Check a restart exists before invoking it

Author: lionel-

DESCRIPTION

@@ -1,5 +1,5 @@
 Package: rlang
-Version: 0.4.0.9001
+Version: 0.4.0.9002
 Title: Functions for Base Types and Core R and 'Tidyverse' Features
 Description: A toolbox for working with base types, core R features
   like the condition system, and core 'Tidyverse' features like tidy

NEWS.md

@@ -1,6 +1,10 @@
 
 # rlang (development)
 
+* `cnd_muffle()` now checks that a restart exists before invoking
+  it. The restart might not exist if the condition is signalled with a
+  different function (such as `stop(warning_cnd)`).
+
 * `trace_length()` returns the number of frames in a backtrace.
 
 * Added internal utility `cnd_entrace()` to add a backtrace to a

R/cnd.R

@@ -499,13 +499,17 @@ interrupt <- function() {
 #'   my_particular_msg = calling(cnd_muffle)
 #' )
 cnd_muffle <- function(cnd) {
-  switch(cnd_type(cnd),
-    message = invokeRestart("muffleMessage"),
-    warning = invokeRestart("muffleWarning"),
-    interrupt = invokeRestart("resume"),
-    invokeRestart("rlang_muffle")
+  restart <- switch(cnd_type(cnd),
+    message = "muffleMessage",
+    warning = "muffleWarning",
+    interrupt = "resume",
+    "rlang_muffle"
   )
 
+  if (!is_null(findRestart(restart))) {
+    invokeRestart(restart)
+  }
+
   abort("Can't find a muffling restart")
 }