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DR 49, 100

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DR 49, 100
	* cp-tree.h (TYPE_REF_OBJ_P): New macro.
	(TYPE_PTR_P, TYPE_PTROB_P, TYPE_PTROBV_P, TYPE_PTRFN_P,
	TYPE_REFFN_P): Document.
	(fold_decl_constant_value): New prototype.
	* pt.c (convert_nontype_argument_function): Rewrite and extract
	parts into...
	(fold_decl_constant_value, convert_nontype_argument_function): New.
	(lookup_template_class): Add comment about useless double call.
	* mangle.c (write_expression): Strip conversions before lowering
	pointer to members.
	* cvt.c (ocp_convert): Check LOOKUP_COMPLAIN for a pedwarn. Disallow
	enum to enum conversion.

	* g++.dg/template/nontype7.C: New test.
	* g++.dg/template/nontype8.C: Likewise.
	* g++.dg/template/nontype9.C: Likewise.
	* g++.dg/template/nontype10.C: Likewise.
	* g++.dg/tc1/dr49.C: Likewise.
	* g++.dg/template/ptrmem8.C: Relax dg-error checks.
	* g++.old-deja/g++.other/null1.C: Remove a buggy error check

From-SVN: r90059
This commit is contained in:
Giovanni Bajo 2004-11-04 13:07:35 +00:00
parent eba7452ba8
commit b6ab6892cc
13 changed files with 474 additions and 365 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

16
gcc/cp/ChangeLog
View File

@ -1,3 +1,19 @@
2004-11-04 Giovanni Bajo <giovannibajo@gcc.gnu.org>
DR 49, 100
* cp-tree.h (TYPE_REF_OBJ_P): New macro.
(TYPE_PTR_P, TYPE_PTROB_P, TYPE_PTROBV_P, TYPE_PTRFN_P,
TYPE_REFFN_P): Document.
(fold_decl_constant_value): New prototype.
* pt.c (convert_nontype_argument_function): Rewrite and extract
parts into...
(fold_decl_constant_value, convert_nontype_argument_function): New.
(lookup_template_class): Add comment about useless double call.
* mangle.c (write_expression): Strip conversions before lowering
pointer to members.
* cvt.c (ocp_convert): Check LOOKUP_COMPLAIN for a pedwarn. Disallow
enum to enum conversion.
2004-11-02 Mark Mitchell <mark@codesourcery.com>
PR c++/18124

12
gcc/cp/cp-tree.h
View File

@ -2398,18 +2398,29 @@ struct lang_decl GTY(())
/* Returns true if NODE is a pointer-to-data-member. */
#define TYPE_PTRMEM_P(NODE) \
(TREE_CODE (NODE) == OFFSET_TYPE)
/* Returns true if NODE is a pointer. */
#define TYPE_PTR_P(NODE) \
(TREE_CODE (NODE) == POINTER_TYPE)
/* Returns true if NODE is a pointer to an object. */
#define TYPE_PTROB_P(NODE) \
(TYPE_PTR_P (NODE) \
&& TREE_CODE (TREE_TYPE (NODE)) != FUNCTION_TYPE \
&& TREE_CODE (TREE_TYPE (NODE)) != METHOD_TYPE \
&& TREE_CODE (TREE_TYPE (NODE)) != VOID_TYPE)
/* Returns true if NODE is a reference to an object. */
#define TYPE_REF_OBJ_P(NODE) \
(TREE_CODE (NODE) == REFERENCE_TYPE \
&& TREE_CODE (TREE_TYPE (NODE)) != FUNCTION_TYPE \
&& TREE_CODE (TREE_TYPE (NODE)) != METHOD_TYPE \
&& TREE_CODE (TREE_TYPE (NODE)) != VOID_TYPE)
/* Returns true if NODE is a pointer to an object, or a pointer to void. */
#define TYPE_PTROBV_P(NODE) \
(TYPE_PTR_P (NODE) && TREE_CODE (TREE_TYPE (NODE)) != FUNCTION_TYPE)
/* Returns true if NODE is a pointer to function. */
#define TYPE_PTRFN_P(NODE) \
(TREE_CODE (NODE) == POINTER_TYPE \
&& TREE_CODE (TREE_TYPE (NODE)) == FUNCTION_TYPE)
/* Returns true if NODE is a reference to function. */
#define TYPE_REFFN_P(NODE) \
(TREE_CODE (NODE) == REFERENCE_TYPE \
&& TREE_CODE (TREE_TYPE (NODE)) == FUNCTION_TYPE)
@ -3976,6 +3987,7 @@ extern tree build_non_dependent_expr (tree);
extern tree build_non_dependent_args (tree);
extern bool reregister_specialization (tree, tree, tree);
extern tree fold_non_dependent_expr (tree);
extern tree fold_decl_constant_value (tree);
/* in repo.c */
extern void init_repo (void);

9
gcc/cp/cvt.c
View File

@ -662,10 +662,13 @@ ocp_convert (tree type, tree expr, int convtype, int flags)
/* enum = enum, enum = int, enum = float, (enum)pointer are all
errors. */
if (TREE_CODE (type) == ENUMERAL_TYPE
&& ((ARITHMETIC_TYPE_P (intype) && ! (convtype & CONV_STATIC))
|| (TREE_CODE (intype) == POINTER_TYPE)))
&& (((INTEGRAL_OR_ENUMERATION_TYPE_P (intype)
|| TREE_CODE (intype) == REAL_TYPE)
&& ! (convtype & CONV_STATIC))
|| TREE_CODE (intype) == POINTER_TYPE))
{
pedwarn ("conversion from %q#T to %q#T", intype, type);
if (flags & LOOKUP_COMPLAIN)
pedwarn ("conversion from %q#T to %q#T", intype, type);
if (flag_pedantic_errors)
return error_mark_node;

20
gcc/cp/mangle.c
View File

@ -1969,6 +1969,16 @@ write_expression (tree expr)
code = TREE_CODE (expr);
/* Skip NOP_EXPRs. They can occur when (say) a pointer argument
is converted (via qualification conversions) to another
type. */
while (TREE_CODE (expr) == NOP_EXPR
|| TREE_CODE (expr) == NON_LVALUE_EXPR)
{
expr = TREE_OPERAND (expr, 0);
code = TREE_CODE (expr);
}
/* Handle pointers-to-members by making them look like expression
nodes. */
if (code == PTRMEM_CST)
@ -1980,16 +1990,6 @@ write_expression (tree expr)
code = TREE_CODE (expr);
}
/* Skip NOP_EXPRs. They can occur when (say) a pointer argument
is converted (via qualification conversions) to another
type. */
while (TREE_CODE (expr) == NOP_EXPR
|| TREE_CODE (expr) == NON_LVALUE_EXPR)
{
expr = TREE_OPERAND (expr, 0);
code = TREE_CODE (expr);
}
/* Handle template parameters. */
if (code == TEMPLATE_TYPE_PARM
|| code == TEMPLATE_TEMPLATE_PARM

691
gcc/cp/pt.c
View File

@ -110,6 +110,7 @@ static int maybe_adjust_types_for_deduction (unification_kind_t, tree*, tree*);
static int type_unification_real (tree, tree, tree, tree,
int, unification_kind_t, int, int);
static void note_template_header (int);
static tree convert_nontype_argument_function (tree, tree);
static tree convert_nontype_argument (tree, tree);
static tree convert_template_argument (tree, tree, tree,
tsubst_flags_t, int, tree);
@ -3302,6 +3303,79 @@ fold_non_dependent_expr (tree expr)
return expr;
}
/* EXPR is an expression which is used in a constant-expression context.
For instance, it could be a VAR_DECL with a constant initializer.
Extract the innest constant expression.
This is basically a more powerful version of decl_constant_value, which
can be used also in templates where initializers can maintain a
syntactic rather than semantic form (even if they are non-dependent, for
access-checking purposes). */
tree
fold_decl_constant_value (tree expr)
{
while (true)
{
tree const_expr = decl_constant_value (expr);
/* In a template, the initializer for a VAR_DECL may not be
marked as TREE_CONSTANT, in which case decl_constant_value
will not return the initializer. Handle that special case
here. */
if (expr == const_expr
&& TREE_CODE (expr) == VAR_DECL
&& DECL_INITIALIZED_BY_CONSTANT_EXPRESSION_P (expr)
&& CP_TYPE_CONST_NON_VOLATILE_P (TREE_TYPE (expr))
/* DECL_INITIAL can be NULL if we are processing a
variable initialized to an expression involving itself.
We know it is initialized to a constant -- but not what
constant, yet. */
&& DECL_INITIAL (expr))
const_expr = DECL_INITIAL (expr);
if (expr == const_expr)
break;
expr = fold_non_dependent_expr (const_expr);
}
return expr;
}
/* Subroutine of convert_nontype_argument. Converts EXPR to TYPE, which
must be a function or a pointer-to-function type, as specified
in [temp.arg.nontype]: disambiguate EXPR if it is an overload set,
and check that the resulting function has external linkage. */
static tree
convert_nontype_argument_function (tree type, tree expr)
{
tree fns = expr;
tree fn, fn_no_ptr;
fn = instantiate_type (type, fns, tf_none);
if (fn == error_mark_node)
return error_mark_node;
fn_no_ptr = fn;
if (TREE_CODE (fn_no_ptr) == ADDR_EXPR)
fn_no_ptr = TREE_OPERAND (fn_no_ptr, 0);
/* [temp.arg.nontype]/1
A template-argument for a non-type, non-template template-parameter
shall be one of:
[...]
-- the address of an object or function with external linkage. */
if (!DECL_EXTERNAL_LINKAGE_P (fn_no_ptr))
{
error ("%qE is not a valid template argument for type %qT "
"because function %qD has not external linkage",
expr, type, fn_no_ptr);
return NULL_TREE;
}
return fn;
}
/* Attempt to convert the non-type template parameter EXPR to the
indicated TYPE. If the conversion is successful, return the
converted value. If the conversion is unsuccessful, return
@ -3309,13 +3383,37 @@ fold_non_dependent_expr (tree expr)
did not. We issue error messages for out-and-out bad template
parameters, but not simply because the conversion failed, since we
might be just trying to do argument deduction. Both TYPE and EXPR
must be non-dependent. */
must be non-dependent.
The conversion follows the special rules described in
[temp.arg.nontype], and it is much more strict than an implicit
conversion.
This function is called twice for each template argument (see
lookup_template_class for a more accurate description of this
problem). This means that we need to handle expressions which
are not valid in a C++ source, but can be created from the
first call (for instance, casts to perform conversions). These
hacks can go away after we fix the double coercion problem. */
static tree
convert_nontype_argument (tree type, tree expr)
{
tree expr_type;
/* Detect immediately string literals as invalid non-type argument.
This special-case is not needed for correctness (we would easily
catch this later), but only to provide better diagnostic for this
common user mistake. As suggested by DR 100, we do not mention
linkage issues in the diagnostic as this is not the point. */
if (TREE_CODE (expr) == STRING_CST)
{
error ("%qE is not a valid template argument for type %qT "
"because string literals can never be used in this context",
expr, type);
return NULL_TREE;
}
/* If we are in a template, EXPR may be non-dependent, but still
have a syntactic, rather than semantic, form. For example, EXPR
might be a SCOPE_REF, rather than the VAR_DECL to which the
@ -3326,374 +3424,262 @@ convert_nontype_argument (tree type, tree expr)
expr = fold_non_dependent_expr (expr);
expr_type = TREE_TYPE (expr);
/* A template-argument for a non-type, non-template
template-parameter shall be one of:
--an integral constant-expression of integral or enumeration
type; or
--the name of a non-type template-parameter; or
--the name of an object or function with external linkage,
including function templates and function template-ids but
excluding non-static class members, expressed as id-expression;
or
--the address of an object or function with external linkage,
including function templates and function template-ids but
excluding non-static class members, expressed as & id-expression
where the & is optional if the name refers to a function or
array; or
--a pointer to member expressed as described in _expr.unary.op_. */
/* An integral constant-expression can include const variables or
. enumerators. Simplify things by folding them to their values,
unless we're about to bind the declaration to a reference
parameter. */
if (INTEGRAL_TYPE_P (expr_type) && TREE_CODE (type) != REFERENCE_TYPE)
while (true)
{
tree const_expr = decl_constant_value (expr);
/* In a template, the initializer for a VAR_DECL may not be
marked as TREE_CONSTANT, in which case decl_constant_value
will not return the initializer. Handle that special case
here. */
if (expr == const_expr
&& DECL_INTEGRAL_CONSTANT_VAR_P (expr)
/* DECL_INITIAL can be NULL if we are processing a
variable initialized to an expression involving itself.
We know it is initialized to a constant -- but not what
constant, yet. */
&& DECL_INITIAL (expr))
const_expr = DECL_INITIAL (expr);
if (expr == const_expr)
break;
expr = fold_non_dependent_expr (const_expr);
}
if (is_overloaded_fn (expr))
/* OK for now. We'll check that it has external linkage later.
Check this first since if expr_type is the unknown_type_node
we would otherwise complain below. */
;
else if (TYPE_PTR_TO_MEMBER_P (expr_type))
/* HACK: Due to double coercion, we can get a
NOP_EXPR<REFERENCE_TYPE>(ADDR_EXPR<POINTER_TYPE> (arg)) here,
which is the tree that we built on the first call (see
below when coercing to reference to object or to reference to
function). We just strip everything and get to the arg.
See g++.old-deja/g++.oliva/template4.C and g++.dg/template/nontype9.C
for examples. */
if (TREE_CODE (expr) == NOP_EXPR)
{
if (TREE_CODE (expr) != PTRMEM_CST)
goto bad_argument;
}
else if (TYPE_PTR_P (expr_type)
|| TREE_CODE (expr_type) == ARRAY_TYPE
|| TREE_CODE (type) == REFERENCE_TYPE
/* If expr is the address of an overloaded function, we
will get the unknown_type_node at this point. */
|| expr_type == unknown_type_node)
{
tree referent;
tree e = expr;
STRIP_NOPS (e);
if (TREE_CODE (expr_type) == ARRAY_TYPE
|| (TREE_CODE (type) == REFERENCE_TYPE
&& TREE_CODE (e) != ADDR_EXPR))
referent = e;
else
if (TYPE_REF_OBJ_P (type) || TYPE_REFFN_P (type))
{
if (TREE_CODE (e) != ADDR_EXPR)
{
bad_argument:
error ("%qE is not a valid template argument", expr);
if (TYPE_PTR_P (expr_type))
{
if (TREE_CODE (TREE_TYPE (expr_type)) == FUNCTION_TYPE)
error ("it must be the address of a function with external linkage");
else
error ("it must be the address of an object with external linkage");
}
else if (TYPE_PTR_TO_MEMBER_P (expr_type))
error ("it must be a pointer-to-member of the form %<&X::Y%>");
/* ??? Maybe we could use convert_from_reference here, but we
would need to relax its constraints because the NOP_EXPR
could actually change the type to something more cv-qualified,
and this is not folded by convert_from_reference. */
tree addr = TREE_OPERAND (expr, 0);
gcc_assert (TREE_CODE (expr_type) == REFERENCE_TYPE);
gcc_assert (TREE_CODE (addr) == ADDR_EXPR);
gcc_assert (TREE_CODE (TREE_TYPE (addr)) == POINTER_TYPE);
gcc_assert (same_type_ignoring_top_level_qualifiers_p
(TREE_TYPE (expr_type),
TREE_TYPE (TREE_TYPE (addr))));
return NULL_TREE;
}
referent = TREE_OPERAND (e, 0);
STRIP_NOPS (referent);
expr = TREE_OPERAND (addr, 0);
expr_type = TREE_TYPE (expr);
}
if (TREE_CODE (referent) == STRING_CST)
/* We could also generate a NOP_EXPR(ADDR_EXPR()) when the
parameter is a pointer to object, through decay and
qualification conversion. Let's strip everything. */
else if (TYPE_PTROBV_P (type))
{
error ("string literal %qE is not a valid template argument "
"because it is the address of an object with static linkage",
referent);
return NULL_TREE;
}
if (TREE_CODE (referent) == SCOPE_REF)
referent = TREE_OPERAND (referent, 1);
if (is_overloaded_fn (referent))
/* We'll check that it has external linkage later. */
;
else if (TREE_CODE (referent) != VAR_DECL)
goto bad_argument;
else if (!DECL_EXTERNAL_LINKAGE_P (referent))
{
error ("address of non-extern %qE cannot be used as "
"template argument", referent);
return error_mark_node;
STRIP_NOPS (expr);
gcc_assert (TREE_CODE (expr) == ADDR_EXPR);
gcc_assert (TREE_CODE (TREE_TYPE (expr)) == POINTER_TYPE);
/* Skip the ADDR_EXPR only if it is part of the decay for
an array. Otherwise, it is part of the original argument
in the source code. */
if (TREE_CODE (TREE_TYPE (TREE_OPERAND (expr, 0))) == ARRAY_TYPE)
expr = TREE_OPERAND (expr, 0);
expr_type = TREE_TYPE (expr);
}
}
else if (INTEGRAL_TYPE_P (expr_type) || TYPE_PTR_TO_MEMBER_P (expr_type))
{
if (! TREE_CONSTANT (expr))
{
non_constant:
error ("non-constant %qE cannot be used as template argument", expr);
return NULL_TREE;
}
}
else
{
if (TYPE_P (expr))
error ("type %qT cannot be used as a value for a non-type "
"template-parameter", expr);
else if (DECL_P (expr))
error ("invalid use of %qD as a non-type template-argument", expr);
else
error ("invalid use of %qE as a non-type template-argument", expr);
return NULL_TREE;
}
/* [temp.arg.nontype]/5, bullet 1
switch (TREE_CODE (type))
For a non-type template-parameter of integral or enumeration type,
integral promotions (_conv.prom_) and integral conversions
(_conv.integral_) are applied. */
if (INTEGRAL_TYPE_P (type))
{
HOST_WIDE_INT saved_processing_template_decl;
case INTEGER_TYPE:
case BOOLEAN_TYPE:
case ENUMERAL_TYPE:
/* For a non-type template-parameter of integral or enumeration
type, integral promotions (_conv.prom_) and integral
conversions (_conv.integral_) are applied. */
if (!INTEGRAL_TYPE_P (expr_type))
return error_mark_node;
/* [conv.integral] does not allow conversions between two different
enumeration types. */
if (TREE_CODE (type) == ENUMERAL_TYPE
&& TREE_CODE (expr_type) == ENUMERAL_TYPE
&& !same_type_ignoring_top_level_qualifiers_p (type, expr_type))
return error_mark_node;
/* It's safe to call digest_init in this case; we know we're
just converting one integral constant expression to another.
*/
saved_processing_template_decl = processing_template_decl;
processing_template_decl = 0;
expr = digest_init (type, expr, (tree*) 0);
processing_template_decl = saved_processing_template_decl;
expr = fold_decl_constant_value (expr);
/* Notice that there are constant expressions like '4 % 0' which
do not fold into integer constants. */
if (TREE_CODE (expr) != INTEGER_CST)
/* Curiously, some TREE_CONSTANT integral expressions do not
simplify to integer constants. For example, `3 % 0',
remains a TRUNC_MOD_EXPR. */
goto non_constant;
return expr;
{
error ("%qE is not a valid template argument for type %qT "
"because it is a non-constant expression", expr, type);
return NULL_TREE;
}
case OFFSET_TYPE:
{
tree e;
/* At this point, an implicit conversion does what we want,
because we already know that the expression is of integral
type. */
expr = ocp_convert (type, expr, CONV_IMPLICIT, LOOKUP_PROTECT);
if (expr == error_mark_node)
return error_mark_node;
/* For a non-type template-parameter of type pointer to data
member, qualification conversions (_conv.qual_) are
applied. */
e = perform_qualification_conversions (type, expr);
if (TREE_CODE (e) == NOP_EXPR)
/* The call to perform_qualification_conversions will
insert a NOP_EXPR over EXPR to do express conversion,
if necessary. But, that will confuse us if we use
this (converted) template parameter to instantiate
another template; then the thing will not look like a
valid template argument. So, just make a new
constant, of the appropriate type. */
e = make_ptrmem_cst (type, PTRMEM_CST_MEMBER (expr));
return e;
}
case POINTER_TYPE:
{
tree type_pointed_to = TREE_TYPE (type);
if (TREE_CODE (type_pointed_to) == FUNCTION_TYPE)
{
/* For a non-type template-parameter of type pointer to
function, only the function-to-pointer conversion
(_conv.func_) is applied. If the template-argument
represents a set of overloaded functions (or a pointer to
such), the matching function is selected from the set
(_over.over_). */
tree fns;
tree fn;
if (TREE_CODE (expr) == ADDR_EXPR)
fns = TREE_OPERAND (expr, 0);
else
fns = expr;
fn = instantiate_type (type_pointed_to, fns, tf_none);
if (fn == error_mark_node)
return error_mark_node;
if (!DECL_EXTERNAL_LINKAGE_P (fn))
{
if (really_overloaded_fn (fns))
return error_mark_node;
else
goto bad_argument;
}
expr = build_unary_op (ADDR_EXPR, fn, 0);
gcc_assert (same_type_p (type, TREE_TYPE (expr)));
return expr;
}
else
{
/* For a non-type template-parameter of type pointer to
object, qualification conversions (_conv.qual_) and the
array-to-pointer conversion (_conv.array_) are applied.
[Note: In particular, neither the null pointer conversion
(_conv.ptr_) nor the derived-to-base conversion
(_conv.ptr_) are applied. Although 0 is a valid
template-argument for a non-type template-parameter of
integral type, it is not a valid template-argument for a
non-type template-parameter of pointer type.]
The call to decay_conversion performs the
array-to-pointer conversion, if appropriate. */
expr = decay_conversion (expr);
if (expr == error_mark_node)
return error_mark_node;
else
return perform_qualification_conversions (type, expr);
}
}
break;
case REFERENCE_TYPE:
{
tree type_referred_to = TREE_TYPE (type);
/* If this expression already has reference type, get the
underlying object. */
if (TREE_CODE (expr_type) == REFERENCE_TYPE)
{
if (TREE_CODE (expr) == NOP_EXPR
&& TREE_CODE (TREE_OPERAND (expr, 0)) == ADDR_EXPR)
STRIP_NOPS (expr);
gcc_assert (TREE_CODE (expr) == ADDR_EXPR);
expr = TREE_OPERAND (expr, 0);
expr_type = TREE_TYPE (expr);
}
if (TREE_CODE (type_referred_to) == FUNCTION_TYPE)
{
/* For a non-type template-parameter of type reference to
function, no conversions apply. If the
template-argument represents a set of overloaded
functions, the matching function is selected from the
set (_over.over_). */
tree fn;
fn = instantiate_type (type_referred_to, expr, tf_none);
if (fn == error_mark_node)
return error_mark_node;
if (!DECL_EXTERNAL_LINKAGE_P (fn))
{
if (really_overloaded_fn (expr))
/* Don't issue an error here; we might get a different
function if the overloading had worked out
differently. */
return error_mark_node;
else
goto bad_argument;
}
gcc_assert (same_type_p (type_referred_to, TREE_TYPE (fn)));
expr = fn;
}
else
{
/* For a non-type template-parameter of type reference to
object, no conversions apply. The type referred to by the
reference may be more cv-qualified than the (otherwise
identical) type of the template-argument. The
template-parameter is bound directly to the
template-argument, which must be an lvalue. */
if (!same_type_p (TYPE_MAIN_VARIANT (expr_type),
TYPE_MAIN_VARIANT (type_referred_to))
|| !at_least_as_qualified_p (type_referred_to,
expr_type)
|| !real_lvalue_p (expr))
return error_mark_node;
}
cxx_mark_addressable (expr);
return build_nop (type, build_address (expr));
}
break;
case RECORD_TYPE:
{
gcc_assert (TYPE_PTRMEMFUNC_P (type));
/* For a non-type template-parameter of type pointer to member
function, no conversions apply. If the template-argument
represents a set of overloaded member functions, the
matching member function is selected from the set
(_over.over_). */
if (!TYPE_PTRMEMFUNC_P (expr_type) &&
expr_type != unknown_type_node)
return error_mark_node;
if (TREE_CODE (expr) == PTRMEM_CST)
{
/* A ptr-to-member constant. */
if (!same_type_p (type, expr_type))
return error_mark_node;
else
return expr;
}
if (TREE_CODE (expr) != ADDR_EXPR)
return error_mark_node;
expr = instantiate_type (type, expr, tf_none);
if (expr == error_mark_node)
return error_mark_node;
if (!same_type_p (type, TREE_TYPE (expr)))
return error_mark_node;
return expr;
}
break;
default:
/* All non-type parameters must have one of these types. */
gcc_unreachable ();
/* Conversion was allowed: fold it to a bare integer constant. */
expr = fold (expr);
}
/* [temp.arg.nontype]/5, bullet 2
return error_mark_node;
For a non-type template-parameter of type pointer to object,
qualification conversions (_conv.qual_) and the array-to-pointer
conversion (_conv.array_) are applied. */
else if (TYPE_PTROBV_P (type))
{
/* [temp.arg.nontype]/1 (TC1 version, DR 49):
A template-argument for a non-type, non-template template-parameter
shall be one of: [...]
-- the name of a non-type template-parameter;
-- the address of an object or function with external linkage, [...]
expressed as "& id-expression" where the & is optional if the name
refers to a function or array, or if the corresponding
template-parameter is a reference.
Here, we do not care about functions, as they are invalid anyway
for a parameter of type pointer-to-object. */
bool constant_address_p =
(TREE_CODE (expr) == ADDR_EXPR
|| TREE_CODE (expr_type) == ARRAY_TYPE
|| (DECL_P (expr) && DECL_TEMPLATE_PARM_P (expr)));
expr = decay_conversion (expr);
if (expr == error_mark_node)
return error_mark_node;
expr = perform_qualification_conversions (type, expr);
if (expr == error_mark_node)
return error_mark_node;
if (!constant_address_p)
{
error ("%qE is not a valid template argument for type %qT "
"because it is not a constant pointer", expr, type);
return NULL_TREE;
}
}
/* [temp.arg.nontype]/5, bullet 3
For a non-type template-parameter of type reference to object, no
conversions apply. The type referred to by the reference may be more
cv-qualified than the (otherwise identical) type of the
template-argument. The template-parameter is bound directly to the
template-argument, which must be an lvalue. */
else if (TYPE_REF_OBJ_P (type))
{
if (!same_type_ignoring_top_level_qualifiers_p (TREE_TYPE (type),
expr_type))
return error_mark_node;
if (!at_least_as_qualified_p (TREE_TYPE (type), expr_type))
{
error ("%qE is not a valid template argument for type %qT "
"because of conflicts in cv-qualification", expr, type);
return NULL_TREE;
}
if (!real_lvalue_p (expr))
{
error ("%qE is not a valid template argument for type %qT "
"because it is not a lvalue", expr, type);
return NULL_TREE;
}
/* [temp.arg.nontype]/1
A template-argument for a non-type, non-template template-parameter
shall be one of: [...]
-- the address of an object or function with external linkage. */
if (!DECL_EXTERNAL_LINKAGE_P (expr))
{
error ("%qE is not a valid template argument for type %qT "
"because object %qD has not external linkage",
expr, type, expr);
return NULL_TREE;
}
expr = build_nop (type, build_address (expr));
}
/* [temp.arg.nontype]/5, bullet 4
For a non-type template-parameter of type pointer to function, only
the function-to-pointer conversion (_conv.func_) is applied. If the
template-argument represents a set of overloaded functions (or a
pointer to such), the matching function is selected from the set
(_over.over_). */
else if (TYPE_PTRFN_P (type))
{
/* If the argument is a template-id, we might not have enough
context information to decay the pointer.
??? Why static5.C requires decay and subst1.C works fine
even without it? */
if (!type_unknown_p (expr_type))
{
expr = decay_conversion (expr);
if (expr == error_mark_node)
return error_mark_node;
}
expr = convert_nontype_argument_function (type, expr);
if (!expr || expr == error_mark_node)
return expr;
}
/* [temp.arg.nontype]/5, bullet 5
For a non-type template-parameter of type reference to function, no
conversions apply. If the template-argument represents a set of
overloaded functions, the matching function is selected from the set
(_over.over_). */
else if (TYPE_REFFN_P (type))
{
if (TREE_CODE (expr) == ADDR_EXPR)
{
error ("%qE is not a valid template argument for type %qT "
"because it is a pointer", expr, type);
inform ("try using %qE instead", TREE_OPERAND (expr, 0));
return NULL_TREE;
}
expr = convert_nontype_argument_function (TREE_TYPE (type), expr);
if (!expr || expr == error_mark_node)
return expr;
expr = build_nop(type, build_address (expr));
}
/* [temp.arg.nontype]/5, bullet 6
For a non-type template-parameter of type pointer to member function,
no conversions apply. If the template-argument represents a set of
overloaded member functions, the matching member function is selected
from the set (_over.over_). */
else if (TYPE_PTRMEMFUNC_P (type))
{
expr = instantiate_type (type, expr, tf_none);
if (expr == error_mark_node)
return error_mark_node;
/* There is no way to disable standard conversions in
resolve_address_of_overloaded_function (called by
instantiate_type). It is possible that the call succeeded by
converting &B::I to &D::I (where B is a base of D), so we need
to reject this conversion here.
Actually, even if there was a way to disable standard conversions,
it would still be better to reject them here so that we can
provide a superior diagnostic. */
if (!same_type_p (TREE_TYPE (expr), type))
{
/* Make sure we are just one standard conversion off. */
gcc_assert (can_convert (type, TREE_TYPE (expr)));
error ("%qE is not a valid template argument for type %qT "
"because it is of type %qT", expr, type,
TREE_TYPE (expr));
inform ("standard conversions are not allowed in this context");
return NULL_TREE;
}
}
/* [temp.arg.nontype]/5, bullet 7
For a non-type template-parameter of type pointer to data member,
qualification conversions (_conv.qual_) are applied. */
else if (TYPE_PTRMEM_P (type))
{
expr = perform_qualification_conversions (type, expr);
if (expr == error_mark_node)
return expr;
}
/* A template non-type parameter must be one of the above. */
else
gcc_unreachable ();
/* Sanity check: did we actually convert the argument to the
right type? */
gcc_assert (same_type_p (type, TREE_TYPE (expr)));
return expr;
}
/* Return 1 if PARM_PARMS and ARG_PARMS matches using rule for
template template parameters. Both PARM_PARMS and ARG_PARMS are
vectors of TREE_LIST nodes containing TYPE_DECL, TEMPLATE_DECL
@ -4300,7 +4286,14 @@ maybe_get_template_decl_from_type_decl (tree decl)
If the template class is really a local class in a template
function, then the FUNCTION_CONTEXT is the function in which it is
being instantiated. */
being instantiated.
??? Note that this function is currently called *twice* for each
template-id: the first time from the parser, while creating the
incomplete type (finish_template_type), and the second type during the
real instantiation (instantiate_template_class). This is surely something
that we want to avoid. It also causes some problems with argument
coercion (see convert_nontype_argument for more information on this). */
tree
lookup_template_class (tree d1,

10
gcc/testsuite/ChangeLog
View File

@ -1,3 +1,13 @@
2004-11-04 Giovanni Bajo <giovannibajo@gcc.gnu.org>
* g++.dg/template/nontype7.C: New test.
* g++.dg/template/nontype8.C: Likewise.
* g++.dg/template/nontype9.C: Likewise.
* g++.dg/template/nontype10.C: Likewise.
* g++.dg/tc1/dr49.C: Likewise.
* g++.dg/template/ptrmem8.C: Relax dg-error checks.
* g++.old-deja/g++.other/null1.C: Remove a buggy error check
2004-11-04 Ben Elliston <bje@au.ibm.com>
* g++.dg/rtti/tinfo1.C: Remove xfails.

19
gcc/testsuite/g++.dg/tc1/dr49.C Normal file
View File

@ -0,0 +1,19 @@
// { dg-do compile }
// Contributed by: Giovanni Bajo <giovannibajo at gcc dot gnu dot org>
// DR 49: Non-constant pointers are invalid template arguments.
template<int *a> struct R { /* ... */ };
template<int b[5]> struct S { /* ... */ };
int p;
template struct R<&p>; // OK
template struct S<&p>; // OK due to parameter adjustment
int *ptr;
template struct R<ptr>; // { dg-error "constant" }
template struct S<ptr>; // { dg-error "constant" }
int v[5];
template struct R<v>; // OK due to implicit argument conversion
template struct S<v>; // OK due to both adjustment and conversion

10
gcc/testsuite/g++.dg/template/nontype10.C Normal file
View File

@ -0,0 +1,10 @@
// { dg-do compile }
// Contributed by: Giovanni Bajo <giovannibajo at gcc dot gnu dot org>
#include <cstddef>
template <int T> struct A {};
template <void* T> struct B {};
A<NULL> a;
B<NULL> b; // { dg-error "" }

15
gcc/testsuite/g++.dg/template/nontype7.C Normal file
View File

@ -0,0 +1,15 @@
// { dg-do compile }
// Origin: C++ standard, [temp.arg.nontype]/2
template<class T, char* p> struct X {
X();
X(const char* q) { /* ... */ }
};
char p[] = "Vivisectionist";
X<int,"Studebaker"> x1; // { dg-error "string literal" }
X<int, p> x2;
// { dg-bogus "" "additional errors" { xfail *-*-* } 11 }

13
gcc/testsuite/g++.dg/template/nontype8.C Normal file
View File

@ -0,0 +1,13 @@
// { dg-do compile }
// Origin: C++ standard, [temp.arg.nontype]/3
template<int* p> class X { };
int a[10];
struct S { int m; static int s; } s;
X<&a[2]> x3; // { dg-error "" } address of array element
X<&s.m> x4; // { dg-error "" } address of non-static member
X<&s.s> x5; // { dg-error "" } &S::s must be used
X<&S::s> x6; // OK: address of static member

18
gcc/testsuite/g++.dg/template/nontype9.C Normal file
View File

@ -0,0 +1,18 @@
// { dg-do compile }
// Contributed by: Giovanni Bajo <giovannibajo at gcc dot gnu dot org>
int i;
template <void (&FN)()>
struct g {
void foo(void) {
FN ();
}
};
void h ()
{
i = 7;
}
template struct g<h>;

4
gcc/testsuite/g++.dg/template/ptrmem8.C
View File

@ -15,6 +15,6 @@ template <int (D::*fun)() const> int Get();
int main ()
{
Get<&B::I>(); // { dg-error "no matching function" }
Get<&D::I>(); // { dg-error "no matching function" }
Get<&B::I>(); // { dg-error "" }
Get<&D::I>(); // { dg-error "" }
}

2
gcc/testsuite/g++.old-deja/g++.other/null1.C
View File

@ -38,7 +38,7 @@ int main()
z = NULL; // { dg-warning "" } converting NULL to non-pointer type
k(NULL); // { dg-warning "" } converting NULL to int
g(NULL); // { dg-warning "" } converting NULL to int
h<NULL>(); // { dg-warning "" } NULL bound to integer template parameter
h<NULL>(); // No warning: NULL bound to integer template parameter
l(NULL); // { dg-warning "" } converting NULL to int
NULL && NULL; // No warning: converting NULL to bool is OK
}