[clang] 5edde18 - [clang][bytecode] Reject non-blockpointer destinations in __builtin_wmemcpy (#232327)

[via cfe-commits]

Author: Timm Baeder
Date: 2026-10-16T07:10:11+02:00
New Revision: 5edde18bf08af1e31efbdc7769bb1a1e49d81798

URL: https://github.com/llvm/llvm-project/commit/5edde18bf08af1e31efbdc7769bb1a1e49d81798
DIFF: https://github.com/llvm/llvm-project/commit/5edde18bf08af1e31efbdc7769bb1a1e49d81798.diff

LOG: [clang][bytecode] Reject non-blockpointer destinations in __builtin_wmemcpy (#232327)

Added: 
    

Modified: 
    clang/lib/AST/ByteCode/InterpBuiltin.cpp
    clang/test/AST/ByteCode/builtin-functions.cpp

Removed: 
    


################################################################################
diff  --git a/clang/lib/AST/ByteCode/InterpBuiltin.cpp b/clang/lib/AST/ByteCode/InterpBuiltin.cpp
index 382a908272849..d73ad308b0c0f 100644
--- a/clang/lib/AST/ByteCode/InterpBuiltin.cpp
+++ b/clang/lib/AST/ByteCode/InterpBuiltin.cpp
@@ -200,6 +200,15 @@ static void diagnoseNonConstexprBuiltin(InterpState &S, CodePtr OpPC,
     S.CCEDiag(Loc, diag::note_invalid_subexpr_in_const_expr);
 }
 
+static bool diagnoseUnreadableObject(InterpState &S, CodePtr OpPC,
+                                     const Pointer &Ptr, AccessKinds AK) {
+  S.FFDiag(S.Current->getSource(OpPC),
+           diag::note_constexpr_access_unreadable_object)
+      << AK << Ptr.toDiagnosticString(S.getASTContext());
+  noteValueLocation(S, Ptr);
+  return false;
+}
+
 static llvm::APSInt convertBoolVectorToInt(const Pointer &Val) {
   assert(Val.getFieldDesc()->isPrimitiveArray() &&
          Val.getFieldDesc()->getElemQualType()->isBooleanType() &&
@@ -2029,7 +2038,10 @@ static bool interp__builtin_memcpy(InterpState &S, CodePtr OpPC,
     return false;
   }
 
-  if (!isReadable(DestPtr) || !isReadable(SrcPtr))
+  if (!DestPtr.isBlockPointer())
+    return diagnoseUnreadableObject(S, OpPC, DestPtr, AK_Assign);
+
+  if (!isReadable(SrcPtr))
     return false;
 
   if (DestPtr.getType()->isIncompleteType()) {
@@ -2531,13 +2543,8 @@ static bool interp__builtin_is_within_lifetime(InterpState &S, CodePtr OpPC,
       return false;
   }
 
-  if (!Ptr.isBlockPointer()) {
-    S.FFDiag(S.Current->getSource(OpPC),
-             diag::note_constexpr_access_unreadable_object)
-        << AK_Read << Ptr.toDiagnosticString(S.getASTContext());
-    noteValueLocation(S, Ptr);
-    return false;
-  }
+  if (!Ptr.isBlockPointer())
+    return diagnoseUnreadableObject(S, OpPC, Ptr, AK_Read);
 
   // Check if we're currently running an initializer.
   if (S.initializingBlock(Ptr.block()))

diff  --git a/clang/test/AST/ByteCode/builtin-functions.cpp b/clang/test/AST/ByteCode/builtin-functions.cpp
index 802207e1e6e4e..9077a14324b7f 100644
--- a/clang/test/AST/ByteCode/builtin-functions.cpp
+++ b/clang/test/AST/ByteCode/builtin-functions.cpp
@@ -1911,6 +1911,11 @@ namespace WMemCpy {
                                                                     // both-note {{source of 'wmemcpy' is nullptr}}
   static_assert(__builtin_wmemcpy(null, &global, sizeof(wchar_t))); // both-error {{}} \
                                                                     // both-note {{destination of 'wmemcpy' is nullptr}}
+
+  static_assert(__builtin_wmemcpy(L"foobar", L"bazqux", 6), ""); // both-warning {{conversion from string literal}} \
+                                                                 // both-error {{}} \
+                                                                 // both-note {{assignment to object}} \
+                                                                 // both-note {{temporary created here}}
 }
 
 namespace WMemMove {