Backport fix handling of formattable types implicitly convertible to pointers (fixes: rhbz#2059736)

Signed-off-by: Michel Alexandre Salim <salimma@fedoraproject.org>

fmt-fix_implicit_ptr_conv.patch

@@ -0,0 +1,72 @@
+From 8f8a1a02d5c5cb967d240feee3ffac00d66f22a2 Mon Sep 17 00:00:00 2001
+From: Victor Zverovich <viz@fb.com>
+Date: Fri, 14 Jan 2022 13:08:14 -0800
+Subject: [PATCH] Fix handling of formattable types implicitly convertible to
+ pointers
+
+---
+ include/fmt/core.h |  5 +++--
+ test/core-test.cc  | 21 ++++++++++++++++++++-
+ 2 files changed, 23 insertions(+), 3 deletions(-)
+
+diff --git a/include/fmt/core.h b/include/fmt/core.h
+index f2d21e5c5a..12571ce0da 100644
+--- a/include/fmt/core.h
++++ b/include/fmt/core.h
+@@ -1398,10 +1398,11 @@ template <typename Context> struct arg_mapper {
+   template <
+       typename T,
+       FMT_ENABLE_IF(
+-          std::is_member_pointer<T>::value ||
++          std::is_pointer<T>::value || std::is_member_pointer<T>::value ||
+           std::is_function<typename std::remove_pointer<T>::type>::value ||
+           (std::is_convertible<const T&, const void*>::value &&
+-           !std::is_convertible<const T&, const char_type*>::value))>
++           !std::is_convertible<const T&, const char_type*>::value &&
++           !has_formatter<T, Context>::value))>
+   FMT_CONSTEXPR auto map(const T&) -> unformattable_pointer {
+     return {};
+   }
+diff --git a/test/core-test.cc b/test/core-test.cc
+index b2f2097ea1..c9eea8ffd8 100644
+--- a/test/core-test.cc
++++ b/test/core-test.cc
+@@ -737,6 +737,24 @@ struct convertible_to_pointer {
+   operator const int*() const { return nullptr; }
+ };
+ 
++struct convertible_to_pointer_formattable {
++  operator const int*() const { return nullptr; }
++};
++
++FMT_BEGIN_NAMESPACE
++template <> struct formatter<convertible_to_pointer_formattable> {
++  auto parse(format_parse_context& ctx) -> decltype(ctx.begin()) {
++    return ctx.begin();
++  }
++
++  auto format(convertible_to_pointer_formattable, format_context& ctx) const
++      -> decltype(ctx.out()) {
++    auto test = string_view("test");
++    return std::copy_n(test.data(), test.size(), ctx.out());
++  }
++};
++FMT_END_NAMESPACE
++
+ enum class test_scoped_enum {};
+ 
+ TEST(core_test, is_formattable) {
+@@ -770,11 +788,12 @@ TEST(core_test, is_formattable) {
+ #endif
+ 
+   static_assert(!fmt::is_formattable<convertible_to_pointer>::value, "");
++  const auto f = convertible_to_pointer_formattable();
++  EXPECT_EQ(fmt::format("{}", f), "test");
+ 
+   static_assert(!fmt::is_formattable<void (*)()>::value, "");
+ 
+   struct s;
+-
+   static_assert(!fmt::is_formattable<int(s::*)>::value, "");
+   static_assert(!fmt::is_formattable<int (s::*)()>::value, "");
+   static_assert(!fmt::is_formattable<test_scoped_enum>::value, "");

fmt.spec

@@ -2,12 +2,14 @@
 
 Name:           fmt
 Version:        8.1.1
-Release:        3%{?dist}
+Release:        4%{?dist}
 
 License:        BSD
 Summary:        Small, safe and fast formatting library for C++
 URL:            https://github.com/fmtlib/%{name}
 Source0:        %{url}/archive/%{version}.tar.gz
+# fix for https://github.com/fmtlib/fmt/issues/2717
+Patch0:         %{url}/commit/8f8a1a02d5c5cb967d240feee3ffac00d66f22a2.patch#/%{name}-fix_implicit_ptr_conv.patch
 
 BuildRequires:  gcc
 BuildRequires:  gcc-c++
@@ -71,6 +73,9 @@ This package contains the header file for using %{name}.
 %{_libdir}/pkgconfig/%{name}.pc
 
 %changelog
+* Tue Mar  1 2022 Michel Alexandre Salim <salimma@fedoraproject.org> - 8.1.1-4
+- Backport fix handling of formattable types implicitly convertible to pointers (fixes: rhbz#2059736)
+
 * Thu Jan 27 2022 Zbigniew Jędrzejewski-Szmek <zbyszek@in.waw.pl> - 8.1.1-3
 - Rebuild with new annobin (rhbz#2046232)