[Sema][SVE] Reject aligned/_Alignas for sizeless types
A previous patch rejected alignof for sizeless types. This patch
extends that to cover the "aligned" attribute and _Alignas. Since
sizeless types are not meant to be used for long-term data, cannot
be used in aggregates, and cannot have static storage duration,
there shouldn't be any need to fiddle with their alignment.
Like with alignof, this is a conservative position that can be
relaxed in future if it turns out to be too restrictive.
Differential Revision: https://reviews.llvm.org/D75573
diff --git a/clang/lib/Sema/SemaDeclAttr.cpp b/clang/lib/Sema/SemaDeclAttr.cpp
index 2e1710f..3385717 100644
--- a/clang/lib/Sema/SemaDeclAttr.cpp
+++ b/clang/lib/Sema/SemaDeclAttr.cpp
@@ -3868,6 +3868,7 @@
// not specify an alignment that is less strict than the alignment that
// would otherwise be required for the entity being declared.
AlignedAttr *AlignasAttr = nullptr;
+ AlignedAttr *LastAlignedAttr = nullptr;
unsigned Align = 0;
for (auto *I : D->specific_attrs<AlignedAttr>()) {
if (I->isAlignmentDependent())
@@ -3875,9 +3876,13 @@
if (I->isAlignas())
AlignasAttr = I;
Align = std::max(Align, I->getAlignment(Context));
+ LastAlignedAttr = I;
}
- if (AlignasAttr && Align) {
+ if (Align && DiagTy->isSizelessType()) {
+ Diag(LastAlignedAttr->getLocation(), diag::err_attribute_sizeless_type)
+ << LastAlignedAttr << DiagTy;
+ } else if (AlignasAttr && Align) {
CharUnits RequestedAlign = Context.toCharUnitsFromBits(Align);
CharUnits NaturalAlign = Context.getTypeAlignInChars(UnderlyingTy);
if (NaturalAlign > RequestedAlign)