[clang] Check (and disallow) "sizeless" vector types in CheckVectorOperands

Fixes #170279

Author: MacDue

clang/lib/Sema/SemaExpr.cpp

@@ -10363,6 +10363,11 @@ QualType Sema::CheckVectorOperands(ExprResult &LHS, ExprResult &RHS,
   QualType LHSType = LHS.get()->getType().getUnqualifiedType();
   QualType RHSType = RHS.get()->getType().getUnqualifiedType();
 
+  // Bail out if either vector is "sizeless". This is only supported in
+  // CheckSizelessVectorOperands.
+  if (LHSType->isSizelessVectorType() || RHSType->isSizelessVectorType())
+    return InvalidOperands(Loc, LHS, RHS);
+
   const VectorType *LHSVecType = LHSType->getAs<VectorType>();
   const VectorType *RHSVecType = RHSType->getAs<VectorType>();
   assert(LHSVecType || RHSVecType);

clang/test/Sema/AArch64/sve-vector-conditional-op.cpp

@@ -22,6 +22,16 @@ auto error_sve_vector_result_matched_element_count(__SVBool_t svbool, __SVUint32
   return svbool ? a : b;
 }
 
+auto error_fixed_cond_mixed_scalar_and_vector_operands(fixed_vector cond, unsigned char a, __SVUint8_t b) {
+  // expected-error@+1 {{invalid operands to binary expression ('unsigned char' and '__SVUint8_t')}}
+  return cond ? a : b;
+}
+
+auto error_scalable_cond_mixed_scalar_and_vector_operands(__SVBool_t svbool, unsigned char a, fixed_vector b) {
+  // expected-error@+1 {{cannot convert between vector and non-scalar values ('unsigned char' and 'fixed_vector' (vector of 1 'int' value))}}
+  return svbool ? a : b;
+}
+
 // The following cases should be supported:
 
 __SVBool_t cond_svbool(__SVBool_t a, __SVBool_t b) {