Make formatter override implicit conversion to a C string

2020-02-07 19:24:36 -08:00
parent 24924128e3
commit 1f1b50707c
3 changed files with 25 additions and 18 deletions
@@ -469,6 +469,10 @@ struct convertible_to_int {
  operator int() const { return 42; }
 };

+struct convertible_to_c_string {
+  operator const char*() const { return "foo"; }
+};
+
 FMT_BEGIN_NAMESPACE
 template <> struct formatter<convertible_to_int> {
  auto parse(format_parse_context& ctx) -> decltype(ctx.begin()) {
@@ -478,10 +482,21 @@ template <> struct formatter<convertible_to_int> {
    return std::copy_n("foo", 3, ctx.out());
  }
 };
+
+template <> struct formatter<convertible_to_c_string> {
+  auto parse(format_parse_context& ctx) -> decltype(ctx.begin()) {
+    return ctx.begin();
+  }
+  auto format(convertible_to_c_string, format_context& ctx)
+      -> decltype(ctx.out()) {
+    return std::copy_n("bar", 3, ctx.out());
+  }
+};
 FMT_END_NAMESPACE

 TEST(CoreTest, FormatterOverridesImplicitConversion) {
  EXPECT_EQ(fmt::format("{}", convertible_to_int()), "foo");
+  EXPECT_EQ(fmt::format("{}", convertible_to_c_string()), "bar");
 }

 namespace my_ns {