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?

Jason

Reply via email to