Add whitespace linter (#673)

Author: NiseVoid

README.md

@@ -216,6 +216,7 @@ scopelint: Scopelint checks for unpinned variables in go programs [fast: true, a
 stylecheck: Stylecheck is a replacement for golint [fast: false, auto-fix: false]
 unconvert: Remove unnecessary type conversions [fast: true, auto-fix: false]
 unparam: Reports unused function parameters [fast: false, auto-fix: false]
+whitespace: Tool for detection of leading and trailing whitespace [fast: true, auto-fix: false]
 ```
 
 Pass `-E/--enable` to enable linter and `-D/--disable` to disable:
@@ -459,6 +460,7 @@ golangci-lint help linters
 - [gochecknoinits](https://github.com/leighmcculloch/gochecknoinits) - Checks that no init functions are present in Go code
 - [gochecknoglobals](https://github.com/leighmcculloch/gochecknoglobals) - Checks that no globals are present in Go code
 - [funlen](https://github.com/ultraware/funlen) - Tool for detection of long functions
+- [whitespace](https://github.com/ultraware/whitespace) - Tool for detection of leading and trailing whitespace
 
 ## Configuration
 

go.mod

@@ -53,6 +53,7 @@ require (
 	github.com/stretchr/testify v1.2.2
 	github.com/timakin/bodyclose v0.0.0-20190721030226-87058b9bfcec
 	github.com/ultraware/funlen v0.0.1
+	github.com/ultraware/whitespace v0.0.2
 	github.com/valyala/quicktemplate v1.1.1
 	golang.org/x/crypto v0.0.0-20190313024323-a1f597ede03a // indirect
 	golang.org/x/sys v0.0.0-20190312061237-fead79001313 // indirect

go.sum

@@ -164,6 +164,8 @@ github.com/stretchr/testify v1.2.2 h1:bSDNvY7ZPG5RlJ8otE/7V6gMiyenm9RtJ7IUVIAoJ1
 github.com/stretchr/testify v1.2.2/go.mod h1:a8OnRcib4nhh0OaRAV+Yts87kKdq0PP7pXfy6kDkUVs=
 github.com/timakin/bodyclose v0.0.0-20190721030226-87058b9bfcec h1:AmoEvWAO3nDx1MEcMzPh+GzOOIA5Znpv6++c7bePPY0=
 github.com/timakin/bodyclose v0.0.0-20190721030226-87058b9bfcec/go.mod h1:Qimiffbc6q9tBWlVV6x0P9sat/ao1xEkREYPPj9hphk=
+github.com/ultraware/whitespace v0.0.2 h1:iL4Un0C3VaMIBGfDogtcdBeSotjfSHYW8OdI1U9Vqas=
+github.com/ultraware/whitespace v0.0.2/go.mod h1:aVMh/gQve5Maj9hQ/hg+F75lr/X5A89uZnzAmWSineA=
 github.com/valyala/bytebufferpool v1.0.0 h1:GqA5TC/0021Y/b9FG4Oi9Mr3q7XYx6KllzawFIhcdPw=
 github.com/valyala/bytebufferpool v1.0.0/go.mod h1:6bBcMArwyJ5K/AmCkWv1jt77kVWyCJ6HpOuEn7z0Csc=
 github.com/valyala/fasthttp v1.2.0/go.mod h1:4vX61m6KN+xDduDNwXrhIAVZaZaZiQ1luJk8LWSxF3s=

pkg/golinters/whitespace.go

@@ -0,0 +1,46 @@
+package golinters
+
+import (
+	"context"
+	"go/token"
+
+	"github.com/golangci/golangci-lint/pkg/lint/linter"
+	"github.com/golangci/golangci-lint/pkg/result"
+
+	"github.com/ultraware/whitespace"
+)
+
+type Whitespace struct{}
+
+func (Whitespace) Name() string {
+	return "whitespace"
+}
+
+func (Whitespace) Desc() string {
+	return "Tool for detection of leading and trailing whitespace"
+}
+
+func (w Whitespace) Run(ctx context.Context, lintCtx *linter.Context) ([]result.Issue, error) {
+	var issues []whitespace.Message
+	for _, file := range lintCtx.ASTCache.GetAllValidFiles() {
+		issues = append(issues, whitespace.Run(file.F, file.Fset)...)
+	}
+
+	if len(issues) == 0 {
+		return nil, nil
+	}
+
+	res := make([]result.Issue, len(issues))
+	for k, i := range issues {
+		res[k] = result.Issue{
+			Pos: token.Position{
+				Filename: i.Pos.Filename,
+				Line:     i.Pos.Line,
+			},
+			Text:       i.Message,
+			FromLinter: w.Name(),
+		}
+	}
+
+	return res, nil
+}

pkg/lint/lintersdb/manager.go

@@ -242,6 +242,10 @@ func (m Manager) GetAllSupportedLinterConfigs() []*linter.Config {
 			WithPresets(linter.PresetStyle).
 			WithSpeed(10).
 			WithURL("https://github.com/ultraware/funlen"),
+		linter.NewConfig(golinters.Whitespace{}).
+			WithPresets(linter.PresetStyle).
+			WithSpeed(10).
+			WithURL("https://github.com/ultraware/whitespace"),
 	}
 
 	isLocalRun := os.Getenv("GOLANGCI_COM_RUN") == ""

test/testdata/whitespace.go

@@ -0,0 +1,20 @@
+//args: -Ewhitespace
+package testdata
+
+func UselessStart() { // ERROR "unnecessary leading newline"
+
+	a := 1
+	_ = a
+}
+
+func UselessEnd() {
+	a := 1
+	_ = a
+
+} // ERROR "unnecessary trailing newline"
+
+func CommentsShouldBeIgnored() {
+	// test
+	a := 1
+	_ = a
+}