CMake: simplify QRC generation

Use configure_file() to avoid stomping on timestamps: if the list
of translations doesn't change, we don't need to rebuild the
translated QRC.

CMakeModules/CalamaresAddTranslations.cmake

@@ -28,12 +28,9 @@ include( CMakeParseArguments )
 macro(add_calamares_translations language)
     list( APPEND CALAMARES_LANGUAGES ${ARGV} )
 
-    set( _rcc_version_support --format-version 1 )
-
-    set( calamares_i18n_qrc_content "<!DOCTYPE RCC><RCC version=\"1.0\">\n" )
+    set( calamares_i18n_qrc_content "" )
 
     # calamares and qt language files
-    set( calamares_i18n_qrc_content "${calamares_i18n_qrc_content}<qresource prefix=\"/lang\">\n" )
     foreach( lang ${CALAMARES_LANGUAGES} )
         foreach( tlsource "calamares_${lang}" "tz_${lang}" )
             if( EXISTS "${CMAKE_SOURCE_DIR}/lang/${tlsource}.ts" )
@@ -43,31 +40,19 @@ macro(add_calamares_translations language)
         endforeach()
     endforeach()
 
-    set( calamares_i18n_qrc_content "${calamares_i18n_qrc_content}</qresource>\n" )
-    set( calamares_i18n_qrc_content "${calamares_i18n_qrc_content}</RCC>\n" )
-
-    file( WRITE ${CMAKE_BINARY_DIR}/lang/calamares_i18n.qrc "${calamares_i18n_qrc_content}" )
-
-    qt5_add_translation(QM_FILES ${TS_FILES})
-
-    ## HACK HACK HACK - around rcc limitations to allow out of source-tree building
     set( trans_file calamares_i18n )
-    set( trans_srcfile ${CMAKE_BINARY_DIR}/lang/${trans_file}.qrc )
     set( trans_infile ${CMAKE_CURRENT_BINARY_DIR}/${trans_file}.qrc )
     set( trans_outfile ${CMAKE_CURRENT_BINARY_DIR}/qrc_${trans_file}.cxx )
 
-    # Copy the QRC file to the output directory
-    add_custom_command(
-        OUTPUT ${trans_infile}
-        COMMAND ${CMAKE_COMMAND} -E copy ${trans_srcfile} ${trans_infile}
-        MAIN_DEPENDENCY ${trans_srcfile}
-    )
+    configure_file( ${CMAKE_SOURCE_DIR}/lang/calamares_i18n.qrc.in ${trans_infile} @ONLY )
+
+    qt5_add_translation(QM_FILES ${TS_FILES})
 
     # Run the resource compiler (rcc_options should already be set)
     add_custom_command(
         OUTPUT ${trans_outfile}
         COMMAND "${Qt5Core_RCC_EXECUTABLE}"
-        ARGS ${rcc_options} ${_rcc_version_support} -name ${trans_file} -o ${trans_outfile} ${trans_infile}
+        ARGS ${rcc_options} --format-version 1 -name ${trans_file} -o ${trans_outfile} ${trans_infile}
         MAIN_DEPENDENCY ${trans_infile}
         DEPENDS ${QM_FILES}
     )

lang/calamares_i18n.qrc.in

@@ -0,0 +1,5 @@
+<!DOCTYPE RCC><RCC version="1.0">
+<qresource prefix="/lang">
+@calamares_i18n_qrc_content@
+</qresource>
+</RCC>