Index: clang-tidy/misc/DefinitionsInHeadersCheck.cpp
===================================================================
--- clang-tidy/misc/DefinitionsInHeadersCheck.cpp
+++ clang-tidy/misc/DefinitionsInHeadersCheck.cpp
@@ -72,6 +72,10 @@
 }
 
 void DefinitionsInHeadersCheck::check(const MatchFinder::MatchResult &Result) {
+  // Don't run the check in failing TUs.
+  if (Result.Context->getDiagnostics().hasErrorOccurred())
+    return;
+
   // C++ [basic.def.odr] p6:
   // There can be more than one definition of a class type, enumeration type,
   // inline function with external linkage, class template, non-static function