Fortran: Fix character(len=cst) dummies with bind(C) [PR102885]

PR fortran/102885

gcc/fortran/ChangeLog:

	* trans-decl.c (gfc_conv_cfi_to_gfc): Properly handle nonconstant
	character lenghts.

gcc/testsuite/ChangeLog:

	* gfortran.dg/lto/bind-c-char_0.f90: New test.

gcc/fortran/trans-decl.c

@@ -6837,6 +6837,13 @@ gfc_conv_cfi_to_gfc (stmtblock_t *init, stmtblock_t *finally,
       gfc_add_modify (&block, sym->ts.u.cl->backend_decl, tmp);
     }
 
+  if (sym->ts.type == BT_CHARACTER
+      && !INTEGER_CST_P (sym->ts.u.cl->backend_decl))
+    {
+      gfc_conv_string_length (sym->ts.u.cl, NULL, init);
+      gfc_trans_vla_type_sizes (sym, init);
+    }
+
   /* gfc->data = cfi->base_addr - or for scalars: gfc = cfi->base_addr.
      assumed-size/explicit-size arrays end up here for character(len=*)
      only. */

gcc/testsuite/gfortran.dg/lto/bind-c-char_0.f90

@@ -0,0 +1,49 @@
+! { dg-lto-do link }
+! { dg-lto-options {{ -O0 -flto }} }
+!
+! PR fortran/102885
+
+module m
+  use iso_c_binding, only: c_char
+  implicit none (type, external)
+
+contains
+
+! Assumed-shape array, nonallocatable/nonpointer
+
+subroutine ar3 (xn, n) bind(C)
+  integer :: n
+  character(len=n) :: xn(..)
+  if (size(xn) /= 6) stop
+  if (len(xn) /= 5) stop  
+  select rank(xn)
+    rank(1)
+      xn = ['FDGhf', &
+            'hdrhg', &
+            'fDgFl', &
+            'DFHs3', &
+            '4a54G', &
+            'hSs6k']
+  rank default
+    stop
+  end select
+end
+
+end
+
+program main
+  use m
+  implicit none (type, external)
+  character(kind=c_char, len=5) :: str5a6(6)
+
+  ! assumed rank - with array descriptor
+
+  str5a6 = ['DDGhf', &
+            'hdrh$', &
+            'fDGSl', &
+            'DFHs3', &
+            '43grG', &
+            'hFG$k']
+  call ar3 (str5a6, 5)
+
+end