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[Patch, Fortran] PR57697/58469 - Fix another defined-assignment issue


This patch fixes two issues:

a) It could happen that no code change has happened. In that case, the one freed an expression which still should be used.

b) In my previous patch, I used a pointer assignment to the temporary of the LHS (after its allocation) [only if the LHS was initially unassigned]. That lead to a problem with double deallocation (temporary + LHS). In the previous test case, it didn't matter as the LHS wasn't freed (implicit SAVE of in the main program). That's now solved by a NULL-pointer assignment.

Finally, I corrected some indenting issues and removed unreachable code.

Build and regtested on x86-64-gnu-linux.
OK for the trunk and the 4.8 branch?

Tobias

PS: For the testcase of (a), I am not quite sure whether the intrinsic assignment should invoke the defined assignment. It currently doesn't for gfortran and crayftn. In any case, the invalid freeing is wrong.
2013-09-19  Tobias Burnus  <burnus@net-b.de>

	PR fortran/57697
	PR fortran/58469
	* resolve.c (generate_component_assignments): Avoid double free
	at runtime and freeing a still-being used expr.

2013-09-19  Tobias Burnus  <burnus@net-b.de>

	PR fortran/57697
	PR fortran/58469
	* gfortran.dg/defined_assignment_8.f90: New.
	* gfortran.dg/defined_assignment_9.f90: New.

diff --git a/gcc/fortran/resolve.c b/gcc/fortran/resolve.c
index d33fe49..4befb9fd 100644
--- a/gcc/fortran/resolve.c
+++ b/gcc/fortran/resolve.c
@@ -9602,8 +9602,9 @@ generate_component_assignments (gfc_code **code, gfc_namespace *ns)
 		  && gfc_expr_attr ((*code)->expr1).allocatable)
 		{
 		  gfc_code *block;
-                  gfc_expr *cond;
-                  cond = gfc_get_expr ();
+		  gfc_expr *cond;
+
+		  cond = gfc_get_expr ();
 		  cond->ts.type = BT_LOGICAL;
 		  cond->ts.kind = gfc_default_logical_kind;
 		  cond->expr_type = EXPR_OP;
@@ -9621,7 +9622,7 @@ generate_component_assignments (gfc_code **code, gfc_namespace *ns)
 		  add_code_to_chain (&block, &head, &tail);
 		}
 	    }
-	  }
+	}
       else if (this_code->op == EXEC_ASSIGN && !this_code->next)
 	{
 	  /* Don't add intrinsic assignments since they are already
@@ -9643,13 +9644,6 @@ generate_component_assignments (gfc_code **code, gfc_namespace *ns)
 	}
     }
 
-  /* This is probably not necessary.  */
-  if (this_code)
-    {
-      gfc_free_statements (this_code);
-      this_code = NULL;
-    }
-
   /* Put the temporary assignments at the top of the generated code.  */
   if (tmp_head && component_assignment_level == 1)
     {
@@ -9658,6 +9652,28 @@ generate_component_assignments (gfc_code **code, gfc_namespace *ns)
       tmp_head = tmp_tail = NULL;
     }
 
+  // If we did a pointer assignment - thus, we need to ensure that the LHS is
+  // not accidentally deallocated. Hence, nullify t1.
+  if (t1 && (*code)->expr1->symtree->n.sym->attr.allocatable
+      && gfc_expr_attr ((*code)->expr1).allocatable)
+    {
+      gfc_code *block;
+      gfc_expr *cond;
+      gfc_expr *e;
+
+      e = gfc_lval_expr_from_sym ((*code)->expr1->symtree->n.sym);
+      cond = gfc_build_intrinsic_call (ns, GFC_ISYM_ASSOCIATED, "associated",
+				       (*code)->loc, 2, gfc_copy_expr (t1), e);
+      block = gfc_get_code (EXEC_IF);
+      block->block = gfc_get_code (EXEC_IF);
+      block->block->expr1 = cond;
+      block->block->next = build_assignment (EXEC_POINTER_ASSIGN,
+					t1, gfc_get_null_expr (&(*code)->loc),
+					NULL, NULL, (*code)->loc);
+      gfc_append_code (tail, block);
+      tail = block;
+    }
+
   /* Now attach the remaining code chain to the input code.  Step on
      to the end of the new code since resolution is complete.  */
   gcc_assert ((*code)->op == EXEC_ASSIGN);
@@ -9667,7 +9683,8 @@ generate_component_assignments (gfc_code **code, gfc_namespace *ns)
   gfc_free_expr ((*code)->expr1);
   gfc_free_expr ((*code)->expr2);
   **code = *head;
-  free (head);
+  if (head != tail)
+    free (head);
   *code = tail;
 
   component_assignment_level--;
diff --git a/gcc/testsuite/gfortran.dg/defined_assignment_8.f90 b/gcc/testsuite/gfortran.dg/defined_assignment_8.f90
new file mode 100644
index 0000000..aab8085
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/defined_assignment_8.f90
@@ -0,0 +1,40 @@
+! { dg-do compile }
+!
+! PR fortran/58469
+!
+! Related: PR fortran/57697
+!
+! Was ICEing before
+!
+module m0
+  implicit none
+  type :: component
+    integer :: i = 42
+  contains
+    procedure :: assign0
+    generic :: assignment(=) => assign0
+  end type
+  type, extends(component) :: comp2
+    real :: aa
+  end type comp2
+  type parent
+    type(comp2) :: foo
+  end type
+contains
+  elemental subroutine assign0(lhs,rhs)
+    class(component), intent(INout) :: lhs
+    class(component), intent(in) :: rhs
+    lhs%i = 20
+  end subroutine
+end module
+
+program main
+  use m0
+  implicit none
+  type(parent), allocatable :: left
+  type(parent) :: right
+  print *, right%foo
+  left = right
+  print *, left%foo
+  if (left%foo%i /= 42) call abort()
+end
diff --git a/gcc/testsuite/gfortran.dg/defined_assignment_9.f90 b/gcc/testsuite/gfortran.dg/defined_assignment_9.f90
new file mode 100644
index 0000000..50fa007
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/defined_assignment_9.f90
@@ -0,0 +1,45 @@
+! { dg-do run }
+!
+! PR fortran/57697
+!
+! Further test of typebound defined assignment
+!
+module m0
+  implicit none
+  type component
+    integer :: i = 42
+  contains
+    procedure :: assign0
+    generic :: assignment(=) => assign0
+  end type
+  type parent
+    type(component) :: foo
+  end type
+contains
+  elemental subroutine assign0(lhs,rhs)
+    class(component), intent(INout) :: lhs
+    class(component), intent(in) :: rhs
+    lhs%i = 20
+  end subroutine
+end module
+
+program main
+  use m0
+  implicit none
+  block
+    type(parent), allocatable :: left
+    type(parent) :: right
+!    print *, right%foo
+    left = right
+!    print *, left%foo
+    if (left%foo%i /= 20) call abort()
+  end block
+  block
+    type(parent), allocatable :: left(:)
+    type(parent) :: right(5)
+!    print *, right%foo
+    left = right
+!    print *, left%foo
+    if (any (left%foo%i /= 20)) call abort()
+  end block
+end

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