From: Boyuan Yang <byang@debian.org>
Date: Sat, 16 Jul 2022 13:49:23 -0400
Subject: Unbundle abseil

---
 CMakeLists.txt | 21 +++------------------
 1 file changed, 3 insertions(+), 18 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 52b1b32..d5e8f95 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -116,7 +116,6 @@ if(LIBGAV1_VERBOSE)
   libgav1_dump_options()
 endif()
 
-set(libgav1_abseil_build "${libgav1_build}/abseil")
 set(libgav1_gtest_build "${libgav1_build}/gtest")
 
 # Compiler/linker flags must be lists, but come in from the environment as
@@ -131,23 +130,9 @@ endif()
 # Set test-only flags based on LIBGAV1_CXX_FLAGS.
 libgav1_set_test_flags()
 
-set(libgav1_abseil "${libgav1_root}/third_party/abseil-cpp")
-if(EXISTS "${libgav1_abseil}")
-  set(ABSL_PROPAGATE_CXX_STD ON)
-  add_subdirectory("${libgav1_abseil}" "${libgav1_abseil_build}"
-                   EXCLUDE_FROM_ALL)
-else()
-  if(use_absl_threading OR LIBGAV1_ENABLE_EXAMPLES OR LIBGAV1_ENABLE_TESTS)
-    message(
-      FATAL_ERROR
-        "Abseil not found. This dependency is required by the"
-        " examples & tests and libgav1 when LIBGAV1_THREADPOOL_USE_STD_MUTEX is"
-        " not defined. To continue, download the Abseil repository to"
-        " third_party/abseil-cpp:\n  git \\\n    -C ${libgav1_root} \\\n"
-        "    clone \\\n"
-        "    https://github.com/abseil/abseil-cpp.git third_party/abseil-cpp")
-  endif()
-endif()
+set(absl "/usr/lib/*/cmake/absl")
+find(absl REQUIRED)
+set(ABSL_PROPAGATE_CXX_STD ON)
 
 libgav1_reset_target_lists()
 libgav1_add_dsp_targets()