all: use errors.As instead of .(type)

7 files changed, 28 insertions, 19 deletions

diff --git a/dashboard/app/access_test.go b/dashboard/app/access_test.go
index f7d02d990..7bd412acf 100644
--- a/dashboard/app/access_test.go
+++ b/dashboard/app/access_test.go
@@ -5,6 +5,7 @@ package main
 
 import (
 	"bytes"
+	"errors"
 	"fmt"
 	"net/http"
 	"strconv"
@@ -387,8 +388,8 @@ func TestAccess(t *testing.T) {
 				t.Fatal(err1)
 			}
 			c.expectNE(err, nil)
-			httpErr, ok := err.(*HTTPError)
-			c.expectTrue(ok)
+			var httpErr *HTTPError
+			c.expectTrue(errors.As(err, &httpErr))
 			c.expectEQ(httpErr.Code, http.StatusTemporaryRedirect)
 			c.expectEQ(httpErr.Headers["Location"], []string{loginURL})
 		} else {
diff --git a/dashboard/app/app_test.go b/dashboard/app/app_test.go
index d7aae91ed..241e5141d 100644
--- a/dashboard/app/app_test.go
+++ b/dashboard/app/app_test.go
@@ -4,6 +4,7 @@
 package main
 
 import (
+	"errors"
 	"fmt"
 	"net/http"
 	"os"
@@ -820,8 +821,8 @@ func checkLoginRedirect(c *Ctx, accessLevel AccessLevel, url string) {
 func checkRedirect(c *Ctx, accessLevel AccessLevel, from, to string, status int) {
 	_, err := c.AuthGET(accessLevel, from)
 	c.expectNE(err, nil)
-	httpErr, ok := err.(*HTTPError)
-	c.expectTrue(ok)
+	var httpErr *HTTPError
+	c.expectTrue(errors.As(err, &httpErr))
 	c.expectEQ(httpErr.Code, status)
 	c.expectEQ(httpErr.Headers["Location"], []string{to})
 }
@@ -829,8 +830,8 @@ func checkRedirect(c *Ctx, accessLevel AccessLevel, from, to string, status int)
 func checkResponseStatusCode(c *Ctx, accessLevel AccessLevel, url string, status int) {
 	_, err := c.AuthGET(accessLevel, url)
 	c.expectNE(err, nil)
-	httpErr, ok := err.(*HTTPError)
-	c.expectTrue(ok)
+	var httpErr *HTTPError
+	c.expectTrue(errors.As(err, &httpErr))
 	c.expectEQ(httpErr.Code, status)
 }
 
diff --git a/dashboard/app/bisect_test.go b/dashboard/app/bisect_test.go
index a61f51286..334d5a04d 100644
--- a/dashboard/app/bisect_test.go
+++ b/dashboard/app/bisect_test.go
@@ -5,6 +5,7 @@ package main
 
 import (
 	"bytes"
+	"errors"
 	"fmt"
 	"net/http"
 	"strings"
@@ -1106,8 +1107,8 @@ func TestBugBisectionInvalidation(t *testing.T) {
 
 	// Mark bisection as invalid.
 	_, err = c.AuthGET(AccessAdmin, "/admin?action=invalidate_bisection&key="+jobKey.Encode())
-	httpErr, ok := err.(*HTTPError)
-	c.expectTrue(ok)
+	var httpErr *HTTPError
+	c.expectTrue(errors.As(err, &httpErr))
 	c.expectEQ(httpErr.Code, http.StatusFound)
 
 	// The invalidated bisection should have vanished from the web UI
diff --git a/dashboard/app/handler.go b/dashboard/app/handler.go
index 6a115d0b2..6b72da0bb 100644
--- a/dashboard/app/handler.go
+++ b/dashboard/app/handler.go
@@ -50,7 +50,8 @@ func handleContext(fn contextHandler) http.Handler {
 				http.Error(w, "403 Forbidden", http.StatusForbidden)
 				return
 			}
-			if redir, ok := err.(ErrRedirect); ok {
+			var redir *ErrRedirect
+			if errors.As(err, &redir) {
 				http.Redirect(w, r, redir.Error(), http.StatusFound)
 				return
 			}
@@ -201,7 +202,7 @@ func commonHeader(c context.Context, r *http.Request, w http.ResponseWriter, ns
 			ns = adminPage
 		}
 		if ns != adminPage || !isAdminPage {
-			return nil, ErrRedirect{fmt.Errorf("/%v", ns)}
+			return nil, &ErrRedirect{fmt.Errorf("/%v", ns)}
 		}
 	}
 	if ns != adminPage {
diff --git a/dashboard/app/reporting_email.go b/dashboard/app/reporting_email.go
index ee87169b7..26a3e57ef 100644
--- a/dashboard/app/reporting_email.go
+++ b/dashboard/app/reporting_email.go
@@ -703,17 +703,19 @@ func handleTestCommand(c context.Context, info *bugInfoResult,
 		user: msg.Author, extID: msg.MessageID, link: msg.Link,
 		patch: []byte(msg.Patch), repo: args[0], branch: args[1], jobCC: msg.Cc})
 	if err != nil {
-		switch e := err.(type) {
-		case *TestRequestDeniedError:
+		var testDenied *TestRequestDeniedError
+		var badTest *BadTestRequestError
+		switch {
+		case errors.As(err, &testDenied):
 			// Don't send a reply in this case.
-			log.Errorf(c, "patch test request denied: %v", e)
-		case *BadTestRequestError:
-			reply = e.Error()
+			log.Errorf(c, "patch test request denied: %v", testDenied)
+		case errors.As(err, &badTest):
+			reply = badTest.Error()
 		default:
 			// Don't leak any details to the reply email.
 			reply = "Processing failed due to an internal error"
 			// .. but they are useful for debugging, so we'd like to see it on the Admin page.
-			log.Errorf(c, "handleTestRequest error: %v", e)
+			log.Errorf(c, "handleTestRequest error: %v", err)
 		}
 	}
 	return reply
diff --git a/dashboard/app/reporting_external.go b/dashboard/app/reporting_external.go
index ffe3f00c8..b296139ec 100644
--- a/dashboard/app/reporting_external.go
+++ b/dashboard/app/reporting_external.go
@@ -5,6 +5,7 @@ package main
 
 import (
 	"encoding/json"
+	"errors"
 	"fmt"
 	"net/http"
 
@@ -95,7 +96,8 @@ func apiNewTestJob(c context.Context, r *http.Request, payload []byte) (interfac
 	err := handleExternalTestRequest(c, req)
 	if err != nil {
 		resp.ErrorText = err.Error()
-		if _, ok := err.(*BadTestRequestError); !ok {
+		var badTest *BadTestRequestError
+		if !errors.As(err, &badTest) {
 			// Log errors that are not related to the invalid input.
 			log.Errorf(c, "external patch posting error: %v", err)
 		}
diff --git a/dashboard/app/util_test.go b/dashboard/app/util_test.go
index f748e0dcd..b0ac1c6fe 100644
--- a/dashboard/app/util_test.go
+++ b/dashboard/app/util_test.go
@@ -8,6 +8,7 @@ package main
 
 import (
 	"bytes"
+	"errors"
 	"fmt"
 	"io"
 	"net/http"
@@ -107,8 +108,8 @@ func (c *Ctx) expectFailureStatus(err error, code int) {
 	if err == nil {
 		c.t.Fatalf("expected to fail as %d, but it does not", code)
 	}
-	httpErr, ok := err.(*HTTPError)
-	if !ok || httpErr.Code != code {
+	var httpErr *HTTPError
+	if !errors.As(err, &httpErr) || httpErr.Code != code {
 		c.t.Fatalf("expected to fail as %d, but it failed as %v", code, err)
 	}
 }