don't cancel tick thread in Windows on Arm

NEWS.md

@@ -1,5 +1,8 @@
 # cli (development version)
 
+* Fixed an issue where the R session could crash on exit when loading cli
+  when running with Windows on Arm. (#494; @kevinushey)
+
 * Vectors are truncated at 20 elements now by default, instead of 100 (#430).
 
 * 20 new spinners from the awesome

cli.Rproj

@@ -18,6 +18,5 @@ LineEndingConversion: Posix
 
 BuildType: Package
 PackageUseDevtools: Yes
-PackageCleanBeforeInstall: Yes
 PackageInstallArgs: --no-multiarch --with-keep.source
 PackageRoxygenize: rd,collate,namespace

src/thread.c

@@ -78,7 +78,22 @@ SEXP clic_start_thread(SEXP pkg, SEXP ticktime, SEXP speedtime) {
 }
 
 int cli__kill_thread() {
+
   int ret = 0;
+
+#ifdef _WIN32
+
+  // On ARM64 builds of Windows (when running through x86 emulation),
+  // cancelling the running tick thread seems to cause issues during
+  // process shutdown. Avoid the issue by just neglecting to cancel
+  // the thread altogether.
+  const char* arch = getenv("PROCESSOR_ARCHITECTURE");
+  if (!strcmp(arch, "ARM64")) {
+    return 0;
+  }
+
+#endif
+
   /* This should not happen, but be extra careful */
   if (tick_thread) {
     ret = pthread_cancel(tick_thread);