[committed] libstdc++: Find make_error_code and make_error_condition via ADL only

Message ID 20220908183010.3290473-1-jwakely@redhat.com
State New, archived
Headers
Series [committed] libstdc++: Find make_error_code and make_error_condition via ADL only |

Commit Message

Jonathan Wakely Sept. 8, 2022, 6:30 p.m. UTC
  Tested powerpc64le-linux, pushed to trunk.

-- >8 --

The new proposed resolution for LWG 3629 says that std::error_code and
std::error_condition should only use ADL to find their customization
points. This means we need to use a poison pill to prevent lookup from
finding overloads in the enclosing namespaces.

We can also remove the forward declarations of std::make_error_code and
std::make_error_condition, because they aren't needed now. ADL can find
them anyway (when std is an associated namespace), and unqualified name
lookup will not (and should not) find them.

libstdc++-v3/ChangeLog:

	* include/std/system_error (__adl_only::make_error_code): Add
	deleted function.
	(__adl_only::make_error_condition): Likewise.
	(error_code::error_code(ErrorCodeEnum)): Add using-declaration
	for deleted function.
	(error_condition::error_condition(ErrorConditionEnum)):
	Likewise.
	* testsuite/19_diagnostics/error_code/cons/lwg3629.cc: New test.
	* testsuite/19_diagnostics/error_condition/cons/lwg3629.cc: New test.
---
 libstdc++-v3/include/std/system_error         | 18 +++++--
 .../19_diagnostics/error_code/cons/lwg3629.cc | 48 +++++++++++++++++++
 .../error_condition/cons/lwg3629.cc           | 48 +++++++++++++++++++
 3 files changed, 109 insertions(+), 5 deletions(-)
 create mode 100644 libstdc++-v3/testsuite/19_diagnostics/error_code/cons/lwg3629.cc
 create mode 100644 libstdc++-v3/testsuite/19_diagnostics/error_condition/cons/lwg3629.cc
  

Comments

Daniel Krügler Sept. 12, 2022, 10:55 a.m. UTC | #1
Am Do., 8. Sept. 2022 um 20:30 Uhr schrieb Jonathan Wakely via
Libstdc++ <libstdc++@gcc.gnu.org>:
>
> Tested powerpc64le-linux, pushed to trunk.
>
> -- >8 --
>
> The new proposed resolution for LWG 3629 says that std::error_code and
> std::error_condition should only use ADL to find their customization
> points. This means we need to use a poison pill to prevent lookup from
> finding overloads in the enclosing namespaces.
>
> We can also remove the forward declarations of std::make_error_code and
> std::make_error_condition, because they aren't needed now. ADL can find
> them anyway (when std is an associated namespace), and unqualified name
> lookup will not (and should not) find them.
>
> libstdc++-v3/ChangeLog:
>
>         * include/std/system_error (__adl_only::make_error_code): Add
>         deleted function.
>         (__adl_only::make_error_condition): Likewise.
>         (error_code::error_code(ErrorCodeEnum)): Add using-declaration
>         for deleted function.
>         (error_condition::error_condition(ErrorConditionEnum)):
>         Likewise.
>         * testsuite/19_diagnostics/error_code/cons/lwg3629.cc: New test.
>         * testsuite/19_diagnostics/error_condition/cons/lwg3629.cc: New test.
> ---
[..]
> +// { dg-do compile { target c++11 } }
> +
> +// 3629. make_error_code and make_error_condition are customization points
> +// Verify that make_error_code is looked up using ADL only.
> +
> +namespace user
> +{
> +  struct E1;
> +}
> +
> +// N.B. not in associated namespace of E1, and declared before <system_error>.
> +user::E1 make_error_code(user::E1);
> +
> +#include <future> // declares std::make_error_code(future_errc)
> +#include <system_error>
> +
> +namespace user
> +{
> +  struct E1
> +  {
> +    operator std::error_code() const;
> +  };
> +
> +  struct E2
> +  {
> +    operator std::future_errc() const;
> +  };
> +
> +  struct E3
> +  {
> +    operator std::errc() const;
> +  };
> +}
> +
> +template<> struct std::is_error_code_enum<user::E1> : std::true_type { };
> +template<> struct std::is_error_code_enum<user::E2> : std::true_type { };
> +template<> struct std::is_error_code_enum<user::E3> : std::true_type { };
> +
> +// ::make_error_code(E1) should not be found by name lookup.
> +std::error_code e1( user::E1{} ); // { dg-error "here" }
> +
> +// std::make_error_code(errc) should not be found by name lookup.
> +std::error_code e2( user::E2{} ); // { dg-error "here" }

(1) Unless I'm misunderstanding something here, the comment above
doesn't match here, it should mention (std::)future_errc instead.

> +// std::make_error_code(future_errc) should not be found by name lookup.
> +std::error_code e3( user::E3{} ); // { dg-error "here" }

(2) Unless I'm misunderstanding something here, the comment above
doesn't match here, it should mention (std::)errc instead.

> +// { dg-error "use of deleted function" "" { target *-*-* } 0 }
> diff --git a/libstdc++-v3/testsuite/19_diagnostics/error_condition/cons/lwg3629.cc b/libstdc++-v3/testsuite/19_diagnostics/error_condition/cons/lwg3629.cc
> new file mode 100644
> index 00000000000..e34b53de8a1
> --- /dev/null
> +++ b/libstdc++-v3/testsuite/19_diagnostics/error_condition/cons/lwg3629.cc
> @@ -0,0 +1,48 @@
> +// { dg-do compile { target c++11 } }
> +
> +// 3629. make_error_code and make_error_condition are customization points
> +// Verify that make_error_condition is looked up using ADL only.
> +
> +namespace user
> +{
> +  struct E1;
> +}
> +
> +// N.B. not in associated namespace of E1, and declared before <system_error>.
> +user::E1 make_error_condition(user::E1);
> +
> +#include <future> // declares std::make_error_condition(future_errc)
> +#include <system_error>
> +
> +namespace user
> +{
> +  struct E1
> +  {
> +    operator std::error_code() const;
> +  };
> +
> +  struct E2
> +  {
> +    operator std::future_errc() const;
> +  };
> +
> +  struct E3
> +  {
> +    operator std::errc() const;
> +  };
> +}
> +
> +template<> struct std::is_error_condition_enum<user::E1> : std::true_type { };
> +template<> struct std::is_error_condition_enum<user::E2> : std::true_type { };
> +template<> struct std::is_error_condition_enum<user::E3> : std::true_type { };
> +
> +// ::make_error_condition(E1) should not be found by name lookup.
> +std::error_condition e1( user::E1{} ); // { dg-error "here" }
> +
> +// std::make_error_condition(errc) should not be found by name lookup.
> +std::error_condition e2( user::E2{} ); // { dg-error "here" }

Ditto here (1)

> +// std::make_error_condition(future_errc) should not be found by name lookup.
> +std::error_condition e3( user::E3{} ); // { dg-error "here" }

Ditto here (2)

> +// { dg-error "use of deleted function" "" { target *-*-* } 0 }
> --
> 2.37.3

- Daniel
  
Jonathan Wakely Sept. 12, 2022, 11:04 a.m. UTC | #2
On Mon, 12 Sept 2022 at 11:55, Daniel Krügler <daniel.kruegler@gmail.com> wrote:
>
> Am Do., 8. Sept. 2022 um 20:30 Uhr schrieb Jonathan Wakely via
> Libstdc++ <libstdc++@gcc.gnu.org>:
> >
> > Tested powerpc64le-linux, pushed to trunk.
> >
> > -- >8 --
> >
> > The new proposed resolution for LWG 3629 says that std::error_code and
> > std::error_condition should only use ADL to find their customization
> > points. This means we need to use a poison pill to prevent lookup from
> > finding overloads in the enclosing namespaces.
> >
> > We can also remove the forward declarations of std::make_error_code and
> > std::make_error_condition, because they aren't needed now. ADL can find
> > them anyway (when std is an associated namespace), and unqualified name
> > lookup will not (and should not) find them.
> >
> > libstdc++-v3/ChangeLog:
> >
> >         * include/std/system_error (__adl_only::make_error_code): Add
> >         deleted function.
> >         (__adl_only::make_error_condition): Likewise.
> >         (error_code::error_code(ErrorCodeEnum)): Add using-declaration
> >         for deleted function.
> >         (error_condition::error_condition(ErrorConditionEnum)):
> >         Likewise.
> >         * testsuite/19_diagnostics/error_code/cons/lwg3629.cc: New test.
> >         * testsuite/19_diagnostics/error_condition/cons/lwg3629.cc: New test.
> > ---
> [..]
> > +// { dg-do compile { target c++11 } }
> > +
> > +// 3629. make_error_code and make_error_condition are customization points
> > +// Verify that make_error_code is looked up using ADL only.
> > +
> > +namespace user
> > +{
> > +  struct E1;
> > +}
> > +
> > +// N.B. not in associated namespace of E1, and declared before <system_error>.
> > +user::E1 make_error_code(user::E1);
> > +
> > +#include <future> // declares std::make_error_code(future_errc)
> > +#include <system_error>
> > +
> > +namespace user
> > +{
> > +  struct E1
> > +  {
> > +    operator std::error_code() const;
> > +  };
> > +
> > +  struct E2
> > +  {
> > +    operator std::future_errc() const;
> > +  };
> > +
> > +  struct E3
> > +  {
> > +    operator std::errc() const;
> > +  };
> > +}
> > +
> > +template<> struct std::is_error_code_enum<user::E1> : std::true_type { };
> > +template<> struct std::is_error_code_enum<user::E2> : std::true_type { };
> > +template<> struct std::is_error_code_enum<user::E3> : std::true_type { };
> > +
> > +// ::make_error_code(E1) should not be found by name lookup.
> > +std::error_code e1( user::E1{} ); // { dg-error "here" }
> > +
> > +// std::make_error_code(errc) should not be found by name lookup.
> > +std::error_code e2( user::E2{} ); // { dg-error "here" }
>
> (1) Unless I'm misunderstanding something here, the comment above
> doesn't match here, it should mention (std::)future_errc instead.
>
> > +// std::make_error_code(future_errc) should not be found by name lookup.
> > +std::error_code e3( user::E3{} ); // { dg-error "here" }
>
> (2) Unless I'm misunderstanding something here, the comment above
> doesn't match here, it should mention (std::)errc instead.
>
> > +// { dg-error "use of deleted function" "" { target *-*-* } 0 }
> > diff --git a/libstdc++-v3/testsuite/19_diagnostics/error_condition/cons/lwg3629.cc b/libstdc++-v3/testsuite/19_diagnostics/error_condition/cons/lwg3629.cc
> > new file mode 100644
> > index 00000000000..e34b53de8a1
> > --- /dev/null
> > +++ b/libstdc++-v3/testsuite/19_diagnostics/error_condition/cons/lwg3629.cc
> > @@ -0,0 +1,48 @@
> > +// { dg-do compile { target c++11 } }
> > +
> > +// 3629. make_error_code and make_error_condition are customization points
> > +// Verify that make_error_condition is looked up using ADL only.
> > +
> > +namespace user
> > +{
> > +  struct E1;
> > +}
> > +
> > +// N.B. not in associated namespace of E1, and declared before <system_error>.
> > +user::E1 make_error_condition(user::E1);
> > +
> > +#include <future> // declares std::make_error_condition(future_errc)
> > +#include <system_error>
> > +
> > +namespace user
> > +{
> > +  struct E1
> > +  {
> > +    operator std::error_code() const;
> > +  };
> > +
> > +  struct E2
> > +  {
> > +    operator std::future_errc() const;
> > +  };
> > +
> > +  struct E3
> > +  {
> > +    operator std::errc() const;
> > +  };
> > +}
> > +
> > +template<> struct std::is_error_condition_enum<user::E1> : std::true_type { };
> > +template<> struct std::is_error_condition_enum<user::E2> : std::true_type { };
> > +template<> struct std::is_error_condition_enum<user::E3> : std::true_type { };
> > +
> > +// ::make_error_condition(E1) should not be found by name lookup.
> > +std::error_condition e1( user::E1{} ); // { dg-error "here" }
> > +
> > +// std::make_error_condition(errc) should not be found by name lookup.
> > +std::error_condition e2( user::E2{} ); // { dg-error "here" }
>
> Ditto here (1)
>
> > +// std::make_error_condition(future_errc) should not be found by name lookup.
> > +std::error_condition e3( user::E3{} ); // { dg-error "here" }
>
> Ditto here (2)


Good catch, thanks.

Fixed by the attached patch, tested x86_64-linux and pushed to trunk.
commit c092d894265f3db590585804c30c1ae3cb7b3773
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Mon Sep 12 12:02:29 2022

    libstdc++: Fix comments in tests to match code
    
    libstdc++-v3/ChangeLog:
    
            * testsuite/19_diagnostics/error_code/cons/lwg3629.cc: Fix
            comments.
            * testsuite/19_diagnostics/error_condition/cons/lwg3629.cc:
            Likewise.

diff --git a/libstdc++-v3/testsuite/19_diagnostics/error_code/cons/lwg3629.cc b/libstdc++-v3/testsuite/19_diagnostics/error_code/cons/lwg3629.cc
index b1e0b7f0c81..70fa5e80503 100644
--- a/libstdc++-v3/testsuite/19_diagnostics/error_code/cons/lwg3629.cc
+++ b/libstdc++-v3/testsuite/19_diagnostics/error_code/cons/lwg3629.cc
@@ -39,10 +39,10 @@ template<> struct std::is_error_code_enum<user::E3> : std::true_type { };
 // ::make_error_code(E1) should not be found by name lookup.
 std::error_code e1( user::E1{} ); // { dg-error "here" }
 
-// std::make_error_code(errc) should not be found by name lookup.
+// std::make_error_code(future_errc) should not be found by name lookup.
 std::error_code e2( user::E2{} ); // { dg-error "here" }
 
-// std::make_error_code(future_errc) should not be found by name lookup.
+// std::make_error_code(errc) should not be found by name lookup.
 std::error_code e3( user::E3{} ); // { dg-error "here" }
 
 // { dg-error "use of deleted function" "" { target *-*-* } 0 }
diff --git a/libstdc++-v3/testsuite/19_diagnostics/error_condition/cons/lwg3629.cc b/libstdc++-v3/testsuite/19_diagnostics/error_condition/cons/lwg3629.cc
index e34b53de8a1..562a99aee3b 100644
--- a/libstdc++-v3/testsuite/19_diagnostics/error_condition/cons/lwg3629.cc
+++ b/libstdc++-v3/testsuite/19_diagnostics/error_condition/cons/lwg3629.cc
@@ -39,10 +39,10 @@ template<> struct std::is_error_condition_enum<user::E3> : std::true_type { };
 // ::make_error_condition(E1) should not be found by name lookup.
 std::error_condition e1( user::E1{} ); // { dg-error "here" }
 
-// std::make_error_condition(errc) should not be found by name lookup.
+// std::make_error_condition(future_errc) should not be found by name lookup.
 std::error_condition e2( user::E2{} ); // { dg-error "here" }
 
-// std::make_error_condition(future_errc) should not be found by name lookup.
+// std::make_error_condition(errc) should not be found by name lookup.
 std::error_condition e3( user::E3{} ); // { dg-error "here" }
 
 // { dg-error "use of deleted function" "" { target *-*-* } 0 }
  

Patch

diff --git a/libstdc++-v3/include/std/system_error b/libstdc++-v3/include/std/system_error
index 050439427cc..e12bb2f0e1e 100644
--- a/libstdc++-v3/include/std/system_error
+++ b/libstdc++-v3/include/std/system_error
@@ -195,7 +195,11 @@  _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2)
    * @{
    */
 
-  error_code make_error_code(errc) noexcept;
+namespace __adl_only
+{
+  void make_error_code() = delete;
+  void make_error_condition() = delete;
+}
 
   /** Class error_code
    *
@@ -231,7 +235,10 @@  _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2)
     template<typename _ErrorCodeEnum,
 	     typename = _Check<_ErrorCodeEnum>>
       error_code(_ErrorCodeEnum __e) noexcept
-      { *this = make_error_code(__e); }
+      {
+	using __adl_only::make_error_code;
+	*this = make_error_code(__e);
+      }
 
     error_code(const error_code&) = default;
     error_code& operator=(const error_code&) = default;
@@ -330,8 +337,6 @@  _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2)
     operator<<(basic_ostream<_CharT, _Traits>& __os, const error_code& __e)
     { return (__os << __e.category().name() << ':' << __e.value()); }
 
-  error_condition make_error_condition(errc) noexcept;
-
   /** Class error_condition
    *
    * This class represents error conditions that may be visible at an API
@@ -363,7 +368,10 @@  _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2)
     template<typename _ErrorConditionEnum,
 	     typename = _Check<_ErrorConditionEnum>>
       error_condition(_ErrorConditionEnum __e) noexcept
-      { *this = make_error_condition(__e); }
+      {
+	using __adl_only::make_error_condition;
+	*this = make_error_condition(__e);
+      }
 
     error_condition(const error_condition&) = default;
     error_condition& operator=(const error_condition&) = default;
diff --git a/libstdc++-v3/testsuite/19_diagnostics/error_code/cons/lwg3629.cc b/libstdc++-v3/testsuite/19_diagnostics/error_code/cons/lwg3629.cc
new file mode 100644
index 00000000000..b1e0b7f0c81
--- /dev/null
+++ b/libstdc++-v3/testsuite/19_diagnostics/error_code/cons/lwg3629.cc
@@ -0,0 +1,48 @@ 
+// { dg-do compile { target c++11 } }
+
+// 3629. make_error_code and make_error_condition are customization points
+// Verify that make_error_code is looked up using ADL only.
+
+namespace user
+{
+  struct E1;
+}
+
+// N.B. not in associated namespace of E1, and declared before <system_error>.
+user::E1 make_error_code(user::E1);
+
+#include <future> // declares std::make_error_code(future_errc)
+#include <system_error>
+
+namespace user
+{
+  struct E1
+  {
+    operator std::error_code() const;
+  };
+
+  struct E2
+  {
+    operator std::future_errc() const;
+  };
+
+  struct E3
+  {
+    operator std::errc() const;
+  };
+}
+
+template<> struct std::is_error_code_enum<user::E1> : std::true_type { };
+template<> struct std::is_error_code_enum<user::E2> : std::true_type { };
+template<> struct std::is_error_code_enum<user::E3> : std::true_type { };
+
+// ::make_error_code(E1) should not be found by name lookup.
+std::error_code e1( user::E1{} ); // { dg-error "here" }
+
+// std::make_error_code(errc) should not be found by name lookup.
+std::error_code e2( user::E2{} ); // { dg-error "here" }
+
+// std::make_error_code(future_errc) should not be found by name lookup.
+std::error_code e3( user::E3{} ); // { dg-error "here" }
+
+// { dg-error "use of deleted function" "" { target *-*-* } 0 }
diff --git a/libstdc++-v3/testsuite/19_diagnostics/error_condition/cons/lwg3629.cc b/libstdc++-v3/testsuite/19_diagnostics/error_condition/cons/lwg3629.cc
new file mode 100644
index 00000000000..e34b53de8a1
--- /dev/null
+++ b/libstdc++-v3/testsuite/19_diagnostics/error_condition/cons/lwg3629.cc
@@ -0,0 +1,48 @@ 
+// { dg-do compile { target c++11 } }
+
+// 3629. make_error_code and make_error_condition are customization points
+// Verify that make_error_condition is looked up using ADL only.
+
+namespace user
+{
+  struct E1;
+}
+
+// N.B. not in associated namespace of E1, and declared before <system_error>.
+user::E1 make_error_condition(user::E1);
+
+#include <future> // declares std::make_error_condition(future_errc)
+#include <system_error>
+
+namespace user
+{
+  struct E1
+  {
+    operator std::error_code() const;
+  };
+
+  struct E2
+  {
+    operator std::future_errc() const;
+  };
+
+  struct E3
+  {
+    operator std::errc() const;
+  };
+}
+
+template<> struct std::is_error_condition_enum<user::E1> : std::true_type { };
+template<> struct std::is_error_condition_enum<user::E2> : std::true_type { };
+template<> struct std::is_error_condition_enum<user::E3> : std::true_type { };
+
+// ::make_error_condition(E1) should not be found by name lookup.
+std::error_condition e1( user::E1{} ); // { dg-error "here" }
+
+// std::make_error_condition(errc) should not be found by name lookup.
+std::error_condition e2( user::E2{} ); // { dg-error "here" }
+
+// std::make_error_condition(future_errc) should not be found by name lookup.
+std::error_condition e3( user::E3{} ); // { dg-error "here" }
+
+// { dg-error "use of deleted function" "" { target *-*-* } 0 }