Check unvendored version of package paths for ignore parameter

Fixes #102

internal/errcheck/errcheck.go

@@ -10,14 +10,13 @@ import (
 	"go/ast"
 	"go/build"
 	"go/token"
+	"go/types"
 	"os"
 	"regexp"
 	"sort"
 	"strings"
 	"sync"
 
-	"go/types"
-
 	"golang.org/x/tools/go/loader"
 )
 
@@ -220,12 +219,31 @@ func (v *visitor) ignoreCall(call *ast.CallExpr) bool {
 			if re, ok := v.ignore[pkg.Path()]; ok {
 				return re.MatchString(id.Name)
 			}
+
+			// if current package being considered is vendored, check to see if it should be ignored based
+			// on the unvendored path.
+			if nonVendoredPkg, ok := nonVendoredPkgPath(pkg.Path()); ok {
+				if re, ok := v.ignore[nonVendoredPkg]; ok {
+					return re.MatchString(id.Name)
+				}
+			}
 		}
 	}
 
 	return false
 }
 
+// nonVendoredPkgPath returns the unvendored version of the provided package path (or returns the provided path if it
+// does not represent a vendored path). The second return value is true if the provided package was vendored, false
+// otherwise.
+func nonVendoredPkgPath(pkgPath string) (string, bool) {
+	lastVendorIndex := strings.LastIndex(pkgPath, "/vendor/")
+	if lastVendorIndex == -1 {
+		return pkgPath, false
+	}
+	return pkgPath[lastVendorIndex+len("/vendor/"):], true
+}
+
 // errorsByArg returns a slice s such that
 // len(s) == number of return types of call
 // s[i] == true iff return type at position i from left is an error type

internal/errcheck/errcheck_test.go

@@ -5,10 +5,14 @@ import (
 	"go/build"
 	"go/parser"
 	"go/token"
+	"regexp"
 	"testing"
 )
 
-const testPackage = "github.com/kisielk/errcheck/testdata"
+const (
+	testPackage       = "github.com/kisielk/errcheck/testdata"
+	testVendorPackage = "github.com/kisielk/errcheck/testvendor"
+)
 
 var (
 	uncheckedMarkers map[marker]bool
@@ -83,6 +87,55 @@ func TestAll(t *testing.T) {
 	test(t, CheckAsserts|CheckBlank)
 }
 
+func TestIgnore(t *testing.T) {
+	cases := []struct {
+		ignore          map[string]*regexp.Regexp
+		numExpectedErrs int
+	}{
+		// basic case has one error
+		{
+			ignore:          nil,
+			numExpectedErrs: 1,
+		},
+		// ignoring vendored import works
+		{
+			ignore: map[string]*regexp.Regexp{
+				"github.com/kisielk/errcheck/testvendor/vendor/github.com/testlog": regexp.MustCompile("Info"),
+			},
+		},
+		// non-vendored path ignores vendored import
+		{
+			ignore: map[string]*regexp.Regexp{
+				"github.com/testlog": regexp.MustCompile("Info"),
+			},
+		},
+	}
+
+	for i, currCase := range cases {
+		checker := &Checker{
+			Ignore: currCase.ignore,
+		}
+		err := checker.CheckPackages(testVendorPackage)
+
+		if currCase.numExpectedErrs == 0 {
+			if err != nil {
+				t.Errorf("Case %d: expected no errors, but got: %v", i, err)
+			}
+			continue
+		}
+
+		uerr, ok := err.(*UncheckedErrors)
+		if !ok {
+			t.Errorf("Case %d: wrong error type returned", i)
+			continue
+		}
+
+		if currCase.numExpectedErrs != len(uerr.Errors) {
+			t.Errorf("Case %d:\nExpected: %d errors\nActual:   %d errors", i, currCase.numExpectedErrs, len(uerr.Errors))
+		}
+	}
+}
+
 func test(t *testing.T, f flags) {
 	var (
 		asserts bool = f&CheckAsserts != 0

testvendor/main.go

@@ -0,0 +1,10 @@
+package main
+
+import (
+	"github.com/testlog"
+)
+
+func main() {
+	// returns an error that is not checked
+	testlog.Info()
+}