[libcxx] Define istream_iterator equality comparison operators out-of-line

Currently libc++ defines operator== and operator!= as friend functions in the
definition of the istream_iterator class template. Such definition has a subtle
difference from an out-of-line definition required by the C++ Standard: these
functions can only be found by argument-dependent lookup, but not by qualified
lookup.

This patch changes the definition, so that it conforms to the C++ Standard and
adds a check involving qualified lookup to the test suite.

Patch contributed by Mikhail Maltsev.

Differential Revision: https://reviews.llvm.org/D40415

llvm-svn: 320363

1 files changed, 3 insertions, 0 deletions

diff --git a/libcxx/test/std/iterators/stream.iterators/istream.iterator/istream.iterator.ops/equal.pass.cpp b/libcxx/test/std/iterators/stream.iterators/istream.iterator/istream.iterator.ops/equal.pass.cpp
index 0bee916d50c..d1824bae6f8 100644
--- a/libcxx/test/std/iterators/stream.iterators/istream.iterator/istream.iterator.ops/equal.pass.cpp
+++ b/libcxx/test/std/iterators/stream.iterators/istream.iterator/istream.iterator.ops/equal.pass.cpp
@@ -49,4 +49,7 @@ int main()
 
     assert(i4 == i4);
     assert(i4 == i5);
+
+    assert(std::operator==(i1, i2));
+    assert(std::operator!=(i1, i3));
 }