[CMake] Problem building libraries with no sources with Visual Studio 9 (2008)

[Pere Mato Vila]

  AFAICS there are three different issues here:

 - Having a .def file as a source in a ADD_LIBRARY() it does the correct thing, which is using it to build the library, but it does not create a dependency to it. I would call this a bug.

- The way to generate the .def file that I have figured out is perhaps not optimal and Bill Hoffman has provided me with a solution that exploits PRE_LINK option in  ADD_CUSTOM_COMMAND().

- If I use ADD_LBRARY() with no real source files and only with a .def file does fail within the IDE (Visual Studio 9) and does work with nmake.

  

On Dec 22, 2010, at 12:09 AM, Michael Hertling wrote:

> On 12/21/2010 08:45 PM, Bill Hoffman wrote:
>> On 12/21/2010 2:17 PM, Michael Hertling wrote:
>> 
>>> AFAIK, this is because CMake does not know how to handle a .def file
>>> for incorporation in the target, i.e. ${library}.def has no LANGUAGE
>> 
>> Actually, it should...
>> 
>> 
>> Something like this should work:
>> (assumes you have a perl script to create a .def file)
>> 
>> cmake_minimum_required (VERSION 2.6)
>> project (myexe)
>> 
>> set (SOURCES mylib.cxx mylib2.cxx)
>> 
>> # create a list of all the object files
>> string (REGEX REPLACE "\\.cxx" ".obj" OBJECTS "${SOURCES}")
>> 
>> # create a shared library with the .def file
>> add_library (mylib SHARED ${SOURCES}
>>   ${CMAKE_CURRENT_BINARY_DIR}/mylib.def
>>   )
>> # set the .def file as generated
>> set_source_files_properties (
>>   ${CMAKE_CURRENT_BINARY_DIR}/mylib.def
>>   PROPERTIES GENERATED 1
>>   )
>> 
>> # create an executable
>> add_executable (myexe myexe.cxx)
>> 
>> # link the executable to the dll
>> target_link_libraries(myexe mylib)
>> 
>> #convert to windows slashes
>> set (OUTDIR
>>   ${CMAKE_CURRENT_BINARY_DIR}/${CMAKE_CFG_INTDIR}
>>   )
>> 
>> string (REGEX REPLACE "/" "\\\\" OUTDIR ${OUTDIR})
>> 
>> # create a custom pre link command that runs
>> # a perl script to create a .def file using dumpbin
>> add_custom_command (
>>   TARGET mylib PRE_LINK
>>   COMMAND perl
>>   ARGS ${CMAKE_CURRENT_SOURCE_DIR}/makedef.pl
>>   ${CMAKE_CURRENT_BINARY_DIR}\\mylib.def mylib
>>   ${OUTDIR} ${OBJECTS} )
> 
> Sorry, I haven't expressed myself precisely. My point is that mentioning
> the .def file in the target's sources does not establish a dependency of
> the target on the .def file, so the target isn't rebuilt when the .def
> file has changed:
> 
> CMAKE_MINIMUM_REQUIRED(VERSION 2.8 FATAL_ERROR)
> PROJECT(DEFS C)
> FILE(WRITE ${CMAKE_BINARY_DIR}/f.c "void f(void){}\n")
> FILE(WRITE ${CMAKE_BINARY_DIR}/f.def.in "")
> ADD_CUSTOM_COMMAND(
>    OUTPUT ${CMAKE_BINARY_DIR}/f1.def
>    COMMAND ${CMAKE_COMMAND} -E
>    copy ${CMAKE_BINARY_DIR}/f.def.in ${CMAKE_BINARY_DIR}/f1.def
>    DEPENDS ${CMAKE_BINARY_DIR}/f.def.in
> )
> SET_SOURCE_FILES_PROPERTIES(
>    ${CMAKE_BINARY_DIR}/f2.def PROPERTIES GENERATED TRUE
> )
> ADD_LIBRARY(f SHARED f.c f1.def f2.def)
> ADD_CUSTOM_COMMAND(
>    TARGET f
>    PRE_LINK
>    COMMAND ${CMAKE_COMMAND} -E copy
>    ${CMAKE_BINARY_DIR}/f.def.in ${CMAKE_BINARY_DIR}/f2.def
> )
> 
> Touching f1.def or f2.def does not make the target rebuild, and touching
> f.def.in just makes f1.def regenerate. It's touching f.c that results in
> rebuilding the target due to the f.c <-- f.c.o <-- libf.so dependencies.
> AFAIK, such a dependency does not exist between the target and the .def
> files, or have I got you wrong?
> 
> Regards,
> 
> Michael
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