ci: Use golangci-lint for linting (#108)

Instead of hand-managing and running linters, use golangci-lint.
This simplifies the Makefile and allows lint to run in parallel
with the build/test job.

Along with the golangci-lint defaults,
enable a couple other linters we generally agree with.
See also uber-go/zap#1323 and uber-go/sally#121 for similar changes.

.github/workflows/ci.yml

@@ -0,0 +1,55 @@
+name: CI
+
+on:
+  push:
+    branches: [master]
+    tags: ['v*']
+  pull_request:
+    branches: ['*']
+
+permissions:
+  contents: read
+
+jobs:
+
+  test:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        go: ["1.20.x", "1.21.x"]
+
+    steps:
+    - name: Checkout code
+      uses: actions/checkout@v3
+    - name: Setup Go
+      uses: actions/setup-go@v4
+      with:
+        go-version: ${{ matrix.go }}
+
+    - name: Test
+      run: make cover
+
+    - name: Upload coverage to codecov.io
+      uses: codecov/codecov-action@v3
+
+  lint:
+    name: Lint
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@v4
+      name: Check out repository
+    - uses: actions/setup-go@v4
+      name: Set up Go
+      with:
+        go-version: 1.21.x
+        cache: false  # managed by golangci-lint
+
+    - uses: golangci/golangci-lint-action@v3
+      name: Install golangci-lint
+      with:
+        version: latest
+        args: --version  # make lint will run the linter
+
+    - run: make lint
+      name: Lint

.golangci.yml

@@ -0,0 +1,28 @@
+output:
+  # Make output more digestible with quickfix in vim/emacs/etc.
+  sort-results: true
+  print-issued-lines: false
+
+linters:
+  enable:
+    - gofumpt
+    - nolintlint
+    - revive
+
+linters-settings:
+  govet:
+    # These govet checks are disabled by default, but they're useful.
+    enable:
+      - niliness
+      - reflectvaluecompare
+      - sortslice
+      - unusedwrite
+
+issues:
+  # Print all issues reported by all linters.
+  max-issues-per-linter: 0
+  max-same-issues: 0
+
+  # Don't ignore some of the issues that golangci-lint considers okay.
+  # This includes documenting all exported entities.
+  exclude-use-default: false

Makefile

@@ -1,19 +1,26 @@
-export GOBIN ?= $(shell pwd)/bin
+# Directory containing the Makefile.
+PROJECT_ROOT = $(dir $(abspath $(lastword $(MAKEFILE_LIST))))
 
-REVIVE = $(GOBIN)/revive
+export GOBIN = $(PROJECT_ROOT)/bin
+export PATH := $(GOBIN):$(PATH)
 
-GO_FILES := $(shell \
-	find . '(' -path '*/.*' -o -path './vendor' ')' -prune \
-	-o -name '*.go' -print | cut -b3-)
+GO_FILES = $(shell find . \
+	   -path '*/.*' -prune -o \
+	   '(' -type f -a -name '*.go' ')' -print)
+
+# Additional test flags.
+TEST_FLAGS ?=
+
+.PHONY: all
+all: lint build test
+
+.PHONY: lint
+lint: golangci-lint tidy-lint
 
 .PHONY: build
 build:
 	go build ./...
 
-.PHONY: install
-install:
-	go mod download
-
 .PHONY: test
 test:
 	go test -v -race ./...
@@ -24,18 +31,15 @@ cover:
 	go test -race -coverprofile=cover.out -coverpkg=./... ./...
 	go tool cover -html=cover.out -o cover.html
 
-$(REVIVE):
-	cd tools && go install github.com/mgechev/revive
+.PHONY: golangci-lint
+golangci-lint:
+	golangci-lint run
 
-.PHONY: lint
-lint: $(REVIVE)
-	@rm -rf lint.log
-	@echo "Checking formatting..."
-	@gofmt -d -s $(GO_FILES) 2>&1 | tee lint.log
-	@echo "Checking vet..."
-	@go vet ./... 2>&1 | tee -a lint.log
-	@echo "Checking lint..."
-	@$(REVIVE) -set_exit_status ./... 2>&1 | tee -a lint.log
-	@echo "Checking for unresolved FIXMEs..."
-	@git grep -i fixme | grep -v -e '^vendor/' -e '^Makefile' | tee -a lint.log
-	@[ ! -s lint.log ]
+.PHONY: tidy
+tidy:
+	go mod tidy
+
+.PHONY: tidy-lint
+tidy-lint:
+	go mod tidy
+	git diff --exit-code -- go.mod go.sum