[clang][Interp] Create global variables for TemplateParamObjectDecls

Author: tbaederr

clang/lib/AST/Interp/ByteCodeExprGen.cpp

@@ -3163,6 +3163,10 @@ bool ByteCodeExprGen<Emitter>::VisitDeclRefExpr(const DeclRefExpr *E) {
   } else if (const auto *FuncDecl = dyn_cast<FunctionDecl>(D)) {
     const Function *F = getFunction(FuncDecl);
     return F && this->emitGetFnPtr(F, E);
+  } else if (isa<TemplateParamObjectDecl>(D)) {
+    if (std::optional<unsigned> Index = P.getOrCreateGlobal(D))
+      return this->emitGetPtrGlobal(*Index, E);
+    return false;
   }
 
   // References are implemented via pointers, so when we see a DeclRefExpr

clang/test/AST/Interp/lambda.cpp

@@ -213,3 +213,15 @@ namespace ThisCapture {
   static_assert(F.a == 33, "");
   static_assert(F.Aplus2() == (33 + 2), "");
 }
+
+namespace GH62611 {
+  template <auto A = [](auto x){}>
+  struct C {
+    static constexpr auto B = A;
+  };
+
+  int test() {
+    C<>::B(42);
+    return 0;
+  }
+}