Merge pull request #159 from coopernurse/155-go-modules

Add back support for go modules (fixes #155)

.travis.yml

@@ -3,9 +3,6 @@ sudo: false
 
 matrix:
   include:
-    - go: "1.6"
-    - go: "1.7"
-    - go: "1.8"
     - go: "1.9"
     - go: "1.10"
     - go: "tip"

README.md

@@ -8,7 +8,7 @@ errcheck is a program for checking for unchecked errors in go programs.
 
     go get -u github.com/kisielk/errcheck
 
-errcheck requires Go 1.6 or newer and depends on the package go/loader from the golang.org/x/tools repository.
+errcheck requires Go 1.9 or newer and depends on the package go/packages from the golang.org/x/tools repository.
 
 ## Use
 
@@ -98,12 +98,9 @@ no arguments.
 
 ## Cgo
 
-Currently errcheck is unable to check packages that `import "C"` due to limitations
-in the importer.
+Currently errcheck is unable to check packages that import "C" due to limitations in the importer when used with versions earlier than Go 1.11.
 
-However, you can use errcheck on packages that depend on those which use cgo. In
-order for this to work you need to `go install` the cgo dependencies before running
-errcheck on the dependent packages.
+However, you can use errcheck on packages that depend on those which use cgo. In order for this to work you need to go install the cgo dependencies before running errcheck on the dependent packages.
 
 See https://github.com/kisielk/errcheck/issues/16 for more details.
 

go.mod

@@ -1,6 +1,3 @@
-module "github.com/kisielk/errcheck"
+module github.com/kisielk/errcheck
 
-require (
-	"github.com/kisielk/gotool" v1.0.0
-	"golang.org/x/tools" v0.0.0-20180221164845-07fd8470d635
-)
+require golang.org/x/tools v0.0.0-20181030221726-6c7e314b6563

go.sum

@@ -0,0 +1,4 @@
+golang.org/x/tools v0.0.0-20180803180156-3c07937fe18c h1:Z6Xcg33osoOLCiz/EFPHedK6zJ9nl1KK4WH/LlykMxs=
+golang.org/x/tools v0.0.0-20180803180156-3c07937fe18c/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
+golang.org/x/tools v0.0.0-20181030221726-6c7e314b6563 h1:NIou6eNFigscvKJmsbyez16S2cIS6idossORlFtSt2E=
+golang.org/x/tools v0.0.0-20181030221726-6c7e314b6563/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=

internal/errcheck/errcheck.go

@@ -8,7 +8,6 @@ import (
 	"errors"
 	"fmt"
 	"go/ast"
-	"go/build"
 	"go/token"
 	"go/types"
 	"os"
@@ -17,9 +16,7 @@ import (
 	"strings"
 	"sync"
 
-	"go/parser"
-
-	"golang.org/x/tools/go/loader"
+	"golang.org/x/tools/go/packages"
 )
 
 var errorType *types.Interface
@@ -175,28 +172,18 @@ func (c *Checker) logf(msg string, args ...interface{}) {
 	}
 }
 
-func (c *Checker) load(paths ...string) (*loader.Program, error) {
-	ctx := build.Default
-	for _, tag := range c.Tags {
-		ctx.BuildTags = append(ctx.BuildTags, tag)
-	}
-	loadcfg := loader.Config{
-		Build: &ctx,
-	}
-
-	if c.WithoutGeneratedCode {
-		loadcfg.ParserMode = parser.ParseComments
-	}
+// loadPackages is used for testing.
+var loadPackages = func(cfg *packages.Config, paths ...string) ([]*packages.Package, error) {
+	return packages.Load(cfg, paths...)
+}
 
-	rest, err := loadcfg.FromArgs(paths, !c.WithoutTests)
-	if err != nil {
-		return nil, fmt.Errorf("could not parse arguments: %s", err)
-	}
-	if len(rest) > 0 {
-		return nil, fmt.Errorf("unhandled extra arguments: %v", rest)
+func (c *Checker) load(paths ...string) ([]*packages.Package, error) {
+	cfg := &packages.Config{
+		Mode:       packages.LoadAllSyntax,
+		Tests:      !c.WithoutTests,
+		BuildFlags: []string{fmt.Sprintf("-tags=%s", strings.Join(c.Tags, " "))},
 	}
-
-	return loadcfg.Load()
+	return loadPackages(cfg, paths...)
 }
 
 var generatedCodeRegexp = regexp.MustCompile("^// Code generated .* DO NOT EDIT\\.$")
@@ -219,27 +206,28 @@ func (c *Checker) shouldSkipFile(file *ast.File) bool {
 
 // CheckPackages checks packages for errors.
 func (c *Checker) CheckPackages(paths ...string) error {
-	program, err := c.load(paths...)
+	pkgs, err := c.load(paths...)
 	if err != nil {
-		return fmt.Errorf("could not type check: %s", err)
+		return err
+	}
+	// Check for errors in the initial packages.
+	for _, pkg := range pkgs {
+		if len(pkg.Errors) > 0 {
+			return fmt.Errorf("errors while loading package %s: %v", pkg.ID, pkg.Errors)
+		}
 	}
 
 	var wg sync.WaitGroup
 	u := &UncheckedErrors{}
-	for _, pkgInfo := range program.InitialPackages() {
-		if pkgInfo.Pkg.Path() == "unsafe" { // not a real package
-			continue
-		}
-
+	for _, pkg := range pkgs {
 		wg.Add(1)
 
-		go func(pkgInfo *loader.PackageInfo) {
+		go func(pkg *packages.Package) {
 			defer wg.Done()
-			c.logf("Checking %s", pkgInfo.Pkg.Path())
+			c.logf("Checking %s", pkg.Types.Path())
 
 			v := &visitor{
-				prog:    program,
-				pkg:     pkgInfo,
+				pkg:     pkg,
 				ignore:  c.Ignore,
 				blank:   c.Blank,
 				asserts: c.Asserts,
@@ -248,28 +236,36 @@ func (c *Checker) CheckPackages(paths ...string) error {
 				errors:  []UncheckedError{},
 			}
 
-			for _, astFile := range v.pkg.Files {
+			for _, astFile := range v.pkg.Syntax {
 				if c.shouldSkipFile(astFile) {
 					continue
 				}
 				ast.Walk(v, astFile)
 			}
 			u.Append(v.errors...)
-		}(pkgInfo)
+		}(pkg)
 	}
 
 	wg.Wait()
 	if u.Len() > 0 {
+		// Sort unchecked errors and remove duplicates. Duplicates may occur when a file
+		// containing an unchecked error belongs to > 1 package.
 		sort.Sort(byName{u})
+		uniq := u.Errors[:0] // compact in-place
+		for i, err := range u.Errors {
+			if i == 0 || err != u.Errors[i-1] {
+				uniq = append(uniq, err)
+			}
+		}
+		u.Errors = uniq
 		return u
 	}
 	return nil
 }
 
 // visitor implements the errcheck algorithm
 type visitor struct {
-	prog    *loader.Program
-	pkg     *loader.PackageInfo
+	pkg     *packages.Package
 	ignore  map[string]*regexp.Regexp
 	blank   bool
 	asserts bool
@@ -294,7 +290,7 @@ func (v *visitor) selectorAndFunc(call *ast.CallExpr) (*ast.SelectorExpr, *types
 		return nil, nil, false
 	}
 
-	fn, ok := v.pkg.ObjectOf(sel.Sel).(*types.Func)
+	fn, ok := v.pkg.TypesInfo.ObjectOf(sel.Sel).(*types.Func)
 	if !ok {
 		// Shouldn't happen, but be paranoid
 		return nil, nil, false
@@ -350,7 +346,7 @@ func (v *visitor) namesForExcludeCheck(call *ast.CallExpr) []string {
 
 	// This will be missing for functions without a receiver (like fmt.Printf),
 	// so just fall back to the the function's fullName in that case.
-	selection, ok := v.pkg.Selections[sel]
+	selection, ok := v.pkg.TypesInfo.Selections[sel]
 	if !ok {
 		return []string{name}
 	}
@@ -377,14 +373,14 @@ func (v *visitor) namesForExcludeCheck(call *ast.CallExpr) []string {
 func (v *visitor) argName(expr ast.Expr) string {
 	// Special-case literal "os.Stdout" and "os.Stderr"
 	if sel, ok := expr.(*ast.SelectorExpr); ok {
-		if obj := v.pkg.ObjectOf(sel.Sel); obj != nil {
+		if obj := v.pkg.TypesInfo.ObjectOf(sel.Sel); obj != nil {
 			vr, ok := obj.(*types.Var)
 			if ok && vr.Pkg() != nil && vr.Pkg().Name() == "os" && (vr.Name() == "Stderr" || vr.Name() == "Stdout") {
 				return "os." + vr.Name()
 			}
 		}
 	}
-	t := v.pkg.Info.TypeOf(expr)
+	t := v.pkg.TypesInfo.TypeOf(expr)
 	if t == nil {
 		return ""
 	}
@@ -435,7 +431,7 @@ func (v *visitor) ignoreCall(call *ast.CallExpr) bool {
 		return true
 	}
 
-	if obj := v.pkg.Uses[id]; obj != nil {
+	if obj := v.pkg.TypesInfo.Uses[id]; obj != nil {
 		if pkg := obj.Pkg(); pkg != nil {
 			if re, ok := v.ignore[pkg.Path()]; ok {
 				return re.MatchString(id.Name)
@@ -469,7 +465,7 @@ func nonVendoredPkgPath(pkgPath string) (string, bool) {
 // len(s) == number of return types of call
 // s[i] == true iff return type at position i from left is an error type
 func (v *visitor) errorsByArg(call *ast.CallExpr) []bool {
-	switch t := v.pkg.Types[call].Type.(type) {
+	switch t := v.pkg.TypesInfo.Types[call].Type.(type) {
 	case *types.Named:
 		// Single return
 		return []bool{isErrorType(t)}
@@ -511,15 +507,15 @@ func (v *visitor) callReturnsError(call *ast.CallExpr) bool {
 // isRecover returns true if the given CallExpr is a call to the built-in recover() function.
 func (v *visitor) isRecover(call *ast.CallExpr) bool {
 	if fun, ok := call.Fun.(*ast.Ident); ok {
-		if _, ok := v.pkg.Uses[fun].(*types.Builtin); ok {
+		if _, ok := v.pkg.TypesInfo.Uses[fun].(*types.Builtin); ok {
 			return fun.Name == "recover"
 		}
 	}
 	return false
 }
 
 func (v *visitor) addErrorAtPosition(position token.Pos, call *ast.CallExpr) {
-	pos := v.prog.Fset.Position(position)
+	pos := v.pkg.Fset.Position(position)
 	lines, ok := v.lines[pos.Filename]
 	if !ok {
 		lines = readfile(pos.Filename)