[flang-commits] [flang] [flang] Avoid crash on conflicting BIND(C) declaration (PR #231816)

[Eugene Epshteyn via flang-commits]

================
@@ -0,0 +1,8 @@
+! RUN: %python %S/test_errors.py %s %flang_fc1
+
+module bind_c_conflicting_type_name
+  type :: x
+  end type
+  !ERROR: 'x' is already declared in this scoping unit
+  integer, bind(c) :: x
+end module
----------------
eugeneepshteyn wrote:

(This comment was generated with the help of AI)

This pins only the derived-type case. The same path is taken whenever the name already belongs to anything that cannot carry a binding label, so please also cover the other kinds mentioned in the issue, a generic, a namelist group and a later module procedure, plus the array form as a control, in this same file:

```fortran
module m2
  interface g
  end interface
  !ERROR: 'g' is already declared in this scoping unit
  integer, bind(c) :: g
end

module m3
  integer :: a
  namelist /nl/ a
  !ERROR: 'nl' is already declared in this scoping unit
  integer, bind(c) :: nl
end

module m4
  !ERROR: Declaration of 's' conflicts with its use as module procedure
  integer, bind(c) :: s
contains
  subroutine s()
  end subroutine
end

module m5
  type :: t
  end type
  !ERROR: 't' is already declared in this scoping unit
  integer, bind(c) :: t(2)
end
```

The expected messages are the ones the compiler already prints for these declarations without `bind(c)`, and all of them pass with this PR applied.


https://github.com/llvm/llvm-project/pull/231816