[flang] harden TypeAndShape for assumed-ranks (#96234)

SIZEOF and C_SIZEOF were broken for assumed-ranks because
`TypeAndShape::MeasureSizeInBytes` behaved as a scalar because the
`TypeAndShape::shape_` member was the same for scalar and assumed-ranks.

The easy fix would have been to add special handling in
`MeasureSizeInBytes` for assumed-ranks using the TypeAndShape
attributes, but I think this solution would leave `TypeAndShape::shape_`
manipulation fragile to future developers. Hence, I went for the
solution that turn shape_ into a `std::optional<Shape>`.

1 files changed, 2 insertions, 2 deletions

diff --git a/flang/lib/Semantics/pointer-assignment.cpp b/flang/lib/Semantics/pointer-assignment.cpp
index 0770720..a5c3897 100644
--- a/flang/lib/Semantics/pointer-assignment.cpp
+++ b/flang/lib/Semantics/pointer-assignment.cpp
@@ -333,8 +333,8 @@ bool PointerAssignmentChecker::Check(const evaluate::Designator<T> &d) {
 
       } else if (!isBoundsRemapping_ &&
           !lhsType_->attrs().test(TypeAndShape::Attr::AssumedRank)) {
-        int lhsRank{evaluate::GetRank(lhsType_->shape())};
-        int rhsRank{evaluate::GetRank(rhsType->shape())};
+        int lhsRank{lhsType_->Rank()};
+        int rhsRank{rhsType->Rank()};
         if (lhsRank != rhsRank) {
           msg = MessageFormattedText{
               "Pointer has rank %d but target has rank %d"_err_en_US, lhsRank,