Revert "[Bounds-Safety] Temporarily relax a `counted_by` attribute restriction on flexible array members"

Together with 0ec3b972e58bcbcdc1bebe1696ea37f2931287c3
breaks https://lab.llvm.org/buildbot/#/builders/5/builds/43403

Issue #92687

This reverts commit cef6387e52578366c2332275dad88b9953b55336.

1 files changed, 2 insertions, 15 deletions

diff --git a/clang/lib/Sema/SemaDeclAttr.cpp b/clang/lib/Sema/SemaDeclAttr.cpp
index e816ea3..c8b7163 100644
--- a/clang/lib/Sema/SemaDeclAttr.cpp
+++ b/clang/lib/Sema/SemaDeclAttr.cpp
@@ -8687,7 +8687,6 @@ static bool CheckCountedByAttrOnField(
   // Note: The `Decl::isFlexibleArrayMemberLike` check earlier on means
   // only `PointeeTy->isStructureTypeWithFlexibleArrayMember()` is reachable
   // when `FieldTy->isArrayType()`.
-  bool ShouldWarn = false;
   if (PointeeTy->isIncompleteType()) {
     InvalidTypeKind = CountedByInvalidPointeeTypeKind::INCOMPLETE;
   } else if (PointeeTy->isSizelessType()) {
@@ -8695,25 +8694,13 @@ static bool CheckCountedByAttrOnField(
   } else if (PointeeTy->isFunctionType()) {
     InvalidTypeKind = CountedByInvalidPointeeTypeKind::FUNCTION;
   } else if (PointeeTy->isStructureTypeWithFlexibleArrayMember()) {
-    if (FieldTy->isArrayType()) {
-      // This is a workaround for the Linux kernel that has already adopted
-      // `counted_by` on a FAM where the pointee is a struct with a FAM. This
-      // should be an error because computing the bounds of the array cannot be
-      // done correctly without manually traversing every struct object in the
-      // array at runtime. To allow the code to be built this error is
-      // downgraded to a warning.
-      ShouldWarn = true;
-    }
     InvalidTypeKind = CountedByInvalidPointeeTypeKind::FLEXIBLE_ARRAY_MEMBER;
   }
 
   if (InvalidTypeKind != CountedByInvalidPointeeTypeKind::VALID) {
-    unsigned DiagID = ShouldWarn
-                          ? diag::warn_counted_by_attr_elt_type_unknown_size
-                          : diag::err_counted_by_attr_pointee_unknown_size;
-    S.Diag(FD->getBeginLoc(), DiagID)
+    S.Diag(FD->getBeginLoc(), diag::err_counted_by_attr_pointee_unknown_size)
         << SelectPtrOrArr << PointeeTy << (int)InvalidTypeKind
-        << (ShouldWarn ? 1 : 0) << FD->getSourceRange();
+        << FD->getSourceRange();
     return true;
   }