Improve error message for missing 'SYSTEM' dependencies. (#2536)
Before:
```
$ cmake .
...
-- Checking for module 'libyuv'
-- Package 'libyuv', required by 'virtual:world', not found
CMake Error at /usr/share/cmake-3.29/Modules/FindPackageHandleStandardArgs.cmake:230 (message):
Could NOT find libyuv (missing: LIBYUV_LIBRARY LIBYUV_LIBRARIES
LIBYUV_INCLUDE_DIR) (found version "")
Call Stack (most recent call first):
/usr/share/cmake-3.29/Modules/FindPackageHandleStandardArgs.cmake:600 (_FPHSA_FAILURE_MESSAGE)
cmake/Modules/Findlibyuv.cmake:52 (find_package_handle_standard_args)
CMakeLists.txt:216 (find_package)
CMakeLists.txt:235 (check_avif_option)
```
After:
```
$ cmake .
...
-- Checking for module 'libyuv'
-- Package 'libyuv', required by 'virtual:world', not found
CMake Error at CMakeLists.txt:219 (message):
Cannot find libyuv. Make sure it's installed on the system, or pass
-DAVIF_LIBYUV=LOCAL (to fetch and build it locally) or -DAVIF_LIBYUV=OFF
(to disable it)
Call Stack (most recent call first):
CMakeLists.txt:242 (check_avif_option)
```
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 26a9bce..fc3f306 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -213,7 +213,14 @@
if(${_VAR} STREQUAL "LOCAL")
include(${_LOCAL_INCLUDE})
elseif(${_VAR} STREQUAL "SYSTEM")
- find_package(${_AVIF_OPTION_PKG_NAME} REQUIRED)
+ # QUIET instead of REQUIRED in order to use a custom error message below.
+ find_package(${_AVIF_OPTION_PKG_NAME} QUIET)
+ if(NOT ${_AVIF_OPTION_PKG_NAME}_FOUND)
+ message(
+ FATAL_ERROR
+ "Cannot find ${_AVIF_OPTION_PKG_NAME}. Make sure it's installed on the system, or pass -D${_VAR}=LOCAL (to fetch and build it locally) or -D${_VAR}=OFF (to disable it)"
+ )
+ endif()
endif()
endif()
endif()
