.RHEL 10 Beta introduces LLVM Toolset 18.1.8 RHEL 10 Beta is distributed with the LLVM Toolset version 18.1.8. Notable LLVM updates: * The constant expression variants of the following instructions have been removed: `and`, `or`, `lshr`, `ashr`, `zext`, `sext`, `fptrunc`, `fpext`, `fptoui`, `fptosi`, `uitofp`, `sitofp`. * The `llvm.exp10` intrinsic has been added. * The `code_model` attribute for global variables has been added. * The backend for the AArch64, AMDGPU, PowerPC, RISC-V, SystemZ and x86 architectures has been improved. * LLVM tools have been improved. Notable Clang enhancements: * C++20 feature support: ** Clang no longer performs One Definition Rule (ODR) checks for declarations in the global module fragment. To enable more strict behavior, use the `-Xclang -fno-skip-odr-check-in-gmf` option. * C++23 feature support: ** A new diagnostic flag `pass:[-Wc++23-lambda-attributes]` has been added to warn about the use of attributes on lambdas. * C++2c feature support: ** Clang now allows using the `_` character as a placeholder variable name multiple times in the same scope. ** Attributes now expect unevaluated strings in attribute parameters that are string literals. ** The deprecated arithmetic conversion on enumerations from C++26 has been removed. ** The specification of template parameter initialization has been improved. * For a complete list of changes, see the link: https://releases.llvm.org/18.1.8/tools/clang/docs/ReleaseNotes.html#what-s-new-in-clang-release [upstream release notes for Clang]. ABI changes in Clang: * Following the SystemV ABI for x86_64, the `__int128` arguments are no longer split between a register and a stack slot. * For more information, see the link: https://releases.llvm.org/18.1.8/tools/clang/docs/ReleaseNotes.html#abi-changes-in-this-version [list of ABI changes in Clang]. Notable backwards incompatible changes: * A bug fix in the reversed argument order for templated operators breaks code in pass:[C++20] that was previously accepted in pass:[C++17]. * The `GCC_INSTALL_PREFIX` CMake variable (which sets the default `--gcc-toolchain=`) is deprecated and will be removed. Specify the `--gcc-install-dir=` or `--gcc-triple=` option in a configuration file instead. * The default extension name for precompiled headers (PCH) generation (`-c -xc-header` and `pass:[-c -xc++-header]`) is now `.pch` instead of `.gch`. * When `-include a.h` probes the `a.h.gch` file, the include now ignores `a.h.gch` if it is not a Clang PCH file or a directory containing any Clang PCH file. * A bug that caused `pass:[__has_cpp_attribute]` and `pass:[__has_c_attribute]` to return incorrect values for certain C++-11-style attributes has been fixed. * A bug in finding a matching `operator!=` while adding a reversed `operator==` has been fixed. * The name mangling rules for function templates have been changed to accept that functions can be overloaded on their template parameter lists or requires-clauses. * The `-Wenum-constexpr-conversion` warning is now enabled by default on system headers and macros. It will be turned into a hard (non-downgradable) error in the next Clang release. * A path to the imported modules for C++20 named modules can no longer be hardcoded. You must specify all the dependent modules from the command line. * It is no longer possible to import modules by using `import <module>`; Clang uses explicitly-built modules. * For more details, see the link: https://releases.llvm.org/18.1.8/tools/clang/docs/ReleaseNotes.html#potentially-breaking-changes [list of potentially breaking changes]. For more information, see the link: https://releases.llvm.org/18.1.8/docs/ReleaseNotes.html [LLVM release notes] and link: https://releases.llvm.org/18.1.8/tools/clang/docs/ReleaseNotes.html [Clang release notes]. LVM Toolset is a rolling Application Stream, and only the latest version is supported.