[PATCH] D33550: Make __wrap_iter constexpr

[Eric Fiselier via Phabricator via cfe-commits]

EricWF added a comment.

@mclow.lists Could you update this diff with more context?


https://reviews.llvm.org/D33550



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[PATCH] D33550: Make __wrap_iter constexpr

[Marshall Clow via Phabricator via cfe-commits]

mclow.lists added inline comments.



Comment at: include/iterator:1409
 
-private:
+// private:
 #if _LIBCPP_DEBUG_LEVEL >= 2

This is testing debris - making the constructors public for testing.


https://reviews.llvm.org/D33550



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[PATCH] D33550: Make __wrap_iter constexpr

[Marshall Clow via Phabricator via cfe-commits]

mclow.lists created this revision.

`__wrap_iter` is an internal libc++ class that is used as an iterator type when 
(for some reason) we don't want to use raw pointers as an iterator.  It is the 
iterator type for `vector` and `string` (but not `array` - not sure why). If we 
used pointers, all the operations on the iterators would be constexpr.  With 
this patch, the corresponding operations on `__wrap_iter` are constexpr as well.

We'll have to do this when 
http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#2938 is adopted.

No tests, because all the interesting constructors of `__wrap_iter` are 
private, and only accessed through friend functions.
I have written tests (after making the appropriate ctors public) and they seem 
to work.


https://reviews.llvm.org/D33550

Files:
  include/algorithm
  include/iterator

Index: include/iterator
===
--- include/iterator
+++ include/iterator
@@ -1199,32 +1199,32 @@
 template  class __wrap_iter;
 
 template 
-_LIBCPP_INLINE_VISIBILITY
+_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
 bool
 operator==(const __wrap_iter<_Iter1>&, const __wrap_iter<_Iter2>&) _NOEXCEPT_DEBUG;
 
 template 
-_LIBCPP_INLINE_VISIBILITY
+_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
 bool
 operator<(const __wrap_iter<_Iter1>&, const __wrap_iter<_Iter2>&) _NOEXCEPT_DEBUG;
 
 template 
-_LIBCPP_INLINE_VISIBILITY
+_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
 bool
 operator!=(const __wrap_iter<_Iter1>&, const __wrap_iter<_Iter2>&) _NOEXCEPT_DEBUG;
 
 template 
-_LIBCPP_INLINE_VISIBILITY
+_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
 bool
 operator>(const __wrap_iter<_Iter1>&, const __wrap_iter<_Iter2>&) _NOEXCEPT_DEBUG;
 
 template 
-_LIBCPP_INLINE_VISIBILITY
+_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
 bool
 operator>=(const __wrap_iter<_Iter1>&, const __wrap_iter<_Iter2>&) _NOEXCEPT_DEBUG;
 
 template 
-_LIBCPP_INLINE_VISIBILITY
+_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
 bool
 operator<=(const __wrap_iter<_Iter1>&, const __wrap_iter<_Iter2>&) _NOEXCEPT_DEBUG;
 
@@ -1236,13 +1236,13 @@
 -> decltype(__x.base() - __y.base());
 #else
 template 
-_LIBCPP_INLINE_VISIBILITY
+_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
 typename __wrap_iter<_Iter1>::difference_type
 operator-(const __wrap_iter<_Iter1>&, const __wrap_iter<_Iter2>&) _NOEXCEPT_DEBUG;
 #endif
 
 template 
-_LIBCPP_INLINE_VISIBILITY
+_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
 __wrap_iter<_Iter>
 operator+(typename __wrap_iter<_Iter>::difference_type, __wrap_iter<_Iter>) _NOEXCEPT_DEBUG;
 
@@ -1254,7 +1254,7 @@
 #if _LIBCPP_DEBUG_LEVEL < 2
 
 template 
-_LIBCPP_INLINE_VISIBILITY
+_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
 typename enable_if
 <
 is_trivially_copy_assignable<_Tp>::value,
@@ -1265,7 +1265,7 @@
 #else
 
 template 
-inline _LIBCPP_INLINE_VISIBILITY
+inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
 typename enable_if
 <
 is_trivially_copy_assignable<_Tp>::value,
@@ -1288,7 +1288,8 @@
 private:
 iterator_type __i;
 public:
-_LIBCPP_INLINE_VISIBILITY __wrap_iter() _NOEXCEPT_DEBUG
+_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
+__wrap_iter() _NOEXCEPT_DEBUG
 #if _LIBCPP_STD_VER > 11
 : __i{}
 #endif
@@ -1297,7 +1298,8 @@
 __get_db()->__insert_i(this);
 #endif
 }
-template  _LIBCPP_INLINE_VISIBILITY __wrap_iter(const __wrap_iter<_Up>& __u,
+template  _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
+  __wrap_iter(const __wrap_iter<_Up>& __u,
 typename enable_if::value>::type* = 0) _NOEXCEPT_DEBUG
 : __i(__u.base())
 {
@@ -1306,13 +1308,13 @@
 #endif
 }
 #if _LIBCPP_DEBUG_LEVEL >= 2
-_LIBCPP_INLINE_VISIBILITY
+_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
 __wrap_iter(const __wrap_iter& __x)
 : __i(__x.base())
 {
 __get_db()->__iterator_copy(this, &__x);
 }
-_LIBCPP_INLINE_VISIBILITY
+_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
 __wrap_iter& operator=(const __wrap_iter& __x)
 {
 if (this != &__x)
@@ -1328,7 +1330,8 @@
 __get_db()->__erase_i(this);
 }
 #endif
-_LIBCPP_INLINE_VISIBILITY reference operator*() const _NOEXCEPT_DEBUG
+_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
+reference operator*() const _NOEXCEPT_DEBUG
 {
 #if _LIBCPP_DEBUG_LEVEL >= 2
 _LIBCPP_ASSERT(__get_const_db()->__dereferenceable(this),
@@ -1336,7 +1339,8 @@
 #endif
 return *__i;
 }
-_LIBCPP_INLINE_VISIBILITY pointer  operator->() const _NOEXCEPT_DEBUG
+_LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
+pointer  operator->() const _NOEXCEPT_DEBUG
 {
 #if _LIBCPP_DEBUG_LEVEL >= 2
 _LIBCPP_ASSERT(__get_const_db()->__dereferenceable(this),
@@ -1344,7 +1348,8 @@