[pushed] c++: __integer_pack with class argument [PR111357]

[pushed] c++: __integer_pack with class argument [PR111357]

[Jason Merrill]

Tested x86_64-pc-linux-gnu, applying to trunk.

-- 8< --

The argument might not already be an integer.

	PR c++/111357

gcc/cp/ChangeLog:

	* pt.cc (expand_integer_pack): Convert argument to int.

gcc/testsuite/ChangeLog:

	* g++.dg/ext/integer-pack7.C: New test.
---
 gcc/cp/pt.cc                             |  2 ++
 gcc/testsuite/g++.dg/ext/integer-pack7.C | 38 ++++++++++++++++++++++++
 2 files changed, 40 insertions(+)
 create mode 100644 gcc/testsuite/g++.dg/ext/integer-pack7.C

diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc
index 838179d5fe3..b583c11eb99 100644
--- a/gcc/cp/pt.cc
+++ b/gcc/cp/pt.cc
@@ -3793,6 +3793,8 @@ expand_integer_pack (tree call, tree args, tsubst_flags_t complain,
     }
   else
     {
+      hi = perform_implicit_conversion_flags (integer_type_node, hi, complain,
+					      LOOKUP_IMPLICIT);
       hi = instantiate_non_dependent_expr (hi, complain);
       hi = cxx_constant_value (hi, complain);
       int len = valid_constant_size_p (hi) ? tree_to_shwi (hi) : -1;
diff --git a/gcc/testsuite/g++.dg/ext/integer-pack7.C b/gcc/testsuite/g++.dg/ext/integer-pack7.C
new file mode 100644
index 00000000000..95b1195bef4
--- /dev/null
+++ b/gcc/testsuite/g++.dg/ext/integer-pack7.C
@@ -0,0 +1,38 @@
+// PR c++/111357
+// { dg-do compile { target c++11 } }
+
+namespace std {
+  template<typename _Tp, _Tp... _Idx>
+    struct integer_sequence
+    { };
+
+  template<typename _Tp, _Tp _Num>
+    using make_integer_sequence
+      = integer_sequence<_Tp, __integer_pack(_Num)...>;
+}
+
+using std::integer_sequence;
+using std::make_integer_sequence;
+
+template<int... V>
+void g(integer_sequence<int,V...>)
+{}
+
+template<typename ...T>
+struct c1
+{
+  static constexpr int value = 1;
+  constexpr operator int() { return value; }
+};
+template<typename T>
+struct R
+{
+	using S = make_integer_sequence<int,c1<T>{}>;
+
+	R() noexcept(noexcept(g(S())))
+	{}
+};
+int main()
+{
+        R<int>();
+}

base-commit: ea5abbb263315e558c876b50c9371b90ddd5e028
-- 
2.39.3

Re: [pushed] c++: __integer_pack with class argument [PR111357]

[Marek Polacek]

On Tue, Sep 12, 2023 at 01:27:44PM -0400, Jason Merrill via Gcc-patches wrote:
> Tested x86_64-pc-linux-gnu, applying to trunk.
> 
> -- 8< --
> 
> The argument might not already be an integer.
> 
> 	PR c++/111357
> 
> gcc/cp/ChangeLog:
> 
> 	* pt.cc (expand_integer_pack): Convert argument to int.
> 
> gcc/testsuite/ChangeLog:
> 
> 	* g++.dg/ext/integer-pack7.C: New test.
> ---
>  gcc/cp/pt.cc                             |  2 ++
>  gcc/testsuite/g++.dg/ext/integer-pack7.C | 38 ++++++++++++++++++++++++
>  2 files changed, 40 insertions(+)
>  create mode 100644 gcc/testsuite/g++.dg/ext/integer-pack7.C
> 
> diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc
> index 838179d5fe3..b583c11eb99 100644
> --- a/gcc/cp/pt.cc
> +++ b/gcc/cp/pt.cc
> @@ -3793,6 +3793,8 @@ expand_integer_pack (tree call, tree args, tsubst_flags_t complain,
>      }
>    else
>      {
> +      hi = perform_implicit_conversion_flags (integer_type_node, hi, complain,
> +					      LOOKUP_IMPLICIT);

FWIW, we have perform_implicit_conversion for this.

Marek

Re: [pushed] c++: __integer_pack with class argument [PR111357]

[Jakub Jelinek]

On Tue, Sep 12, 2023 at 01:34:43PM -0400, Marek Polacek via Gcc-patches wrote:
> On Tue, Sep 12, 2023 at 01:27:44PM -0400, Jason Merrill via Gcc-patches wrote:
> > Tested x86_64-pc-linux-gnu, applying to trunk.
> > 
> > -- 8< --
> > 
> > The argument might not already be an integer.
> > 
> > 	PR c++/111357
> > 
> > gcc/cp/ChangeLog:
> > 
> > 	* pt.cc (expand_integer_pack): Convert argument to int.
> > 
> > gcc/testsuite/ChangeLog:
> > 
> > 	* g++.dg/ext/integer-pack7.C: New test.
> > ---
> >  gcc/cp/pt.cc                             |  2 ++
> >  gcc/testsuite/g++.dg/ext/integer-pack7.C | 38 ++++++++++++++++++++++++
> >  2 files changed, 40 insertions(+)
> >  create mode 100644 gcc/testsuite/g++.dg/ext/integer-pack7.C
> > 
> > diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc
> > index 838179d5fe3..b583c11eb99 100644
> > --- a/gcc/cp/pt.cc
> > +++ b/gcc/cp/pt.cc
> > @@ -3793,6 +3793,8 @@ expand_integer_pack (tree call, tree args, tsubst_flags_t complain,
> >      }
> >    else
> >      {
> > +      hi = perform_implicit_conversion_flags (integer_type_node, hi, complain,
> > +					      LOOKUP_IMPLICIT);
> 
> FWIW, we have perform_implicit_conversion for this.

Is it correct to convert exactly to integer_type_node though?
Consider
#include <utility>

using std::integer_sequence;
using std::make_integer_sequence;

template<long... V>
void g(integer_sequence<long,V...>)
{}

template<typename ...T>
struct c1
{
  static constexpr int value = 1;
  constexpr operator int() { return value; } 
  constexpr operator long() { return value + 1; }
};
template<typename T>
struct R
{
	using S = make_integer_sequence<long,c1<T>{}>;

	R() noexcept(noexcept(g(S())))
	{}
};
int main()
{
        R<int>();
}
Shouldn't that invoke c1<T>{}.operator long() rather than operator int()?
I thought the conversion was supposed to be done a few lines earlier,
instead of doing
          CALL_EXPR_ARG (call, 0) = hi;
do
          CALL_EXPR_ARG (call, 0)
	    = perform_implicit_conversion_flags (TREE_TYPE (ohi), hi,
						 complain, LOOKUP_IMPLICIT);
or tsubst that TREE_TYPE (ohi) as well?  I.e. convert to type of the
template parameter.

	Jakub

[pushed] c++ __integer_pack conversion again [PR111357]

[Jason Merrill]

Tested x86_64-pc-linux-gnu, applying to trunk.

-- 8< --

As Jakub pointed out, the real problem here is that in a partial
substitution we're forgetting the conversion to the type of the non-type
template argument, because maybe_convert_nontype_argument doesn't do
anything with value-dependent arguments.  I'm experimenting with changing
that, but in the meantime we can work around it here.

	PR c++/111357

gcc/cp/ChangeLog:

	* pt.cc (expand_integer_pack): Use IMPLICIT_CONV_EXPR.
---
 gcc/cp/pt.cc | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc
index ea5379098a5..73ac1cb597c 100644
--- a/gcc/cp/pt.cc
+++ b/gcc/cp/pt.cc
@@ -3769,6 +3769,13 @@ expand_integer_pack (tree call, tree args, tsubst_flags_t complain,
     {
       if (hi != ohi)
 	{
+	  /* Work around maybe_convert_nontype_argument not doing this for
+	     dependent arguments.  Don't use IMPLICIT_CONV_EXPR_NONTYPE_ARG
+	     because that will make tsubst_copy_and_build ignore it.  */
+	  tree type = tsubst (TREE_TYPE (ohi), args, complain, in_decl);
+	  if (!TREE_TYPE (hi) || !same_type_p (type, TREE_TYPE (hi)))
+	    hi = build1 (IMPLICIT_CONV_EXPR, type, hi);
+
 	  call = copy_node (call);
 	  CALL_EXPR_ARG (call, 0) = hi;
 	}
@@ -3779,8 +3786,6 @@ expand_integer_pack (tree call, tree args, tsubst_flags_t complain,
     }
   else
     {
-      hi = perform_implicit_conversion_flags (integer_type_node, hi, complain,
-					      LOOKUP_IMPLICIT);
       hi = instantiate_non_dependent_expr (hi, complain);
       hi = cxx_constant_value (hi, complain);
       int len = valid_constant_size_p (hi) ? tree_to_shwi (hi) : -1;

base-commit: 22cda0ca5fb406f22925bbf51ab152a958e3319d
-- 
2.39.3