Merge pull request Antonboom#1 from Antonboom/nilnil

nilnil

.github/workflows/ci.yml

@@ -0,0 +1,36 @@
+name: CI
+
+on:
+  push:
+    branches: [ master ]
+  pull_request:
+    branches: [ master ]
+
+jobs:
+  go_get:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/setup-go@v2
+        with:
+          go-version: ^1.17
+      - run: cd /tmp && go install github.com/Antonboom/nilnil@latest && nilnil -h
+
+  lint:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - uses: golangci/golangci-lint-action@v2
+        with:
+          version: latest
+
+  tests:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/setup-go@v2
+        with:
+          go-version: ^1.17
+      - uses: actions/checkout@v2
+      - run: go test -coverprofile=coverage.out ./...
+      - uses: shogo82148/actions-goveralls@v1
+        with:
+          path-to-profile: coverage.out

.gitignore

@@ -0,0 +1,4 @@
+.idea/
+.vscode/
+.DS_Store
+coverage.out

.golangci.yml

@@ -0,0 +1,70 @@
+run:
+  tests: true
+
+issues:
+  max-same-issues: 0
+
+linters-settings:
+  gci:
+    local-prefixes: github.com/Antonboom/nilnil
+
+linters:
+  disable-all: true
+  enable:
+    - asciicheck
+    - bodyclose
+    - deadcode
+    - depguard
+    - dogsled
+    - dupl
+    - durationcheck
+    - errcheck
+    - errname
+    - exhaustive
+    - exportloopref
+    - forbidigo
+    - gci
+    - goconst
+    - gocritic
+    - gocyclo
+    - godot
+    - godox
+    - gofmt
+    - gofumpt
+    - goheader
+    - goimports
+    - gomoddirectives
+    - gomodguard
+    - goprintffuncname
+    - gosec
+    - gosimple
+    - govet
+    - ifshort
+    - importas
+    - ineffassign
+    - lll
+    - makezero
+    - misspell
+    - nakedret
+    - nilerr
+    - nestif
+    - noctx
+    - nolintlint
+    - prealloc
+    - predeclared
+    - revive
+    - rowserrcheck
+    - sqlclosecheck
+    - staticcheck
+    - structcheck
+    - stylecheck
+    - tagliatelle
+    - testpackage
+    - thelper
+    - typecheck
+    - unconvert
+    - unparam
+    - unused
+    - varcheck
+    - wastedassign
+    - whitespace

LICENSE

@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2021 Anton Telyshev
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

README.md

@@ -0,0 +1 @@
+# nilnil

Taskfile.yml

@@ -0,0 +1,50 @@
+# https://taskfile.dev/#/installation
+version: '3'
+
+silent: true
+
+tasks:
+  default:
+    cmds:
+      - task: tools:install
+      - task: tidy
+      - task: fmt
+      - task: lint
+      - task: tests
+      - task: install
+
+  tools:install:
+    - echo "Install local tools..."
+    - (which gci > /dev/null) || GO111MODULE=off go install github.com/daixiang0/gci@latest
+    - (which gofumpt > /dev/null) || GO111MODULE=off go install mvdan.cc/gofumpt@latest
+
+  tidy:
+    cmds:
+      - echo "Tidy..."
+      - go mod tidy
+
+  fmt:
+    cmds:
+      - echo "Fmt..."
+      - gofumpt -w .
+      - gci -local github.com/Antonboom/nilnil -w . > /dev/null
+
+  lint:
+    cmds:
+      - echo "Lint..."
+      - golangci-lint run --fix ./...
+
+  tests:
+    cmds:
+      - echo "Tests..."
+      - go test ./...
+
+  tests:coverage:
+    cmds:
+      - echo "Tests with coverage..."
+      - go test -coverprofile=coverage.out ./...
+
+  install:
+    cmds:
+      - echo "Install..."
+      - go install ./...

go.mod

@@ -1,3 +1,11 @@
 module github.com/Antonboom/nilnil
 
 go 1.17
+
+require golang.org/x/tools v0.1.5
+
+require (
+	golang.org/x/mod v0.4.2 // indirect
+	golang.org/x/sys v0.0.0-20210510120138-977fb7262007 // indirect
+	golang.org/x/xerrors v0.0.0-20200804184101-5ec99f83aff1 // indirect
+)

go.sum

@@ -0,0 +1,27 @@
+github.com/yuin/goldmark v1.3.5/go.mod h1:mwnBkeHKe2W/ZEtQ+71ViKU8L12m81fl3OWwC1Zlc8k=
+golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
+golang.org/x/crypto v0.0.0-20191011191535-87dc89f01550/go.mod h1:yigFU9vqHzYiE8UmvKecakEJjdnWj3jj499lnFckfCI=
+golang.org/x/mod v0.4.2 h1:Gz96sIWK3OalVv/I/qNygP42zyoKp3xptRVCWRFEBvo=
+golang.org/x/mod v0.4.2/go.mod h1:s0Qsj1ACt9ePp/hMypM3fl4fZqREWJwdYDEqhRiZZUA=
+golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
+golang.org/x/net v0.0.0-20190620200207-3b0461eec859/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
+golang.org/x/net v0.0.0-20210405180319-a5a99cb37ef4/go.mod h1:p54w0d4576C0XHj96bSt6lcn1PtDYWL6XObtHCRCNQM=
+golang.org/x/sync v0.0.0-20190423024810-112230192c58/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
+golang.org/x/sync v0.0.0-20210220032951-036812b2e83c/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
+golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
+golang.org/x/sys v0.0.0-20190412213103-97732733099d/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20201119102817-f84b799fce68/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20210330210617-4fbd30eecc44/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20210510120138-977fb7262007 h1:gG67DSER+11cZvqIMb8S8bt0vZtiN6xWYARwirrOSfE=
+golang.org/x/sys v0.0.0-20210510120138-977fb7262007/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
+golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
+golang.org/x/text v0.3.3/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
+golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
+golang.org/x/tools v0.0.0-20191119224855-298f0cb1881e/go.mod h1:b+2E5dAYhXwXZwtnZ6UAqBI28+e2cm9otk0dWdXHAEo=
+golang.org/x/tools v0.1.5 h1:ouewzE6p+/VEB31YYnTbEJdi8pFqKp4P4n85vwo3DHA=
+golang.org/x/tools v0.1.5/go.mod h1:o0xws9oXOQQZyjljx8fwUC0k7L1pTE6eaCbjGeHmOkk=
+golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
+golang.org/x/xerrors v0.0.0-20191011141410-1b5146add898/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
+golang.org/x/xerrors v0.0.0-20200804184101-5ec99f83aff1 h1:go1bK/D/BFZV2I8cIQd1NKEZ+0owSTG1fDTci4IqFcE=
+golang.org/x/xerrors v0.0.0-20200804184101-5ec99f83aff1/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=

main.go

@@ -0,0 +1,11 @@
+package main
+
+import (
+	"golang.org/x/tools/go/analysis/singlechecker"
+
+	"github.com/Antonboom/nilnil/pkg/analyzer"
+)
+
+func main() {
+	singlechecker.Main(analyzer.New())
+}

pkg/analyzer/analyzer.go

@@ -0,0 +1,115 @@
+package analyzer
+
+import (
+	"go/ast"
+
+	"golang.org/x/tools/go/analysis"
+	"golang.org/x/tools/go/analysis/passes/inspect"
+	"golang.org/x/tools/go/ast/inspector"
+)
+
+const reportMsg = "return both the `nil` error and invalid value: use a sentinel error instead"
+
+// New returns new nilnil analyzer.
+func New() *analysis.Analyzer {
+	return &analysis.Analyzer{
+		Name:     "nilnil",
+		Doc:      "Checks that there is no simultaneous return of `nil` error and an invalid value.",
+		Run:      run,
+		Requires: []*analysis.Analyzer{inspect.Analyzer},
+	}
+}
+
+var (
+	types = []ast.Node{(*ast.TypeSpec)(nil)}
+
+	funcAndReturns = []ast.Node{
+		(*ast.FuncDecl)(nil),
+		(*ast.FuncLit)(nil),
+		(*ast.ReturnStmt)(nil),
+	}
+)
+
+type typeSpecByName map[string]*ast.TypeSpec
+
+func run(pass *analysis.Pass) (interface{}, error) {
+	insp := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)
+
+	typeSpecs := typeSpecByName{}
+	insp.Preorder(types, func(n ast.Node) {
+		t := n.(*ast.TypeSpec)
+		typeSpecs[t.Name.Name] = t
+	})
+
+	var fs FuncTypeStack
+	insp.Nodes(funcAndReturns, func(n ast.Node, push bool) (proceed bool) {
+		switch v := n.(type) {
+		case *ast.FuncLit:
+			if push {
+				fs.Push(v.Type)
+			} else {
+				fs.Pop()
+			}
+
+		case *ast.FuncDecl:
+			if push {
+				fs.Push(v.Type)
+			} else {
+				fs.Pop()
+			}
+
+		case *ast.ReturnStmt:
+			ft := fs.Top() // Current function.
+
+			if !push || len(v.Results) != 2 || ft == nil || ft.Results == nil || len(ft.Results.List) != 2 {
+				return false
+			}
+
+			fRes1, fRes2 := ft.Results.List[0], ft.Results.List[1]
+			if !(isDangerNilField(fRes1, typeSpecs) && isErrorField(fRes2)) {
+				return
+			}
+
+			rRes1, rRes2 := v.Results[0], v.Results[1]
+			if isNil(rRes1) && isNil(rRes2) {
+				pass.Reportf(v.Pos(), reportMsg)
+			}
+		}
+
+		return true
+	})
+
+	return nil, nil
+}
+
+func isDangerNilField(f *ast.Field, types typeSpecByName) bool {
+	return isDangerNilType(f.Type, types)
+}
+
+func isDangerNilType(t ast.Expr, types typeSpecByName) bool {
+	switch v := t.(type) {
+	case *ast.StarExpr, *ast.ChanType, *ast.FuncType, *ast.InterfaceType, *ast.MapType:
+		return true
+	case *ast.Ident:
+		if t, ok := types[v.Name]; ok {
+			return isDangerNilType(t.Type, nil)
+		}
+	}
+	return false
+}
+
+func isErrorField(f *ast.Field) bool {
+	return isIdent(f.Type, "error")
+}
+
+func isNil(e ast.Expr) bool {
+	return isIdent(e, "nil")
+}
+
+func isIdent(n ast.Node, name string) bool {
+	i, ok := n.(*ast.Ident)
+	if !ok {
+		return false
+	}
+	return i.Name == name
+}

pkg/analyzer/analyzer_test.go

@@ -0,0 +1,16 @@
+package analyzer_test
+
+import (
+	"testing"
+
+	"golang.org/x/tools/go/analysis/analysistest"
+
+	"github.com/Antonboom/nilnil/pkg/analyzer"
+)
+
+func TestNilNil(t *testing.T) {
+	pkgs := []string{
+		"examples",
+	}
+	analysistest.Run(t, analysistest.TestData(), analyzer.New(), pkgs...)
+}