From 46be68fda3c8dc5a5d19cbdae2061ef1018b8045 Mon Sep 17 00:00:00 2001
From: Sam Yates <halfflat@gmail.com>
Date: Tue, 6 Sep 2016 14:46:58 +0200
Subject: [PATCH] Workaround: type member test failure in gcc 4.9.3
Void default argument SFINAE test for presence of
type definition within in a class fails in gcc 4.9.3.
This commit uses a different SFINAE approach to work around
the compiler bug.
---
src/util/iterutil.hpp | 2 +-
src/util/meta.hpp | 19 ++++++++++----
tests/unit/test_range.cpp | 53 ++++++++++++++++++---------------------
3 files changed, 40 insertions(+), 34 deletions(-)
diff --git a/src/util/iterutil.hpp b/src/util/iterutil.hpp
index a357b667..68539857 100644
--- a/src/util/iterutil.hpp
+++ b/src/util/iterutil.hpp
@@ -44,7 +44,7 @@ upto(I iter, E end) {
}
template <typename I, typename E,
- typename C = typename common_random_access_iterator<I,E>::type>
+ typename C = common_random_access_iterator_t<I,E>>
enable_if_t<std::is_same<I, E>::value ||
(has_common_random_access_iterator<I,E>::value &&
is_forward_iterator<I>::value),
diff --git a/src/util/meta.hpp b/src/util/meta.hpp
index e45d3160..e3d7fc95 100644
--- a/src/util/meta.hpp
+++ b/src/util/meta.hpp
@@ -171,13 +171,22 @@ struct common_random_access_iterator<
>;
};
-template <typename I, typename E, typename = void>
-struct has_common_random_access_iterator: public std::false_type {};
+template <typename I, typename E>
+using common_random_access_iterator_t = typename common_random_access_iterator<I, E>::type;
+// NB: using this version of SFINAE instead of a void default template
+// parameter because of a bug in gcc 4.9.3.
template <typename I, typename E>
-struct has_common_random_access_iterator<
- I, E, void_t<typename common_random_access_iterator<I, E>::type>
-> : public std::true_type {};
+struct has_common_random_access_iterator {
+private:
+ constexpr static bool test(...) { return false; }
+
+ template <typename U = I>
+ constexpr static bool test(typename common_random_access_iterator<U, E>::type*) { return true; }
+
+public:
+ constexpr static bool value = test(nullptr);
+};
diff --git a/tests/unit/test_range.cpp b/tests/unit/test_range.cpp
index 5b1d84cb..118a4dc1 100644
--- a/tests/unit/test_range.cpp
+++ b/tests/unit/test_range.cpp
@@ -96,33 +96,30 @@ TEST(range, empty) {
EXPECT_EQ(0u, empty_range_rr.size());
}
-template<typename I, typename E, typename = void>
-struct util_distance_enabled : public std::false_type {};
-
-// This is the same test for enabling util::distance
-template<typename I, typename E>
-struct util_distance_enabled<
- I, E, util::void_t<
- util::enable_if_t<
- !util::has_common_random_access_iterator<I, E>::value &&
- util::is_forward_iterator<I>::value
- >>> : public std::true_type {};
-
-TEST(range, size) {
- static_assert(util_distance_enabled<
- typename std::list<int>::iterator,
- typename std::list<int>::const_iterator>::value,
- "util::distance not enabled");
- static_assert(!util_distance_enabled<
- typename std::vector<int>::const_iterator,
- typename std::vector<int>::iterator>::value,
- "util::distance erroneously enabled");
- static_assert(!util_distance_enabled<int*, int*>::value,
- "util::distance erroneously enabled");
- static_assert(!util_distance_enabled<int*, const int*>::value,
- "util::distance erroneously enabled");
- static_assert(!util_distance_enabled<const int*, int*>::value,
- "util::distance erroneously enabled");
+// This is the same test for enabling the incrementing util::distance
+// implementation.
+template <typename I, typename E>
+constexpr bool uses_incrementing_distance() {
+ return !util::has_common_random_access_iterator<I, E>::value &&
+ util::is_forward_iterator<I>::value;
+}
+
+TEST(range, size_implementation) {
+ ASSERT_TRUE((uses_incrementing_distance<
+ std::list<int>::iterator,
+ std::list<int>::const_iterator
+ >()));
+
+ ASSERT_FALSE((uses_incrementing_distance<
+ std::vector<int>::iterator,
+ std::vector<int>::const_iterator
+ >()));
+
+ ASSERT_FALSE((uses_incrementing_distance<int*, int*>()));
+
+ ASSERT_FALSE((uses_incrementing_distance<const int*, int*>()));
+
+ ASSERT_FALSE((uses_incrementing_distance<int*, const int*>()));
}
TEST(range, input_iterator) {
@@ -228,7 +225,7 @@ TYPED_TEST_P(counter_range, size) {
auto r = counter{signed_int_type{3}};
auto range = util::make_range(l, r);
EXPECT_FALSE(range.empty());
- EXPECT_EQ(6, range.size());
+ EXPECT_EQ(6u, range.size());
}
--
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