fix: make std::bitset formattable again

It used to be formattable via operator<<(ostream&) implicitly. Make it formattable the same way again, but this time explicitly.
fmtlib · Sep 29, 2023 · d87baa8 · d87baa8
1 parent 7529af8
commit d87baa8
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diff --git a/include/fmt/std.h b/include/fmt/std.h
@@ -145,6 +145,10 @@ FMT_END_NAMESPACE
 #endif
 
 FMT_BEGIN_NAMESPACE
+FMT_EXPORT
+template <std::size_t N, typename Char>
+struct formatter<std::bitset<N>, Char> : basic_ostream_formatter<Char> {};
+
 FMT_EXPORT
 template <typename Char>
 struct formatter<std::thread::id, Char> : basic_ostream_formatter<Char> {};

diff --git a/test/std-test.cc b/test/std-test.cc
@@ -237,6 +237,11 @@ TEST(std_test, format_const_bit_reference) {
   EXPECT_EQ(fmt::format("{} {}", v[0], v[1]), "true false");
 }
 
+TEST(std_test, format_bitset) {
+  const std::bitset<6> bs(42);
+  EXPECT_EQ(fmt::format("{}", bs), "101010");
+}
+
 TEST(std_test, format_atomic) {
   std::atomic<bool> b(false);
   EXPECT_EQ(fmt::format("{}", b), "false");