3 files changed, 36 insertions, 5 deletions
diff --git a/clang/lib/Basic/Diagnostic.cpp b/clang/lib/Basic/Diagnostic.cpp
index 6bdef78c074..c355445dc1e 100644
--- a/clang/lib/Basic/Diagnostic.cpp
+++ b/clang/lib/Basic/Diagnostic.cpp
@@ -146,10 +146,9 @@ void DiagnosticsEngine::SetDelayedDiagnostic(unsigned DiagID, StringRef Arg1,
 }
 
 void DiagnosticsEngine::ReportDelayed() {
-  Report(DelayedDiagID) << DelayedDiagArg1 << DelayedDiagArg2;
+  unsigned ID = DelayedDiagID;
   DelayedDiagID = 0;
-  DelayedDiagArg1.clear();
-  DelayedDiagArg2.clear();
+  Report(ID) << DelayedDiagArg1 << DelayedDiagArg2;
 }
 
 void DiagnosticsEngine::DiagStateMap::appendFirst(
@@ -420,11 +419,10 @@ bool DiagnosticsEngine::EmitCurrentDiagnostic(bool Force) {
   }
 
   // Clear out the current diagnostic object.
-  unsigned DiagID = CurDiagID;
   Clear();
 
   // If there was a delayed diagnostic, emit it now.
-  if (!Force && DelayedDiagID && DelayedDiagID != DiagID)
+  if (!Force && DelayedDiagID)
     ReportDelayed();
 
   return Emitted;
diff --git a/clang/lib/Basic/DiagnosticIDs.cpp b/clang/lib/Basic/DiagnosticIDs.cpp
index 2852b40026c..ce493c1e5ca 100644
--- a/clang/lib/Basic/DiagnosticIDs.cpp
+++ b/clang/lib/Basic/DiagnosticIDs.cpp
@@ -666,6 +666,10 @@ bool DiagnosticIDs::ProcessDiag(DiagnosticsEngine &Diag) const {
     }
   }
 
+  // Make sure we set FatalErrorOccurred to ensure that the notes from the
+  // diagnostic that caused `fatal_too_many_errors` won't be emitted.
+  if (Diag.CurDiagID == diag::fatal_too_many_errors)
+    Diag.FatalErrorOccurred = true;
   // Finally, report it.
   EmitDiag(Diag, DiagLevel);
   return true;
diff --git a/clang/test/Index/KeepGoingWithLotsOfErrors.mm b/clang/test/Index/KeepGoingWithLotsOfErrors.mm
new file mode 100644
index 00000000000..078ea6e2ea1
--- /dev/null
+++ b/clang/test/Index/KeepGoingWithLotsOfErrors.mm
@@ -0,0 +1,29 @@
+// RUN: env CINDEXTEST_KEEP_GOING=1 c-index-test -code-completion-at=%s:25:1 %s
+// Shouldn't crash!
+// This is the minimized test that triggered an infinite recursion:
+
++(BOOL) onEntity {
+}
+
+-(const Object &) a_200 {
+}
+
+-(int) struct {
+}
+
+-(int) bar {
+}
+
+-(int) part {
+}
+
++(some_type_t) piece {
+}
+
++(void) z_Z_42 {
+  ([self onEntity: [] { 42];
+  } class: ^ {  }
+];
+  [super];
+  BOOL struct;
+}