive_NAME}: ${errors}")
-  endif()
-
-  if (NOT http_archive_DATA_ONLY)
-    add_subdirectory(
-      "${http_archive_SOURCE_DIR}/${http_archive_CMAKE_SUBDIR}"
-      "${http_archive_BINARY_DIR}" EXCLUDE_FROM_ALL)
+  FetchContent_GetProperties(${http_archive_NAME})
+  if(NOT ${http_archive_NAME}_POPULATED)
+    FetchContent_Populate(${http_archive_NAME})
+    if (NOT http_archive_DATA_ONLY)
+      add_subdirectory(
+        ${${http_archive_NAME}_SOURCE_DIR}/${http_archive_CMAKE_SUBDIR}
+        ${${http_archive_NAME}_BINARY_DIR}
+        EXCLUDE_FROM_ALL)
+    endif()
+    # Expose these variables to the caller.
+    set(
+      "${http_archive_NAME}_SOURCE_DIR"
+      "${${http_archive_NAME}_SOURCE_DIR}"
+      PARENT_SCOPE)
+    set(
+      "${http_archive_NAME}_BINARY_DIR"
+      "${${http_archive_NAME}_BINARY_DIR}"
+      PARENT_SCOPE)
   endif()
 endfunction(http_archive)
diff --git a/cmake/HttpArchiveDownloader.cmake.in b/cmake/HttpArchiveDownloader.cmake.in
deleted file mode 100644
index 03a314b7b..000000000
--- a/cmake/HttpArchiveDownloader.cmake.in
+++ /dev/null
@@ -1,37 +0,0 @@
-# Copyright 2019 Google LLC
-#
-# Licensed under the Apache License, Version 2.0 (the "License");
-# you may not use this file except in compliance with the License.
-# You may obtain a copy of the License at
-#
-# http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS,
-# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-# See the License for the specific language governing permissions and
-# limitations under the License.
-
-# This template is used by http_archive() to download, unpack and configure Tink
-# dependencies. You shouldn't need to use it directly.
-
-cmake_minimum_required(VERSION 3.13)
-project(http-archive-${http_archive_NAME})
-
-include(ExternalProject)
-
-ExternalProject_Add(${http_archive_NAME}
-  URL "${http_archive_URL}"
-  URL_HASH SHA256=${http_archive_SHA256}
-  TLS_VERIFY true
-  SOURCE_DIR "${http_archive_SOURCE_DIR}"
-  BINARY_DIR "${http_archive_BINARY_DIR}"
-  SOURCE_SUBDIR "${http_archive_CMAKE_SUBDIR}"
-  CMAKE_ARGS ${http_archive_CMAKE_ARGS}
-  CONFIGURE_COMMAND ""
-  BUILD_COMMAND ""
-  TEST_COMMAND ""
-  INSTALL_COMMAND ""
-  ${http_archive_EXTRA_OPTIONS}
-  EXCLUDE_FROM_ALL
-)
diff --git a/cmake/TinkWorkspace.cmake b/cmake/TinkWorkspace.cmake
index 0245a233b..077293727 100644
--- a/cmake/TinkWorkspace.cmake
+++ b/cmake/TinkWorkspace.cmake
@@ -60,7 +60,7 @@ if (TINK_BUILD_TESTS)
     _create_interface_target(gtest_main GTest::gtest_main)
   else()
     http_archive(
-      NAME com_google_googletest
+      NAME googletest
       URL https://github.com/google/googletest/archive/refs/tags/release-1.11.0.tar.gz
       SHA256 b4870bf121ff7795ba20d20bcdd8627b8e088f2d1dab299a031c1034eddc93d5
     )
@@ -72,7 +72,6 @@ if (TINK_BUILD_TESTS)
     SHA256 eb1d558071acf1aa6d677d7f1cabec2328d1cf8381496c17185bd92b52ce7545
     DATA_ONLY
   )
-
   # Symlink the Wycheproof test data.
   # Tests expect Wycheproof test vectors to be in a local testvectors/ folder.
   add_directory_alias("${wycheproof_SOURCE_DIR}/testvectors"
@@ -82,7 +81,7 @@ endif()
 if (NOT TINK_USE_INSTALLED_ABSEIL)
   # Commit from 2023-01-25
   http_archive(
-    NAME com_google_absl
+    NAME abseil
     URL https://github.com/abseil/abseil-cpp/archive/refs/tags/20230125.0.zip
     SHA256 70a2e30f715a7adcf5b7fcd2fcef7b624204b8e32ede8a23fd35ff5bd7d513b0
   )
@@ -129,14 +128,12 @@ http_archive(
   URL https://github.com/Tencent/rapidjson/archive/v1.1.0.tar.gz
   SHA256 bf7ced29704a1e696fbccf2a2b4ea068e7774fa37f6d7dd4039d0787f8bed98e
 )
-
 # Rapidjson is a header-only library with no explicit target. Here we create one.
 add_library(rapidjson INTERFACE)
 target_include_directories(rapidjson INTERFACE "${rapidjson_SOURCE_DIR}")
 
 set(protobuf_BUILD_TESTS OFF CACHE BOOL "Tink dependency override" FORCE)
 set(protobuf_BUILD_EXAMPLES OFF CACHE BOOL "Tink dependency override" FORCE)
-
 ## Use protobuf X.21.9.
 http_archive(
   NAME com_google_protobuf