diff --git a/clang/lib/Sema/SemaTemplateInstantiate.cpp b/clang/lib/Sema/SemaTemplateInstantiate.cpp
--- a/clang/lib/Sema/SemaTemplateInstantiate.cpp
+++ b/clang/lib/Sema/SemaTemplateInstantiate.cpp
@@ -1230,7 +1230,7 @@
 
       // We recreated a local declaration, but not by instantiating it. There
       // may be pending dependent diagnostics to produce.
-      if (auto *DC = dyn_cast<DeclContext>(Old))
+      if (auto *DC = dyn_cast<DeclContext>(Old); DC && DC->isDependentContext())
         SemaRef.PerformDependentDiagnostics(DC, TemplateArgs);
     }
 
diff --git a/clang/test/SemaCXX/lambda-unevaluated.cpp b/clang/test/SemaCXX/lambda-unevaluated.cpp
--- a/clang/test/SemaCXX/lambda-unevaluated.cpp
+++ b/clang/test/SemaCXX/lambda-unevaluated.cpp
@@ -144,3 +144,7 @@
 using d = decltype(sizeof([] static { return 0; }));
 
 }
+
+namespace lambda_in_trailing_decltype {
+auto x = ([](auto) -> decltype([] {}()) {}(0), 2);
+}