1 files changed, 20 insertions, 5 deletions

diff --git a/clang/lib/Sema/SemaDeclCXX.cpp b/clang/lib/Sema/SemaDeclCXX.cpp
index cc50e6c1d99..c31ec7deef7 100644
--- a/clang/lib/Sema/SemaDeclCXX.cpp
+++ b/clang/lib/Sema/SemaDeclCXX.cpp
@@ -10164,19 +10164,34 @@ struct DeclaringSpecialMember {
   bool WasAlreadyBeingDeclared;
 
   DeclaringSpecialMember(Sema &S, CXXRecordDecl *RD, Sema::CXXSpecialMember CSM)
-    : S(S), D(RD, CSM), SavedContext(S, RD) {
+      : S(S), D(RD, CSM), SavedContext(S, RD) {
     WasAlreadyBeingDeclared = !S.SpecialMembersBeingDeclared.insert(D).second;
     if (WasAlreadyBeingDeclared)
       // This almost never happens, but if it does, ensure that our cache
       // doesn't contain a stale result.
       S.SpecialMemberCache.clear();
-
-    // FIXME: Register a note to be produced if we encounter an error while
-    // declaring the special member.
+    else {
+      // Register a note to be produced if we encounter an error while
+      // declaring the special member.
+      Sema::CodeSynthesisContext Ctx;
+      Ctx.Kind = Sema::CodeSynthesisContext::DeclaringSpecialMember;
+      // FIXME: We don't have a location to use here. Using the class's
+      // location maintains the fiction that we declare all special members
+      // with the class, but (1) it's not clear that lying about that helps our
+      // users understand what's going on, and (2) there may be outer contexts
+      // on the stack (some of which are relevant) and printing them exposes
+      // our lies.
+      Ctx.PointOfInstantiation = RD->getLocation();
+      Ctx.Entity = RD;
+      Ctx.SpecialMember = CSM;
+      S.pushCodeSynthesisContext(Ctx);
+    }
   }
   ~DeclaringSpecialMember() {
-    if (!WasAlreadyBeingDeclared)
+    if (!WasAlreadyBeingDeclared) {
       S.SpecialMembersBeingDeclared.erase(D);
+      S.popCodeSynthesisContext();
+    }
   }
 
   /// \brief Are we already trying to declare this special member?