Re: [PATCH] PR fortran/99205 - [10/11 Regression] Out of memory with undefined character length

[Harald Anlauf <anlauf@gmx.de>]

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Dear Tobias, all,

> The reason that it is not permitted is the "automatic data object"
> (see *...* highlighted parts in the quote):
>
> C876   (R839) A *variable* whose *designator* appears as a
> *data-stmt-object* or a data-i-do-object hall not be a
> dummy argument, accessed by use or host association,
> in a named common block unless the DATA statement is
> in a block data program unit, in blank common, a function name,
> a function result name, an *automatic* *data* *object,*
> or an allocatable variable.
>
> With the definition: "3.11 automatic data object
> nondummy data object with a type parameter or array bound that
> depends on the value of aspecification-expr that is not
> a constant expression (8.3)"

inspired by Tobias' (although invalid) code example I found another
testcase which lead to trouble during error recovery due to a NULL
pointer dereference.  Here's the updated changelog for the updated
patch (attached).  I also renamed the first testcase so that they
fit better to the existing scheme.

Again regtested on x86_64-pc-linux-gnu.  Now OK for mainline / 10?

Thanks,
Harald


PR fortran/99205 - Out of memory with undefined character length

A character variable appearing as a data statement object cannot
be automatic, thus it shall have constant length.

gcc/fortran/ChangeLog:

	PR fortran/99205
	* data.c (gfc_assign_data_value): Reject non-constant character
	length for lvalue.
	* trans-array.c (gfc_conv_array_initializer): Restrict loop to
	elements which are defined to avoid NULL pointer dereference.

gcc/testsuite/ChangeLog:

	PR fortran/99205
	* gfortran.dg/data_char_4.f90: New test.
	* gfortran.dg/data_char_5.f90: New test.


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diff --git a/gcc/fortran/data.c b/gcc/fortran/data.c
index 25e97930169..71e2552025d 100644
--- a/gcc/fortran/data.c
+++ b/gcc/fortran/data.c
@@ -595,6 +595,9 @@ gfc_assign_data_value (gfc_expr *lvalue, gfc_expr *rvalue, mpz_t index,
       /* An initializer has to be constant.  */
       if (lvalue->ts.u.cl->length == NULL && !(ref && ref->u.ss.length != NULL))
 	return false;
+      if (lvalue->ts.u.cl->length
+	  && lvalue->ts.u.cl->length->expr_type != EXPR_CONSTANT)
+	return false;
       expr = create_character_initializer (init, last_ts, ref, rvalue);
       if (!expr)
 	return false;
diff --git a/gcc/fortran/trans-array.c b/gcc/fortran/trans-array.c
index c6725659093..478cddda070 100644
--- a/gcc/fortran/trans-array.c
+++ b/gcc/fortran/trans-array.c
@@ -6162,7 +6162,7 @@ gfc_conv_array_initializer (tree type, gfc_expr * expr)
     case EXPR_ARRAY:
       /* Create a vector of all the elements.  */
       for (c = gfc_constructor_first (expr->value.constructor);
-	   c; c = gfc_constructor_next (c))
+	   c && c->expr; c = gfc_constructor_next (c))
         {
           if (c->iterator)
             {
diff --git a/gcc/testsuite/gfortran.dg/data_char_4.f90 b/gcc/testsuite/gfortran.dg/data_char_4.f90
new file mode 100644
index 00000000000..ed0782ce8a0
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/data_char_4.f90
@@ -0,0 +1,11 @@
+! { dg-do compile }
+! PR fortran/99205 - Out of memory with undefined character length
+! { dg-options "-w" }
+
+program p
+  character(l) :: c(2) ! { dg-error "must have constant character length" }
+  data c /'a', 'b'/
+  common c
+end
+
+! { dg-error "cannot appear in the expression at" " " { target *-*-* } 6 }
diff --git a/gcc/testsuite/gfortran.dg/data_char_5.f90 b/gcc/testsuite/gfortran.dg/data_char_5.f90
new file mode 100644
index 00000000000..ea26687e3d5
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/data_char_5.f90
@@ -0,0 +1,15 @@
+! { dg-do compile }
+! PR fortran/99205 - Issues with non-constant character length
+
+subroutine sub ()
+  integer :: ll = 4
+  block
+    character(ll) :: c(2) ! { dg-error "non-constant" }
+    data c /'a', 'b'/
+  end block
+contains
+  subroutine sub1 ()
+    character(ll) :: d(2) ! { dg-error "non-constant" }
+    data d /'a', 'b'/
+  end subroutine sub1
+end subroutine sub