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c++: merge default targs for function templates [PR65396]

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We currently merge default template arguments for class templates, but
not for function templates.  This patch fixes this by factoring out the
argument merging logic in redeclare_class_template into a separate
function and using it in duplicate_decls as well.

	PR c++/65396

gcc/cp/ChangeLog:

	* cp-tree.h (merge_default_template_args): Declare.
	* decl.cc (merge_default_template_args): Define, factored out
	from redeclare_class_template.
	(duplicate_decls): Use it when merging member function template
	and free function declarations.
	* pt.cc (redeclare_class_template): Factor out default argument
	merging logic into merge_default_template_args.  Improve location
	of a note when there's a template parameter kind mismatch.

gcc/testsuite/ChangeLog:

	* g++.dg/cpp0x/vt-34314.C: Adjust expected location of
	"redeclared here" note.
	* g++.dg/template/pr92440.C: Likewise.
	* g++.old-deja/g++.pt/redecl1.C: Adjust expected location of
	"redefinition of default argument" error.
	* g++.dg/template/defarg23.C: New test.
	* g++.dg/template/defarg23a.C: New test.
This commit is contained in:
Patrick Palka 2022-03-09 08:42:19 -05:00
parent 4470e813b0
commit fe548eb843
8 changed files with 121 additions and 42 deletions
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1
gcc/cp/cp-tree.h
View file

@ -6787,6 +6787,7 @@ extern void note_iteration_stmt_body_end (bool);
extern void determine_local_discriminator (tree);
extern int decls_match (tree, tree, bool = true);
extern bool maybe_version_functions (tree, tree, bool);
extern bool merge_default_template_args (tree, tree, bool);
extern tree duplicate_decls (tree, tree,
bool hiding = false,
bool was_hidden = false);

58
gcc/cp/decl.cc
View file

@ -1470,6 +1470,43 @@ duplicate_function_template_decls (tree newdecl, tree olddecl)
return false;
}
/* OLD_PARMS is the innermost set of template parameters for some template
declaration, and NEW_PARMS is the corresponding set of template parameters
for a redeclaration of that template. Merge the default arguments within
these two sets of parameters. CLASS_P is true iff the template in
question is a class template. */
bool
merge_default_template_args (tree new_parms, tree old_parms, bool class_p)
{
gcc_checking_assert (TREE_VEC_LENGTH (new_parms)
== TREE_VEC_LENGTH (old_parms));
for (int i = 0; i < TREE_VEC_LENGTH (new_parms); i++)
{
tree new_parm = TREE_VALUE (TREE_VEC_ELT (new_parms, i));
tree old_parm = TREE_VALUE (TREE_VEC_ELT (old_parms, i));
tree& new_default = TREE_PURPOSE (TREE_VEC_ELT (new_parms, i));
tree& old_default = TREE_PURPOSE (TREE_VEC_ELT (old_parms, i));
if (new_default != NULL_TREE && old_default != NULL_TREE)
{
auto_diagnostic_group d;
error ("redefinition of default argument for %q+#D", new_parm);
inform (DECL_SOURCE_LOCATION (old_parm),
"original definition appeared here");
return false;
}
else if (new_default != NULL_TREE)
/* Update the previous template parameters (which are the ones
that will really count) with the new default value. */
old_default = new_default;
else if (class_p && old_default != NULL_TREE)
/* Update the new parameters, too; they'll be used as the
parameters for any members. */
new_default = old_default;
}
return true;
}
/* If NEWDECL is a redeclaration of OLDDECL, merge the declarations.
If the redeclaration is invalid, a diagnostic is issued, and the
error_mark_node is returned. Otherwise, OLDDECL is returned.
@ -1990,7 +2027,21 @@ duplicate_decls (tree newdecl, tree olddecl, bool hiding, bool was_hidden)
template shall be specified on the initial declaration
of the member function within the class template. */
|| CLASSTYPE_TEMPLATE_INFO (CP_DECL_CONTEXT (olddecl))))
check_redeclaration_no_default_args (newdecl);
{
check_redeclaration_no_default_args (newdecl);
if (DECL_TEMPLATE_INFO (olddecl)
&& DECL_MEMBER_TEMPLATE_P (DECL_TI_TEMPLATE (olddecl)))
{
tree new_parms = DECL_TEMPLATE_INFO (newdecl)
? DECL_INNERMOST_TEMPLATE_PARMS (DECL_TI_TEMPLATE (newdecl))
: INNERMOST_TEMPLATE_PARMS (current_template_parms);
tree old_parms
= DECL_INNERMOST_TEMPLATE_PARMS (DECL_TI_TEMPLATE (olddecl));
merge_default_template_args (new_parms, old_parms,
/*class_p=*/false);
}
}
else
{
tree t1 = FUNCTION_FIRST_USER_PARMTYPE (olddecl);
@ -2235,6 +2286,11 @@ duplicate_decls (tree newdecl, tree olddecl, bool hiding, bool was_hidden)
translation unit." */
check_no_redeclaration_friend_default_args
(old_result, new_result);
tree new_parms = DECL_INNERMOST_TEMPLATE_PARMS (newdecl);
tree old_parms = DECL_INNERMOST_TEMPLATE_PARMS (olddecl);
merge_default_template_args (new_parms, old_parms,
/*class_p=*/false);
}
if (!DECL_UNIQUE_FRIEND_P (old_result))
DECL_UNIQUE_FRIEND_P (new_result) = false;

31
gcc/cp/pt.cc
View file

@ -6274,8 +6274,6 @@ redeclare_class_template (tree type, tree parms, tree cons)
{
tree tmpl_parm;
tree parm;
tree tmpl_default;
tree parm_default;
if (TREE_VEC_ELT (tmpl_parms, i) == error_mark_node
|| TREE_VEC_ELT (parms, i) == error_mark_node)
@ -6286,8 +6284,6 @@ redeclare_class_template (tree type, tree parms, tree cons)
return false;
parm = TREE_VALUE (TREE_VEC_ELT (parms, i));
tmpl_default = TREE_PURPOSE (TREE_VEC_ELT (tmpl_parms, i));
parm_default = TREE_PURPOSE (TREE_VEC_ELT (parms, i));
/* TMPL_PARM and PARM can be either TYPE_DECL, PARM_DECL, or
TEMPLATE_DECL. */
@ -6303,7 +6299,7 @@ redeclare_class_template (tree type, tree parms, tree cons)
{
auto_diagnostic_group d;
error ("template parameter %q+#D", tmpl_parm);
inform (input_location, "redeclared here as %q#D", parm);
inform (DECL_SOURCE_LOCATION (parm), "redeclared here as %q#D", parm);
return false;
}
@ -6321,28 +6317,6 @@ redeclare_class_template (tree type, tree parms, tree cons)
return false;
}
if (tmpl_default != NULL_TREE && parm_default != NULL_TREE)
{
/* We have in [temp.param]:
A template-parameter may not be given default arguments
by two different declarations in the same scope. */
auto_diagnostic_group d;
error_at (input_location, "redefinition of default argument for %q#D", parm);
inform (DECL_SOURCE_LOCATION (tmpl_parm),
"original definition appeared here");
return false;
}
if (parm_default != NULL_TREE)
/* Update the previous template parameters (which are the ones
that will really count) with the new default value. */
TREE_PURPOSE (TREE_VEC_ELT (tmpl_parms, i)) = parm_default;
else if (tmpl_default != NULL_TREE)
/* Update the new parameters, too; they'll be used as the
parameters for any members. */
TREE_PURPOSE (TREE_VEC_ELT (parms, i)) = tmpl_default;
/* Give each template template parm in this redeclaration a
DECL_CONTEXT of the template for which they are a parameter. */
if (TREE_CODE (parm) == TEMPLATE_DECL)
@ -6352,6 +6326,9 @@ redeclare_class_template (tree type, tree parms, tree cons)
}
}
if (!merge_default_template_args (parms, tmpl_parms, /*class_p=*/true))
return false;
tree ci = get_constraints (tmpl);
tree req1 = ci ? CI_TEMPLATE_REQS (ci) : NULL_TREE;
tree req2 = cons ? CI_TEMPLATE_REQS (cons) : NULL_TREE;

12
gcc/testsuite/g++.dg/cpp0x/vt-34314.C
View file

@ -3,8 +3,8 @@
template<typename Fun, typename... Args> // { dg-error "template parameter" }
struct call;
template<typename Fun, typename Arg0>
struct call // { dg-message "note: redeclared here" }
template<typename Fun, typename Arg0> // { dg-message "note: redeclared here" }
struct call
{
template<typename Sig>
struct result;
@ -20,8 +20,8 @@ struct call // { dg-message "note: redeclared here" }
template<typename Fun, int... N> // { dg-error "template parameter" }
struct call2;
template<typename Fun, int N>
struct call2 // { dg-message "note: redeclared here" }
template<typename Fun, int N> // { dg-message "note: redeclared here" }
struct call2
{
template<typename Sig>
struct result;
@ -36,8 +36,8 @@ struct call2 // { dg-message "note: redeclared here" }
template<typename Fun, template<typename> class... TT> // { dg-error "template parameter" }
struct call3;
template<typename Fun, template<typename> class TT>
struct call3 // { dg-message "note: redeclared here" }
template<typename Fun, template<typename> class TT> // { dg-message "note: redeclared here" }
struct call3
{
template<typename Sig>
struct result;

21
gcc/testsuite/g++.dg/template/defarg23.C Normal file
View file

@ -0,0 +1,21 @@
// PR c++/65396
// { dg-do compile { target c++11 } }
template<class T> void f();
template<class T=int> void f();
template<class T=int> void g(); // { dg-message "original definition" }
template<class T=int> void g(); // { dg-error "redefinition of default" }
template<class T, class U=bool> void h();
template<class T=char, class U>
void h() {
static_assert(__is_same(T, char), "");
static_assert(__is_same(U, bool), "");
}
int main() {
f();
g();
h();
}

24
gcc/testsuite/g++.dg/template/defarg23a.C Normal file
View file

@ -0,0 +1,24 @@
// PR c++/65396
// { dg-do compile { target c++11 } }
// Like defarg23.C, but for member functions.
struct A {
template<class T> void f();
template<class T=int> void g(); // { dg-message "original definition" }
template<class T=char, class U> void h();
};
template<class T=int> void A::f() { }
template<class T=int> void A::g() { } // { dg-error "redefinition of default" }
template<class T, class U=bool>
void A::h() {
static_assert(__is_same(T, char), "");
static_assert(__is_same(U, bool), "");
}
int main() {
A a;
a.f();
a.g();
a.h();
}

4
gcc/testsuite/g++.dg/template/pr92440.C
View file

@ -3,8 +3,8 @@
template <int T> // { dg-error "template parameter" }
struct S {
template <class U>
friend struct S; // { dg-message "note: redeclared here as" }
template <class U> // { dg-message "note: redeclared here as" }
friend struct S;
};
S<0> s;

12
gcc/testsuite/g++.old-deja/g++.pt/redecl1.C
View file

@ -9,14 +9,14 @@ struct S1 {}; // { dg-error "redeclared" } used 1 template parameter
template <class T = int> // { dg-message "original definition" }
struct S2;
template <class T = int>
struct S2; // { dg-error "redefinition of default" }
template <class T = int> // { dg-error "redefinition of default" }
struct S2;
template <class T> // { dg-error "template parameter" }
struct S3;
template <int I>
struct S3; // { dg-message "note: redeclared here" }
template <int I> // { dg-message "note: redeclared here" }
struct S3;
template <template <class T> class C>
struct S3; // { dg-message "note: redeclared here" }
template <template <class T> class C> // { dg-message "note: redeclared here" }
struct S3;