ci: pylint target via flake8

Ref: https://github.com/neovim/neovim/pull/10631#issuecomment-515756591

.flake8

@@ -0,0 +1,2 @@
+[flake8]
+max-line-length = 88

CMakeLists.txt

@@ -516,6 +516,7 @@ if(NOT BUSTED_OUTPUT_TYPE)
 endif()
 
 find_program(LUACHECK_PRG luacheck)
+find_program(FLAKE8_PRG flake8)
 find_program(GPERF_PRG gperf)
 
 include(InstallHelpers)
@@ -667,6 +668,15 @@ else()
     COMMENT "lualint: LUACHECK_PRG not defined")
 endif()
 
+if(FLAKE8_PRG)
+  add_custom_target(pylint
+    COMMAND ${FLAKE8_PRG} contrib/ scripts/ src/ test/
+    WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR})
+else()
+  add_custom_target(pylint false
+    COMMENT "flake8: FLAKE8_PRG not defined")
+endif()
+
 set(CPACK_PACKAGE_NAME "Neovim")
 set(CPACK_PACKAGE_VENDOR "neovim.io")
 set(CPACK_PACKAGE_VERSION ${NVIM_VERSION_MEDIUM})

Makefile

@@ -138,6 +138,9 @@ functionaltest-lua: | nvim
 lualint: | build/.ran-cmake deps
 	$(BUILD_CMD) -C build lualint
 
+pylint: | build/.ran-cmake deps
+	$(BUILD_CMD) -C build pylint
+
 unittest: | nvim
 	+$(BUILD_CMD) -C build unittest
 
@@ -179,6 +182,6 @@ appimage:
 appimage-%:
 	bash scripts/genappimage.sh $*
 
-lint: check-single-includes clint lualint
+lint: check-single-includes clint lualint pylint
 
-.PHONY: test lualint functionaltest unittest lint clint clean distclean nvim libnvim cmake deps install appimage checkprefix
+.PHONY: test lualint pylint functionaltest unittest lint clint clean distclean nvim libnvim cmake deps install appimage checkprefix

ci/install.sh

@@ -4,6 +4,7 @@ set -e
 set -o pipefail
 
 if [[ "${CI_TARGET}" == lint ]]; then
+  python -m pip -q install --user --upgrade flake8
   exit
 fi
 

ci/run_lint.sh

@@ -9,26 +9,24 @@ source "${CI_DIR}/common/build.sh"
 source "${CI_DIR}/common/suite.sh"
 
 enter_suite 'clint'
-
 run_test 'make clint-full' clint
-
 exit_suite --continue
 
 enter_suite 'lualint'
-
 run_test 'make lualint' lualint
+exit_suite --continue
 
+enter_suite 'pylint'
+run_test 'make pylint' pylint
 exit_suite --continue
 
 enter_suite single-includes
-
 CLICOLOR_FORCE=1 run_test_wd \
   --allow-hang \
   10s \
   'make check-single-includes' \
   'csi_clean' \
   single-includes
-
 exit_suite --continue
 
 end_tests