Merge pull request swiftlang#80413 from rintaro/macros-plugin-wait1

[Macros] Ensure to kill and reap plugin process

Author: rintaro

lib/AST/PluginRegistry.cpp

@@ -214,7 +214,13 @@ LoadedExecutablePlugin::PluginProcess::~PluginProcess() {
   close(input);
   close(output);
 #endif
-  llvm::sys::Wait(process, /*SecondsToWait=*/0);
+
+  // Set `SecondsToWait` non-zero so it waits for the timeout and kill it after
+  // that. Usually when the pipe is closed above, the plugin detects the EOF in
+  // the stdin and exits immediately, so this usually doesn't wait for the
+  // timeout. Note that we can't use '0' because it performs a non-blocking
+  // wait, which make the plugin a zombie if it hasn't exited.
+  llvm::sys::Wait(process, /*SecondsToWait=*/1);
 }
 
 ssize_t LoadedExecutablePlugin::PluginProcess::read(void *buf,