On Mon, Jan 27, 2025 at 10:20:05AM -0500, Patrick Palka wrote:
> [snip]
>
> > @@ -18486,6 +18562,12 @@ dependent_operand_p (tree t)
> > {
> > while (TREE_CODE (t) == IMPLICIT_CONV_EXPR)
> > t = TREE_OPERAND (t, 0);
> > +
> > + /* If we contain a TU_LOCAL_ENTITY assume we're non-dependent; we'll
> > error
> > + later when instantiating. */
> > + if (expr_contains_tu_local_entity (t))
> > + return false;
>
> I think it'd be more robust and cheaper (avoiding a separate tree walk)
> to teach the general constexpr/dependence predicates about
> TU_LOCAL_ENTITY instead of handling it only here.
>
> > +
> > ++processing_template_decl;
> > bool r = (potential_constant_expression (t)
> > ? value_dependent_expression_p (t)
> > @@ -20255,6 +20337,9 @@ tsubst_expr (tree t, tree args, tsubst_flags_t
> > complain, tree in_decl)
> > else
> > object = NULL_TREE;
> >
> > + if (function_contains_tu_local_entity (templ))
> > + RETURN (error_mark_node);
> > +
> > tree tid = lookup_template_function (templ, targs);
> > protected_set_expr_location (tid, EXPR_LOCATION (t));
> >
> > @@ -20947,6 +21032,9 @@ tsubst_expr (tree t, tree args, tsubst_flags_t
> > complain, tree in_decl)
> > qualified_p = true;
> > }
> >
> > + if (function_contains_tu_local_entity (function))
> > + RETURN (error_mark_node);
>
> Similarly, maybe it'd suffice to check this more generally in the
> OVERLOAD case of tsubst_expr?
>
So I'd completely missed the idea of handling it in the OVERLOAD case;
doing this also fixes the issues I'd been having trying to handle it in
potential_constant_expression. I think this should be a lot cleaner
now.
Bootstrapped and regtested on x86_64-pc-linux-gnu, OK for trunk?
-- >8 --
Subject: [PATCH] c++: Handle TU_LOCAL_ENTITY in tsubst_expr and
potential_constant_expression
This cleans up the TU_LOCAL_ENTITY handling to avoid unnecessary
tree walks and make the logic more robust.
gcc/cp/ChangeLog:
* constexpr.cc (potential_constant_expression_1): Handle
TU_LOCAL_ENTITY.
* pt.cc (expr_contains_tu_local_entity): Remove.
(function_contains_tu_local_entity): Remove.
(dependent_operand_p): Remove special handling for
TU_LOCAL_ENTITY.
(tsubst_expr): Handle TU_LOCAL_ENTITY when tsubsting OVERLOADs;
remove now-unnecessary extra handling.
(type_dependent_expression_p): Handle TU_LOCAL_ENTITY.
Signed-off-by: Nathaniel Shead <nathanielosh...@gmail.com>
---
gcc/cp/constexpr.cc | 5 +++
gcc/cp/pt.cc | 80 ++++++++-------------------------------------
2 files changed, 19 insertions(+), 66 deletions(-)
diff --git a/gcc/cp/constexpr.cc b/gcc/cp/constexpr.cc
index f142dd32bc8..b36705fd4ce 100644
--- a/gcc/cp/constexpr.cc
+++ b/gcc/cp/constexpr.cc
@@ -10825,6 +10825,11 @@ potential_constant_expression_1 (tree t, bool
want_rval, bool strict, bool now,
case CO_RETURN_EXPR:
return false;
+ /* Assume a TU-local entity is not constant, we'll error later when
+ instantiating. */
+ case TU_LOCAL_ENTITY:
+ return false;
+
case NONTYPE_ARGUMENT_PACK:
{
tree args = ARGUMENT_PACK_ARGS (t);
diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc
index f857b3f1180..966050a6608 100644
--- a/gcc/cp/pt.cc
+++ b/gcc/cp/pt.cc
@@ -9935,61 +9935,6 @@ complain_about_tu_local_entity (tree e)
inform (TU_LOCAL_ENTITY_LOCATION (e), "declared here");
}
-/* Checks if T contains a TU-local entity. */
-
-static bool
-expr_contains_tu_local_entity (tree t)
-{
- if (!modules_p ())
- return false;
-
- auto walker = [](tree *tp, int *walk_subtrees, void *) -> tree
- {
- if (TREE_CODE (*tp) == TU_LOCAL_ENTITY)
- return *tp;
- if (!EXPR_P (*tp))
- *walk_subtrees = false;
- return NULL_TREE;
- };
- return cp_walk_tree (&t, walker, nullptr, nullptr);
-}
-
-/* Errors and returns TRUE if X is a function that contains a TU-local
- entity in its overload set. */
-
-static bool
-function_contains_tu_local_entity (tree x)
-{
- if (!modules_p ())
- return false;
-
- if (!x || x == error_mark_node)
- return false;
-
- if (TREE_CODE (x) == OFFSET_REF
- || TREE_CODE (x) == COMPONENT_REF)
- x = TREE_OPERAND (x, 1);
- x = MAYBE_BASELINK_FUNCTIONS (x);
- if (TREE_CODE (x) == TEMPLATE_ID_EXPR)
- x = TREE_OPERAND (x, 0);
-
- if (OVL_P (x))
- for (tree ovl : lkp_range (x))
- if (TREE_CODE (ovl) == TU_LOCAL_ENTITY)
- {
- x = ovl;
- break;
- }
-
- if (TREE_CODE (x) == TU_LOCAL_ENTITY)
- {
- complain_about_tu_local_entity (x);
- return true;
- }
-
- return false;
-}
-
/* Return a TEMPLATE_ID_EXPR corresponding to the indicated FNS and
ARGLIST. Valid choices for FNS are given in the cp-tree.def
documentation for TEMPLATE_ID_EXPR. */
@@ -18797,11 +18742,6 @@ dependent_operand_p (tree t)
while (TREE_CODE (t) == IMPLICIT_CONV_EXPR)
t = TREE_OPERAND (t, 0);
- /* If we contain a TU_LOCAL_ENTITY assume we're non-dependent; we'll error
- later when instantiating. */
- if (expr_contains_tu_local_entity (t))
- return false;
-
++processing_template_decl;
bool r = (potential_constant_expression (t)
? value_dependent_expression_p (t)
@@ -20629,9 +20569,6 @@ tsubst_expr (tree t, tree args, tsubst_flags_t
complain, tree in_decl)
else
object = NULL_TREE;
- if (function_contains_tu_local_entity (templ))
- RETURN (error_mark_node);
-
tree tid = lookup_template_function (templ, targs);
protected_set_expr_location (tid, EXPR_LOCATION (t));
@@ -21324,9 +21261,6 @@ tsubst_expr (tree t, tree args, tsubst_flags_t
complain, tree in_decl)
qualified_p = true;
}
- if (function_contains_tu_local_entity (function))
- RETURN (error_mark_node);
-
nargs = call_expr_nargs (t);
releasing_vec call_args;
tsubst_call_args (t, args, complain, in_decl, call_args);
@@ -22122,7 +22056,16 @@ tsubst_expr (tree t, tree args, tsubst_flags_t
complain, tree in_decl)
RETURN (t);
case NAMESPACE_DECL:
+ RETURN (t);
+
case OVERLOAD:
+ if (modules_p ())
+ for (tree ovl : lkp_range (t))
+ if (TREE_CODE (ovl) == TU_LOCAL_ENTITY)
+ {
+ complain_about_tu_local_entity (ovl);
+ RETURN (error_mark_node);
+ }
RETURN (t);
case TEMPLATE_DECL:
@@ -28990,6 +28933,11 @@ type_dependent_expression_p (tree expression)
STRIP_ANY_LOCATION_WRAPPER (expression);
+ /* Assume a TU-local entity is not dependent, we'll error later when
+ instantiating anyway. */
+ if (TREE_CODE (expression) == TU_LOCAL_ENTITY)
+ return false;
+
/* An unresolved name is always dependent. */
if (identifier_p (expression)
|| TREE_CODE (expression) == USING_DECL)
--
2.47.0
