On 4/4/24 14:43, Marek Polacek wrote:
On Wed, Apr 03, 2024 at 01:14:46PM -0400, Jason Merrill wrote:
On 4/2/24 13:52, Marek Polacek wrote:
Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk/13?
-- >8 --
We evaluate constexpr functions on the original, pre-genericization bodies.
That means that the function body we're evaluating will not have gone
through cp_genericize_r's "Map block scope extern declarations to visible
declarations with the same name and type in outer scopes if any". Here:
constexpr bool bar() { return true; } // #1
constexpr bool foo() {
constexpr bool bar(void); // #2
return bar();
}
it means that we:
1) register_constexpr_fundef (#1)
2) cp_genericize (#1)
nothing interesting happens
3) register_constexpr_fundef (foo)
does copy_fn, so we have two copies of the BIND_EXPR
4) cp_genericize (foo)
this remaps #2 to #1, but only on one copy of the BIND_EXPR
5) retrieve_constexpr_fundef (foo)
we find it, no problem
6) retrieve_constexpr_fundef (#2)
and here #2 isn't found in constexpr_fundef_table, because
we're working on the BIND_EXPR copy where #2 wasn't mapped to #1
so we fail. We've only registered #1.
It should work to use DECL_LOCAL_DECL_ALIAS (which used to be
extern_decl_map). We evaluate constexpr functions on pre-cp_fold
bodies to avoid diagnostic problems, but the remapping I'm proposing
should not interfere with diagnostics.
This is not a problem for a global scope redeclaration; there we go
through duplicate_decls which keeps the DECL_UID:
DECL_UID (olddecl) = olddecl_uid;
and DECL_UID is what constexpr_fundef_hasher::hash uses.
PR c++/111132
gcc/cp/ChangeLog:
* constexpr.cc (get_function_named_in_call): If there's
a DECL_LOCAL_DECL_ALIAS, use it.
Perhaps this function should use cp_get_fndecl_from_callee, and this change
should be made there instead?
It doesn't seem that get_function_named_in_call can use
cp_get_fndecl_from_callee,
(or be replaced with cp_get_callee_fndecl_nofold). We can get e.g. a CALL_EXPR
whose CALL_EXPR_FN is a TEMPLATE_ID_EXPR, and get_function_named_in_call
returns the TEMPLATE_ID_EXPR whereas cp_get_fndecl_from_callee would return
null:
if (TREE_CODE (fn) == FUNCTION_DECL)
return fn;
tree type = TREE_TYPE (fn);
if (type == NULL_TREE || !INDIRECT_TYPE_P (type))
return NULL_TREE;
Why couldn't this function use cp_get_fndecl_from_callee and return the
original argument if that function returns null?
Jason
