Re: [PATCH] c++: ICE with template NEW_EXPR [PR105803]

[Marek Polacek <polacek@redhat.com>]

On Thu, Jun 02, 2022 at 04:26:27PM -0400, Jason Merrill wrote:
> On 6/2/22 16:10, Marek Polacek wrote:
> > index 1346a1d4c10..2bbd8785627 100644
> > --- a/gcc/cp/constexpr.cc
> > +++ b/gcc/cp/constexpr.cc
> > @@ -9039,10 +9039,18 @@ potential_constant_expression_1 (tree t, bool want_rval, bool strict, bool now,
> >   		  "before C++17");
> >         return false;
> > -    case DYNAMIC_CAST_EXPR:
> > -    case PSEUDO_DTOR_EXPR:
> >       case NEW_EXPR:
> >       case VEC_NEW_EXPR:
> > +      if (cxx_dialect >= cxx20)
> > +	/* In C++20, new-expressions are potentially constant.  */
> > +	return true;
> > +      else if (flags & tf_error)
> > +	error_at (loc, "new-expression is not a constant expression "
> > +		  "before C++20");
> > +      return false;
> > +
> > +    case DYNAMIC_CAST_EXPR:
> > +    case PSEUDO_DTOR_EXPR:
> >       case DELETE_EXPR:
> >       case VEC_DELETE_EXPR:
> 
> Delete, too.

Duh.  Fixed:

From 2423f6548405185e256036df3d0ef3c13fd996c5 Mon Sep 17 00:00:00 2001
From: Marek Polacek <polacek@redhat.com>
Date: Thu, 2 Jun 2022 15:56:18 -0400
Subject: [PATCH] c++: new-expression is potentially constant in C++20

... so adjust p_c_e accordingly.

gcc/cp/ChangeLog:

	* constexpr.cc (potential_constant_expression_1): Treat
	{,VEC_}NEW_EXPR and {,VEC_}DELETE_EXPRas potentially constant in C++20.
---
 gcc/cp/constexpr.cc | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/gcc/cp/constexpr.cc b/gcc/cp/constexpr.cc
index 1346a1d4c10..684238883dc 100644
--- a/gcc/cp/constexpr.cc
+++ b/gcc/cp/constexpr.cc
@@ -9039,12 +9039,20 @@ potential_constant_expression_1 (tree t, bool want_rval, bool strict, bool now,
 		  "before C++17");
       return false;
 
-    case DYNAMIC_CAST_EXPR:
-    case PSEUDO_DTOR_EXPR:
     case NEW_EXPR:
     case VEC_NEW_EXPR:
     case DELETE_EXPR:
     case VEC_DELETE_EXPR:
+      if (cxx_dialect >= cxx20)
+	/* In C++20, new-expressions are potentially constant.  */
+	return true;
+      else if (flags & tf_error)
+	error_at (loc, "new-expression is not a constant expression "
+		  "before C++20");
+      return false;
+
+    case DYNAMIC_CAST_EXPR:
+    case PSEUDO_DTOR_EXPR:
     case THROW_EXPR:
     case OMP_PARALLEL:
     case OMP_TASK:

base-commit: 7b98910406b5000a6429c188b0c6cc14e3140637
-- 
2.36.1