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C++ PATCH for mishandling of multiple inheritance in templates
- To: egcs-patches at cygnus dot com
- Subject: C++ PATCH for mishandling of multiple inheritance in templates
- From: Mark Mitchell <mark at markmitchell dot com>
- Date: Wed, 17 Feb 1999 19:03:37 -0800
- Reply-to: mark at markmitchell dot com
Folks --
We were silently generating bad code for some cases involving
multiple inheritance and templates. This patch should fix them, and
illustrates an important design principle for implementation of
templates: do things at instantiation time just as you would for an
ordinary, non-template declaration. We had duplicated some, but not
all, of the functionality of xref_basetypes in instantiate_class_template.
Here's the fix.
--
Mark Mitchell mark@markmitchell.com
Mark Mitchell Consulting http://www.markmitchell.com
1999-02-17 Mark Mitchell <mark@markmitchell.com>
* decl.c (xref_basetypes): Comment.
* pt.c (instantiate_class_template): Use xref_basetypes.
Index: testsuite/g++.old-deja/g++.pt/inherit1.C
===================================================================
RCS file: inherit1.C
diff -N inherit1.C
*** /dev/null Sat Dec 5 20:30:03 1998
--- inherit1.C Wed Feb 17 18:56:16 1999
***************
*** 0 ****
--- 1,25 ----
+ // Origin: Wolfgang Bangerth <wolf@gaia.iwr.uni-heidelberg.de>
+
+ int i = 1;
+
+ struct Base1 { int local1; };
+ struct Base2 { int local2; };
+
+ template <int dim> class Derived;
+
+ template <>
+ class Derived<1> : public Base1, public Base2 {};
+
+ template <int dim>
+ class FinalClass : public Derived<dim> {
+ public:
+ FinalClass () {
+ if (&local1 != &local2)
+ i = 0;
+ }
+ };
+
+ int main () {
+ FinalClass<1> a1;
+ return i;
+ }
Index: cp/decl.c
===================================================================
RCS file: /egcs/carton/cvsfiles/egcs/gcc/cp/decl.c,v
retrieving revision 1.310
diff -c -p -r1.310 decl.c
*** decl.c 1999/02/16 11:32:47 1.310
--- decl.c 1999/02/18 02:56:31
*************** xref_tag_from_type (old, id, globalize)
*** 12357,12362 ****
--- 12357,12368 ----
return xref_tag (code_type_node, id, globalize);
}
+ /* REF is a type (named NAME), for which we have just seen some
+ baseclasses. BINFO is a list of those baseclasses; the
+ TREE_PURPOSE is an access_* node, and the TREE_VALUE is the type of
+ the base-class. CODE_TYPE_NODE indicates whether REF is a class,
+ struct, or union. */
+
void
xref_basetypes (code_type_node, name, ref, binfo)
tree code_type_node;
Index: cp/pt.c
===================================================================
RCS file: /egcs/carton/cvsfiles/egcs/gcc/cp/pt.c,v
retrieving revision 1.262
diff -c -p -r1.262 pt.c
*** pt.c 1999/02/16 11:32:51 1.262
--- pt.c 1999/02/18 02:56:46
*************** instantiate_class_template (type)
*** 4688,4740 ****
DECL_TI_ARGS of some instantiated member template. */
args = copy_to_permanent (args);
! {
! tree binfo = TYPE_BINFO (type);
! tree pbases = TYPE_BINFO_BASETYPES (pattern);
!
! if (pbases)
! {
! tree bases;
! int i;
! int len = TREE_VEC_LENGTH (pbases);
! bases = make_tree_vec (len);
! for (i = 0; i < len; ++i)
! {
! tree elt, basetype;
!
! TREE_VEC_ELT (bases, i) = elt
! = tsubst (TREE_VEC_ELT (pbases, i), args,
! /*complain=*/1, NULL_TREE);
! BINFO_INHERITANCE_CHAIN (elt) = binfo;
!
! basetype = TREE_TYPE (elt);
!
! if (! IS_AGGR_TYPE (basetype))
! cp_error
! ("base type `%T' of `%T' fails to be a struct or class type",
! basetype, type);
! else if (TYPE_SIZE (complete_type (basetype)) == NULL_TREE)
! cp_error ("base class `%T' of `%T' has incomplete type",
! basetype, type);
!
! /* These are set up in xref_basetypes for normal classes, so
! we have to handle them here for template bases. */
!
! unshare_base_binfos (elt);
!
! if (TYPE_USES_VIRTUAL_BASECLASSES (basetype))
! {
! TYPE_USES_VIRTUAL_BASECLASSES (type) = 1;
! TYPE_USES_COMPLEX_INHERITANCE (type) = 1;
! }
! TYPE_GETS_NEW (type) |= TYPE_GETS_NEW (basetype);
! TYPE_GETS_DELETE (type) |= TYPE_GETS_DELETE (basetype);
! }
! /* Don't initialize this until the vector is filled out, or
! lookups will crash. */
! BINFO_BASETYPES (binfo) = bases;
! }
! }
for (t = CLASSTYPE_TAGS (pattern); t; t = TREE_CHAIN (t))
{
--- 4688,4751 ----
DECL_TI_ARGS of some instantiated member template. */
args = copy_to_permanent (args);
! if (TYPE_BINFO_BASETYPES (pattern))
! {
! tree base_list = NULL_TREE;
! tree pbases = TYPE_BINFO_BASETYPES (pattern);
! int i;
!
! /* Substitute into each of the bases to determine the actual
! basetypes. */
! for (i = 0; i < TREE_VEC_LENGTH (pbases); ++i)
! {
! tree base;
! tree access;
! tree pbase;
!
! pbase = TREE_VEC_ELT (pbases, i);
!
! /* Substitue to figure out the base class. */
! base = tsubst (BINFO_TYPE (pbase), args,
! /*complain=*/1, NULL_TREE);
! if (base == error_mark_node)
! continue;
!
! /* Calculate the correct access node. */
! if (TREE_VIA_VIRTUAL (pbase))
! {
! if (TREE_VIA_PUBLIC (pbase))
! access = access_public_virtual_node;
! else if (TREE_VIA_PROTECTED (pbase))
! access = access_protected_virtual_node;
! else if (TREE_VIA_PRIVATE (pbase))
! access = access_private_virtual_node;
! }
! else
! {
! if (TREE_VIA_PUBLIC (pbase))
! access = access_public_node;
! else if (TREE_VIA_PROTECTED (pbase))
! access = access_protected_node;
! else if (TREE_VIA_PRIVATE (pbase))
! access = access_private_node;
! }
!
! base_list = tree_cons (access, base, base_list);
! }
!
! /* The list is now in reverse order; correct that. */
! base_list = nreverse (base_list);
!
! /* Now call xref_basetypes to set up all the base-class
! information. */
! xref_basetypes (TREE_CODE (pattern) == RECORD_TYPE
! ? (CLASSTYPE_DECLARED_CLASS (pattern)
! ? class_type_node : record_type_node)
! : union_type_node,
! DECL_NAME (TYPE_NAME (pattern)),
! type,
! base_list);
! }
for (t = CLASSTYPE_TAGS (pattern); t; t = TREE_CHAIN (t))
{