re PR fortran/81735 (double free or corruption (fasttop) error (SIGABRT) with…

re PR fortran/81735 (double free or corruption (fasttop) error (SIGABRT) with character(:) and custom return type with allocatable)

2017-11-04  Paul Thomas  <pault@gcc.gnu.org>

	PR fortran/81735
	* trans-decl.c (gfc_trans_deferred_vars): Do a better job of a
	case where 'tmp' was used unititialized and remove TODO.

2017-11-04  Paul Thomas  <pault@gcc.gnu.org>

	PR fortran/81735
	* gfortran.dg/pr81735.f90: New test.

From-SVN: r254404

gcc/fortran/ChangeLog

+2017-11-04  Paul Thomas  <pault@gcc.gnu.org>
+
+	PR fortran/81735
+	* trans-decl.c (gfc_trans_deferred_vars): Do a better job of a
+	case where 'tmp' was used unititialized and remove TODO.
+
 2017-11-03  Steven G. Kargl  <kargl@gcc.gnu.org>
 
 	PR fortran/82796

gcc/fortran/trans-decl.c

@@ -4584,7 +4584,10 @@ gfc_trans_deferred_vars (gfc_symbol * proc_sym, gfc_wrapped_block * block)
 		    && sym->ts.u.cl->passed_length)
 		tmp = gfc_null_and_pass_deferred_len (sym, &init, &loc);
 	      else
-		gfc_restore_backend_locus (&loc);
+		{
+		  gfc_restore_backend_locus (&loc);
+		  tmp = NULL_TREE;
+		}
 
 	      /* Deallocate when leaving the scope. Nullifying is not
 		 needed.  */
@@ -4636,10 +4639,6 @@ gfc_trans_deferred_vars (gfc_symbol * proc_sym, gfc_wrapped_block * block)
 		}
 
 	      gfc_add_init_cleanup (block, gfc_finish_block (&init), tmp);
-	      /* TODO find out why this is necessary to stop double calls to
-		 free.  Somebody is reusing the expression in 'tmp' because
-		 it is being used unititialized.  */
-	      tmp = NULL_TREE;
 	    }
 	}
       else if (sym->ts.type == BT_CHARACTER && sym->ts.deferred)

gcc/testsuite/ChangeLog

+2017-11-04  Paul Thomas  <pault@gcc.gnu.org>
+
+	PR fortran/81735
+	* gfortran.dg/pr81735.f90: New test.
+
 2017-11-03  Steven G. Kargl  <kargl@gcc.gnu.org>
 
 	PR fortran/82796

gcc/testsuite/gfortran.dg/pr81735.f90

+! { dg-do compile }
+! { dg-options "-fdump-tree-original" }
+!
+! Contributed by Danila  <flashmozzg@gmail.com>
+!
+program fooprog
+    implicit none
+    type FooType
+        integer, allocatable :: x
+    end type FooType
+
+    type(FooType), pointer :: bar
+
+    bar => foo()
+
+contains
+    function foo() result(res)
+        type(FooType), pointer :: res
+
+        character(:), allocatable :: rt
+        rt = ""
+        res => null()
+    end function foo
+end program fooprog
+! { dg-final { scan-tree-dump-times "__builtin_free" 1 "original" } }