kde4_automoc change (need help)

[David Faure]

I want to implement "Q_OBJECT in .cpp file and no .h file at all, and .cpp includes .moc" support
in kde4_automoc, for unit tests. Would be much more convenient than having to write a .h file
for each, and by having the "no header file" condition there we avoid grepping both .h and .cpp
for Q_OBJECT in all cases, which might slow things down.

But my current implementation doesn't work - no moc file, and the binary is being linked 
without any source file as input... I'm stumped.

--- KDE4Macros.cmake    (revision 538918)
+++ KDE4Macros.cmake    (working copy)
@@ -240,6 +240,19 @@
                get_filename_component(_basename ${_current_MOC} NAME_WE)
 #               set(_header ${CMAKE_CURRENT_SOURCE_DIR}/${_basename}.h)
                set(_header ${_abs_PATH}/${_basename}.h)
+
+               # Check if the header exists
+               if (NOT EXISTS ${_header})
+                   # Otherwise check if the cpp file has Q_OBJECT
+                   string(REGEX MATCH "Q_OBJECT" _match "${_contents}")
+                   if (_match)
+                      # Yes -> moc the cpp file, not the non-existing header file.
+                      set(_header ${_abs_FILE})
+                   else (_match)
+                      message(FATAL_ERROR "${_abs_FILE} includes ${_moc_INCS} but there's no ${_header} file and no Q_OBJECT in ${_abs_FILE} either")
+                   endif (_match)
+               endif (NOT EXISTS ${_header})
+
                set(_moc    ${CMAKE_CURRENT_BINARY_DIR}/${_current_MOC})
               #set(_moc    ${_abs_PATH}/${_current_MOC})
                add_custom_command(OUTPUT ${_moc}
                  COMMAND ${QT_MOC_EXECUTABLE}
                  ARGS ${_moc_INCS} ${_header} -o ${_moc}
                  MAIN_DEPENDENCY ${_header}
               )

The testcase:
set(kovariabletest_SRCS kovariabletest.cpp)
kde4_automoc(${kovariabletest_SRCS})
kde4_add_executable(kovariabletest RUN_UNINSTALLED ${kovariabletest_SRCS})
target_link_libraries(kovariabletest kotext ${QT_QTTEST_LIBRARY})

with kovariabletest.cpp defining a QObject-derived class, with Q_OBJECT macro and #include "kovariabletest.moc"

What happens:
Linking CXX executable kovariabletest
/usr/lib/gcc/x86_64-linux-gnu/4.0.3/../../../../lib64/crt1.o: In function `_start':../sysdeps/x86_64/elf/start.S:109: undefined reference to `main'
Indeed in CMakeFiles/kovariabletest.dir/build.make, kovariabletest_OBJECTS is empty!
How could this happen, given that I checked and ${kovariabletest_SRCS} is definitely
not empty just before the call to kde4_add_executable...

-- 
David Faure, faure at kde.org, sponsored by Trolltech to work on KDE,
Konqueror (http://www.konqueror.org), and KOffice (http://www.koffice.org).