cmake: teach add_formatter to support configured formatters

Check in the build tree before the source tree.

src/CMakeLists.txt

@@ -19,12 +19,18 @@ function (add_formatter name type)
     endif ()
   endforeach ()
 
+  if(EXISTS "${CMAKE_CURRENT_BINARY_DIR}/format.${name}")
+    set(script "${CMAKE_CURRENT_BINARY_DIR}/format.${name}")
+  else()
+    set(script "${CMAKE_CURRENT_SOURCE_DIR}/format.${name}")
+  endif()
+
   set_property(GLOBAL APPEND
     PROPERTY formatters "${name}")
   set_property(GLOBAL APPEND
     PROPERTY "formatter_${name}_tools" "${tools_exist}")
   set_property(GLOBAL APPEND
-    PROPERTY "formatter_${name}_script" "${CMAKE_CURRENT_SOURCE_DIR}/format.${name}")
+    PROPERTY "formatter_${name}_script" "${script}")
 
   option("ENABLE_${name}" "Install the ${tool} formatter script" "${tools_exist}")
 
@@ -41,12 +47,18 @@ function (add_formatter name type)
 endfunction ()
 
 function (install_formatter name)
+  get_property(script GLOBAL PROPERTY "formatter_${name}_script")
   install(
-    PROGRAMS    "${CMAKE_CURRENT_SOURCE_DIR}/format.${name}"
+    PROGRAMS    "${script}"
     DESTINATION "bin"
     COMPONENT   "formatters")
+  if(EXISTS "${CMAKE_CURRENT_BINARY_DIR}/${name}.yaml.in")
+    set(yaml_in "${CMAKE_CURRENT_BINARY_DIR}/${name}.yaml.in")
+  else()
+    set(yaml_in "${CMAKE_CURRENT_SOURCE_DIR}/${name}.yaml.in")
+  endif()
   configure_file(
-    "${CMAKE_CURRENT_SOURCE_DIR}/${name}.yaml.in"
+    "${yaml_in}"
     "${CMAKE_CURRENT_BINARY_DIR}/${name}.yaml"
     @ONLY)
   install(