[cmake-developers] [PATCH] Qt4Macros generate resources with same file name

[Clinton Stimpson]

On Tuesday, November 24, 2015 11:01:27 AM Joseph Shen wrote:
> Dear CMake developers:
> 
> Please view attached small patch that try to fix Qt4Macros generate
> resources with same file name error.
> 
> Right now, in the CMake main branch, using cmake with Qt4 library
> add resources project can be done like this:
> 
>      qt4_add_resources(app_source_res res_a.qrc)
>      qt4_add_resources(app_source_res res_b.qrc)
> 
> and above two line added two resource file, but if we try to add resource
> file with same name, a very subtle error will happen: only one file will
> be compile the as resources, and the other was totally ignored.
> 
> In some big projects, using the same file name as resource file name
> can be very common, especially when we using multi cmake files try
> to make the whole project into small ones, in each cmake files someone
> maybe just using the same resources file name like res.qrc which is
> located in the sub module resources folder.
> 
>        qt4_add_resources(app_source_res res.qrc)
> 
> so, if they try to do this, and in the last add ${app_source_res} to the
> dependency list using:
> 
>       add_executable(project_name ${app_source_res} ...)
> 
> but in reality they just add one resources file, but CMake do not report
> any error or warning.
> 
> From the source of Qt4Macros we can see:
> 
> line 211:   get_filename_component(outfilename ${it} NAME_WE)
> line 244:   ARGS ${rcc_options} -name ${outfilename} -o ${outfile} ${infile}
> 
> 
> became we just using NAME_WE as the output file, if two files with same
> file name, one will overwrite the other, and this is the reason why the
> error
> will happen.
> 
> To fix this, I view the whole Qt4Macros source file, find a function
> QT4_MAKE_OUTPUT_FILE already exist to do something just what we
> need. so I work out a patch add two line code and remove two, and it works
> good to me, and I think this might fix the problem.
> 
> Please view this patch, thanks :)


Back on list with a more concrete example, and also to prevent others from 
merging this patch, because I don't think this patch should be accepted.  The 
random string breaks using the Q_INIT_RESOURCE() macro.


For example:
=======
project(qrc)

find_package(Qt4)
include(${QT_USE_FILE})

qt4_add_resources(qrc_srcs ${CMAKE_CURRENT_SOURCE_DIR}/my.qrc)

add_library(qrc STATIC ${qrc_srcs})

add_executable(main main.cpp)
target_link_libraries(main qrc)
========

main.cpp has:
int main()
{
  Q_INIT_RESOURCE(my);
}

With the patch applied, I now get the link error:

main.cpp:(.text+0x5): undefined reference to `qInitResources_my()'

"my" comes from the basename of my.qrc, and is the name used for the resource.
With CMake generating a random name, there would be no way to reference that 
name when calling Q_INIT_RESOURCE.

I would prefer allowing the caller to pass in an alternate -name option for 
rcc, as I said in my first review.  With that, the caller would be able to pass 
a random string.

Clint