[clang] Correct MarkFunctionReferenced for local class

[futogergely]

Summary

Minor correction after commit 4a941e25f2b57f85eef00a9cbfbc2569639570ad.

If during the instantiation of a local class a method of the
local class is referenced, don't try to instantiate it.

PR48839

[futogergely]

formatting in instantiate-local-class.cpp

[futogergely]

clang-format

[futogergely]

ping

clang/lib/Sema/SemaExpr.cpp

runWithSufficientStackSpace(Loc, [&] {
             Func->setTemplateSpecializationKind(TSK, PointOfInstantiation);
         } else if (TSK != TSK_ImplicitInstantiation) {
           // Use the point of use as the point of instantiation, instead of the
           // point of explicit instantiation (which we track as the actual point
           // of instantiation). This gives better backtraces in diagnostics.
           PointOfInstantiation = Loc;
         }
 
+        const bool isLocalClass =
+            isa<CXXRecordDecl>(Func->getDeclContext()) &&
+            cast<CXXRecordDecl>(Func->getDeclContext())->isLocalClass();
         if (FirstInstantiation || TSK != TSK_ImplicitInstantiation ||
-            Func->isConstexpr()) {
-          if (isa<CXXRecordDecl>(Func->getDeclContext()) &&
-              cast<CXXRecordDecl>(Func->getDeclContext())->isLocalClass() &&
+            (!isLocalClass && Func->isConstexpr())) {
+          if (isLocalClass &&
               CodeSynthesisContexts.size())
             PendingLocalImplicitInstantiations.push_back(
                 std::make_pair(Func, PointOfInstantiation));
           else if (Func->isConstexpr())
             // Do not defer instantiations of constexpr functions, to avoid the
             // expression evaluator needing to call back into Sema if it sees a
             // call to such a function.
             InstantiateFunctionDefinition(PointOfInstantiation, Func);

clang/test/SemaTemplate/instantiate-local-class.cpp

 namespace LambdaInDefaultMemberInitializer {
   template<typename T> void f() {
     struct S {
       void *p = [this] { return &p; }();
     };
   }
   template void f<int>();
 }
+
+namespace PR48839 {
+  template <typename T>
+  void construct() {
+    T(0);
+  }
+
+  template <typename T>
+  void tester() {
+    struct d {
+      void test() {
+        construct<d>();
+    }
+    constexpr d(T b) : a(b) {}
+
+    T a;
+    };
+  }
+
+  void g() { tester<int>(); }
+}