[flang] Fix code that deletes unit from bad OPEN

[klausler]

When an OPEN statement fails, a unit that was created for the OPEN needs to be removed from the unit map. The code that tried to do this was incorrect -- it needs to re-acquire the unit via LookUpForClose as a CLOSE statement does. (The failure to do this completely was leaving a zombie unit active that could break a later OPEN on the same unit number.)

[llvmbot]

@llvm/pr-subscribers-flang-runtime

Author: Peter Klausler (klausler)

Changes

When an OPEN statement fails, a unit that was created for the OPEN needs to be removed from the unit map. The code that tried to do this was incorrect -- it needs to re-acquire the unit via LookUpForClose as a CLOSE statement does. (The failure to do this completely was leaving a zombie unit active that could break a later OPEN on the same unit number.)

---

Full diff: https://github.com/llvm/llvm-project/pull/108994.diff

1 Files Affected:

• (modified) flang/runtime/io-stmt.cpp (+5-2)

diff --git a/flang/runtime/io-stmt.cpp b/flang/runtime/io-stmt.cpp
index 265bd0dc9d9499..cd7a196335d31e 100644
--- a/flang/runtime/io-stmt.cpp
+++ b/flang/runtime/io-stmt.cpp
@@ -329,8 +329,11 @@ void OpenStatementState::CompleteOperation() {
   }
   if (!wasExtant_ && InError()) {
     // Release the new unit on failure
-    unit().CloseUnit(CloseStatus::Delete, *this);
-    unit().DestroyClosed();
+    if (ExternalFileUnit *
+        toClose{unit().LookUpForClose(unit().unitNumber())}) {
+      toClose->Close(CloseStatus::Delete, *this);
+      toClose->DestroyClosed();
+    }
   }
   IoStatementBase::CompleteOperation();
 }

[jeanPerier]

LGTM