Require gperf at build-time

Rather than allowing the build to continue without gperf, we should
fail with an error so that the colour behaviour does not change in a
backward incompatible manner. The old colour behaviour should continue
to work going forward.

This resolves #1868.

cmake/Conky.cmake

@@ -155,6 +155,10 @@ endif(NOT APP_UNAME)
 
 find_program(APP_GPERF gperf)
 
+if(NOT APP_GPERF)
+  message(FATAL_ERROR "Unable to find program 'gperf' (required at build-time as of Conky v1.20.2)")
+endif(NOT APP_GPERF)
+
 if(NOT RELEASE)
   find_program(APP_GIT git)
 

src/CMakeLists.txt

@@ -51,21 +51,16 @@ if(EXISTS ${CMAKE_CURRENT_SOURCE_DIR}/defconfig.h)
 endif(EXISTS ${CMAKE_CURRENT_SOURCE_DIR}/defconfig.h)
 
 # Generate colour-names.hh with gperf
-if(APP_GPERF)
-  execute_process(
-    INPUT_FILE "${CMAKE_SOURCE_DIR}/data/color-names.yml"
-    OUTPUT_FILE "${CMAKE_BINARY_DIR}/data/color-names.gperf"
-    COMMAND sh "${CMAKE_SOURCE_DIR}/bin/format-colors.sh"
-  )
-  execute_process(
-    INPUT_FILE "${CMAKE_BINARY_DIR}/data/color-names.gperf"
-    OUTPUT_FILE "${CMAKE_CURRENT_BINARY_DIR}/colour-names.hh"
-    COMMAND ${APP_GPERF} --ignore-case -LC++ -Zcolor_name_hash -t -7 -m1 -C -E
-  )
-else(APP_GPERF)
-  message(WARNING "'gperf' program not found, using stub colour-names.hh; colors names will not be parsed")
-  configure_file("${CMAKE_CURRENT_SOURCE_DIR}/colour-names-stub.hh" "${CMAKE_CURRENT_BINARY_DIR}/colour-names.hh" COPYONLY)
-endif(APP_GPERF)
+execute_process(
+  INPUT_FILE "${CMAKE_SOURCE_DIR}/data/color-names.yml"
+  OUTPUT_FILE "${CMAKE_BINARY_DIR}/data/color-names.gperf"
+  COMMAND sh "${CMAKE_SOURCE_DIR}/bin/format-colors.sh"
+)
+execute_process(
+  INPUT_FILE "${CMAKE_BINARY_DIR}/data/color-names.gperf"
+  OUTPUT_FILE "${CMAKE_CURRENT_BINARY_DIR}/colour-names.hh"
+  COMMAND ${APP_GPERF} --ignore-case -LC++ -Zcolor_name_hash -t -7 -m1 -C -E
+)
 
 set(conky_sources
   ${conky_sources}