Commit Graph

76 Commits

Author SHA1 Message Date
Marek Kurdej 3e895085de [libc++][P1115][C++20] Improving the Return Value of Erase-Like Algorithms II: Free erase/erase if.
Summary:
This patch adds return type to std::erase and std::erase_if functions.

Also:
* Update __cpp_lib_erase_if to 202002L.
* Fix synopsis in unordered_map.
* Fix generate_feature_test_macro_components.py script.

Reviewers: EricWF, mclow.lists, ldionne, #libc

Reviewed By: ldionne, #libc

Subscribers: broadwaylamb, zoecarver, dexonsmith, ldionne, libcxx-commits

Tags: #libc

Differential Revision: https://reviews.llvm.org/D75905
2020-05-02 14:04:50 +02:00
Zoe Carver a17b1aed6a Add contains method to associative containers. This patch implements P0458R2, adding contains to map, multimap, unordered_map, unordered_multimap, set, multiset, unordered_set, and unordered_multiset.
llvm-svn: 366170
2019-07-16 03:21:01 +00:00
Louis Dionne dfcd4384cb [libc++] Implement P0433: deduction guides for <unordered_map>
Thanks to Arthur O'Dwyer for the patch.

Differential Revision: https://reviews.llvm.org/D58590

llvm-svn: 366124
2019-07-15 20:06:01 +00:00
Louis Dionne a2a1ec27d0 [NFC][libcxx] Remove trailing whitespace
It's incredibly annoying when trying to create diffs

llvm-svn: 361981
2019-05-29 16:01:36 +00:00
Louis Dionne 7c142fcc06 [libc++] Make sure we don't eagerly diagnose non-const comparators for containers of incomplete types
Summary:
In r348529, I improved the library-defined diagnostic for using containers
with a non-const comparator/hasher. However, the check is now performed
too early, which leads to the diagnostic being emitted in cases where it
shouldn't. See PR41360 for details.

This patch moves the diagnostic to the destructor of the containers, which
means that the diagnostic will only be emitted when the container is instantiated
at a point where the comparator and the key/value are required to be complete.
We still retain better diagnostics than before r348529, because the diagnostics
are performed in the containers themselves instead of __tree and __hash_table.

As a drive-by fix, I improved the diagnostic to mention that we can't find
a _viable_ const call operator, as suggested by EricWF in PR41360.

Reviewers: EricWF, mclow.lists

Subscribers: christof, jkorous, dexonsmith, libcxx-commits, zoecarver

Tags: #libc

Differential Revision: https://reviews.llvm.org/D60540

llvm-svn: 358189
2019-04-11 16:14:56 +00:00
Louis Dionne 7232a84e68 [libc++] Avoid UB in the no-exceptions mode in a few places
Summary:
A few places in the library seem to behave unexpectedly when the library
is compiled or used with exceptions disabled. For example, not throwing
an exception when a pointer is NULL can lead us to dereference the pointer
later on, which is UB. This patch fixes such occurences.

It's hard to tell whether there are other places where the no-exceptions
mode misbehaves like this, because the replacement for throwing an
exception does not always seem to be abort()ing, but at least this
patch will improve the situation somewhat.

See http://lists.llvm.org/pipermail/libcxx-dev/2019-January/000172.html

Reviewers: mclow.lists, EricWF

Subscribers: christof, jkorous, dexonsmith, libcxx-commits

Differential Revision: https://reviews.llvm.org/D57761

llvm-svn: 353850
2019-02-12 16:06:02 +00:00
Chandler Carruth 57b08b0944 Update more file headers across all of the LLVM projects in the monorepo
to reflect the new license. These used slightly different spellings that
defeated my regular expressions.

We understand that people may be surprised that we're moving the header
entirely to discuss the new license. We checked this carefully with the
Foundation's lawyer and we believe this is the correct approach.

Essentially, all code in the project is now made available by the LLVM
project under our new license, so you will see that the license headers
include that license only. Some of our contributors have contributed
code under our old license, and accordingly, we have retained a copy of
our old license notice in the top-level files in each project and
repository.

llvm-svn: 351648
2019-01-19 10:56:40 +00:00
Marshall Clow f60c63c090 Implement P1209 - Adopt Consistent Container Erasure from Library Fundamentals 2 for C++20. Reviewed as https://reviews.llvm.org/D55532
llvm-svn: 349178
2018-12-14 18:49:35 +00:00
Louis Dionne 3560fbf304 [libc++] Improve diagnostics for non-const comparators and hashers in associative containers
Summary:
When providing a non-const-callable comparator in a map or set, the
warning diagnostic does not include the point of instantiation of
the container that triggered the warning, which makes it difficult
to track down the problem. This commit improves the diagnostic by
placing it directly in the body of the associative container.

The same change is applied to unordered associative containers, which
had a similar problem.

Finally, this commit cleans up the forward declarations of several
map and unordered_map helpers, which are not needed anymore.

<rdar://problem/41370747>

Reviewers: EricWF, mclow.lists

Subscribers: christof, dexonsmith, llvm-commits

Differential Revision: https://reviews.llvm.org/D48955

llvm-svn: 348529
2018-12-06 21:46:17 +00:00
Erik Pilkington 5c4e07ae5c Second half of C++17's splicing maps and sets
This commit adds a merge member function to all the map and set containers,
which splices nodes from the source container. This completes support for
P0083r3.

Differential revision: https://reviews.llvm.org/D48896

llvm-svn: 345744
2018-10-31 17:31:35 +00:00
Marshall Clow f56972e224 Implement the infrastructure for feature-test macros. Very few actual feature test macros, though. Reviewed as: https://reviews.llvm.org/D51955
llvm-svn: 342073
2018-09-12 19:41:40 +00:00
Erik Pilkington b0386a515b First half of C++17's splicing maps and sets
This commit adds a node handle type, (located in __node_handle), and adds
extract() and insert() members to all map and set types, as well as their
implementations in __tree and __hash_table.

The second half of this feature is adding merge() members, which splice nodes
in bulk from one container into another. This will be committed in a follow-up.

Differential revision: https://reviews.llvm.org/D46845

llvm-svn: 338472
2018-08-01 01:33:38 +00:00
Erik Pilkington f52318b47b Fix a strict aliasing violation in map and unordered_map.
These containers type-punned between pair<K, V> and pair<const K, V> as an
optimization. This commit instead provides access to the pair via a pair of
references that assign through to the underlying object. It's still undefined to
mutate a const object, but clang doesn't optimize on this for data members, so
this should be safe.

Differential revision: https://reviews.llvm.org/D47607

llvm-svn: 333948
2018-06-04 20:38:23 +00:00
Marshall Clow 72c8fad427 First part of P0600 - '[[nodiscard] in the standard library'. Mark the 'empty()' methods of all the containers as nodiscard. If you're calling empty() w/o looking at the result, you probably meanto to call 'clear()'. c++2a only
llvm-svn: 318269
2017-11-15 05:51:26 +00:00
Eric Fiselier 6a470bcb6d Cleanup _LIBCPP_HAS_NO_<c++11-feature> in std::unordered_map and std::unordered_multimap
This completes the cleanup of the containers, at least within the tests.

llvm-svn: 300620
2017-04-18 22:50:56 +00:00
Eric Fiselier b3f5742551 Fix more bad member swap definitions in unordered_map.
The __unordered_map_equal and __unordered_map_hash wrappers
attempt to swap const qualified predicates whenever the predicate
is empty, and is subject to the EBO.

Swapping const values seems blatently incorrect. This patch removes
the const qualifier so the values are swapped as non-const.

llvm-svn: 300154
2017-04-13 01:02:41 +00:00
Eric Fiselier 04333f9bda Diagnose non-const-callable hash functions and comparators
llvm-svn: 291969
2017-01-13 22:42:53 +00:00
Eric Fiselier e2f2d1edef [NFC] Rename _LIBCPP_TYPE_VIS_ONLY to _LIBCPP_TEMPLATE_VIS
The name _LIBCPP_TYPE_VIS_ONLY is no longer accurate because both
_LIBCPP_TYPE_VIS and _LIBCPP_TYPE_VIS_ONLY expand to
__attribute__((__type_visibility__)) with Clang. The only remaining difference
is that _LIBCPP_TYPE_VIS_ONLY can be applied to templates whereas
_LIBCPP_TYPE_VIS cannot (due to dllimport/dllexport not being allowed on
templates).

This patch renames _LIBCPP_TYPE_VIS_ONLY to _LIBCPP_TEMPLATE_VIS.

llvm-svn: 291035
2017-01-04 23:56:00 +00:00
Eric Fiselier 780b51df1d Add tests for unordered container tests and std::string
llvm-svn: 290655
2016-12-28 05:53:01 +00:00
Eric Fiselier fd83822741 Fix unused parameters and variables
llvm-svn: 290459
2016-12-23 23:37:52 +00:00
Oleg Ranevskyy eef9b35c6d [libc++] Fix typos causing compilation errors when _LIBCPP_DEBUG_LEVEL >= 2
Summary: This patch fixes a couple of typos that cause compilation errors when application includes <unordered_map> and enables the libc++'s debugging capabilities.

Reviewers: EricWF

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D24883

llvm-svn: 282446
2016-09-26 21:39:38 +00:00
Marshall Clow 2a10c960fa Support allocators with explicit conversion constructors. Fixes bug #29000
llvm-svn: 278904
2016-08-17 05:58:40 +00:00
Marshall Clow 2ee837256a Change a couple ifdefs from '#if __cplusplus >= 2011xxx' to '#ifndef _LIBCPP_CXX03_LANG'. No functionality change.
llvm-svn: 275787
2016-07-18 13:19:00 +00:00
Evgeniy Stepanov cd31b4348a Cleanup: move visibility/linkage attributes to the first declaration.
http://reviews.llvm.org/D15404

llvm-svn: 267093
2016-04-22 01:04:55 +00:00
Eric Fiselier 87c4104d30 Mark LWG issue 2469 as done. Also simplify try_emplace and insert_or_assign implementations in unordered_map
llvm-svn: 266591
2016-04-18 06:51:33 +00:00
Eric Fiselier 7a9f500fcb Fix LWG issue 2345 - Add insert(value_type&&)
llvm-svn: 266585
2016-04-18 01:40:45 +00:00
Eric Fiselier 0f90567744 Fix LWG issue 2469 - Use piecewise construction in unordered_map::operator[].
unordered_map's allocator may only be used to construct objects of 'value_type',
or in this case 'pair<const Key, Value>'. In order to respect this requirement
in operator[], which requires default constructing the 'mapped_type', we have
to use pair's piecewise constructor with '(tuple<Kep>, tuple<>)'.

Unfortunately we still need to provide a fallback implementation for C++03
since we don't have <tuple>. Even worse this fallback is the last remaining
user of '__hash_map_node_destructor' and '__construct_node_with_key'.

llvm-svn: 260601
2016-02-11 21:45:53 +00:00
Eric Fiselier 614ed76c37 Revert r260514 because it has a bogus commit message.
llvm-svn: 260556
2016-02-11 18:21:18 +00:00
Eric Fiselier 45c4d45ead Teach __hash_table how to handle unordered_map's __hash_value_type.
This patch is fairly large and contains a number of changes. The main change
is teaching '__hash_table' how to handle '__hash_value_type'. Unfortunately
this change is a rampant layering violation, but it's required to make
unordered_map conforming without re-writing all of __hash_table.
After this change 'unordered_map' can delegate to '__hash_table' in almost all cases.

The major changes found in this patch are:

  * Teach __hash_table to differentiate between the true container value type
    and the node value type by introducing the "__container_value_type" and
    "__node_value_type" typedefs. In the case of unordered_map '__container_value_type'
    is 'pair<const Key, Value>' and '__node_value_type' is '__hash_value_type'.
    
  * Switch almost all overloads in '__hash_table' previously taking 'value_type'
    (AKA '__node_value_type) to take  '__container_value_type' instead. Previously
    'pair<K, V>' would be implicitly converted to '__hash_value_type<K, V>' because
    of the function signature.
    
  * Add '__get_key', '__get_value', '__get_ptr', and '__move' static functions to
    '__key_value_types'. These functions allow '__hash_table' to unwrap
    '__node_value_type' objects into '__container_value_type' and its sub-parts.

  * Pass  '__hash_value_type::__value_'  to 'a.construct(p, ...)' instead of
    '__hash_value_type' itself. The C++14 standard requires that 'a.construct()'
    and 'a.destroy()' are only ever instantiated for the containers value type.

  * Remove '__hash_value_type's constructors and destructors. We should never
    construct an instance of this type.
    (TODO this is UB but we already do it in plenty of places).
  
  * Add a generic "try-emplace" function to '__hash_table' called
    '__emplace_unique_key_args(Key const&, Args...)'.

  
The following changes were done as cleanup:

  * Introduce the '_LIBCPP_CXX03_LANG' macro to be used in place of
    '_LIBCPP_HAS_NO_VARIADICS' or '_LIBCPP_HAS_NO_RVALUE_REFERENCE'.
    
  * Cleanup C++11 only overloads that assume an incomplete C++11 implementation.
    For example this patch removes the __construct_node overloads that do
    manual pack expansion.
    
  * Forward 'unordered_map::emplace' to '__hash_table' and remove dead code
    resulting from the change. This includes almost all
    'unordered_map::__construct_node' overloads.


The following changes are planed for future revisions:

  * Fix LWG issue #2469 by delegating 'unordered_map::operator[]' to use
    '__emplace_unique_key_args'.
    
  * Rewrite 'unordered_map::try_emplace' in terms of '__emplace_unique_key_args'.
  
  * Optimize '__emplace_unique' to call '__emplace_unique_key_args' when possible.
    This prevent unneeded allocations when inserting duplicate entries.


The additional follow up work needed after this patch:

  * Respect the lifetime rules for '__hash_value_type' by actually constructing it.
  * Make '__insert_multi' act similar to '__insert_unique' for objects of type
    'T&' and 'T const &&' with 'T = __container_value_type'.
  
  

llvm-svn: 260514
2016-02-11 12:25:27 +00:00
Eric Fiselier fcd0221118 Teach __hash_table how to handle unordered_map's __hash_value_type.
This patch is fairly large and contains a number of changes. The main change
is teaching '__hash_table' how to handle '__hash_value_type'. Unfortunately
this change is a rampant layering violation, but it's required to make
unordered_map conforming without re-writing all of __hash_table.
After this change 'unordered_map' can delegate to '__hash_table' in almost all cases.

The major changes found in this patch are:

  * Teach __hash_table to differentiate between the true container value type
    and the node value type by introducing the "__container_value_type" and
    "__node_value_type" typedefs. In the case of unordered_map '__container_value_type'
    is 'pair<const Key, Value>' and '__node_value_type' is '__hash_value_type'.
    
  * Switch almost all overloads in '__hash_table' previously taking 'value_type'
    (AKA '__node_value_type) to take  '__container_value_type' instead. Previously
    'pair<K, V>' would be implicitly converted to '__hash_value_type<K, V>' because
    of the function signature.
    
  * Add '__get_key', '__get_value', '__get_ptr', and '__move' static functions to
    '__key_value_types'. These functions allow '__hash_table' to unwrap
    '__node_value_type' objects into '__container_value_type' and its sub-parts.

  * Pass  '__hash_value_type::__value_'  to 'a.construct(p, ...)' instead of
    '__hash_value_type' itself. The C++14 standard requires that 'a.construct()'
    and 'a.destroy()' are only ever instantiated for the containers value type.

  * Remove '__hash_value_type's constructors and destructors. We should never
    construct an instance of this type.
    (TODO this is UB but we already do it in plenty of places).
  
  * Add a generic "try-emplace" function to '__hash_table' called
    '__emplace_unique_key_args(Key const&, Args...)'.

  
The following changes were done as cleanup:

  * Introduce the '_LIBCPP_CXX03_LANG' macro to be used in place of
    '_LIBCPP_HAS_NO_VARIADICS' or '_LIBCPP_HAS_NO_RVALUE_REFERENCE'.
    
  * Cleanup C++11 only overloads that assume an incomplete C++11 implementation.
    For example this patch removes the __construct_node overloads that do
    manual pack expansion.
    
  * Forward 'unordered_map::emplace' to '__hash_table' and remove dead code
    resulting from the change. This includes almost all
    'unordered_map::__construct_node' overloads.


The following changes are planed for future revisions:

  * Fix LWG issue #2469 by delegating 'unordered_map::operator[]' to use
    '__emplace_unique_key_args'.
    
  * Rewrite 'unordered_map::try_emplace' in terms of '__emplace_unique_key_args'.
  
  * Optimize '__emplace_unique' to call '__emplace_unique_key_args' when possible.
    This prevent unneeded allocations when inserting duplicate entries.


The additional follow up work needed after this patch:

  * Respect the lifetime rules for '__hash_value_type' by actually constructing it.
  * Make '__insert_multi' act similar to '__insert_unique' for objects of type
    'T&' and 'T const &&' with 'T = __container_value_type'.
  
  

llvm-svn: 260513
2016-02-11 11:59:44 +00:00
Eric Fiselier d262b368d5 Remove changes that snuck in within r260431
llvm-svn: 260443
2016-02-10 21:58:36 +00:00
Eric Fiselier 75d0dcfde7 Recommit r260012 - Cleanup node-type handling in the unordered containers.
This time I kept <ext/hash_map> working!

This patch is the first in a series of patches that's meant to better
support unordered_map. unordered_map has a special "value_type" that
differs from pair<const Key, Value>. In order to meet the EmplaceConstructible
and CopyInsertable requirements we need to teach __hash_table about this
special value_type.

This patch creates a "__hash_node_types" traits class that contains
all of the typedefs needed by the unordered containers and it's iterators.
These typedefs include ones for each node type and  node pointer type,
as well as special typedefs for "unordered_map"'s value type.

As a result of this change all of the unordered containers now all support
incomplete types.

As a drive-by fix I changed the difference_type in __hash_table to always
be ptrdiff_t. There is a corresponding change to size_type but it cannot
take affect until an ABI break.

This patch will be followed up shortly with fixes for various unordered_map
bugs and problems.

llvm-svn: 260431
2016-02-10 20:46:23 +00:00
Eric Fiselier 20af59e38c Revert r260012 due to __gnu_cxx::hash_map breakage
llvm-svn: 260172
2016-02-08 23:47:13 +00:00
Eric Fiselier 1b2e4ffa58 Cleanup node-type handling in the unordered containers
This patch is the first in a series of patches that's meant to better
support unordered_map. unordered_map has a special "value_type" that
differs from pair<const Key, Value>. In order to meet the EmplaceConstructible
and CopyInsertable requirements we need to teach __hash_table about this
special value_type.

This patch creates a "__hash_node_types" traits class that contains
all of the typedefs needed by the unordered containers and it's iterators.
These typedefs include ones for each node type and  node pointer type,
as well as special typedefs for "unordered_map"'s value type.

As a result of this change all of the unordered containers now all support
incomplete types.

As a drive-by fix I changed the difference_type in __hash_table to always
be ptrdiff_t. There is a corresponding change to size_type but it cannot
take affect until an ABI break.

This patch will be followed up shortly with fixes for various unordered_map
fixes.

llvm-svn: 260012
2016-02-07 00:36:33 +00:00
Duncan P. N. Exon Smith ad783ce909 Revert "unordered_map: Reuse insert logic in emplace when possible, NFC"
This reverts commit r258575.  EricWF sent me an email (no link since it
was off-list) requesting to review this pre-commit instead of
post-commit.

llvm-svn: 258625
2016-01-23 15:12:47 +00:00
Duncan P. N. Exon Smith 8af8a407fe unordered_map: Reuse insert logic in emplace when possible, NFC
An upcoming commit will add an optimization to insert() that avoids
unnecessary mallocs when we can safely extract the key type.  This
commit shares code between emplace() and insert():
- if emplace() is given a single argument, and
- value_type is constructible from that argument
so that we have a single code path for the two.

I also updated the debug version of emplace_hint() to defer to
emplace(), like the non-debug version does.

In both cases, there should be NFC here.

llvm-svn: 258575
2016-01-22 22:48:02 +00:00
Eric Fiselier 934b092186 Use __rebind_pointer to avoid #ifdef block
llvm-svn: 256654
2015-12-30 21:52:00 +00:00
Dimitry Andric 251c629117 Fix warnings about pessimizing return moves for C++11 and higher
Summary:
Throughout the libc++ headers, there are a few instances where
_VSTD::move() is used to return a local variable.  Howard commented in
r189039 that these were there "for non-obvious reasons such as to help
things limp along in C++03 language mode".

However, when compiling these headers with warnings on, and in C++11 or
higher mode (like we do in FreeBSD), they cause the following complaints
about pessimizing moves:

    In file included from tests.cpp:26:
    In file included from tests.hpp:29:
    /usr/include/c++/v1/map:1368:12: error: moving a local object in a return statement prevents copy elision [-Werror,-Wpessimizing-move]
        return _VSTD::move(__h);  // explicitly moved for C++03
               ^
    /usr/include/c++/v1/__config:368:15: note: expanded from macro '_VSTD'
    #define _VSTD std::_LIBCPP_NAMESPACE
                  ^

Attempt to fix this by adding a _LIBCPP_EXPLICIT_MOVE() macro to
__config, which gets defined to _VSTD::move for pre-C++11, and to
nothing for C++11 and later.

I am not completely satisfied with the macro name (I also considered
_LIBCPP_COMPAT_MOVE and some other variants), so suggestions are
welcome. :)

Reviewers: mclow.lists, howard.hinnant, EricWF

Subscribers: arthur.j.odwyer, cfe-commits

Differential Revision: http://reviews.llvm.org/D11394

llvm-svn: 245421
2015-08-19 06:43:33 +00:00
Marshall Clow e3fbe1433b Implement the first part of N4258: 'Cleaning up noexcept in the Library'. This patch deals with swapping containers, and implements a more strict noexcept specification (a conforming extension) than the standard mandates.
llvm-svn: 242056
2015-07-13 20:04:56 +00:00
Marshall Clow bc4c89a977 The rest of N4279 and LWG#2464 - for unordered_map
llvm-svn: 241555
2015-07-07 05:45:35 +00:00
Eric Fiselier ee187e247b [libcxx] Fix detection of __is_final.
Summary: Currently we only enable the use of __is_final(...) with Clang. GCC also provides __is_final(...) since 4.7 in all standard modes. This patch creates the macro _LIBCPP_HAS_IS_FINAL to note the availability of `__is_final`.

Reviewers: danalbert, mclow.lists

Reviewed By: mclow.lists

Subscribers: cfe-commits

Differential Revision: http://reviews.llvm.org/D8795

llvm-svn: 239664
2015-06-13 07:08:02 +00:00
Marshall Clow ec39296875 Fix for LWG Issue 2059: C++0x ambiguity problem with map::erase
llvm-svn: 236950
2015-05-10 13:35:00 +00:00
Marshall Clow 2764799450 Replace two naked references of 'std::' with the macro '_VSTD::'. No functionality change.
llvm-svn: 236593
2015-05-06 12:11:22 +00:00
Marshall Clow 1f508014df In many places, there was an #ifdef/#else block that selected one of two implmentations of rebind_alloc based on whether or not we had template aliases. Create a helper struct to encapsulate that bit of logic, and replace all the ifdefs with uses of that struct. No functionality change intented.
llvm-svn: 234296
2015-04-07 05:21:38 +00:00
Eric Fiselier c1bd9197eb NFC. Move definition of _LIBCPP_ASSERT into __debug header and remove external include guards.
Things done in this patch:

1. Make __debug include __config since it uses macros from it.

2. The current method of defining _LIBCPP_ASSERT is prone to redefinitions. Move
the null _LIBCPP_ASSERT definition into the __debug header to prevent this.

3. Remove external <__debug> include gaurds. <__debug> guards almost all of its
contents internally. There is no reason to be doing it externally.

This patch should not change any functionality.

llvm-svn: 215332
2014-08-10 23:53:08 +00:00
Marshall Clow 74cf6ff5e5 Fix for PR18735 - self-assignment for map/multimap gives incorrect results in C++03
llvm-svn: 201021
2014-02-08 04:03:14 +00:00
Howard Hinnant 9fd9f84f48 SCARY/N2913 iterator support between the multi and non-multi versions of the associative and unordered containers. I beleive lack of support for this was accidentally recently introduced (by me) and this is fixing a regression. This time tests are put in to prevent such a regression in the future.
llvm-svn: 191692
2013-09-30 19:08:22 +00:00
Marshall Clow 3cd37e6456 LWG Issue 2210 (Part #6): unordered_map and unordered_multimap
llvm-svn: 190576
2013-09-12 03:00:31 +00:00
Howard Hinnant 872ac4b5f0 A collection of minor type-o fixes. The first two aren't testable, but all tests pass with them. I stumbled across them while experimenting with a std::move that checks its argument for non-const. The third corrects a test that is currently failing.
llvm-svn: 190563
2013-09-12 00:10:44 +00:00
Howard Hinnant 179b1f8cf2 Zhihao Yuan noted that there were a few unneeded statements. Eliminated the unnecessary ones, and commented the ones that are there for non-obvious reasons such as to help things limp along in C++03 language mode.
llvm-svn: 189039
2013-08-22 18:29:50 +00:00