On Fri, Apr 12, 2024 at 03:05:26PM -0400, Jason Merrill wrote:
> > --- gcc/cp/constexpr.cc.jj 2024-02-13 10:29:57.979155641 +0100
> > +++ gcc/cp/constexpr.cc 2024-03-07 19:35:01.032412221 +0100
> > @@ -1877,13 +1877,21 @@ cxx_bind_parameters_in_call (const const
> > x = build_address (x);
> > }
> > if (TREE_ADDRESSABLE (type))
> > - /* Undo convert_for_arg_passing work here. */
> > - x = convert_from_reference (x);
> > - /* Normally we would strip a TARGET_EXPR in an initialization context
> > - such as this, but here we do the elision differently: we keep the
> > - TARGET_EXPR, and use its CONSTRUCTOR as the value of the parm. */
> > - arg = cxx_eval_constant_expression (ctx, x, vc_prvalue,
> > - non_constant_p, overflow_p);
> > + {
> > + /* Undo convert_for_arg_passing work here. */
> > + if (TYPE_REF_P (TREE_TYPE (x))
> > + && !same_type_p (type, TREE_TYPE (TREE_TYPE (x))))
> > + x = cp_fold_convert (build_reference_type (type), x);
> > + x = convert_from_reference (x);
> > + arg = cxx_eval_constant_expression (ctx, x, vc_glvalue,
> > + non_constant_p, overflow_p);
> > + }
> > + else
> > + /* Normally we would strip a TARGET_EXPR in an initialization context
> > + such as this, but here we do the elision differently: we keep the
> > + TARGET_EXPR, and use its CONSTRUCTOR as the value of the parm. */
> > + arg = cxx_eval_constant_expression (ctx, x, vc_prvalue,
> > + non_constant_p, overflow_p);
>
> It seems simpler to move the convert_for_reference after the
> cxx_eval_constant_expression rather than duplicate the call to
> cxx_eval_constant_expression.
They weren't the same, one was trying to evaluate the convert_from_reference
with vc_glvalue, the other evaluates it without that and with vc_prvalue.
Now, I guess the
+ /* Undo convert_for_arg_passing work here. */
+ if (TYPE_REF_P (TREE_TYPE (x))
+ && !same_type_p (type, TREE_TYPE (TREE_TYPE (x))))
+ x = cp_fold_convert (build_reference_type (type), x);
part could be thrown away, given the other !same_type_p check (that one is
needed because adjust_temp_type can't deal with that), at least
when I remove that
GXX_TESTSUITE_STDS=98,11,14,17,20,23,26 make check-g++
RUNTESTFLAGS="dg.exp='constexpr-dtor* pr114426.C constexpr-111284.C
constexpr-lifetime7.C'"
still passes. But if I try to remove even more, like in the patch below,
then I see
FAIL: g++.dg/cpp2a/constexpr-dtor5.C -std=c++20 (test for excess errors)
FAIL: g++.dg/cpp2a/constexpr-dtor5.C -std=c++23 (test for excess errors)
FAIL: g++.dg/cpp2a/constexpr-dtor5.C -std=c++26 (test for excess errors)
FAIL: g++.dg/cpp2a/constexpr-dtor7.C -std=c++20 (test for errors, line 6)
FAIL: g++.dg/cpp2a/constexpr-dtor7.C -std=c++20 (test for excess errors)
FAIL: g++.dg/cpp2a/constexpr-dtor7.C -std=c++23 (test for errors, line 6)
FAIL: g++.dg/cpp2a/constexpr-dtor7.C -std=c++23 (test for excess errors)
FAIL: g++.dg/cpp2a/constexpr-dtor7.C -std=c++26 (test for errors, line 6)
FAIL: g++.dg/cpp2a/constexpr-dtor7.C -std=c++26 (test for excess errors)
regressions.
E.g.
.../g++.dg/cpp2a/constexpr-dtor5.C:30:20: error: non-constant condition for
static assertion
.../g++.dg/cpp2a/constexpr-dtor5.C:13:7: error: modification of '<anonymous>'
from outside current evaluation is not a constant expression
.../g++.dg/cpp2a/constexpr-dtor5.C:31:20: error: non-constant condition for
static assertion
.../g++.dg/cpp2a/constexpr-dtor5.C:13:7: error: modification of '<anonymous>'
from outside current evaluation is not a constant expression
.../g++.dg/cpp2a/constexpr-dtor5.C:32:20: error: non-constant condition for
static assertion
.../g++.dg/cpp2a/constexpr-dtor5.C:13:7: error: modification of '<anonymous>'
from outside current evaluation is not a constant expression
.../g++.dg/cpp2a/constexpr-dtor5.C:13:7: error: modification of '<anonymous>'
from outside current evaluation is not a constant expression
.../g++.dg/cpp2a/constexpr-dtor5.C:13:7: error: modification of '<anonymous>'
from outside current evaluation is not a constant expression
.../g++.dg/cpp2a/constexpr-dtor5.C:13:7: error: modification of '<anonymous>'
from outside current evaluation is not a constant expression
--- gcc/cp/constexpr.cc.jj 2024-02-13 10:29:57.979155641 +0100
+++ gcc/cp/constexpr.cc 2024-03-07 19:35:01.032412221 +0100
@@ -1871,9 +1871,6 @@ cxx_bind_parameters_in_call (const const
x = ctx->object;
x = build_address (x);
}
- if (TREE_ADDRESSABLE (type))
- /* Undo convert_for_arg_passing work here. */
- x = convert_from_reference (x);
/* Normally we would strip a TARGET_EXPR in an initialization context
such as this, but here we do the elision differently: we keep the
TARGET_EXPR, and use its CONSTRUCTOR as the value of the parm. */
@@ -1904,7 +1901,13 @@ cxx_bind_parameters_in_call (const const
{
/* Make sure the binding has the same type as the parm. But
only for constant args. */
- if (!TYPE_REF_P (type))
+ if (TREE_ADDRESSABLE (type))
+ {
+ if (!same_type_p (type, TREE_TYPE (TREE_TYPE (arg))))
+ arg = cp_fold_convert (build_reference_type (type), arg);
+ arg = convert_from_reference (arg);
+ }
+ else if (!TYPE_REF_P (type))
arg = adjust_temp_type (type, arg);
if (!TREE_CONSTANT (arg))
*non_constant_args = true;
@@ -7494,9 +7497,19 @@ cxx_eval_constant_expression (const cons
case PARM_DECL:
if (lval && !TYPE_REF_P (TREE_TYPE (t)))
- /* glvalue use. */;
+ {
+ /* glvalue use. */
+ if (TREE_ADDRESSABLE (TREE_TYPE (t)))
+ if (tree v = ctx->global->get_value (t))
+ r = v;
+ }
else if (tree v = ctx->global->get_value (t))
- r = v;
+ {
+ r = v;
+ if (TREE_ADDRESSABLE (TREE_TYPE (t)))
+ r = cxx_eval_constant_expression (ctx, r, vc_prvalue,
+ non_constant_p, overflow_p);
+ }
else if (lval)
/* Defer in case this is only used for its type. */;
else if (ctx->global->is_outside_lifetime (t))
Jakub
