[CMake] COMPILE_FLAGS property that appends instead of replaces

[aaron.meadows at thomsonreuters.com]

I believe that is the defined behavior.  Usually, people would use
add_definitions() to add the flags before creating the target.  If you
have one target per subdirectory, you don't have to worry about removing
them afterwards:

 

CMakeLists.txt:

   add_definitions(/foo)

 

   add_subdirectory(baz)

   add_subdirectory(qux)

 

baz/CMakeLists.txt

   add_definitions(/bar)

   add_executable(baz baz.cpp)

 

qux/CMakeLists.txt

   add_executable(qux qux.cpp)

 

 

baz gets the compiler flags "/foo /bar", qux only gets "/foo".

 

 

 

As an aside, I ran into a similar issue, but with Linker Flags in the
cache.  To overcome that, I wrote a few functions to encapsulate the
writing of flags and handle checking for duplicates.  You could
certainly do something similar with properties:

 

############################################################

## Cache Set Helper Functions

############################################################

function(AppendIfMissing _outVar _inVar _value)

  string(REGEX REPLACE " " ";" _inList "${${_inVar}}")

  list(FIND _inList "${_value}" _pos)

 

  if(${_pos} EQUAL -1)

    set(${_outVar} "${${_inVar}} ${_value}" PARENT_SCOPE)

  else()

    set(${_outVar} "${${_inVar}}" PARENT_SCOPE)

  endif()

endfunction(AppendIfMissing)

 

function(CheckAndAppendCacheForce _varName _value _type )

  AppendIfMissing(_outvar ${_varName} ${_value})

 

  foreach(_arg IN LISTS ARGN)

    set(_desc "${_desc} ${_arg}")

  endforeach()

 

  set(${_varName} "${_outvar}" CACHE ${_type} "${_desc}" FORCE)

endfunction(CheckAndAppendCacheForce)

 

function(CheckAndAppendCache _varName _value _type )

  AppendIfMissing(_outvar ${_varName} ${_value})

 

  foreach(_arg IN LISTS ARGN)

    set(_desc "${_desc} ${_arg}")

  endforeach()

 

  set(${_varName} "${_outvar}" CACHE ${_type} "${_desc}")

endfunction(CheckAndAppendCache)

 

 

Aaron Meadows

 

From: cmake-bounces at cmake.org [mailto:cmake-bounces at cmake.org] On Behalf
Of Robert Dailey
Sent: Monday, February 06, 2012 3:58 PM
To: CMake ML
Subject: [CMake] COMPILE_FLAGS property that appends instead of replaces

 

I would like to set the COMPILE_FLAGS property multiple times on the
same target through set_target_properties(), however only the last call
seems to persist. Previous flags set get overridden. Is this the correct
behavior? If so, is there a way to make this property append instead of
replace on the same target?


 

---------

Robert Dailey


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