A response without a body can't have trailers

client.go

@@ -1365,9 +1365,7 @@ func (c *HostClient) do(req *Request, resp *Response) (bool, error) {
 		defer ReleaseResponse(resp)
 	}
 
-	ok, err := c.doNonNilReqResp(req, resp)
-
-	return ok, err
+	return c.doNonNilReqResp(req, resp)
 }
 
 func (c *HostClient) doNonNilReqResp(req *Request, resp *Response) (bool, error) {

client_test.go

@@ -3484,3 +3484,52 @@ func TestDialTimeout(t *testing.T) {
 		})
 	}
 }
+
+func TestClientHeadWithBody(t *testing.T) {
+	t.Parallel()
+
+	ln := fasthttputil.NewInmemoryListener()
+	defer ln.Close()
+
+	go func() {
+		c, err := ln.Accept()
+		if err != nil {
+			t.Error(err)
+		}
+		c.Write([]byte("HTTP/1.1 200 OK\r\n" + //nolint:errcheck
+			"content-type: text/plain\r\n" +
+			"transfer-encoding: chunked\r\n\r\n" +
+			"24\r\nThis is the data in the first chunk \r\n" +
+			"1B\r\nand this is the second one \r\n" +
+			"0\r\n\r\n",
+		))
+	}()
+
+	c := &Client{
+		Dial: func(addr string) (net.Conn, error) {
+			return ln.Dial()
+		},
+		ReadTimeout:               time.Millisecond * 10,
+		MaxIdemponentCallAttempts: 1,
+	}
+
+	req := AcquireRequest()
+	req.SetRequestURI("http://127.0.0.1:7070")
+	req.Header.SetMethod(MethodHead)
+
+	resp := AcquireResponse()
+
+	err := c.Do(req, resp)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// The second request on the same connection is going to give a timeout as it can't find
+	// a proper request in what is left on the connection.
+	err = c.Do(req, resp)
+	if err == nil {
+		t.Error("expected timeout error")
+	} else if err != ErrTimeout {
+		t.Error(err)
+	}
+}

header_test.go

@@ -2961,6 +2961,8 @@ func verifyRequestHeader(t *testing.T, h *RequestHeader, expectedContentLength i
 }
 
 func verifyResponseTrailer(t *testing.T, h *ResponseHeader, expectedTrailers map[string]string) {
+	t.Helper()
+
 	for k, v := range expectedTrailers {
 		got := h.Peek(k)
 		if !bytes.Equal(got, []byte(v)) {

http.go

@@ -1446,7 +1446,8 @@ func (resp *Response) ReadLimitBody(r *bufio.Reader, maxBodySize int) error {
 		}
 	}
 
-	if resp.Header.ContentLength() == -1 && !resp.StreamBody {
+	// A response without a body can't have trailers.
+	if resp.Header.ContentLength() == -1 && !resp.StreamBody && !resp.mustSkipBody() {
 		err = resp.Header.ReadTrailer(r)
 		if err != nil && err != io.EOF {
 			if isConnectionReset(err) {

http_test.go

@@ -2021,25 +2021,27 @@ func TestResponseReadWithoutBody(t *testing.T) {
 	var resp Response
 
 	testResponseReadWithoutBody(t, &resp, "HTTP/1.1 304 Not Modified\r\nContent-Type: aa\r\nContent-Length: 1235\r\n\r\n", false,
-		304, 1235, "aa", nil)
+		304, 1235, "aa")
 
-	testResponseReadWithoutBody(t, &resp, "HTTP/1.1 204 Foo Bar\r\nContent-Type: aab\r\nTransfer-Encoding: chunked\r\n\r\n0\r\nFoo: bar\r\n\r\n", false,
-		204, -1, "aab", map[string]string{"Foo": "bar"})
+	testResponseReadWithoutBody(t, &resp, "HTTP/1.1 204 Foo Bar\r\nContent-Type: aab\r\nTransfer-Encoding: chunked\r\n\r\n0\r\n\r\n", false,
+		204, -1, "aab")
 
 	testResponseReadWithoutBody(t, &resp, "HTTP/1.1 123 AAA\r\nContent-Type: xxx\r\nContent-Length: 3434\r\n\r\n", false,
-		123, 3434, "xxx", nil)
+		123, 3434, "xxx")
 
 	testResponseReadWithoutBody(t, &resp, "HTTP 200 OK\r\nContent-Type: text/xml\r\nContent-Length: 123\r\n\r\nfoobar\r\n", true,
-		200, 123, "text/xml", nil)
+		200, 123, "text/xml")
 
 	// '100 Continue' must be skipped.
 	testResponseReadWithoutBody(t, &resp, "HTTP/1.1 100 Continue\r\nFoo-bar: baz\r\n\r\nHTTP/1.1 329 aaa\r\nContent-Type: qwe\r\nContent-Length: 894\r\n\r\n", true,
-		329, 894, "qwe", nil)
+		329, 894, "qwe")
 }
 
 func testResponseReadWithoutBody(t *testing.T, resp *Response, s string, skipBody bool,
-	expectedStatusCode, expectedContentLength int, expectedContentType string, expectedTrailer map[string]string,
+	expectedStatusCode, expectedContentLength int, expectedContentType string,
 ) {
+	t.Helper()
+
 	r := bytes.NewBufferString(s)
 	rb := bufio.NewReader(r)
 	resp.SkipBody = skipBody
@@ -2051,7 +2053,6 @@ func testResponseReadWithoutBody(t *testing.T, resp *Response, s string, skipBod
 		t.Fatalf("Unexpected response body %q. Expected %q. response=%q", resp.Body(), "", s)
 	}
 	verifyResponseHeader(t, &resp.Header, expectedStatusCode, expectedContentLength, expectedContentType, "")
-	verifyResponseTrailer(t, &resp.Header, expectedTrailer)
 
 	// verify that ordinal response is read after null-body response
 	resp.SkipBody = false