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| author | Kjell Ahlstedt <kjellahlstedt@gmail.com> | 2019-09-02 10:20:32 +0200 |
|---|---|---|
| committer | Kjell Ahlstedt <kjellahlstedt@gmail.com> | 2019-09-02 10:20:32 +0200 |
| commit | 8453a701af8b7f3daa0667306bcf54613470cd34 (patch) | |
| tree | bc6c2be7c07887e72925f664d3605b3e9f7d825b | |
| parent | c47ec07fbb4930f456174008b15e64e2b8a6ea59 (diff) | |
| download | sigc++-8453a701af8b7f3daa0667306bcf54613470cd34.tar.gz | |
tuple_transform_each(): Fix for libc++
Tuples which are input data to std::tuple_cat() are not declared const.
Some versions of libc++ has a bug in std::tuple_cat(): All output
elements coming from a const tuple become const.
It can break 'make check' when using clang++ and -stdlib=libc++.
Fixes issue #25
| -rw-r--r-- | sigc++/tuple-utils/tuple_transform_each.h | 13 |
1 files changed, 8 insertions, 5 deletions
diff --git a/sigc++/tuple-utils/tuple_transform_each.h b/sigc++/tuple-utils/tuple_transform_each.h index 46c4271..023cdbd 100644 --- a/sigc++/tuple-utils/tuple_transform_each.h +++ b/sigc++/tuple-utils/tuple_transform_each.h @@ -18,7 +18,6 @@ #ifndef SIGC_TUPLE_UTILS_TUPLE_TRANSFORM_EACH_H #define SIGC_TUPLE_UTILS_TUPLE_TRANSFORM_EACH_H -// #include <sigc++/tuple-utils/tuple_cat.h> #include <sigc++/tuple-utils/tuple_cdr.h> #include <sigc++/tuple-utils/tuple_end.h> #include <sigc++/tuple-utils/tuple_start.h> @@ -47,14 +46,18 @@ struct tuple_transform_each_impl { using from_element_type = typename std::tuple_element<index, std::decay_t<T_original>>::type; using to_element_type = typename std::invoke_result<decltype ( &T_transformer<from_element_type>::transform), from_element_type&>::type; - const auto t_element = + // Tuples which are input data to std::tuple_cat() should not be declared const. + // Some versions of libc++ has a bug in std::tuple_cat(): All output elements + // coming from a const tuple become const. + // https://github.com/libsigcplusplus/libsigcplusplus/issues/25 + auto t_element = std::tuple<to_element_type>(T_transformer<from_element_type>::transform(std::get<index>(t_original))); if constexpr(size_from_index == 1) { - const auto tuple_rest = tuple_start<size - 1>(std::forward<T_current>(t)); + auto tuple_rest = tuple_start<size - 1>(std::forward<T_current>(t)); return std::tuple_cat(tuple_rest, t_element); } else { - const auto t_start = tuple_start<index>(std::forward<T_current>(t)); + auto t_start = tuple_start<index>(std::forward<T_current>(t)); // t_end's elements will be copies of the elements in t, so this method's // caller won't see the changes made in the subsequent call of @@ -62,7 +65,7 @@ struct tuple_transform_each_impl { // through too, so we can modify that directly. // the const version (tuple_transform_each_const()) doesn't have to worry // about this, though avoiding copying would be more efficient. - const auto t_end = tuple_end<size - index - 1>(t); + auto t_end = tuple_end<size - index - 1>(t); auto t_with_transformed_element = std::tuple_cat(t_start, t_element, t_end); return tuple_transform_each_impl<T_transformer, |