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[2603:7000:9500:34a5::1db4]) by smtp.gmail.com with ESMTPSA id bt14-20020ad455ce000000b006994aae00e9sm42102qvb.7.2024.04.10.14.26.24 for (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 10 Apr 2024 14:26:25 -0700 (PDT) Date: Wed, 10 Apr 2024 17:26:23 -0400 From: Marek Polacek To: GCC Patches Subject: [wwwdocs] Document more C++ changes Message-ID: MIME-Version: 1.0 User-Agent: Mutt/2.2.12 (2023-09-09) X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline X-Spam-Status: No, score=-13.1 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,GIT_PATCH_0,KAM_LOTSOFHASH,KAM_SHORT,RCVD_IN_DNSWL_NONE,RCVD_IN_MSPIKE_H4,RCVD_IN_MSPIKE_WL,SPF_HELO_NONE,SPF_NONE,TXREP,URIBL_SBL_A autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org List-Id: I went through all cp/ commits in GCC 14 and documented a few interesting user-visible changes, modulo Modules. W3 validated. Pushed. commit d65752191baaa137eb6d604b802e7b9170a39752 Author: Marek Polacek Date: Wed Apr 10 17:21:09 2024 -0400 gcc-14/changes: Document more C++ changes diff --git a/htdocs/gcc-14/changes.html b/htdocs/gcc-14/changes.html index 4a063346..5c2439ab 100644 --- a/htdocs/gcc-14/changes.html +++ b/htdocs/gcc-14/changes.html @@ -273,6 +273,9 @@ a work-in-progress.

  • Several C++23 features have been implemented:
      +
    • P0847R7, Deducing this + (PR102609) +
    • P2280R4, Using unknown references in constant expressions (PR106650) @@ -289,12 +292,26 @@ a work-in-progress.

    • Several C++ Defect Reports have been resolved, e.g.:
        +
      • DR 532, + Member/nonmember operator template partial ordering
      • DR 976, Deduction for const T& conversion operators
        • +
      • DR 2262, + Attributes for asm-definition
        • +
      • DR 2359, + Unintended copy initialization with designated initializers
        • +
      • DR 2386, + tuple_size requirements for structured binding
      • DR 2406, [[fallthrough]] attribute and iteration statements
      • DR 2543, constinit and optimized dynamic initialization
        • +
      • DR 2586, + Explicit object parameter for assignment and comparison
        • +
      • DR 2735, + List-initialization and conversions in overload resolution
        • +
      • DR 2799, + Inheriting default constructors
    • @@ -304,6 +321,85 @@ a work-in-progress.

      the template is instantiated ("required from here"), rather than just print filename and line/column numbers.
      • +
    • New built-in __type_pack_element to speed up traits + such as std::tuple_element + (PR100157)
      • +
    • goto can cross the initialization of a trivially initialized + object with a non-trivial destructor + (DR 2256)
      • +
    • -Wdangling-reference false positives have been reduced. The + warning does not warn about std::span-like classes; there is + also a new attribute gnu::no_dangling to suppress the + warning. See + the manual + for more info.
      • +
    • noexcept(expr) is now mangled as per the Itanium ABI
      • +
    • the named return value optimization can now be performed even for + variables declared in an inner block of a function, see the + + test
      • +
    • New -Wnrvo warning, to warn if the named return value + optimization is not performed although it is allowed by + [class.copy.elision]. See + the manual + for more info.
      • +
    • The backing array for std::initializer_list has been made + static, allowing combining multiple equivalent initializer-lists + (git) +
      • +
    • New -Welaborated-enum-base warning, to warn if an additional + enum-base is used in an elaborated-type-specifier
      • +
    • Better #include hints for missing headers + (PR110164)
      • +
    • The arguments of a variable template-id are coerced earlier than + before, so various problems are detected earlier + (PR89442)
      • +
    • -Wmissing-field-initializers is no longer emitted for + empty classes + (PR110064)
      • +
    • The constexpr code now tracks lifetimes in constant evaluation; this + change helps to detect bugs such as accessing a variable whose + lifetime has ended + (PR70331, + PR96630, + PR98675) +
      • +
    • Array destruction can now be devirtualized
      • +
    • In-class member variable template partial specializations are now + accepted (PR71954)
      • +
    • Improved diagnostic for explicit conversion functions: when a conversion + doesn't work out only because the conversion function necessary to do the + conversion couldn't be used because it was marked explicit, explain that + to the user + (git)
      • +
    • Corrected mangling of static/thread_local + structured bindings at function/block scope + (PR111069)
      • +
    • [basic.scope.block]/2 violations are detected even in compound-stmt of + function-try-block and for block-scope external variables + (PR52953)
      • +
    • Improved "not a constant expression" diagnostic when taking the address + of a non-static constexpr variable + (PR91483)
      • +
    • Non-dependent simple assignments are checked even in templates + (PR18474)
      • +
    • Attributes hot and cold can be applied to + classes as well. See + the manual + for more info.
      • +
    • Function template constraints, as well as CTAD placeholders, are + now mangled
      • +
    • Various decltype fixes: + PR79620, + PR79378, + PR83167, + PR96917
      • +
    • New option -fdiagnostics-all-candidates to note all + candidates during overload resolution failure
      • +
    • -Walloc-size and -Wcalloc-transposed-args + warnings are enabled for C++ as well
      • +
    • The DR 2237 code no longer gives an error, it emits + a -Wtemplate-id-cdtor warning instead

    Runtime Library (libstdc++)