enable flake8 lint (pytorch#14)

Summary:
This enables flake8 linting with a similar config to pytorch https://github.com/pytorch/pytorch/blob/master/.flake8

Pull Request resolved: pytorch#14

Reviewed By: tierex

Differential Revision: D28686729

Pulled By: d4l3k

fbshipit-source-id: 3f6ab1034554490e3bc039437404389218989fcd

Author: d4l3k

.flake8

@@ -0,0 +1,22 @@
+[flake8]
+select = B,C,E,F,P,T4,W,B9
+max-line-length = 120
+# C408 ignored because we like the dict keyword argument syntax
+# E501 is not flexible enough, we're using B950 instead
+ignore =
+    E203,E305,E402,E501,E721,E741,F405,F821,F841,F999,W503,W504,C408,E302,W291,E303,
+    # shebang has extra meaning in fbcode lints, so I think it's not worth trying
+    # to line this up with executable bit
+    EXE001,
+    # these ignores are from flake8-bugbear; please fix!
+    B007,B008,
+    # these ignores are from flake8-comprehensions; please fix!
+    C400,C401,C402,C403,C404,C405,C407,C411,C413,C414,C415
+optional-ascii-coding = True
+exclude =
+    ./.git,
+    ./docs
+    ./build
+    ./scripts,
+    ./venv,
+    *.pyi

.github/workflows/lint.yaml

@@ -22,6 +22,7 @@ jobs:
           set -eux
           pip install isort==4.3.21
           pip install black
+          pip install flake8==3.9.0
       - name: Run Lint
         run: |
           git config --global url."https://${{ secrets.GITHUB_TOKEN }}:x-oauth-basic@github.com/".insteadOf "https://github.com/"

dev-requirements.txt

@@ -8,3 +8,4 @@ pytorch-lightning>=0.5.3
 torch>=1.8.1
 torchvision>=0.9.1
 classy-vision>=0.5.0
+flake8==3.9.0

scripts/lint.sh

@@ -17,6 +17,11 @@ then
     echo "Please install isort."
     exit 1
 fi
+if [ ! "$(flake8 --version)" ]
+then
+    echo "Please install flake8."
+    exit 1
+fi
 
 # cd to the project directory
 cd "$(dirname "$0")/.." || exit 1
@@ -51,8 +56,9 @@ then
     do
         echo "Checking $file"
         isort "$file" --recursive --multi-line 3 --trailing-comma --force-grid-wrap 0 \
-                --line-width 88 --lines-after-imports 2 --combine-as --section-default THIRDPARTY
-        black "$file"
+            --line-width 88 --lines-after-imports 2 --combine-as --section-default THIRDPARTY -q
+        black "$file" -q
+        flake8 "$file" || LINT_ERRORS=1
     done
 else
     echo "No changes made to any Python files. Nothing to do."
@@ -62,7 +68,7 @@ fi
 # Check if any files were modified by running isort + black
 # If so, then the files were formatted incorrectly (e.g. did not pass lint)
 CHANGED_FILES="$(git diff --name-only | grep '\.py$' | tr '\n' ' ')"
-if [ "$CHANGED_FILES" != "" ]
+if [ "$CHANGED_FILES" != "" ] || [ "$LINT_ERRORS" != "" ]
 then
     # need this so that CircleCI fails
     exit 1