This is PR ada/48844, a regression present on the mainline and 4.6 branch.
The compiler aborts on an assignment of an aggregate to another object, if the
nominal subtype of the former is a discriminated record type with a variant
part for which the variants all have the same size and one of the variant
contains a component whose type is tagged or controlled. It is trying to
create a temporary for a VIEW_CONVERT_EXPR and the type doesn't allow it.
Fixed by not generating the VIEW_CONVERT_EXPR in the first place.
Tested on i586-suse-linux, applied on the mainline and 4.6 branch.
2011-05-05 Eric Botcazou <ebotca...@adacore.com>
PR ada/48844
* gcc-interface/gigi.h (get_variant_part): Declare.
* gcc-interface/decl.c (get_variant_part): Make global.
* gcc-interface/utils2.c (find_common_type): Do not return T1 if the
types have the same constant size, are record types and T1 has a
variant part while T2 doesn't.
2011-05-05 Eric Botcazou <ebotca...@adacore.com>
* gnat.dg/discr29.ad[sb]: New test.
* gnat.dg/discr30.adb: Likewise.
--
Eric Botcazou
Index: gcc-interface/decl.c
===================================================================
--- gcc-interface/decl.c (revision 173422)
+++ gcc-interface/decl.c (working copy)
@@ -177,7 +177,6 @@ static void check_ok_for_atomic (tree, E
static tree create_field_decl_from (tree, tree, tree, tree, tree,
VEC(subst_pair,heap) *);
static tree get_rep_part (tree);
-static tree get_variant_part (tree);
static tree create_variant_part_from (tree, VEC(variant_desc,heap) *, tree,
tree, VEC(subst_pair,heap) *);
static void copy_and_substitute_in_size (tree, tree, VEC(subst_pair,heap) *);
@@ -8509,7 +8508,7 @@ get_rep_part (tree record_type)
/* Return the variant part of RECORD_TYPE, if any. Otherwise return NULL. */
-static tree
+tree
get_variant_part (tree record_type)
{
tree field;
Index: gcc-interface/utils2.c
===================================================================
--- gcc-interface/utils2.c (revision 173422)
+++ gcc-interface/utils2.c (working copy)
@@ -193,15 +193,21 @@ find_common_type (tree t1, tree t2)
calling into build_binary_op), some others are really expected and we
have to be careful. */
- /* We must prevent writing more than what the target may hold if this is for
+ /* We must avoid writing more than what the target can hold if this is for
an assignment and the case of tagged types is handled in build_binary_op
- so use the lhs type if it is known to be smaller, or of constant size and
- the rhs type is not, whatever the modes. We also force t1 in case of
+ so we use the lhs type if it is known to be smaller or of constant size
+ and the rhs type is not, whatever the modes. We also force t1 in case of
constant size equality to minimize occurrences of view conversions on the
- lhs of assignments. */
+ lhs of an assignment, except for the case of record types with a variant
+ part on the lhs but not on the rhs to make the conversion simpler. */
if (TREE_CONSTANT (TYPE_SIZE (t1))
&& (!TREE_CONSTANT (TYPE_SIZE (t2))
- || !tree_int_cst_lt (TYPE_SIZE (t2), TYPE_SIZE (t1))))
+ || tree_int_cst_lt (TYPE_SIZE (t1), TYPE_SIZE (t2))
+ || (TYPE_SIZE (t1) == TYPE_SIZE (t2)
+ && !(TREE_CODE (t1) == RECORD_TYPE
+ && TREE_CODE (t2) == RECORD_TYPE
+ && get_variant_part (t1) != NULL_TREE
+ && get_variant_part (t2) == NULL_TREE))))
return t1;
/* Otherwise, if the lhs type is non-BLKmode, use it. Note that we know
Index: gcc-interface/gigi.h
===================================================================
--- gcc-interface/gigi.h (revision 173422)
+++ gcc-interface/gigi.h (working copy)
@@ -150,6 +150,9 @@ extern tree choices_to_gnu (tree operand
extern void annotate_object (Entity_Id gnat_entity, tree gnu_type, tree size,
bool by_ref, bool by_double_ref);
+/* Return the variant part of RECORD_TYPE, if any. Otherwise return NULL. */
+extern tree get_variant_part (tree record_type);
+
/* Given a type T, a FIELD_DECL F, and a replacement value R, return a new
type with all size expressions that contain F updated by replacing F
with R. If F is NULL_TREE, always make a new RECORD_TYPE, even if
package body Discr29 is
procedure Proc (R : out Rec3) is
begin
R := (False, Tmp);
end;
end Discr29;
-- { dg-do compile }
package Discr29 is
type Rec1 is record
I1 : Integer;
I2 : Integer;
I3 : Integer;
end record;
type Rec2 is tagged record
I1 : Integer;
I2 : Integer;
end record;
type Rec3 (D : Boolean) is record
case D is
when True => A : Rec1;
when False => B : Rec2;
end case;
end record;
procedure Proc (R : out Rec3);
Tmp : Rec2;
end Discr29;
-- PR ada/48844
-- Reported by Georg Bauhaus <bauh...@futureapps.de> */
-- { dg-do compile }
procedure Discr30 is
generic
type Source is private;
type Target is private;
function Conversion (S : Source) return Target;
function Conversion (S : Source) return Target is
type Source_Wrapper is tagged record
S : Source;
end record;
type Target_Wrapper is tagged record
T : Target;
end record;
type Selector is (Source_Field, Target_Field);
type Magic (Sel : Selector := Target_Field) is record
case Sel is
when Source_Field => S : Source_Wrapper;
when Target_Field => T : Target_Wrapper;
end case;
end record;
M : Magic;
function Convert (T : Target_Wrapper) return Target is
begin
M := (Sel => Source_Field, S => (S => S));
return T.T;
end Convert;
begin
return Convert (M.T);
end Conversion;
type Integer_Access is access all Integer;
I : aliased Integer;
I_Access : Integer_Access := I'Access;
function Convert is new Conversion (Integer_Access, Integer);
begin
I := Convert (I_Access);
end;
