On Wed, 1 May 2024, Jason Merrill wrote:
> On 5/1/24 13:40, Patrick Palka wrote:
> > On Wed, 1 May 2024, Jason Merrill wrote:
> >
> > > On 5/1/24 12:41, Patrick Palka wrote:
> > > > On Fri, 2 Feb 2024, Patrick Palka wrote:
> > > >
> > > > > Bootstrapped and regtested on x86_64-pc-linux, does this look like
> > > > > an improvement? This is not a bugfix and barely related to the
> > > > > previous
> > > > > patch, but the previous patch's new use of entering_scope=true
> > > > > motivated
> > > > > me to submit this patch since it seems like a nice simplification.
> > > >
> > > > Ping, now that stage 1 is open.
> > >
> > > Thanks for the ping. The earlier message isn't showing up in Thunderbird
> > > for
> > > some reason, though I see it in the gmail web interface...
> >
> > Ah, weird. No worries, this patch was very much stage 1 material anyway.
> >
> > >
> > > > > @@ -16771,9 +16722,10 @@ tsubst (tree t, tree args, tsubst_flags_t
> > > > > complain, tree in_decl)
> > > > > ctx = TREE_VEC_ELT (ctx, 0);
> > > > > }
> > > > > else
> > > > > - ctx = tsubst_aggr_type (ctx, args,
> > > > > - complain | tf_qualifying_scope,
> > > > > - in_decl, /*entering_scope=*/1);
> > > > > + {
> > > > > + ctx = tsubst_scope (ctx, args, complain, in_decl);
> > >
> > > Why is this one tsubst_scope while the others are all plain tsubst?
> >
> > Ah, just because the call to tsubst_aggr_type being replace passes
> > tf_qualifying_scope already, so we might as well use tsubst_scope
> > as shorthand.
> >
> > > Do we want a tsubst_entering_scope function?
> >
> > Which is just shorthand for tsubst + adjust_type_for_entering_scope?
>
> That's what I was thinking.
>
> > Sure, though I was wondering if we eventually might want to get rid of
> > the distinction between the primary template type A<T> and the generic
> > instantiation A<T>, and we could treat this as an incremental step
> > towards that (then we'd just eventually remove the
> > adjust_type_for_entering_scope calls and keep the tsubst calls).
>
> I don't think we want that; having the distinction helps to avoid wrongly
> looking up members of the primary template in contexts that shouldn't be able
> to.
Makes sense. How does the following look?
The name tsubst_entering_scope sounds confusingly similar to
tsubst_scope, but I can't think of a better name for it or for
adjust_type_for_entering_scope :/
-- >8 --
Subject: [PATCH] c++: remove lookup_template_class's entering_scope flag
gcc/cp/ChangeLog:
* coroutines.cc (instantiate_coro_traits): Adjust call to
lookup_template_class.
(instantiate_coro_handle_for_promise_type): Likewise.
* cp-tree.h (adjust_type_for_entering_scope): Declare.
(lookup_template_class): Adjust declaration.
* decl.cc (make_typename_type): Adjust call to
lookup_template_class. Likewise.
(get_tuple_size): Likewise.
(get_tuple_element_type): Likewise.
* pt.cc (adjust_type_for_entering_scope): Define.
(tsubst_entering_scope): Define.
(lookup_template_class): Remove entering_scope parameter.
Replace tsubst_aggr_type call with tsubst_entering_scope.
(tsubst_aggr_type): Remove.
(tsubst_aggr_type_1): Inline into tsubst.
(tsubst_function_decl): Replace tsubst_aggr_type call
with tsubst_entering_scope.
(tsubst_template_decl): Likewise.
(tsubst_decl): Likewise.
(tsubst) <case RECORD_TYPE, UNION_TYPE, ENUMERAL_TYPE>:
Inlined from tsubst_aggr_type_1.
<case BOUND_TEMPLATE_TEMPLATE_PARM>: Adjust calls to
lookup_template_class.
<case TYPENAME_TYPE>: Replace tsubst_aggr_type call with
tsubst_scope followed by adjust_type_for_entering_scope.
<case UNBOUND_CLASS_TEMPLATE>: Replace tsubst_aggr_type
call with tsubst_entering_scope.
Increment processing_template_decl when substituting the
context.
(tsubst_expr) <case FIELD_DECL>: Replace tsubst_aggr_type
call with tsubst_entering_scope.
<case TEMPLATE_DECL>: Likewise.
(instantiate_template): Likewise.
(resolve_typename_type): Adjust lookup_template_class call
and call adjust_type_for_entering_scope afterward.
(listify): Adjust lookup_template_class call.
(alias_ctad_tweaks): Likewise.
* semantics.cc (finish_template_type): Adjust lookup_template_class
call and maybe call adjust_type_for_entering_scope afterward.
---
gcc/cp/coroutines.cc | 4 +-
gcc/cp/cp-tree.h | 3 +-
gcc/cp/decl.cc | 4 +-
gcc/cp/pt.cc | 209 +++++++++++++++++--------------------------
gcc/cp/semantics.cc | 4 +-
5 files changed, 90 insertions(+), 134 deletions(-)
diff --git a/gcc/cp/coroutines.cc b/gcc/cp/coroutines.cc
index b05cb9eb330..97bc211ff67 100644
--- a/gcc/cp/coroutines.cc
+++ b/gcc/cp/coroutines.cc
@@ -353,7 +353,7 @@ instantiate_coro_traits (tree fndecl, location_t kw)
tree traits_class
= lookup_template_class (coro_traits_templ, targ,
/*in_decl=*/NULL_TREE, /*context=*/NULL_TREE,
- /*entering scope=*/false, tf_warning_or_error);
+ tf_warning_or_error);
if (traits_class == error_mark_node)
{
@@ -400,7 +400,7 @@ instantiate_coro_handle_for_promise_type (location_t kw,
tree promise_type)
= lookup_template_class (coro_handle_identifier, targ,
/* in_decl=*/NULL_TREE,
/* context=*/std_node,
- /* entering scope=*/false, tf_warning_or_error);
+ tf_warning_or_error);
if (handle_type == error_mark_node)
{
diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h
index 5d1bd6ba493..bc8e22cc39f 100644
--- a/gcc/cp/cp-tree.h
+++ b/gcc/cp/cp-tree.h
@@ -7521,8 +7521,9 @@ extern tree push_template_decl (tree,
bool is_friend = false);
extern tree add_inherited_template_parms (tree, tree);
extern void template_parm_level_and_index (tree, int*, int*);
extern bool redeclare_class_template (tree, tree, tree);
+extern tree adjust_type_for_entering_scope (tree);
extern tree lookup_template_class (tree, tree, tree, tree,
- int, tsubst_flags_t);
+ tsubst_flags_t);
extern tree lookup_template_function (tree, tree);
extern tree lookup_template_variable (tree, tree, tsubst_flags_t);
extern bool uses_template_parms (tree);
diff --git a/gcc/cp/decl.cc b/gcc/cp/decl.cc
index df855334133..876f77cbbe3 100644
--- a/gcc/cp/decl.cc
+++ b/gcc/cp/decl.cc
@@ -4574,7 +4574,6 @@ make_typename_type (tree context, tree name, enum
tag_types tag_type,
{
t = lookup_template_class (t, TREE_OPERAND (fullname, 1),
NULL_TREE, context,
- /*entering_scope=*/0,
complain | tf_user);
if (t == error_mark_node)
return error_mark_node;
@@ -9168,7 +9167,7 @@ get_tuple_size (tree type)
tree inst = lookup_template_class (tuple_size_identifier, args,
/*in_decl*/NULL_TREE,
/*context*/std_node,
- /*entering_scope*/false, tf_none);
+ tf_none);
inst = complete_type (inst);
if (inst == error_mark_node
|| !COMPLETE_TYPE_P (inst)
@@ -9197,7 +9196,6 @@ get_tuple_element_type (tree type, unsigned i)
tree inst = lookup_template_class (tuple_element_identifier, args,
/*in_decl*/NULL_TREE,
/*context*/std_node,
- /*entering_scope*/false,
tf_warning_or_error);
return make_typename_type (inst, type_identifier,
none_type, tf_warning_or_error);
diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc
index 1c3eef60c06..261d6b9f4c8 100644
--- a/gcc/cp/pt.cc
+++ b/gcc/cp/pt.cc
@@ -185,8 +185,6 @@ static int unify_pack_expansion (tree, tree, tree,
static tree copy_template_args (tree);
static tree tsubst_template_parms (tree, tree, tsubst_flags_t);
static void tsubst_each_template_parm_constraints (tree, tree, tsubst_flags_t);
-static tree tsubst_aggr_type (tree, tree, tsubst_flags_t, tree, int);
-static tree tsubst_aggr_type_1 (tree, tree, tsubst_flags_t, tree, int);
static tree tsubst_arg_types (tree, tree, tree, tsubst_flags_t, tree);
static tree tsubst_function_type (tree, tree, tsubst_flags_t, tree);
static bool check_specialization_scope (void);
@@ -9901,6 +9899,34 @@ maybe_get_template_decl_from_type_decl (tree decl)
? CLASSTYPE_TI_TEMPLATE (TREE_TYPE (decl)) : decl;
}
+/* If TYPE is the generic implicit instantiation A<T>, return the primary
+ template type A<T> (which is suitable for entering into e.g. for name
+ lookup), otherwise return TYPE. */
+
+tree
+adjust_type_for_entering_scope (tree type)
+{
+ if (CLASS_TYPE_P (type)
+ && dependent_type_p (type)
+ && TYPE_TEMPLATE_INFO (type)
+ /* We detect the generic implicit instantiation A<T> by inspecting
+ TYPE_CANONICAL, which lookup_template_class sets to the primary
+ template type A<T>. */
+ && TYPE_CANONICAL (type) == TREE_TYPE (TYPE_TI_TEMPLATE (type)))
+ type = TYPE_CANONICAL (type);
+ return type;
+}
+
+/* Convenience wrapper over tsubst that does adjust_type_for_entering_scope
+ on the result. */
+
+static tree
+tsubst_entering_scope (tree t, tree args, tsubst_flags_t complain, tree
in_decl)
+{
+ t = tsubst (t, args, complain, in_decl);
+ return adjust_type_for_entering_scope (t);
+}
+
/* Given an IDENTIFIER_NODE (or type TEMPLATE_DECL) and a chain of
parameters, find the desired type.
@@ -9909,9 +9935,6 @@ maybe_get_template_decl_from_type_decl (tree decl)
IN_DECL, if non-NULL, is the template declaration we are trying to
instantiate.
- If ENTERING_SCOPE is nonzero, we are about to enter the scope of
- the class we are looking up.
-
Issue error and warning messages under control of COMPLAIN.
If the template class is really a local class in a template
@@ -9927,7 +9950,7 @@ maybe_get_template_decl_from_type_decl (tree decl)
tree
lookup_template_class (tree d1, tree arglist, tree in_decl, tree context,
- int entering_scope, tsubst_flags_t complain)
+ tsubst_flags_t complain)
{
auto_timevar tv (TV_TEMPLATE_INST);
@@ -10139,9 +10162,10 @@ lookup_template_class (tree d1, tree arglist, tree
in_decl, tree context,
template <class T> class C { void f(C<T>); }
the `C<T>' is just the same as `C'. Outside of the
- class, however, such a reference is an instantiation. */
- if (entering_scope
- || !PRIMARY_TEMPLATE_P (gen_tmpl)
+ class, however, such a reference is an instantiation.
+ One can use adjust_type_for_entering_scope to make
+ this adjustment as needed. */
+ if (!PRIMARY_TEMPLATE_P (gen_tmpl)
|| currently_open_class (template_type))
{
tree tinfo = TYPE_TEMPLATE_INFO (template_type);
@@ -10207,8 +10231,8 @@ lookup_template_class (tree d1, tree arglist, tree
in_decl, tree context,
context = DECL_CONTEXT (templ);
else
{
- context = tsubst_aggr_type (context, arglist,
- complain, in_decl, true);
+ context = tsubst_entering_scope (context, arglist,
+ complain, in_decl);
/* Try completing the enclosing context if it's not already so.
*/
if (context != error_mark_node
&& !COMPLETE_TYPE_P (context))
@@ -14148,94 +14172,6 @@ tsubst_each_template_parm_constraints (tree parms,
tree args,
--processing_template_decl;
}
-/* Substitute the ARGS into the indicated aggregate (or enumeration)
- type T. If T is not an aggregate or enumeration type, it is
- handled as if by tsubst. IN_DECL is as for tsubst. If
- ENTERING_SCOPE is nonzero, T is the context for a template which
- we are presently tsubst'ing. Return the substituted value. */
-
-static tree
-tsubst_aggr_type (tree t,
- tree args,
- tsubst_flags_t complain,
- tree in_decl,
- int entering_scope)
-{
- if (t == NULL_TREE)
- return NULL_TREE;
-
- /* Handle typedefs via tsubst so that they get consistently reused. */
- if (typedef_variant_p (t))
- {
- t = tsubst (t, args, complain, in_decl);
- if (t == error_mark_node)
- return error_mark_node;
-
- /* The effect of entering_scope is that for a dependent specialization
- A<T>, lookup_template_class prefers to return A's primary template
- type instead of the implicit instantiation. So when entering_scope,
- we mirror this behavior by inspecting TYPE_CANONICAL appropriately,
- taking advantage of the fact that lookup_template_class links the two
- types by setting TYPE_CANONICAL of the latter to the former. */
- if (entering_scope
- && CLASS_TYPE_P (t)
- && dependent_type_p (t)
- && TYPE_TEMPLATE_INFO (t)
- && TYPE_CANONICAL (t) == TREE_TYPE (TYPE_TI_TEMPLATE (t)))
- t = TYPE_CANONICAL (t);
-
- return t;
- }
-
- switch (TREE_CODE (t))
- {
- case RECORD_TYPE:
- case ENUMERAL_TYPE:
- case UNION_TYPE:
- return tsubst_aggr_type_1 (t, args, complain, in_decl, entering_scope);
-
- default:
- return tsubst (t, args, complain, in_decl);
- }
-}
-
-/* The part of tsubst_aggr_type that's shared with the RECORD_, UNION_
- and ENUMERAL_TYPE cases of tsubst. */
-
-static tree
-tsubst_aggr_type_1 (tree t,
- tree args,
- tsubst_flags_t complain,
- tree in_decl,
- int entering_scope)
-{
- if (TYPE_TEMPLATE_INFO (t) && uses_template_parms (t))
- {
- complain &= ~tf_qualifying_scope;
-
- /* Figure out what arguments are appropriate for the
- type we are trying to find. For example, given:
-
- template <class T> struct S;
- template <class T, class U> void f(T, U) { S<U> su; }
-
- and supposing that we are instantiating f<int, double>,
- then our ARGS will be {int, double}, but, when looking up
- S we only want {double}. */
- tree argvec = tsubst_template_args (TYPE_TI_ARGS (t), args,
- complain, in_decl);
- if (argvec == error_mark_node)
- return error_mark_node;
-
- tree r = lookup_template_class (t, argvec, in_decl, NULL_TREE,
- entering_scope, complain);
- return cp_build_qualified_type (r, cp_type_quals (t), complain);
- }
- else
- /* This is not a template type, so there's nothing to do. */
- return t;
-}
-
/* Map from a FUNCTION_DECL to a vec of default argument instantiations,
indexed in reverse order of the parameters. */
@@ -14601,8 +14537,7 @@ tsubst_function_decl (tree t, tree args, tsubst_flags_t
complain,
lambda_fntype = static_fn_type (lambda_fntype);
if (member && !closure)
- ctx = tsubst_aggr_type (ctx, args,
- complain, t, /*entering_scope=*/1);
+ ctx = tsubst_entering_scope (ctx, args, complain, t);
tree type = (lambda_fntype ? lambda_fntype
: tsubst (TREE_TYPE (t), args,
@@ -14996,8 +14931,7 @@ tsubst_template_decl (tree t, tree args, tsubst_flags_t
complain,
inner = TREE_TYPE (inner);
}
if (class_p)
- inner = tsubst_aggr_type (inner, args, complain,
- in_decl, /*entering*/1);
+ inner = tsubst_entering_scope (inner, args, complain, in_decl);
else
inner = tsubst_decl (inner, args, complain, /*use_spec_table=*/false);
}
@@ -15501,9 +15435,7 @@ tsubst_decl (tree t, tree args, tsubst_flags_t complain,
local_p = false;
if (DECL_CLASS_SCOPE_P (t))
{
- ctx = tsubst_aggr_type (ctx, args,
- complain,
- in_decl, /*entering_scope=*/1);
+ ctx = tsubst_entering_scope (ctx, args, complain, in_decl);
if (DECL_SELF_REFERENCE_P (t))
/* The context and type of an injected-class-name are
the same, so we don't need to substitute both. */
@@ -16299,8 +16231,31 @@ tsubst (tree t, tree args, tsubst_flags_t complain,
tree in_decl)
/* Fall through. */
case UNION_TYPE:
case ENUMERAL_TYPE:
- return tsubst_aggr_type_1 (t, args, complain, in_decl,
- /*entering_scope=*/0);
+ if (TYPE_TEMPLATE_INFO (t) && uses_template_parms (t))
+ {
+ complain &= ~tf_qualifying_scope;
+
+ /* Figure out what arguments are appropriate for the
+ type we are trying to find. For example, given:
+
+ template <class T> struct S;
+ template <class T, class U> void f(T, U) { S<U> su; }
+
+ and supposing that we are instantiating f<int, double>,
+ then our ARGS will be {int, double}, but, when looking up
+ S we only want {double}. */
+ tree argvec = tsubst_template_args (TYPE_TI_ARGS (t), args,
+ complain, in_decl);
+ if (argvec == error_mark_node)
+ return error_mark_node;
+
+ tree r = lookup_template_class (t, argvec, in_decl, NULL_TREE,
+ complain);
+ return cp_build_qualified_type (r, cp_type_quals (t), complain);
+ }
+ else
+ /* This is not a template type, so there's nothing to do. */
+ return t;
case ERROR_MARK:
case IDENTIFIER_NODE:
@@ -16492,7 +16447,6 @@ tsubst (tree t, tree args, tsubst_flags_t complain,
tree in_decl)
r = lookup_template_class (arg,
argvec, in_decl,
DECL_CONTEXT (arg),
- /*entering_scope=*/0,
complain);
return cp_build_qualified_type
(r, cp_type_quals (t) | cp_type_quals (r), complain);
@@ -16584,7 +16538,7 @@ tsubst (tree t, tree args, tsubst_flags_t complain,
tree in_decl)
if (argvec == error_mark_node)
return error_mark_node;
r = lookup_template_class (tmpl, argvec, in_decl, NULL_TREE,
- /*entering_scope=*/false, complain);
+ complain);
r = cp_build_qualified_type (r, cp_type_quals (t), complain);
break;
}
@@ -16839,9 +16793,10 @@ tsubst (tree t, tree args, tsubst_flags_t complain,
tree in_decl)
ctx = TREE_VEC_ELT (ctx, 0);
}
else
- ctx = tsubst_aggr_type (ctx, args,
- complain | tf_qualifying_scope,
- in_decl, /*entering_scope=*/1);
+ {
+ ctx = tsubst_scope (ctx, args, complain, in_decl);
+ ctx = adjust_type_for_entering_scope (ctx);
+ }
if (ctx == error_mark_node)
return error_mark_node;
@@ -16914,8 +16869,10 @@ tsubst (tree t, tree args, tsubst_flags_t complain,
tree in_decl)
case UNBOUND_CLASS_TEMPLATE:
{
- tree ctx = tsubst_aggr_type (TYPE_CONTEXT (t), args, complain,
- in_decl, /*entering_scope=*/1);
+ ++processing_template_decl;
+ tree ctx = tsubst_entering_scope (TYPE_CONTEXT (t), args,
+ complain, in_decl);
+ --processing_template_decl;
tree name = TYPE_IDENTIFIER (t);
tree parm_list = DECL_TEMPLATE_PARMS (TYPE_NAME (t));
@@ -21564,9 +21521,7 @@ tsubst_expr (tree t, tree args, tsubst_flags_t
complain, tree in_decl)
When we instantiate f<7>::S::g(), say, lookup_name is not
clever enough to find f<7>::a. */
- enum_type
- = tsubst_aggr_type (DECL_CONTEXT (t), args, complain, in_decl,
- /*entering_scope=*/0);
+ enum_type = tsubst (DECL_CONTEXT (t), args, complain, in_decl);
for (v = TYPE_VALUES (enum_type);
v != NULL_TREE;
@@ -21586,8 +21541,8 @@ tsubst_expr (tree t, tree args, tsubst_flags_t
complain, tree in_decl)
{
tree ctx;
- ctx = tsubst_aggr_type (DECL_CONTEXT (t), args, complain, in_decl,
- /*entering_scope=*/1);
+ ctx = tsubst_entering_scope (DECL_CONTEXT (t), args,
+ complain, in_decl);
if (ctx != DECL_CONTEXT (t))
{
tree r = lookup_field (ctx, DECL_NAME (t), 0, false);
@@ -21630,8 +21585,8 @@ tsubst_expr (tree t, tree args, tsubst_flags_t
complain, tree in_decl)
TEMPLATE_DECL with `D<T>' as its DECL_CONTEXT. Now we
have to substitute this with one having context `D<int>'. */
- tree context = tsubst_aggr_type (DECL_CONTEXT (t), args, complain,
- in_decl, /*entering_scope=*/true);
+ tree context = tsubst_entering_scope (DECL_CONTEXT (t), args,
+ complain, in_decl);
RETURN (lookup_field (context, DECL_NAME(t), 0, false));
}
else
@@ -22161,8 +22116,8 @@ instantiate_template (tree tmpl, tree orig_args,
tsubst_flags_t complain)
already non-dependent, then we might as well use it. */
ctx = DECL_CONTEXT (tmpl);
else
- ctx = tsubst_aggr_type (DECL_CONTEXT (gen_tmpl), targ_ptr,
- complain, gen_tmpl, true);
+ ctx = tsubst_entering_scope (DECL_CONTEXT (gen_tmpl), targ_ptr,
+ complain, gen_tmpl);
push_nested_class (ctx);
}
@@ -29324,8 +29279,8 @@ resolve_typename_type (tree type, bool only_current_p)
tree args = TREE_OPERAND (fullname, 1);
/* Instantiate the template. */
result = lookup_template_class (tmpl, args, NULL_TREE, NULL_TREE,
- /*entering_scope=*/true,
tf_error | tf_user);
+ result = adjust_type_for_entering_scope (result);
if (result == error_mark_node)
result = NULL_TREE;
}
@@ -29564,7 +29519,7 @@ listify (tree arg)
TREE_VEC_ELT (argvec, 0) = arg;
return lookup_template_class (std_init_list, argvec, NULL_TREE,
- NULL_TREE, 0, tf_warning_or_error);
+ NULL_TREE, tf_warning_or_error);
}
/* Replace auto in TYPE with std::initializer_list<auto>. */
@@ -30510,7 +30465,7 @@ alias_ctad_tweaks (tree tmpl, tree uguides)
fprime = copy_decl (fprime);
tree fntype = TREE_TYPE (fprime);
ret = lookup_template_class (TPARMS_PRIMARY_TEMPLATE (atparms), targs,
- in_decl, NULL_TREE, false, complain);
+ in_decl, NULL_TREE, complain);
fntype = build_function_type (ret, TYPE_ARG_TYPES (fntype));
TREE_TYPE (fprime) = fntype;
if (TREE_CODE (fprime) == TEMPLATE_DECL)
diff --git a/gcc/cp/semantics.cc b/gcc/cp/semantics.cc
index 2dde65a970b..d0fa324fe5c 100644
--- a/gcc/cp/semantics.cc
+++ b/gcc/cp/semantics.cc
@@ -4011,8 +4011,10 @@ finish_template_type (tree name, tree args, int
entering_scope)
tree type;
type = lookup_template_class (name, args,
- NULL_TREE, NULL_TREE, entering_scope,
+ NULL_TREE, NULL_TREE,
tf_warning_or_error | tf_user);
+ if (entering_scope)
+ type = adjust_type_for_entering_scope (type);
/* If we might be entering the scope of a partial specialization,
find the one with the right constraints. */
--
2.45.0.31.gd4cc1ec35f
