[flang-commits] [flang] [flang] Set SAVE attribute for EQUIVALENCEd symbols consistently. (PR #67078)

[Slava Zakharin via flang-commits]

================
@@ -2390,7 +2390,7 @@ Symbol &ScopeHandler::MakeHostAssocSymbol(
   // These attributes can be redundantly reapplied without error
   // on the host-associated name, at most once (C815).
   symbol.implicitAttrs() =
-      symbol.attrs() & Attrs{Attr::ASYNCHRONOUS, Attr::VOLATILE};
+      symbol.attrs() & Attrs{Attr::ASYNCHRONOUS, Attr::VOLATILE, Attr::SAVE};
----------------
vzakhari wrote:

I had to make this change to resolve the following issue:
```
subroutine host
  integer :: x = 1
  integer :: y
  common /blk/ y
  equivalence(x,y)
contains
  subroutine inner
    x = y
  end subroutine inner
end subroutine host
```

Without propagating to the host-associated symbol the fact that `SAVE` is implicit, I would get this error:
```
./save.f90:8:5: error: The entity 'x' in COMMON block /blk/ may not have an explicit SAVE attribute
      x = y
      ^
./save.f90:8:9: error: The entity 'y' in COMMON block /blk/ may not have an explicit SAVE attribute
      x = y
          ^
bbc: semantic errors in save.f90
```

As you said, explicit `SAVE` statement in a nested scope will create a new symbol, so this code should not affect this case.

https://github.com/llvm/llvm-project/pull/67078