June 4th, 2020 – GSL version 3.1.0 has been released. Please see the latest release page<\/a> for information regarding GSL 3.1.0. For all future updates, please see refer to the release page<\/a> on GitHub.<\/p>\n <\/p>\n Version 3.0.0 of Microsoft’s implementation of the C++ Core Guidelines Support Library<\/a> (GSL) is now available for you to download on the releases page<\/a>. Microsoft\u2019s implementation of By default, use\u00a0<\/span><\/span> With the standardization of span nearing completion, we decided it was time to align our implementation with the design changes in the standard. The new implementation provides full bounds checking, guaranteeing bounds safety if the underlying data is valid.<\/p>\n These are the changes required to align Our implementation of The new implementation can perform all of the bounds checks by itself, instead of calling into the span. By relying on pointers to the underlying data, rather than a pointer to the span, the new The <gsl\/span_ext> header was created to support our customers who rely on portions of the old span implementation that no longer exist in the standard definition of span.<\/p>\n Contract violations are no longer configurable. Contract violations always result in termination, rather than providing a compile-time option to throw or disregard the contract violation. This is subject to change in the future. Some concerns over this decision have been raised and the conversation continues here: CppCoreGuidelines#1561<\/a>. As a side note, the removal of the throwing behavior required the migration of our test infrastructure from Catch2 to Google Test, whose support of death tests easily enabled testing of contract violation behavior.<\/p>\n This release now supports To more closely align Microsoft\u2019s GSL to the C++ Core Guidelines, we decided to deprecate our implementation of Change: <\/strong>The change from signed Mitigation: <\/strong>Use <\/p>\n Change: <\/strong> Mitigation: <\/strong>Pass multi-dimensional arrays as constant references instead of <\/p>\n Change: <\/strong>Code that makes use of\u00a0<\/span><\/span>moved<\/span><\/span>\u00a0span<\/span><\/span>\u00a0helper<\/span><\/span>\u00a0functions<\/span><\/span>\u00a0will g<\/span><\/span>enerate compiler errors. <\/span><\/span>Examples of these functions include span comparison operators, Mitigation: <\/strong>Include <gsl\/span_ext> instead of <gsl\/span> in files where you use these functions.<\/p>\n <\/p>\n Change: <\/strong>Throwing contract violation behavior is removed.<\/p>\n Mitigation:<\/strong> Use a terminate handler to log relevant information before termination executes for debugging. Relying on throwing behavior does not guarantee safety.<\/p>\n The paper P1976R2<\/a> that came out of the WG21 Prague meeting has yet to be implemented in GSL. A minor release will be issued when this is added to GSL.<\/p>\n We look forward to hearing your feedback. If you would like to reach us, please use the comments below or email visualcpp@microsoft.com<\/a>. Visit our page on GitHub<\/a> if you would like to file issues or contribute to the project.<\/p>\n 4\/23\/2020 – Released GSL version 3.0.1<\/p>\n 6\/4\/2020 – Released GSL version 3.1.0<\/p>\n","protected":false},"excerpt":{"rendered":" Update June 4th, 2020 – GSL version 3.1.0 has been released. Please see the latest release page for information regarding GSL 3.1.0. For all future updates, please see refer to the release page on GitHub. GSL 3.0.0 Release Version 3.0.0 of Microsoft’s implementation of the C++ Core Guidelines Support Library (GSL) is now available […]<\/p>\n","protected":false},"author":6068,"featured_media":35994,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[270,1,512,277],"tags":[],"class_list":["post-25836","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-announcement","category-cplusplus","category-general-cpp-series","category-writing-code"],"acf":[],"blog_post_summary":" Update June 4th, 2020 – GSL version 3.1.0 has been released. Please see the latest release page for information regarding GSL 3.1.0. For all future updates, please see refer to the release page on GitHub. GSL 3.0.0 Release Version 3.0.0 of Microsoft’s implementation of the C++ Core Guidelines Support Library (GSL) is now available […]<\/p>\n","_links":{"self":[{"href":"https:\/\/devblogs.microsoft.com\/cppblog\/wp-json\/wp\/v2\/posts\/25836","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/devblogs.microsoft.com\/cppblog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/devblogs.microsoft.com\/cppblog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/cppblog\/wp-json\/wp\/v2\/users\/6068"}],"replies":[{"embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/cppblog\/wp-json\/wp\/v2\/comments?post=25836"}],"version-history":[{"count":0,"href":"https:\/\/devblogs.microsoft.com\/cppblog\/wp-json\/wp\/v2\/posts\/25836\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/cppblog\/wp-json\/wp\/v2\/media\/35994"}],"wp:attachment":[{"href":"https:\/\/devblogs.microsoft.com\/cppblog\/wp-json\/wp\/v2\/media?parent=25836"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/cppblog\/wp-json\/wp\/v2\/categories?post=25836"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/cppblog\/wp-json\/wp\/v2\/tags?post=25836"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}GSL 3.0.0 Release<\/h2>\n
gsl::span<\/code> has played a pivotal role in the standardization of span for C++20. However, the standard does not provide any runtime checking guarantees for memory bounds safety. The bounds safety provided by gsl::span<\/code> has been very successful in preventing security issues in Microsoft products. This release maintains the safety guarantees that we have always offered but modernizes our implementation to align with C++20 span.<\/p>\nWhat changed in this release?<\/h2>\n
\n
gsl::span<\/code> and gsl::span_iterator<\/code> that align to the C++ 20 standard.<\/li>\ngsl::multi_span<\/code> and gsl::strided_span<\/code>.<\/li>\n<\/ul>\nWhen should I use gsl::span instead of std::span?<\/h2>\n
std::<\/span>span<\/span><\/span><\/code>\u00a0<\/span><\/span>which\u00a0<\/span><\/span>is shipping in VS2019 16.6<\/span><\/span>\u00a0(<\/span><\/span>with additional interface changes in 16.7,\u00a0<\/span><\/span>see release notes<\/span><\/span><\/a>)<\/span><\/span>\u00a0if you have enabled C++20 mode and do not need runtime bounds checking guarantees<\/span><\/span>.<\/span><\/span>\u00a0Use<\/span><\/span>\u00a0<\/span><\/span>gsl<\/span>::span<\/span><\/span><\/code>\u00a0<\/span><\/span>if you need support for a ver<\/span><\/span>s<\/span><\/span>ion of C++ lower than C++20 (<\/span><\/span>gsl<\/span>::span<\/span><\/span><\/code>\u00a0<\/span><\/span>supports C++14 and\u00a0<\/span><\/span>higher) or<\/span><\/span>\u00a0<\/span><\/span>runtime bounds checking guarantees (a<\/span><\/span>ll operations performed on\u00a0<\/span><\/span>gsl<\/span>::span<\/span><\/span><\/code>\u00a0and its iterators have explicit bounds safety checks.<\/span><\/span>)<\/span><\/span>\u00a0<\/span><\/span>\u00a0<\/span><\/p>\ngsl::span<\/h2>\n
General changes<\/h3>\n
gsl::span<\/code> was rewritten to have its interface align to std::span<\/code>. The biggest change is that span’s Extent is now unsigned. It is now implemented as std::size_t<\/code> whereas previously it was std::ptrdiff_t.<\/code> By extension, dynamic_extent<\/code> is now defined as static_cast<std::size_t>(-1)<\/code> instead of just -1<\/code>.<\/p>\n\n
span::index_type<\/code> was removed, superseded by span::size_type<\/code>.<\/li>\nInterface alignment<\/h3>\n
gsl::span<\/code> to the interface of std::span<\/code>.<\/p>\nRemoved functions<\/h4>\n
\n
span::operator()<\/code><\/li>\nspan::at<\/code><\/li>\nspan::cbegin<\/code><\/li>\nspan::cend<\/code><\/li>\nspan::crbegin<\/code><\/li>\nspan::crend<\/code><\/li>\n<\/ul>\nAdded functions<\/h4>\n
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span::front<\/code><\/li>\nspan::back<\/code><\/li>\n<\/ul>\nRenamed functions<\/h4>\n
\n
span::as_writeable_bytes<\/code> was renamed to span::as_writable_bytes<\/code><\/li>\n<\/ul>\ngsl::span_iterator<\/h2>\n
General changes<\/h3>\n
span_iterator<\/code> has been completely rewritten to be more range-like. Previously, the implementation consisted of a span pointer and an offset. The new implementation is a set of three pointers: begin, end, and current.<\/p>\nBenefits of our new implementation<\/h3>\n
span_iterator<\/code> can outlive the underlying span.<\/p>\nThe new <gsl\/span_ext> header<\/h2>\n
Elements moved from <gsl\/span> and inserted into <gsl\/span_ext><\/h3>\n
\n
gsl::make_span<\/code><\/li>\ngsl::at<\/code><\/li>\ngsl::begin<\/code><\/li>\ngsl::rbegin<\/code><\/li>\ngsl::crbegin<\/code><\/li>\ngsl::end<\/code><\/li>\ngsl::rend<\/code><\/li>\ngsl::crend<\/code><\/li>\n<\/ul>\nContract violations<\/h2>\n
CMake improvements<\/h2>\n
find_package<\/code>. Once installed, use find_package(Microsoft.GSL CONFIG)<\/code> to easily consume the GSL.<\/p>\nDeprecation of multi_span and strided_span<\/h2>\n
gsl::multi_span<\/code> and gsl::strided_span<\/code>. For the time being, we will continue to provide these headers, but they will not be actively worked on or maintained unless the C++ Core Guidelines identifies a need for them.<\/p>\nImprovement<\/span><\/span>\u00a0<\/span>change<\/span><\/span>s\u00a0<\/span><\/span>c<\/span><\/span>ausing\u00a0<\/span><\/span>p<\/span><\/span>otential\u00a0<\/span><\/span>b<\/span><\/span>uild<\/span><\/span>\u00a0<\/span><\/span>b<\/span><\/span>reaks<\/span><\/span>\u00a0<\/span><\/span>and\u00a0<\/span><\/span>m<\/span><\/span>itigations<\/span><\/span>\u00a0<\/span><\/h2>\n
std::ptrdiff_t<\/code> to unsigned std::size_t<\/code> in gsl::span<\/code> may introduce signed\/unsigned mismatches.<\/p>\nstatic_cast<\/code> or gsl::narrow_cast<\/code> to resolve mismatches.<\/p>\ngsl::multi_span<\/code> and gsl::strided_span<\/code> have been deprecated.<\/p>\ngsl::multi_span<\/code>.<\/p>\ngsl::make_span<\/code>, etc.<\/p>\nUpcoming changes<\/h2>\n
Feedback<\/h2>\n
<\/h2>\n
Update History<\/h2>\n