[flang-commits] [flang] [flang][Semantics] Break recursion on illegal recursive type in I/O check (PR #194284)

[Eugene Epshteyn via flang-commits]

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@@ -74,3 +74,82 @@ subroutine test4(u)
   end subroutine
 end module
 
+! Regression test: an illegal recursive derived-type component used to cause
+! infinite recursion in FindUnsafeIoDirectComponent when the object appeared
+! in an I/O list (issue #192387).
+subroutine test_recursive_io
+  type t1
+    !ERROR: Recursive use of the derived type requires POINTER or ALLOCATABLE
+    type(t1) :: b
+  end type t1
+  type(t1) :: obj
+  print *, obj
+end subroutine
+
+! Same regression covering the FindInaccessibleComponent walk: the type
+! must be defined in a module and used in I/O outside that module so the
+! recursive component traversal in FindInaccessibleComponent is reached.
+module m_recursive
+  type t2
+    !ERROR: Recursive use of the derived type requires POINTER or ALLOCATABLE
+    type(t2) :: b
+  end type t2
+end module
+subroutine test_recursive_io_module
+  use m_recursive
+  type(t2) :: obj
+  print *, obj
+end subroutine
+
+! Positive cases: a recursive type is legal when the recursive component
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eugeneepshteyn wrote:

I wanted to have some known good tests here to ensure that nothing got broken. I'm not sure if I need to check for "not failed" or just leave them as is.

https://github.com/llvm/llvm-project/pull/194284