From a27d47bfae8c231891919c00ec2dfc92c59d764f Mon Sep 17 00:00:00 2001
From: Dan Katz <katzdm@gmail.com>
Date: Wed, 17 Jul 2024 09:22:33 -0400
Subject: [PATCH] Disallow splicing of unnamed bit-fields.

Closes issue #76.
---
 clang/include/clang/Basic/DiagnosticSemaKinds.td | 2 ++
 clang/lib/Sema/SemaReflect.cpp                   | 6 ++++++
 2 files changed, 8 insertions(+)

diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index fc7491fbcc3f9a..826bf8a5595fd5 100644
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -3132,6 +3132,8 @@ def err_splice_global_scope_as_namespace : Error<
 def err_member_access_splice_not_class_member : Error<
   "use of splice as qualified member access requires the reflection to be a "
   "member of a class">;
+def err_splice_unnamed_bit_field : Error<
+  "cannot splice a reflection of an unnamed bit-field">;
 def err_unsupported_splice_kind : Error<
   "splicing %0 %select{as template arguments is|is}1 %select{not|not yet}2 "
   "%select{supported|implemented}2">;
diff --git a/clang/lib/Sema/SemaReflect.cpp b/clang/lib/Sema/SemaReflect.cpp
index e11d95e8aa64c8..380e9afea6e99c 100644
--- a/clang/lib/Sema/SemaReflect.cpp
+++ b/clang/lib/Sema/SemaReflect.cpp
@@ -816,6 +816,12 @@ ExprResult Sema::BuildReflectionSpliceExpr(
         return ExprError();
       }
 
+      if (auto *FD = dyn_cast<FieldDecl>(TheDecl);
+          FD && FD->isUnnamedBitField()) {
+        Diag(Operand->getExprLoc(), diag::err_splice_unnamed_bit_field);
+        return ExprError();
+      }
+
       // Create a new DeclRefExpr, since the operand of the reflect expression
       // was parsed in an unevaluated context (but a splice expression is not
       // necessarily, and frequently not, in such a context).