OpenE2K/gcc
2
0
Fork 0
Code Issues Pull Requests Projects Releases Wiki Activity

c++: Fix up calls to immediate functions returning reference [PR99507]

Browse Source 
build_cxx_call calls convert_from_reference at the end, so if an immediate
function returns a reference, we were constant evaluating not just that
call, but that call wrapped in an INDIRECT_REF.  That unfortunately means
it can constant evaluate to something non-addressable, so if code later
needs to take its address it will fail.

The following patch fixes that by undoing the convert_from_reference
wrapping for the cxx_constant_value evaluation and readdding it ad the end.

2021-03-12  Jakub Jelinek  <jakub@redhat.com>

	PR c++/99507
	* call.c (build_over_call): For immediate evaluation of functions
	that return references, undo convert_from_reference effects before
	calling cxx_constant_value and call convert_from_reference
	afterwards.

	* g++.dg/cpp2a/consteval19.C: New test.
This commit is contained in:
Jakub Jelinek 2021-03-12 10:11:24 +01:00
parent 0df3eb2622
commit 425afe1f0c
2 changed files with 10 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
gcc/cp/call.c
View File

@ -9504,6 +9504,9 @@ build_over_call (struct z_candidate *cand, int flags, tsubst_flags_t complain)
if (immediate_invocation_p (fndecl, nargs))
{
tree obj_arg = NULL_TREE;
/* Undo convert_from_reference called by build_cxx_call. */
if (REFERENCE_REF_P (call))
call = TREE_OPERAND (call, 0);
if (DECL_CONSTRUCTOR_P (fndecl))
obj_arg = cand->first_arg ? cand->first_arg : (*args)[0];
if (obj_arg && is_dummy_object (obj_arg))
@ -9527,6 +9530,7 @@ build_over_call (struct z_candidate *cand, int flags, tsubst_flags_t complain)
call = cxx_constant_value (call, obj_arg);
if (obj_arg && !error_operand_p (call))
call = build2 (INIT_EXPR, void_type_node, obj_arg, call);
call = convert_from_reference (call);
}
}
return call;

6
gcc/testsuite/g++.dg/cpp2a/consteval19.C Normal file
View File

@ -0,0 +1,6 @@
// PR c++/99507
// { dg-do compile { target c++20 } }
constexpr int i{0};
consteval const int &iref () { return i; }
const int *a{&iref ()};