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Improve error message when formatting unknown types

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Jonathan Müller 2018-09-19 14:51:01 +02:00 committed by Victor Zverovich
parent 70a6a4bb01
commit 9d2221b954
1 changed files with 14 additions and 1 deletions
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15
include/fmt/core.h
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@ -340,9 +340,22 @@ class basic_format_arg;
template <typename Context> template <typename Context>
class basic_format_args; class basic_format_args;
template <typename T>
struct no_formatter_error : std::false_type {};
// A formatter for objects of type T. // A formatter for objects of type T.
template <typename T, typename Char = char, typename Enable = void> template <typename T, typename Char = char, typename Enable = void>
struct formatter; struct formatter {
static_assert(no_formatter_error<T>::value,
"don't know how to format the type, include fmt/ostream.h if it provides "
"an operator<< that should be used");
// The following functions are not defined intentionally.
template <typename ParseContext>
typename ParseContext::iterator parse(ParseContext &);
template <typename FormatContext>
auto format(const T &val, FormatContext &ctx) -> decltype(ctx.out());
};
template <typename T, typename Char, typename Enable = void> template <typename T, typename Char, typename Enable = void>
struct convert_to_int { struct convert_to_int {