Fix a minor bug with std::next and prev not and negative numbers. In particular, std::prev cannot require Bidirectional Iterators, because you might 'go back' -1 places, which goes forward. Thanks to Ville and Jonathan for the bug report.

llvm-svn: 356818

2 files changed, 23 insertions, 13 deletions

diff --git a/libcxx/test/std/iterators/iterator.primitives/iterator.operations/next.pass.cpp b/libcxx/test/std/iterators/iterator.primitives/iterator.operations/next.pass.cpp
index 87f79fbd32b..26ec32cab29 100644
--- a/libcxx/test/std/iterators/iterator.primitives/iterator.operations/next.pass.cpp
+++ b/libcxx/test/std/iterators/iterator.primitives/iterator.operations/next.pass.cpp
@@ -55,10 +55,12 @@ int main(int, char**)
 {
     {
     const char* s = "1234567890";
-    test(input_iterator<const char*>(s), 10, input_iterator<const char*>(s+10));
-    test(forward_iterator<const char*>(s), 10, forward_iterator<const char*>(s+10));
-    test(bidirectional_iterator<const char*>(s), 10, bidirectional_iterator<const char*>(s+10));
-    test(random_access_iterator<const char*>(s), 10, random_access_iterator<const char*>(s+10));
+    test(input_iterator<const char*>(s),             10, input_iterator<const char*>(s+10));
+    test(forward_iterator<const char*>(s),           10, forward_iterator<const char*>(s+10));
+    test(bidirectional_iterator<const char*>(s),     10, bidirectional_iterator<const char*>(s+10));
+    test(bidirectional_iterator<const char*>(s+10), -10, bidirectional_iterator<const char*>(s));
+    test(random_access_iterator<const char*>(s),     10, random_access_iterator<const char*>(s+10));
+    test(random_access_iterator<const char*>(s+10), -10, random_access_iterator<const char*>(s));
     test(s, 10, s+10);
 
     test(input_iterator<const char*>(s), input_iterator<const char*>(s+1));
@@ -70,10 +72,12 @@ int main(int, char**)
 #if TEST_STD_VER > 14
     {
     constexpr const char* s = "1234567890";
-    static_assert( constexpr_test(input_iterator<const char*>(s), 10, input_iterator<const char*>(s+10)), "" );
-    static_assert( constexpr_test(forward_iterator<const char*>(s), 10, forward_iterator<const char*>(s+10)), "" );
-    static_assert( constexpr_test(bidirectional_iterator<const char*>(s), 10, bidirectional_iterator<const char*>(s+10)), "" );
-    static_assert( constexpr_test(random_access_iterator<const char*>(s), 10, random_access_iterator<const char*>(s+10)), "" );
+    static_assert( constexpr_test(input_iterator<const char*>(s),             10, input_iterator<const char*>(s+10)), "" );
+    static_assert( constexpr_test(forward_iterator<const char*>(s),           10, forward_iterator<const char*>(s+10)), "" );
+    static_assert( constexpr_test(bidirectional_iterator<const char*>(s),     10, bidirectional_iterator<const char*>(s+10)), "" );
+    static_assert( constexpr_test(bidirectional_iterator<const char*>(s+10), -10, bidirectional_iterator<const char*>(s)), "" );
+    static_assert( constexpr_test(random_access_iterator<const char*>(s),     10, random_access_iterator<const char*>(s+10)), "" );
+    static_assert( constexpr_test(random_access_iterator<const char*>(s+10), -10, random_access_iterator<const char*>(s)), "" );
     static_assert( constexpr_test(s, 10, s+10), "" );
 
     static_assert( constexpr_test(input_iterator<const char*>(s), input_iterator<const char*>(s+1)), "" );
diff --git a/libcxx/test/std/iterators/iterator.primitives/iterator.operations/prev.pass.cpp b/libcxx/test/std/iterators/iterator.primitives/iterator.operations/prev.pass.cpp
index 2ee0444ce14..8faaf3d05f0 100644
--- a/libcxx/test/std/iterators/iterator.primitives/iterator.operations/prev.pass.cpp
+++ b/libcxx/test/std/iterators/iterator.primitives/iterator.operations/prev.pass.cpp
@@ -8,7 +8,7 @@
 
 // <iterator>
 
-// template <BidirectionalIterator Iter>
+// template <InputIterator Iter>
 //   Iter prev(Iter x, Iter::difference_type n = 1);
 
 #include <iterator>
@@ -53,8 +53,11 @@ int main(int, char**)
 {
     {
     const char* s = "1234567890";
-    test(bidirectional_iterator<const char*>(s+10), 10, bidirectional_iterator<const char*>(s));
-    test(random_access_iterator<const char*>(s+10), 10, random_access_iterator<const char*>(s));
+    test(forward_iterator      <const char*>(s),    -10, forward_iterator      <const char*>(s+10));
+    test(bidirectional_iterator<const char*>(s+10),  10, bidirectional_iterator<const char*>(s));
+    test(bidirectional_iterator<const char*>(s),    -10, bidirectional_iterator<const char*>(s+10));
+    test(random_access_iterator<const char*>(s+10),  10, random_access_iterator<const char*>(s));
+    test(random_access_iterator<const char*>(s),    -10, random_access_iterator<const char*>(s+10));
     test(s+10, 10, s);
 
     test(bidirectional_iterator<const char*>(s+1), bidirectional_iterator<const char*>(s));
@@ -64,8 +67,11 @@ int main(int, char**)
 #if TEST_STD_VER > 14
     {
     constexpr const char* s = "1234567890";
-    static_assert( constexpr_test(bidirectional_iterator<const char*>(s+10), 10, bidirectional_iterator<const char*>(s)), "" );
-    static_assert( constexpr_test(random_access_iterator<const char*>(s+10), 10, random_access_iterator<const char*>(s)), "" );
+    static_assert( constexpr_test(forward_iterator      <const char*>(s),    -10, forward_iterator      <const char*>(s+10)), "" );
+    static_assert( constexpr_test(bidirectional_iterator<const char*>(s+10),  10, bidirectional_iterator<const char*>(s)), "" );
+    static_assert( constexpr_test(forward_iterator      <const char*>(s),    -10, forward_iterator      <const char*>(s+10)), "" );
+    static_assert( constexpr_test(random_access_iterator<const char*>(s+10),  10, random_access_iterator<const char*>(s)), "" );
+    static_assert( constexpr_test(forward_iterator      <const char*>(s),    -10, forward_iterator      <const char*>(s+10)), "" );
     static_assert( constexpr_test(s+10, 10, s), "" );
 
     static_assert( constexpr_test(bidirectional_iterator<const char*>(s+1), bidirectional_iterator<const char*>(s)), "" );