feat: ignore signatures via regex (#21)

* Ignore error signatures via regexp

* Update docs with new ignoreSigRegexps configuration

* Fix docs typo

README.md

@@ -39,6 +39,12 @@ ignoreSigs:
 - .WithMessagef(
 - .WithStack(
 
+# An array of strings which specify regular expressions of signatures to ignore.
+# This is similar to the ignoreSigs configuration above, but gives slightly more
+# flexibility.
+ignoreSigRegexps:
+- \.New.*Error\(
+
 # An array of glob patterns which, if any match the package of the function
 # returning the error, will skip wrapcheck analysis for this error. This is
 # useful for broadly ignoring packages and/or subpackages from wrapcheck

wrapcheck/testdata/config_ignoreSigRegexps/.wrapcheck.yaml

@@ -0,0 +1,4 @@
+ignoreSigRegexps:
+- json\.[a-zA-Z0-9_-]+\(
+- ^func[\s]+\(.+wrapcheck.+\.error.*\)
+- \.NewMod[\d]+Error\(

wrapcheck/testdata/config_ignoreSigRegexps/main.go

@@ -0,0 +1,58 @@
+package main
+
+import (
+	"encoding/json"
+	"fmt"
+	"strings"
+
+	"github.com/pkg/errors"
+)
+
+type errorer interface {
+	Decode(v interface{}) error
+}
+
+func main() {
+	do1()
+
+	d := json.NewDecoder(strings.NewReader("hello world"))
+	do2(d)
+
+	do3(5)
+	do4(5)
+}
+
+func do1() error {
+	_, err := json.Marshal(struct{}{}) // external package ignored by package+method-name regexp
+	if err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func do2(fn errorer) error {
+	var str string
+	err := fn.Decode(&str) // interface ignored by regexp
+	if err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func do3(i int) error {
+	if i%2 == 0 {
+		return errors.NewMod2Error(fmt.Sprintf("%d is an even number", i)) // external package ignored by method-name regexp
+	}
+
+	return nil
+}
+
+func do4(i int) error {
+	if i%3 == 0 {
+		return errors.NewMod3Error(fmt.Sprintf("%d is divisible by 3", i)) // external package ignored by method-name regexp
+	}
+
+	return nil
+}

wrapcheck/testdata/config_ignoreSigRegexps/src/github.com/pkg/errors/errors.go

@@ -0,0 +1,25 @@
+package errors
+
+type Mod2Error struct {
+	msg string
+}
+
+func NewMod2Error(msg string) error {
+	return &Mod2Error{msg}
+}
+
+func (e Mod2Error) Error() string {
+	return e.msg
+}
+
+type Mod3Error struct {
+	msg string
+}
+
+func NewMod3Error(msg string) error {
+	return &Mod3Error{msg}
+}
+
+func (e Mod3Error) Error() string {
+	return e.msg
+}

wrapcheck/wrapcheck.go

@@ -6,6 +6,7 @@ import (
 	"go/types"
 	"log"
 	"os"
+	"regexp"
 	"strings"
 
 	"github.com/gobwas/glob"
@@ -33,7 +34,7 @@ type WrapcheckConfig struct {
 	// allows you to specify functions that wrapcheck will not report as
 	// unwrapped.
 	//
-	// For example, an ingoredSig of `[]string{"errors.New("}` will ignore errors
+	// For example, an ignoreSig of `[]string{"errors.New("}` will ignore errors
 	// returned from the stdlib package error's function:
 	//
 	//   `func errors.New(message string) error`
@@ -45,6 +46,20 @@ type WrapcheckConfig struct {
 	// list to your config.
 	IgnoreSigs []string `mapstructure:"ignoreSigs" yaml:"ignoreSigs"`
 
+	// IgnoreSigRegexps defines a list of regular expressions which if matched
+	// to the signature of the function call returning the error, will be ignored. This
+	// allows you to specify functions that wrapcheck will not report as
+	// unwrapped.
+	//
+	// For example, an ignoreSigRegexp of `[]string{"\.New.*Err\("}`` will ignore errors
+	// returned from any signture whose method name starts with "New" and ends with "Err"
+	// due to the signature matching the regular expression `\.New.*Err\(`.
+	//
+	// Note that this is similar to the ignoreSigs configuration, but provides
+	// slightly more flexibility in defining rules by which signtures will be
+	// ignored.
+	IgnoreSigRegexps []string `mapstructure:"ignoreSigRegexps" yaml:"ignoreSigRegexps"`
+
 	// IgnorePackageGlobs defines a list of globs which, if matching the package
 	// of the function returning the error, will ignore the error when doing
 	// wrapcheck analysis.
@@ -62,6 +77,7 @@ type WrapcheckConfig struct {
 func NewDefaultConfig() WrapcheckConfig {
 	return WrapcheckConfig{
 		IgnoreSigs:         DefaultIgnoreSigs,
+		IgnoreSigRegexps:   []string{},
 		IgnorePackageGlobs: []string{},
 	}
 }
@@ -206,6 +222,8 @@ func reportUnwrapped(pass *analysis.Pass, call *ast.CallExpr, tokenPos token.Pos
 	fnSig := pass.TypesInfo.ObjectOf(sel.Sel).String()
 	if contains(cfg.IgnoreSigs, fnSig) {
 		return
+	} else if containsMatch(cfg.IgnoreSigRegexps, fnSig) {
+		return
 	}
 
 	// Check if the underlying type of the "x" in x.y.z is an interface, as
@@ -317,6 +335,22 @@ func contains(slice []string, el string) bool {
 	return false
 }
 
+func containsMatch(slice []string, el string) bool {
+	for _, s := range slice {
+		re, err := regexp.Compile(s)
+		if err != nil {
+			log.Printf("unable to parse regexp: %s\n", s)
+			os.Exit(1)
+		}
+
+		if re.MatchString(el) {
+			return true
+		}
+	}
+
+	return false
+}
+
 // isError returns whether or not the provided type interface is an error
 func isError(typ types.Type) bool {
 	if typ == nil {