-Wunused is not active for Clang

[Lei Qiao]

Dear all,

 A piece of my own code got two -Wunused warnings when compiled with gcc on linux system.

 But every thing finished silently with Clang on my Mac.

Is this a designed feature of the deal.II CMake system?

Best,

Lei

[Matthias Maier]

> Is this a designed feature of the deal.II CMake system?

To some extend, yes. Have a look at the output of detailed.log

Details can be found in cmake/setup_compiler_flags_gnu.cmake:

79 IF(CMAKE_CXX_COMPILER_ID MATCHES "Clang")
# [...]
92 ENABLE_IF_SUPPORTED(DEAL_II_CXX_FLAGS "-Wno-unused-parameter")
93 ENABLE_IF_SUPPORTED(DEAL_II_CXX_FLAGS "-Wno-unused-variable")
# [...]
100 IF(CMAKE_CXX_COMPILER_VERSION VERSION_LESS "3.6")
101 #
102 # Clang versions prior to 3.6 emit a lot of false positives wrt
103 # "-Wunused-function".
104 #
105 ENABLE_IF_SUPPORTED(DEAL_II_CXX_FLAGS "-Wno-unused-function")
106 ENDIF()
107 ENDIF()

[Lei Qiao]

Thank you for your instantaneous response.

So, is there any way to enable these warning's for user code?

[Matthias Maier]

> So, is there any way to enable these warning's for user code?

You have two options:

(a) Quick'n'dirty: Look for lib{...}/cmake/deal.IIConfig.cmake
in your installation and remove the flags you don't want to have.

(b) Directly after the inclusion of the project configuration with
FIND_PACKAGE(deal.II ...)
in your CMakeLists.txt file, you can filter out all unwanted strings
in the variables DEAL_II_CXX_FLAGS, DEAL_II_CXX_FLAGS_RELEASE and
DEAL_II_CXX_FLAGS_DEBUG.

Best,
Matthias

[Lei Qiao]

Great. I choose (b), once for all.

Thank you.