Add source code with updated README and License

LICENSE

@@ -27,3 +27,36 @@ SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
 CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+This software includes some portions from Go. Go is used under the terms of the
+BSD like license.
+
+Copyright (c) 2012 The Go Authors. All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are
+met:
+
+   * Redistributions of source code must retain the above copyright
+notice, this list of conditions and the following disclaimer.
+   * Redistributions in binary form must reproduce the above
+copyright notice, this list of conditions and the following disclaimer
+in the documentation and/or other materials provided with the
+distribution.
+   * Neither the name of Google Inc. nor the names of its
+contributors may be used to endorse or promote products derived from
+this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+The Go gopher was designed by Renee French. http://reneefrench.blogspot.com/ The design is licensed under the Creative Commons 3.0 Attributions license. Read this article for more details: https://blog.golang.org/gopher

README.md

@@ -1,2 +1,61 @@
 # errwrap
-Wrap and fix Go errors with the new %w verb directive
+
+Wrap and fix Go errors with the new %w verb directive. This tool analyzes
+`fmt.Errorf()` calls and reports calls that contain a verb directive that is
+different than the new `%w` verb directive [introduced in Go v1.13](https://golang.org/doc/go1.13#error_wrapping). It's also capable of rewriting calls to use the new `%w` wrap verb directive.
+
+
+# Install
+
+```bash
+go get github.com/fatih/errwrap/cmd/errwrap
+```
+
+# Usage
+
+By default, `errwrap` prints the output of the analyzer to stdout. You can pass
+a file, directory or a Go package:
+
+```sh
+$ errwrap foo.go # pass a file
+$ errwrap ./...  # recursively analyze all files
+$ errwrap github.com/fatih/gomodifytags # or pass a package
+```
+
+When called it displays the error with the line and column:
+
+```
+gomodifytags@v1.0.1/main.go:200:16: call could wrap the error with error-wrapping directive %w
+gomodifytags@v1.0.1/main.go:641:17: call could wrap the error with error-wrapping directive %w
+gomodifytags@v1.0.1/main.go:749:15: call could wrap the error with error-wrapping directive %w
+```
+
+`errwrap` is also able to rewrite your source code to replace any verb
+directive used for an `error` type with the `%w` verb directive. Assume we have
+the following source code:
+
+```
+$ cat demo.go
+package main
+
+import (
+        "errors"
+        "fmt"
+)
+
+func main() {
+        _ = foo()
+}
+
+func foo() error {
+        err := errors.New("bar!")
+        return fmt.Errorf("foo failed: %s: %w bar ...", "foo", err)
+}
+```
+
+Calling `errwrap` with the `-fix` flag will rewrite the source code:
+
+```
+$ errwrap -fix example.go
+demo.go:14:9: call could wrap the error with error-wrapping directive %w
+```

cmd/errwrap/main.go

@@ -0,0 +1,10 @@
+package main
+
+import (
+	"github.com/fatih/errwrap/internal/errwrap"
+	"golang.org/x/tools/go/analysis/singlechecker"
+)
+
+func main() {
+	singlechecker.Main(errwrap.Analyzer)
+}

go.mod

@@ -0,0 +1,5 @@
+module github.com/fatih/errwrap
+
+go 1.13
+
+require golang.org/x/tools v0.0.0-20191014205221-18e3458ac98b

go.sum

@@ -0,0 +1,8 @@
+golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
+golang.org/x/net v0.0.0-20190620200207-3b0461eec859/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
+golang.org/x/sync v0.0.0-20190423024810-112230192c58/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
+golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
+golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
+golang.org/x/tools v0.0.0-20191014205221-18e3458ac98b h1:EsQHTYgcM562dq02r6y2Yt9VpvvLNIyNECx96XQeolA=
+golang.org/x/tools v0.0.0-20191014205221-18e3458ac98b/go.mod h1:b+2E5dAYhXwXZwtnZ6UAqBI28+e2cm9otk0dWdXHAEo=
+golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=