gcc

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Use flags of 17.0.0_p20260726

• test Enable dependencies and/or preparations necessary to run tests (usually controlled by FEATURES=test but can be toggled independently)
• vanilla Do not add extra patches which change default behaviour; DO NOT USE THIS ON A GLOBAL SCALE as the severity of the meaning changes drastically
• +nls Add Native Language Support (using gettext - GNU locale utilities)
• debug Enables GCC's 'checking' (assertions) facility. For released GCCs: * USE=debug sets --enable-checking=yes,extra,rtl * USE=-debug sets --enable-checking=release For unreleased GCCs: * USE=debug sets --enable-checking=yes,extra,rtl * USE=-debug sets --enable-checking=yes,extra This adds checks to various compiler passes for integrity and input validation. This can help catch possible miscompilations early as well as latent bugs which could become real problems in future, but at the cost of slower compile times when using GCC. Unrelated to backtraces.
• +cxx Build support for C++ (bindings, extra libraries, code generation, ...)
• +fortran Add support for fortran
• doc Add extra documentation (API, Javadoc, etc). It is recommended to enable per package instead of globally
• hardened Activate default security enhancements for toolchain (gcc, glibc, binutils)
• multilib On 64bit systems, if you want to be able to compile 32bit and 64bit binaries
• objc Build support for the Objective C code language
• pgo Build GCC using Profile Guided Optimization (PGO). GCC will build itself and then analyze the just-built binary and then rebuild itself using the data obtained from analysis of codepaths taken. It does not affect whether GCC itself supports PGO when building other software. This substantially increases the build time needed for building GCC itself.
• objc-gc Build support for the Objective C code language Garbage Collector
• libssp Build SSP support into a dedicated library rather than use the code in the C library (DO NOT ENABLE THIS IF YOU DON'T KNOW WHAT IT DOES)
• objc++ Build support for the Objective C++ language
• openmp Build support for the OpenMP (support parallel computing), requires >=sys-devel/gcc-4.2 built with USE="openmp"
• fixed-point Enable fixed-point arithmetic support for MIPS targets in gcc (Warning: significantly increases compile time!)
• go Build the GCC Go language frontend.
• +sanitize Build support for various sanitizer functions (ASAN/TSAN/etc...) to find runtime problems in applications.
• graphite Add support for the framework for loop optimizations based on a polyhedral intermediate representation
• ada Build the Ada language (GNAT) frontend
• vtv Build support for virtual table verification (a C++ hardening feature). This does not control whether GCC defaults to using VTV> Note that actually using VTV breaks ABI and hence the whole system must be built with -fvtable-verify.
• jit Enable libgccjit so other applications can embed gcc for Just-In-Time compilation.
• +pie Build programs as Position Independent Executables (a security hardening technique)
• +ssp Build packages with stack smashing protection on by default
• pch Enable precompiled header support for faster compilation at the expense of disk space and memory
• systemtap Enable enhanced debugging hooks/interface via SystemTap static probe points in libgcc and libstdc++. Note that this isn't exclusive to SystemTap, despite the name. This provides an interface which dev-debug/gdb optionally uses, see https://sourceware.org/gdb/wiki/LinkerInterface and https://sourceware.org/gdb/wiki/DistroAdvice#sys.2Fsdt.h_probes.
• d Enable support for the D programming language
• lto Build using Link Time Optimizations (LTO). Note that GCC is always built with support for building other programs with LTO. This USE flag is for whether GCC itself is built and optimized with LTO.
• cet Enable support for control flow hijacking protection. On amd64, this provides Intel Control Flow Enforcement Technology (CET). On arm64, this provides Branch Target Identification (BTI) and Pointer Authentication Code (PAC) support. This is only effective on amd64 or arm64. Only provides benefits on newer CPUs. For Intel, the CPU must be at least as new as Tiger Lake. For AMD, it must be at least as new as Zen 3. This is harmless on older CPUs, but provides no benefit either. For ARM64, PAC was introduced in armv8.3-a, and BTI was introduced in armv8.5-a. When combined with USE=hardened on amd64, GCC will set -fcf-protection by default when building software. The effect is minimal on systems which do not support it, other than a possible small increase in codesize for the NOPs. The generated code is therefore compatible with i686 at the earliest. On arm64, GCC will set -mbranch-protection=standard by default when building software.
• zstd Enable support for ZSTD compression
• valgrind Enable annotations for accuracy. May slow down runtime slightly. Safe to use even if not currently using dev-debug/valgrind
• custom-cflags Build with user-specified CFLAGS (unsupported)
• ieee-long-double Use accelerated 128-bit IEEE long double ABI (ppc64le only)
• default-znow Request full relocation on start from ld.so by default. This sets the -z,now (BIND_NOW) flag by default on all linker invocations. By resolving all dynamic symbols at application startup, parts of the program can be made read-only as a hardening measure. This is closely related to RELRO which is also separately enabled by default. In some applications with many unresolved symbols (heavily plugin based, for example), startup time may be impacted.
• default-stack-clash-protection Build packages with stack clash protection on by default as a hardening measure. This enables -fstack-clash-protection by default which protects against large memory allocations allowing stack smashing. May cause slightly increased codesize, but modern compilers have been adapted to optimize well for this case, as this mitigation is now quite common. See https://developers.redhat.com/blog/2020/05/22/stack-clash-mitigation-in-gcc-part-3 and https://www.qualys.com/2017/06/19/stack-clash/stack-clash.txt.
• modula2 Build the GCC Modula-2 language frontend.
• rust Build support for the Rust language, installs gccrs.
• time64 Use 64-bit time_t type instead of the regular 32-bit type. This flag is forced on time64 profiles, and masked elsewhere. It should be only used when detection of type width is not possible (e.g. for SRC_URI)
• libgdiagnostics Provide libgdiagnostics (https://gcc.gnu.org/wiki/libgdiagnostics). This also installs the 'sarif-replay' tool.
• cobol Enable support for the COBOL programming language
• algol68 Build the Algol 68 frontend

Runtime dependencies of 17.0.0_p20260726