[PATCH] Fortran: diagnose strings of non-constant length in DATA statements [PR68569]

[Harald Anlauf <anlauf@gmx.de>]

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Dear all,

the attached patch fixes an ICE-on-invalid after use of strings of
non-constant length in DATA statements.

Regtested on x86_64-pc-linux-gnu.  OK for mainline?

Thanks,
Harald


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From b5b13db48c169ef18a8b75739bd4f22f9fd5654e Mon Sep 17 00:00:00 2001
From: Harald Anlauf <anlauf@gmx.de>
Date: Wed, 26 Jul 2023 20:46:50 +0200
Subject: [PATCH] Fortran: diagnose strings of non-constant length in DATA
 statements [PR68569]

gcc/fortran/ChangeLog:

	PR fortran/68569
	* resolve.cc (check_data_variable): Do not accept strings with
	deferred length or non-constant length in a DATA statement.
	Reject also substrings of string variables of non-constant length.

gcc/testsuite/ChangeLog:

	PR fortran/68569
	* gfortran.dg/data_char_6.f90: New test.
---
 gcc/fortran/resolve.cc                    | 22 ++++++++++++++++++-
 gcc/testsuite/gfortran.dg/data_char_6.f90 | 26 +++++++++++++++++++++++
 2 files changed, 47 insertions(+), 1 deletion(-)
 create mode 100644 gcc/testsuite/gfortran.dg/data_char_6.f90

diff --git a/gcc/fortran/resolve.cc b/gcc/fortran/resolve.cc
index f7cfdfc133f..3cd470ddcca 100644
--- a/gcc/fortran/resolve.cc
+++ b/gcc/fortran/resolve.cc
@@ -16771,7 +16771,6 @@ check_data_variable (gfc_data_variable *var, locus *where)
     return false;

   ar = NULL;
-  mpz_init_set_si (offset, 0);
   e = var->expr;

   if (e->expr_type == EXPR_FUNCTION && e->value.function.isym
@@ -16838,8 +16837,24 @@ check_data_variable (gfc_data_variable *var, locus *where)
 		     "attribute", ref->u.c.component->name, &e->where);
 	  return false;
 	}
+
+      /* Reject substrings of strings of non-constant length.  */
+      if (ref->type == REF_SUBSTRING
+	  && ref->u.ss.length
+	  && ref->u.ss.length->length
+	  && !gfc_is_constant_expr (ref->u.ss.length->length))
+	goto bad_charlen;
     }

+  /* Reject strings with deferred length or non-constant length.  */
+  if (e->ts.type == BT_CHARACTER
+      && (e->ts.deferred
+	  || (e->ts.u.cl->length
+	      && !gfc_is_constant_expr (e->ts.u.cl->length))))
+    goto bad_charlen;
+
+  mpz_init_set_si (offset, 0);
+
   if (e->rank == 0 || has_pointer)
     {
       mpz_init_set_ui (size, 1);
@@ -16967,6 +16982,11 @@ check_data_variable (gfc_data_variable *var, locus *where)
   mpz_clear (offset);

   return t;
+
+bad_charlen:
+  gfc_error ("Non-constant character length at %L in DATA statement",
+	     &e->where);
+  return false;
 }


diff --git a/gcc/testsuite/gfortran.dg/data_char_6.f90 b/gcc/testsuite/gfortran.dg/data_char_6.f90
new file mode 100644
index 00000000000..4e32c647d4d
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/data_char_6.f90
@@ -0,0 +1,26 @@
+! { dg-do compile }
+! PR fortran/68569 - ICE with automatic character object and DATA
+! Contributed by G. Steinmetz
+
+subroutine s1 (n)
+  implicit none
+  integer, intent(in) :: n
+  character(n) :: x
+  data x /'a'/         ! { dg-error "Non-constant character length" }
+end
+
+subroutine s2 (n)
+  implicit none
+  integer, intent(in) :: n
+  character(n) :: x
+  data x(1:1) /'a'/    ! { dg-error "Non-constant character length" }
+end
+
+subroutine s3 ()
+  implicit none
+  type t
+     character(:) :: c ! { dg-error "must be a POINTER or ALLOCATABLE" }
+  end type t
+  type(t) :: tp
+  data tp%c /'a'/      ! { dg-error "Non-constant character length" }
+end
--
2.35.3