Make is_formattable work with void

fmtlib · Sep 4, 2024 · 3df47a4 · 3df47a4
1 parent b4aea98
commit 3df47a4
Show file tree

Hide file tree

Showing 2 changed files with 6 additions and 2 deletions.
diff --git a/include/fmt/base.h b/include/fmt/base.h
@@ -2810,8 +2810,11 @@ template <typename Char, typename... T> class fstring {
 template <typename... T> using format_string = typename fstring<char, T...>::t;
 
 template <typename T, typename Char = char>
-using is_formattable = bool_constant<
-    !std::is_base_of<detail::unformattable, detail::mapped_t<T, Char>>::value>;
+using is_formattable = bool_constant<!std::is_base_of<
+    detail::unformattable,
+    detail::mapped_t<
+        conditional_t<std::is_same<T, void>::value, detail::unformattable, T>,
+        Char>>::value>;
 
 #ifdef __cpp_concepts
 template <typename T, typename Char = char>

diff --git a/test/base-test.cc b/test/base-test.cc
@@ -624,6 +624,7 @@ FMT_END_NAMESPACE
 enum class unformattable_scoped_enum {};
 
 TEST(base_test, is_formattable) {
+  EXPECT_FALSE(fmt::is_formattable<void>::value);
   EXPECT_FALSE(fmt::is_formattable<wchar_t>::value);
 #ifdef __cpp_char8_t
   EXPECT_FALSE(fmt::is_formattable<char8_t>::value);