Document number: N2705=08-0215

Alisdair Meredith
2008年07月29日

State of C++ Evolution (Mid-term 2008 Mailing)

This paper presents a quick summary of all papers submitted to WG21 for consideration by the Evolution Working Group, with an indication of their progress towards inclusion in the next C++ Standard or future TRs. It is based on the post-Antipolis 2008 mailing.

There are no library papers here, unless highlighted by the Registration Document submitted following the Portland meeting. Otherwise this list focuses entirely on changes affecting clauses 1 -> 16. Library progress can be followed in the companion document N2706. Note that most of the overlap is related to threading and atomic libraries.

Note on progress

A clear statement of intent was made to complete work on all features for the new standard and distribute a CD for ISO ballot following the San Francisco meeting in 2008, followed by an FCD for ballot at the end of 2009 proceeding to FDIS and final publication in late 2010.

In order to reach this goal, the threading library produced by the draughting comittee at Kona has been adopted, although concern was expressed by the Review Committee about the time-related portion of that document. Subsequently, chapter 31 of the working paper has been removed, and replaced by N2661.

A second proposed compromise to meet the timetable is the scaling back of the garbage collection feature. This has now been adopted as N2670.

The third compromise of a reduce scope 'asynchronous return buffer' was presented to the Library Working Group in Bellevue, and is close to final form in N2671, which has been held back one additional meeting to reduce complexity of the exception hierarchy used.

Key to the tables

Papers have been grouped according to theme, and related papers joined into the same row, even when submitted by different authors. The intent is to capture the feature, rather than the workflow. Papers are ordered by theme, and themes ordered by document number for the first submission on that theme.

Note that while the deadline for new proposals for C++0x is long past, it is not unusual to split a specific feature out of an existing proposal, to ease their progress. Likewise, existing Core Working Group issues may grow large enough to merit a paper that would not have previously shown on this list.

Proposals in a green font have advanced a category since the last meeting, those in red have moved back, while those in yellow are new or have been updated since the last meeting.

Proposals with a green background have been highlighted as the features that will be delivered in the next version of the standard in the Registration Document.

WG21 Number(s) Title Authors

Integrated into working paper

These proposals are already incorporated into the latest working paper, N2691, or the project editor has been directed to include them in the next draught.

N1377 N1385 N1690 N1770 N1855 N1952 N2118 A Proposal to Add an Rvalue Reference to the C++ Language H. Hinnant, P. Dimov, D. Abrahams, J. Adamczyk, A. Hommel

N1610 Clarification of Initialization of Class Objects by rvalues D. Abrahams, G. Powell

N1784 N1821 N2377 N2439 Extending Move Semantics To *this (Revision 2) Bronek Kozicki

N1381 N1604 N1617 N1720 static_assert R. Klarer, J. Maddock, B. Dawes, H. Hinnant

N1406 N1449 N1451 N1489 N2112 N2258 Template aliases for C++ B. Stroustrup, G. Dos Reis, Mat Marcus, Walter E. Brown, Herb Sutter

N1427 N1945 N2187 N2402 N2635 N2657 Making Local Classes more Useful Anthony Williams; John Spicer

N1448 N1960 N1987 Extern template Matt Marcus, Garbriel Dos Reis, John Spicer

N1483 N1603 N1704 N2080 N2152 N2191 N2242 Variadic Templates D. Gregor, J. Järvi, G. Powell

N2488 N2555 Extending Variadic Template Template Parameters D. Gregor, E. Niebler

N1488 N1601 N2214 N2431 A name for the null pointer: nullptr H. Sutter, B. Stroustrup

N2656 Core issue 654: Convertibility of 0-literal H. Sutter, B. Stroustrup

N1509 N1890 N1919 N2100 N2215 N2385 N2531 N2672 Initializer lists Bjarne Stroustrup, G. Dos Reis, J. S. Adamczyk

N1513 N1579 N1719 N2213 N2347 Strongly Typed Enums H. Sutter, D. Miller, B. Stroustrup

N1520 N1616 N1722 N1791 Extended friend Declarations William M. Miller

N1521 N1972 N1980 N2116 N2235 Generalized Constant Expressions Gabriel Dos Reis

N1526 N2013 N2331 N2535 Namespace Association ("Strong Using") Benjamin Kosnik, Jason Merril

N1545 N1566 N1653 Synchronizing the C++ preprocessor with C99 Clark Nelson, Paul Mensonides

N1546 N1877 N1971 N2140 N2165 N2252 N2301 N2341 Adding Alignment Support to the C++ Programming Language Attila (Farkas) Fehér, C. Nelson

N1564 N1627 "Conditionally-Supported Behavior" William M. Miller

N1727 Changing Undefined Behavior into Diagnosable Errors William M. Miller

N1565 N1693 N1735 N1811 Adding the long long type to C++ J. Stephen Adamczyk

N1746 N1988 Adding extended integer types to C++ J. Stephen Adamczyk

N1581 N1618 N1895 N1986 Delegating Constructors H. Sutter, F. Glassborow

N1592 N2223 N2333 N2380 N2437 Explicit Conversion Operators Lois Goldthwaite, Michael Wong, J Maurer, A Meredith

N1628 N1823 N1955 N2018 N2149 N2249 New Character Types in C++ Lawrence Crowl

N1649 N1699 N1757 Right Angle Brackets Daveed Vandevoorde

N1721 N1794 N1894 N1984 Deducing the type of variable from its initializer expression J. Jaarvi, B. Stroustrup, G. Dos Reis

N2337 N2546 The Syntax of auto Declarations Daveed Vandevoorde

N1874 N1966 N2147 N2280 N2545 N2659 Thread-Local Storage Lawrence Crowl

N1898 N2119 N2203 N2254 N2376 N2438 N2512 N2540 Inheriting Constructors M. Wong, A. Meredith, J. Maurer

N1944 N2052 N2171 N2239 A finer-grained alternative to sequence points Clark Nelson

N1968 N2329 N2413 N2487 N2529 N2550 (monomorphic) Lambda expressions and closures for C++ J Willcock, J Järvi, D Gregor, A Lumsdaine, J. Freeman, L. Crowl

N2561 N2658 Constness of lambda functions J Järvi, P Dimov, J Freeman

N1970 N2202 N2251 N2340 Proposed addition of __func__ predefined identifier from C99 Alisdair Meredith, J Maurer

N2047 N2145 N2324 N2381 N2393 N2427 Atomic operations with multi-threaded environments Hans Boehm, Lawrence Crowl

N2492 N2556 N2664 C++ Data-Dependency Ordering: Atomics and Memory Model P. McKenney, H.-J. Boehm, L. Crowl

N2052 N2171 N2300 N2334 N2429 Sequencing and the concurrency memory model Clark Nelson, Hans Boehm

N2053 N2146 N2295 N2384 N2442 Raw String Literals Beman Dawes

N2062 N2102 N2172 N2230 N2294 N2342 PODs unstrung Beman Dawes

N2096 N2179 Propagating exceptions when joining threads Peter Dimov

N2148 N2325 N2382 N2444 N2513 N2670 Dynamic initialization and concurrency Lawrence Crowl

N2115 N2343 Decltype J. Järvi, B. Stroustrup, D. Gregor, J. Siek, G. Dos Reis

N2150 N2253 Extending sizeof Jens Maurer

N2159 N2209 N2295 N2384 N2442 UTF8 Literals Lawrence Crowl

N2170 Universal Character Names in Literals Lawrence Crowl

N2210 N2326 N2346 Defaulted and Deleted Functions Lawrence Crowl

N2248 N2430 N2544 Unrestricted Unions L. Goldthwaite, A. Talbot, L. Crowl, J. Maurer

N2320 N2447 A Multi-threading Library for Standard C++ H. Hinnant, B. Dawes, L. Crowl, J. Garland, A. Williams

N2383 N2440 Abandoning a Process Lawrence Crowl

N2445 N2541 New function declaration syntax for deduced return types Jason Merrill (wording proposal by J. Järvi, B. Stroustrup, D. Gregor, J. Siek, G. Dos Reis)

N2459 N2547 Allow atomics use in signal handlers Hans-J. Boehm

N2481 N2527 N2585 N2586 N2670 Minimal Support for Garbage Collection and Reachability-Based Leak Detection H.-J. Boehm, M. Spertus, C.Nelson

N2634 Solving the SFINAE problem for expressions J Spicer, S Adamczyk

Proposed wording under review in Core

These papers are undergoing final scrutiny in Core Working group. Full wording is available, and each has been reviewed at least once by the CWG. However, some draughting issues remain to be resolved before moving into the Working Paper.

N1959 N2354 N2426 N2628 N2673 Member Initializers M Spertus, Bill Seymour

N2042 N2081 N2193 N2307 N2398 N2421 N2501 N2617 N2676 Concepts (unified proposal) D. Gregor, B. Stroustrup, J. Siek, J. Widman

N2049 N2196 N2243 N2394 Proposal for new for-loop Thorsten Ottosen, Doug Gregor

N2236 N2379 N2418 N2553 General Attributes for C++ Michael Wong, Jens Maurer

N1511 N1892 N2282 N2378 Extensible Literals I. McIntosh, M. Wong, R. Mak, R.Klarer Bjarne Stroustrup

Blessed by evolution - wording available for initial review by Core

The design of these features is deemed complete and accepted by EWG, and there is a paper with complete wording for Core to review. However, CWG have not yet devoted any committee time to this issue. Typically papers in this state have been accepted by EWG at the previous meeting, or the version with proposed wording was not available by the post-meeting mailing (so the final update may be in this current mailing, or the next.)

N2499 N2568 N2687 Forward declaration of enumerations Alberto Ganesh Barbati

Core issues addressed by specific papers

The design of these features are being handled by the Core Working Group as part of their issue resolution process, but the issue is large enough to prompt a full paper.

N1528 Syntactic Disambiguation Using the Template Keyword John H. Spicer

N2605 Changing some "undefined behavior" into "ill-formed" Tom Plum

N2631 Resolving the difference between C and C++ with regards to object representation of integers James Kanze

Active topics in the Concurrency sub-group

These topics are in final review, with the intention to incorporate each one in the next standard. Papers should mostly be handled directly the the Core and Library working groups at the next meeting.

N2275 Non-Memory Actions (Library) Nick Maclaren

N2274 Object Aliasing and Threads Nick Maclaren

N2361 N2493 N2643 C++ Data-Dependency Ordering: Function Annotation Paul E. McKenney, L. Crowl

N2633 Improved support for bidirectional fences Peter Dimov

N2534 N2647 N2668 Concurrency Modifications to basic_string A. Meredith, H. Boehm, L. Crowl, P. Dimov, D. Krügler

N2561 An Asynchronous Return Buffer D. Vollmann, H. Hinnant, A. Williams

N2633 Improved support for bidirectional fences Peter Dimov

N2561 N2627 N2671 An Asynchronous Return Buffer D. Vollmann, H. Hinnant, A. Williams

New work for Evolution

These papers are ammendments or additions to existing designs, and will require consideration from Evolution before moving forward. While the submission deadline for new topics for Evolution is long past, it is expected some small time must be allocated each meeting to review design decisions as features work their way through Core and into the working paper.

N2576 Type-Soundness and Optimization in the Concepts Proposal Douglas Gregor

N2581 Named Requirements for C++0X Concepts W Brown, J Widman, C Jefferson, A Meredith

N2582 Unified Function Syntax Lawrence Crowl, Alisdair Meredith

N2583 Default Move Functions Lawrence Crowl

N2584 Default swap Functions Lawrence Crowl

N2646 Concept Implication and Requirement Propagation Peter Gottschling

N2693 Requirements on programs and backwards compatibility Jens Maurer

Background papers for reference

The papers do not contain actual proposals, but rather motivation, rationale and background to support other papers.

N1395 Aspects of Forwarding (was C++ Support For Delegation) Lois Goldthwaite

N1648 Motivation, Objectives and Design Decisions Attila Fehér

N1680 N1738 N1777 N1876 N1911 N1942 N2010 Memory model for multithreaded C++: Issues A. Alexandrescu, H. Boehm, K. Henney, B. Hutchings, D. Lea, B. Pugh

N1815 ISO C++ Strategic Plan for Multithreading Lawrence Crowl

N1834 A Pleading for Reasonable Parallel Processing Support in C++ Detlef Vollmann

N2012 Thread Subcommittee minutes from Berlin Lawrence Crowl

N2075 N2197 Prism: A Principle-Based Sequential Memory Model for Microsoft Native Code Platforms H Sutter

N2138 N2480 A Less Formal Explanation of the Proposed C++ Concurrency Memory Model Hans-J. Boehm

N2176 Memory Model Rationales Hans-J. Boehm

N2338 Concurrency memory model compiler consequences Hans-J. Boehm

N2392 A Memory Model for C++: Sequential Consistency for Race-Free Programs Hans-J. Boehm

N1799 C++ Language Support for Generic Programming J. Siek, D. Gregor, R. Garcia, J. Willcock, J. Järvi, A. Lumsdaine

N1885 A formalism for C++ G. Dos Reis, B. Stroustrup

N1899 Concept proposal comparison Matt Austern

N2221 An analysis of concept intersection Bjarne Stroustrup, Gabriel Dos Reis

N2399 A Tour of the Concepts Wording Douglas Gregor

N1956 Design Rationale for C++/CLI H Sutter

N1976 Shared dynamic objects : review and issues Benjamin Kosnik

N2027 A Brief Introduction to Rvalue References Howard Hinnant, Bjarne Stroustrup, Brokek Kozicki

N2087 A brief introduction to variadic templates Doug Gregor

N2167 Linux Kernel Reference Counting Paul E. McKenney

N2177 Sequential Consistency for Atomics Hans-J. Boehm

N2272 Optional Sequential Consistency Nick Maclaren

N2216 Report on language support for Multi-Methods and Open-Methods for C++ P. Pirkelbauer, Y. Solodkyy, B. Stroustrup

N2417 C++0x Timing Options for Kona Discussion Herb Sutter

N2362 Converting Memory Fences to N2324 Form P. McKenney, L. Crowl

N2466 WG 14: Towards Attributes for C N. Stoughton, J. Benito, T. Plum, A. Bijanki, J. Muller

N2536 POSIX Liaison Report Nick Stoughton

Evolution of current proposals

These papers are the inspiration or history behind the active or accepted proposals. They might have been absorded into a larger proposal to ease taking a whole package through review. They are retained here as they capture a large part of the rationale that will produce C++0x.

N1401 Atomic operations with multi-threaded environments Jan Kristoffersen

N2016 Should volatile Acquire Atomicity and Thread Visibility Semantics? Nick McLaren, Hans Boehm

N2153 N2237 Memory model for weak ordering Raúl Silvera, Michael Wong, Paul McKenney, Bob Blainey

N2195 Proposed Text for Chapter 29, Atomic Operations Library Peter Dimov

N2260 C++ Data-Dependency Ordering Paul E. McKenney

N2359 C++ Data-Dependency Ordering: Atomics Paul E. McKenney

N2360 C++ Data-Dependency Ordering: Memory Model Paul E. McKenney

N2262 Explicit Memory Fences R. Silvera, P. Dimov

N2273 Non-Memory Actions Nick Maclaren

N1445 N1582 N1702 N1717 Explicit class and default definitions F. Glassborow, L. Goldthwaite

N1602 Class Scope Using Declarations & private Members Francis Glassborow

N2123 Adding the prohibited access specifier to C++0x Alisdair Meredith

N1467 N1824 Extending Aggregate Initialization Alisdair Meredith, Daniel F. Gutson

N1493 Braces Initialization Overloading Daniel F. Gutson

N1584 N1701 Regularizing Initialization Syntax Francis Glassborow

N2477 N2532 Uniform initialization design choices Bjarne Stroustrup

N2575 N2640 Initializer Lists — Alternative Mechanism and Rationale J. Merrill, D. Vandevoorde

N1478 N1527 N1607 N1705 N1978 Auto, decltype and a new function declaration syntax J. Järvi, B. Stroustrup, D. Gregor, J. Siek, G. Dos Reis

N1737 A Proposal to Restore Multi-declarator auto Declarations Walter E. Brown

N1510 N1522 N1536 N1782 N1886 Concepts - syntax and composition B. Stroustrup, G. Dos Reis

N1758 N1798 N1848 N1849 Concepts for C++0x J. Siek, D. Gregor et al.

N2098 N2414 Scoped Concept maps J. Siek, J. Widman

N2161 Combining concepts Doug Gregor, Andrew Lumsdaine

N2520 Proposed Wording for Concepts (Changes from Revision 3 to Revision 4) D. Gregor, B. Stroustrup, J. Siek, J. Widman

N1534 N1642 Proposed addition of __func__ predefined identifier from C99 Alex Rosenberg

N1583 Inheriting Constructors F. Glassborow

N1682 N1907 N2285 A Multi-threading Library for Standard C++, Revision 2 Pete Becker

N1875 C++ Threads Lawrence Crowl

N2090 ; N2178 Proposed Text for Chapter 30, Thread Support Library Peter Dimov

N2094 N2184 Thread Launching for C++0X Howard Hinnant

N2139 Thoughts on a Thread Library for C++ Anthony Williams

N2455 Thread Cancellation WG14

N1796 N1868 N1961 Proposal for new for-loop Thorsten Ottosen

N1958 A proposal to add lambda functions to the C++ standard V Samko

N2510 BSI Position on Lambda Functions BSI

N2511 Named Lambdas and Local Functions Alisdair Meredith

N2061 N2106 N2229 ; N2107 Propagating exceptions when joining threads Beman Dawes; Alisdair Meredith, Jens Maurer

N2105 Choosing Keywords Beman Dawes

N2173 Core Extensions for Evolution Alisdair Meredith

N2224 General Attributes for C++ Alisdair Meredith

Not quite ready for C++0x timetable, but actively pursued

Papers in this category have been in development and reviewed several times over the evolution of C++0x. However, although there is a strong interest the feature has not quite stabilised fast enough to meet the 2009 target deadline. Work will proceed outside the main committee meetings, and will be picked up with a view to an early adoption.

N1833 N1943 N2128 N2129 N2286 N2287 N2310 Transparent Garbage Collection for C++ H. Boehm, M. Spertus

N2261 Optimization-robust finalization H. J. Boehm, M. Spertus

N2185 Proposed Text for Parallel Task Execution Peter Dimov

N2276 Thread Pools and Futures Anthony Williams

Heading for a separate TR

These topics are deemed too important to wait for another standard after C++0x before being published, but too experimental to be finalised in time for the next Standard. Therefore, these features will be delivered by a technical report at the earliest opportunity.

N1567 N1776 N1839 N1965 N1977 Decimal Types for C++ Robert Klarer, P.J. Plauger

N1736 N1778 N1964 N2006 N2015 N2073 N2074 N2316 Modules in C++ Daveed Vandevoorde

Not ready for C++0x, but open to resubmit in future

Papers in this category have been reviewed in EWG but for various reasons they have not been accepted for C++0x. This may have been a lack of time to finalise the issues, a lack of motivation compared to competing papers, or simply the authors being pulled in different directions. This list is retained as a potential working list for EWG to pick up for the next standard revision.

N1384 ; N1600 ; N1615 PME: Properties, methods and events John Wiegley; Daveed Vandevoorde; Lois Goldthwaite

N1400 N1418 N1428 N1496 Draft Proposal for Dynamic Libraries in C++ Pete Becker, Matt Austern

N2117 N2407 N2425 Minimal Dynamic Library Support Lawrence Crowl

N1408 N1691 Explicit Namespaces David Abrahams

N1792 N1893 N1912 N2103 A Modest Proposal: Fixing ADL Herb Sutter, Daveed Vandevoorde

N1420 Proposed Addition to C++: Class Namespaces Carl Daniel

N1461 Security and Standard C Libraries Martyn Lovell

N1462 Safe Exceptions and Compiler Security Checks Brandon Bray

N1463 N1529 Draft proposal for adding Multimethods to C++ Julian Smith

N1466 Expliciting default parameters Daniel Gutson

N1470 ; N1741 Extending / checking Switch statements Daniel Gutson; Francis Glassborow

N1471 Reflective Metaprogramming in C++ Daveed Vandevoorde

N1524 Nested Namespace Definition Proposal Jon Jagger

N1585 N1716 N1742 Uniform Calling Syntax (Re-opening public interfaces) Francis Glassborow

N1611 Implicitly-Callable Functions in C++0x Walter E. Brown

N1613 N1669 N1773 N1800 N1866 N1867 N1962 Contract Programming For C++0x L. Crowl, T. Ottosen, D. Abrahams, J. Widman

N1614 N1625 N1726 N1740 Macro scopes Thomas Plum, Bjarne Stroustrup

N1664 ; N1703 Toward Improved Optimization Opportunities in C++0x W. Brown,M. Paterno; Francis Glassborow

N1671 N2200 Overloading Operator.() & Operator.*() G. Powell, D. Gregor, J. Jarvi

N1676 ; N2200 Non-member overloaded copy assignment operator Bronek Kozicki; G. Powell, D. Gregor, J. Jarvi

N1695 A Proposal to Make Pointers to Members Callable Peter Dimov

N1696 Language Support for Restricted Templates Peter Dimov

N1706 N1891 N2141 Toward Opaque typedefs in C++0X Walter E. Brown; Alisdair Meredith

N1751 ; N1775 Reflection in C++ Detlef Vollmann; Walter E. Brown, et al.

N1785 Toward a Proposal for Object Templates in C++0x Walter E. Brown

N1825 Addressing Exception Specifications for Next Generation of C++ Alisdair Meredith

N2281 Digit Separators Lawrence Crowl

N2312 N2386 Namespace Regions Michael Spertus

N2332 Argument Deduction for Constructors Michael Spertus

No interest, or superseded by other proposals

These papers have either been superseded by different set of proposals, or were identified as a something we do not want to do. While everyone is free to submit papers they feel strongly about, it is unlikely any of these topics will gain favour for a future standard unless something significantly new is presented with the updated paper.

N1394 Some proposed extensions to C++ language David Miller

N1464 Anonymous array members Daniel Gutson

N1465 Constant inheritance Daniel Gutson

N1468 Self methods Daniel Gutson

N1469 Inline Constants Daniel Gutson

N1492 Exclusive Inheritance Daniel Gutson

N1494 Pure implementation method declaration Daniel F. Gutson

N1827 N2108 N2365 An Explicit Override Syntax for C++ C. Uzdavinis, A. Meredith, Jens Maurer

N1605 Extending Template Type Parameters I: Namespace and scope Daniel Gutson

N1612 N1869 How we might remove the remaining shortcomings of std::complex<T> Thorsten Ottosen

N1694 A Proposal to Extend the Function Call Operator Peter Dimov

N2518 Compiler Support for type_traits James Widman