build(cmake): simplify def_cmd_target function

Instead of appending to a command output, append to an existing target
instead. The primary benefit is intermediary ...-cmd targets aren't
needed, we can instead append commands to the relevant target directly.

CMakeLists.txt

@@ -618,20 +618,28 @@ find_program(SHELLCHECK_PRG shellcheck)
 include(DefCmdTarget)
 def_cmd_target(lintlua ${LUACHECK_PRG} LUACHECK_PRG true)
 if(LUACHECK_PRG)
-  add_custom_command(OUTPUT lintlua-cmd APPEND COMMAND ${LUACHECK_PRG} -q runtime/ scripts/ src/ test/)
+  add_custom_command(TARGET lintlua
+    WORKING_DIRECTORY ${CMAKE_SOURCE_DIR}
+    COMMAND ${LUACHECK_PRG} -q runtime/ scripts/ src/ test/)
 endif()
 if(STYLUA_PRG)
-  add_custom_command(OUTPUT lintlua-cmd APPEND COMMAND ${STYLUA_PRG} --color=always --check runtime/)
+  add_custom_command(TARGET lintlua
+    WORKING_DIRECTORY ${CMAKE_SOURCE_DIR}
+    COMMAND ${STYLUA_PRG} --color=always --check runtime/)
 else()
-  add_custom_command(OUTPUT lintlua-cmd APPEND COMMAND ${CMAKE_COMMAND} -E echo "STYLUA_PRG not found")
+  add_custom_command(TARGET lintlua COMMAND ${CMAKE_COMMAND} -E echo "STYLUA_PRG not found")
 endif()
 def_cmd_target(lintpy ${FLAKE8_PRG} FLAKE8_PRG false)
 if(FLAKE8_PRG)
-  add_custom_command(OUTPUT lintpy-cmd APPEND COMMAND ${FLAKE8_PRG} contrib/ scripts/ src/ test/)
+  add_custom_command(TARGET lintpy
+    WORKING_DIRECTORY ${CMAKE_SOURCE_DIR}
+    COMMAND ${FLAKE8_PRG} contrib/ scripts/ src/ test/)
 endif()
 def_cmd_target(lintsh ${SHELLCHECK_PRG} SHELLCHECK_PRG false)
 if(SHELLCHECK_PRG)
-  add_custom_command(OUTPUT lintsh-cmd APPEND COMMAND ${SHELLCHECK_PRG} scripts/vim-patch.sh)
+  add_custom_command(TARGET lintsh
+    WORKING_DIRECTORY ${CMAKE_SOURCE_DIR}
+    COMMAND ${SHELLCHECK_PRG} scripts/vim-patch.sh)
 endif()
 
 include(InstallHelpers)

cmake/DefCmdTarget.cmake

@@ -1,27 +1,19 @@
-# Defines a target named ${target} and a command with (symbolic) output
-# ${target}-cmd. If ${prg} is undefined the target prints "not found".
+# Defines a target named ${target}. If ${prg} is undefined the target prints
+# "not found".
 #
-# - Use add_custom_command(…APPEND) to build the command after this.
-# - Use add_custom_target(…DEPENDS) to run the command from a target.
+# - Use add_custom_command(TARGET <target_name> ...) to append a command to the
+# target.
 function(def_cmd_target target prg prg_name prg_fatal)
-  # Define a mostly-empty command, which can be appended-to.
-  add_custom_command(OUTPUT ${target}-cmd
-      WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}
-      COMMAND ${CMAKE_COMMAND} -E echo "${target}"
-  )
-  # Symbolic (does not generate an artifact).
-  set_source_files_properties(${target}-cmd PROPERTIES SYMBOLIC "true")
+  add_custom_target(${target})
 
-  if(prg OR NOT prg_fatal)
-    add_custom_target(${target}
-      WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}
-      DEPENDS ${target}-cmd)
-    if(NOT prg)
-      add_custom_command(OUTPUT ${target}-cmd APPEND
+  if(NOT prg)
+    if(prg_fatal)
+      add_custom_command(TARGET ${target}
+        COMMAND ${CMAKE_COMMAND} -E echo "${target}: ${prg_name} not found"
+        COMMAND false)
+    else()
+      add_custom_command(TARGET ${target}
         COMMAND ${CMAKE_COMMAND} -E echo "${target}: SKIP: ${prg_name} not found")
     endif()
-  else()
-    add_custom_target(${target} false
-      COMMENT "${target}: ${prg_name} not found")
   endif()
 endfunction()

src/nvim/CMakeLists.txt

@@ -805,7 +805,7 @@ add_custom_target(lintc DEPENDS ${LINT_TARGETS})
 
 def_cmd_target(lintuncrustify ${UNCRUSTIFY_PRG} UNCRUSTIFY_PRG false)
 if(UNCRUSTIFY_PRG)
-  add_custom_command(OUTPUT lintuncrustify-cmd APPEND
+  add_custom_command(TARGET lintuncrustify
     COMMAND ${CMAKE_COMMAND}
       -D UNCRUSTIFY_PRG=${UNCRUSTIFY_PRG}
       -D PROJECT_SOURCE_DIR=${PROJECT_SOURCE_DIR}