From cfca06d7963fa0909f90483b42a6d7d194d01e08 Mon Sep 17 00:00:00 2001
From: Dimitry Andric <dim@FreeBSD.org>
Date: Sun, 26 Jul 2020 19:36:28 +0000
Subject: Vendor import of llvm-project master 2e10b7a39b9, the last commit
 before the llvmorg-12-init tag, from which release/11.x was branched.

---
 .../DirectoryWatcher/mac/DirectoryWatcher-mac.cpp  | 53 +++++++++++++++-------
 1 file changed, 37 insertions(+), 16 deletions(-)

(limited to 'clang/lib/DirectoryWatcher/mac')

diff --git a/clang/lib/DirectoryWatcher/mac/DirectoryWatcher-mac.cpp b/clang/lib/DirectoryWatcher/mac/DirectoryWatcher-mac.cpp
index 7a60369a4da0a..bdc3895162898 100644
--- a/clang/lib/DirectoryWatcher/mac/DirectoryWatcher-mac.cpp
+++ b/clang/lib/DirectoryWatcher/mac/DirectoryWatcher-mac.cpp
@@ -14,10 +14,13 @@
 #include "llvm/Support/Error.h"
 #include "llvm/Support/Path.h"
 #include <CoreServices/CoreServices.h>
+#include <TargetConditionals.h>
 
 using namespace llvm;
 using namespace clang;
 
+#if TARGET_OS_OSX
+
 static void stopFSEventStream(FSEventStreamRef);
 
 namespace {
@@ -43,24 +46,32 @@ namespace {
 class DirectoryWatcherMac : public clang::DirectoryWatcher {
 public:
   DirectoryWatcherMac(
-      FSEventStreamRef EventStream,
+      dispatch_queue_t Queue, FSEventStreamRef EventStream,
       std::function<void(llvm::ArrayRef<DirectoryWatcher::Event>, bool)>
           Receiver,
       llvm::StringRef WatchedDirPath)
-      : EventStream(EventStream), Receiver(Receiver),
+      : Queue(Queue), EventStream(EventStream), Receiver(Receiver),
         WatchedDirPath(WatchedDirPath) {}
 
   ~DirectoryWatcherMac() override {
-    stopFSEventStream(EventStream);
-    EventStream = nullptr;
-    // Now it's safe to use Receiver as the only other concurrent use would have
-    // been in EventStream processing.
-    Receiver(DirectoryWatcher::Event(
-                 DirectoryWatcher::Event::EventKind::WatcherGotInvalidated, ""),
-             false);
+    // FSEventStreamStop and Invalidate must be called after Start and
+    // SetDispatchQueue to follow FSEvents API contract. The call to Receiver
+    // also uses Queue to not race with the initial scan.
+    dispatch_sync(Queue, ^{
+      stopFSEventStream(EventStream);
+      EventStream = nullptr;
+      Receiver(
+          DirectoryWatcher::Event(
+              DirectoryWatcher::Event::EventKind::WatcherGotInvalidated, ""),
+          false);
+    });
+
+    // Balance initial creation.
+    dispatch_release(Queue);
   }
 
 private:
+  dispatch_queue_t Queue;
   FSEventStreamRef EventStream;
   std::function<void(llvm::ArrayRef<Event>, bool)> Receiver;
   const std::string WatchedDirPath;
@@ -173,7 +184,7 @@ FSEventStreamRef createFSEventStream(
       if (::realpath(P.begin(), Buffer) != nullptr)
         RealPath = Buffer;
       else
-        RealPath = Path;
+        RealPath = Path.str();
     }
 
     FSEventStreamContext Context;
@@ -217,11 +228,11 @@ llvm::Expected<std::unique_ptr<DirectoryWatcher>> clang::DirectoryWatcher::creat
   assert(EventStream && "EventStream expected to be non-null");
 
   std::unique_ptr<DirectoryWatcher> Result =
-      std::make_unique<DirectoryWatcherMac>(EventStream, Receiver, Path);
+      std::make_unique<DirectoryWatcherMac>(Queue, EventStream, Receiver, Path);
 
   // We need to copy the data so the lifetime is ok after a const copy is made
   // for the block.
-  const std::string CopiedPath = Path;
+  const std::string CopiedPath = Path.str();
 
   auto InitWork = ^{
     // We need to start watching the directory before we start scanning in order
@@ -230,10 +241,6 @@ llvm::Expected<std::unique_ptr<DirectoryWatcher>> clang::DirectoryWatcher::creat
     // inital scan and handling events ONLY AFTER the scan finishes.
     FSEventStreamSetDispatchQueue(EventStream, Queue);
     FSEventStreamStart(EventStream);
-    // We need to decrement the ref count for Queue as initialize() will return
-    // and FSEvents has incremented it. Since we have to wait for FSEvents to
-    // take ownership it's the easiest to do it here rather than main thread.
-    dispatch_release(Queue);
     Receiver(getAsFileEvents(scanDirectory(CopiedPath)), /*IsInitial=*/true);
   };
 
@@ -245,3 +252,17 @@ llvm::Expected<std::unique_ptr<DirectoryWatcher>> clang::DirectoryWatcher::creat
 
   return Result;
 }
+
+#else // TARGET_OS_OSX
+
+llvm::Expected<std::unique_ptr<DirectoryWatcher>>
+clang::DirectoryWatcher::create(
+    StringRef Path,
+    std::function<void(llvm::ArrayRef<DirectoryWatcher::Event>, bool)> Receiver,
+    bool WaitForInitialSync) {
+  return llvm::make_error<llvm::StringError>(
+      "DirectoryWatcher is not implemented for this platform!",
+      llvm::inconvertibleErrorCode());
+}
+
+#endif // TARGET_OS_OSX
-- 
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