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[committed] Fortran: Fix character(len=cst) dummies with bind(C) [PR102885] (erratum: should be: 'len=noncst')

Message ID 14c3ac17-0bb1-f36c-5d3c-500a1290ffee@codesourcery.com
State New
Headers show
Series [committed] Fortran: Fix character(len=cst) dummies with bind(C) [PR102885] (erratum: should be: 'len=noncst') | expand

Commit Message

Tobias Burnus Oct. 26, 2021, 9:04 a.m. UTC 
I forgot to handle len=<nonconst> correctly. This patch does the
same as for non-BIND(C). In the latter case, the call is:

   gfc_generate_function_code → gfc_trans_deferred_vars → gfc_trans_deferred_array

and that function has

   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);
     }

Expect a déjà vu if you read the attached patch ...

Thanks to Dominique for testing with -flto and finding this issue
and to Richard for helping me to understand what goes wrong.

Committed as obvious as r12-4703.

Tobias
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Patch

commit a31a3d0421f0cf1f7eefacfec8cbf37e7f91600d
Author: Tobias Burnus <tobias@codesourcery.com>
Date:   Tue Oct 26 10:53:53 2021 +0200

    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                        |  7 ++++
 gcc/testsuite/gfortran.dg/lto/bind-c-char_0.f90 | 49 +++++++++++++++++++++++++
 2 files changed, 56 insertions(+)

diff --git a/gcc/fortran/trans-decl.c b/gcc/fortran/trans-decl.c
index fe5511b5285..49ba9060eae 100644
--- a/gcc/fortran/trans-decl.c
+++ b/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. */
diff --git a/gcc/testsuite/gfortran.dg/lto/bind-c-char_0.f90 b/gcc/testsuite/gfortran.dg/lto/bind-c-char_0.f90
new file mode 100644
index 00000000000..48b495b1d29
--- /dev/null
+++ b/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