• Doing it Right¶. Let’s install a real version of Python. Before installing Python, you’ll need to install GCC. GCC can be obtained by downloading Xcode, the smaller Command Line Tools (must have an Apple account) or the even smaller OSX-GCC-Installer package.
• I want to install pip for python 2.7 on my Mac. I think this is the python located in /usr/bin/python. Unfortunately I have already installed Anaconda, which installs python 3.6.3, and changes things so that the command python xxx.py automatically runs xxx.py using python 3.6.3.
• Other projects packaging GCC (and gfortran) binaries for Mac include: Homebrew offers the latest stable gfortran release as part of the 'gcc' package. HPC Mac OS X offers GCC builds, which include gfortran. MacPorts (package name, e.g., 'gcc48') - the fastest way to get a developer version of GCC.
• For Linux/Unix based machines, a complete instruction is available at the installation page of gcc website. For Mac users, there are more choices except for the one above (installing from source, gcc version 6.1 which can be replaced!): 1. Port Install: sudo port install gcc6 sudo port select -list gcc sudo port select -set gcc mp-gcc6.

1. Linux Mac Os X
2. Gcc For Mac Os X

This page gathers links to all unofficial gfortran binary packages people regularly build, based on the current development gfortran source code.

• Windows

• MacOS

• GNU/Linux

• Build GNU Fortran from source

Mac OS X v10.3の後継であり、PowerPC版でClassic環境が使える最後のOSとなった。 2005年 4月12日 公式発表され、同年 4月29日 に発売開始された。 最終セキュリティアップデートは、2009年9月10日にリリースされた Security Update 2009-005 1 2 3 である。.

Note: There do not exist any official FSF/GNU/GCC binary builds (only source packages). Most of the builds below come from gfortran maintainers but not all.

Windows

If in doubt, or if you don't know what Cygwin and MinGW are, the package for you is the MinGW ('native Windows') package!

• MinGW for Win64: The Mingw-w64 project has regularly updated snapshots of compilers generating 64-bit Windows executables. They provides several compilers, which run on Windows (32-bit and 64-bit Windows), Cygwin, Linux, and Darwin/MacOS - and which generate binaries for 32bit or 64bit Windows. The file name pattern is <target>-<host>-<option-version>-<date>; thus, mingw-w64-bin_x86_64-mingw_20100527.zip is a compiler targeting 64bit Windows (mingw-w64) but also running ('host') on 64bit Windows (xx86-64-mingw); you might search for the file in Toolchains targetting Win64 (Personal Builds or Automatized Builds).

• MinGW build ('native Windows' build)

  • Official MinGW builds (only releases), last seen was 6.3.0 (2017-05-30)

  • The MinGW for Win64 project has also binaries for 32bit Windows; e.g. mingw-w32-bin_i686-mingw_<date>.zip runs on and generates binaries for 32bit Windows (cf. above); you might search for the file in Toolchains targetting Win32 (Personal Builds or Automatized Builds).

• TDM GCC: MinGW/MinGW-W64 Builds

• MinGW 32/64bit builds by www.Equation.com (builds were announced at comp.lang.fortran; note - equation.com is not affiliated with any MinGW or GCC developer. Use at your own risk)

• Cygwin: The Cygwin project offers up-to-date builds of GCC and gfortran

• Octave: Octave 6.1 comes with gcc/gfortran-9.3.1. From the Windows start menu, open up Octave and you will find the bash shell. Stick it to your task bar so it's always to hand. Combined with Notepad++ (https://notepad-plus-plus.org/), you will be able to get on with fortran development using nothing but GPL tools. Alternatively, the 'system' command can be used to run gfortran from the Octave GUI together with the Octave editor.

• 
  

macOS

Linux Mac Os X

The gfortran maintainers offer nice Apple-style installers for macOS: https://github.com/fxcoudert/gfortran-for-macOS/releasesDetailed instructions can be found here.

Other projects packaging GCC (and gfortran) binaries for Mac include:

• Homebrew offers the latest stable gfortran release as part of the 'gcc' package.

• HPC Mac OS X offers GCC builds, which include gfortran

• MacPorts (package name, e.g., 'gcc48') - the fastest way to get a developer version of GCC. MacPorts comes with a packing software, but all software is compiled before installation. For the developer version, the 'Portfile' is updated approx. weekly.

• Fink offers GCC packages (all released versions) - similar to MacPorts, but also offers binaries; it does not have the developer versions, just the releases.

GNU/Linux

Most Linux distributions offer gfortran packages, some have also builds for the experimental versions

Nightly builds are available at:

• 32-bit processors (i686)

  • Download from gfortran.com

  • Installation instructions

• 64-bit AMD-compatible processors (x86_64, AMD64,Intel64, em64t)

  • Download from gfortran.com (README, nightly builds, 4.3 to 4.9 snapshots)

  • gcc-4.8-infrastructure package (GCC 4.8 and later; for GCC 4.3 to 4.7 use gcc-infrastructure), which contains required libraries (GMP, MPFR, MPC, etc.) - simply unpack in the 'gcc-trunk' (or 'gcc-4.6' or ..) directory

  • To unpack .xz files: Use xzcat with tar. It is contained in pre-build xz package, if you don't have it.

  • Needs to be updated: Installation instructions

Building from Source

See also InstallingGCC and http://gcc.gnu.org/install/

1. Obtain the source code either via

   • subversion

   • git Osx zip.

   • Bazaar

   • unpacking a tarball

2. You should have the right versions of GMP, MPFR and MPC (and optionally for Graphite: CLOOG and ISL) installed, which you can download from ftp://gcc.gnu.org/pub/gcc/infrastructure/ (They can also be automatically build with GCC.)

   • Note: You can use ./contrib/download_prerequisites to download them.

3. Follow the instructions; in a nutshell, you will do

   • create a build directory, e.g. gcc-build underneath the source directory

   • go to the build directory and run configure from there; for instance: ./configure --prefix=$HOME/gcc-trunk --enable-languages=c,fortran

   • run make

   • run make install

Useful configure options: --enable-checking=release which disables some compile-time checks which slow down the compiler; --disable-bootstrap which speeds up the build but uses the system compiler and disables some consistency checks; --disable-build-poststage1-with-cxx (for 4.7 or higher) avoids building GCC with a C++ compiler, esp. useful if no C++ should be compiled; --disable-libstdcxx-pch speeds up the compilation a bit by not creating pre-compiled header files.

This page is a 'brief' summary of some of the huge number of improvementsin GCC 11.You may also want to check out ourPorting to GCC 11 page and thefull GCC documentation.

Note: GCC 11 has not been released yet, so this document isa work-in-progress.

Caveats

• The default mode for C++ is now -std=gnu++17 instead of -std=gnu++14. Note that C++17 changes to template template parameter matching can be disabled independently of other features with -fno-new-ttp-matching.
• When building GCC itself, the host compiler must now support C++11, rather than C++98. In particular bootstrapping GCC 11 using an older version of GCC requires a binary of GCC 4.8 or later, rather than of GCC 3.4 or later as was the case for bootstrapping GCC 10.
• Naming and location of auxiliary and dump output files changed. If you compile multiple input files in a single command, if you enable Link Time Optimization, or if you use -dumpbase, -dumpdir, -save-temps=*, and you expect any file other than the primary output file(s) to be created as a side effect, watch out for improvements and a few surprises. See the patch, particularly its textual description, for more details about the changes.
• -gsplit-dwarf no longer enables debug info generation on its own but requires a separate -g for this.
• The libstdc++ configure option --enable-cheaders=c_std is deprecated and will be removed in a future release. It should be possible to use --enable-cheaders=c_global (the default) with no change in behaviour.
• The front end for compiling BRIG format of Heterogeneous System Architecture Intermediate Language (HSAIL) has been deprecated and will likely be removed in a future release.

General Improvements

• ThreadSanitizer improvements to support alternative runtimes and environments. The Linux Kernel Concurrency Sanitizer (KCSAN) is now supported.
  • Add --param tsan-distinguish-volatile to optionally emit instrumentation distinguishing volatile accesses.
  • Add --param tsan-instrument-func-entry-exit to optionally control if function entries and exits should be instrumented.

• In previous releases of GCC, the 'column numbers' emitted in diagnostics were actually a count of bytes from the start of the source line. This could be problematic, both because of:

  • multibyte characters (requiring more than one byte to encode), and
  • multicolumn characters (requiring more than one column to display in a monospace font)

  For example, the character π ('GREEK SMALL LETTER PI (U+03C0)') occupies one column, and its UTF-8 encoding requires two bytes; the character 🙂 ('SLIGHTLY SMILING FACE (U+1F642)') occupies two columns, and its UTF-8 encoding requires four bytes.

  In GCC 11 the column numbers default to being column numbers, respecting multi-column characters. The old behavior can be restored using a new option -fdiagnostics-column-unit=byte. There is also a new option -fdiagnostics-column-origin=, allowing the pre-existing default of the left-hand column being column 1 to be overridden if desired (e.g. for 0-based columns). The output of -fdiagnostics-format=json has been extended to supply both byte counts and column numbers for all source locations.

  Additionally, in previous releases of GCC, tab characters in the source would be emitted verbatim when quoting source code, but be prefixed with whitespace or line number information, leading to misalignments in the resulting output when compared with the actual source. Tab characters are now printed as an appropriate number of spaces, using the -ftabstop option (which defaults to 8 spaces per tab stop).

• Introduce Hardware-assisted AddressSanitizer support. This sanitizer currently only works for the AArch64 target. It helps debug address problems similarly to AddressSanitizer but is based on partial hardware assistance and provides probabilistic protection to use less RAM at run time. Hardware-assisted AddressSanitizer is not production-ready for user space, and is provided mainly for use compiling the Linux Kernel.

  To use this sanitizer the command line arguments are:
  • -fsanitize=hwaddress to instrument userspace code.
  • -fsanitize=kernel-hwaddress to instrument kernel code.

• For targets that produce DWARF debugging information GCC now defaults to DWARF version 5 (with the exception of VxWorks and Darwin/Mac OS X which default to version 2 and AIX which defaults to version 4). This can produce up to 25% more compact debug information compared to earlier versions.

  To take full advantage of DWARF version 5 GCC needs to be build against binutils version 2.35.2 or higher. When GCC is build against earlier versions of binutils GCC will still emit DWARF version 5 for most debuginfo data, but will generate version 4 debug line tables (even when explicitly given -gdwarf-5).

  The following debug information consumers can process DWARF version 5:

  • GDB 8.0, or higher
  • valgrind 3.17.0
  • elfutils 0.172, or higher (for use with systemtap, dwarves/pahole, perf and libabigail)
  • dwz 0.14

  Programs embedding libbacktrace are urged to upgrade to the version shipping with GCC 11.

  To make GCC 11 generate an older DWARF version use -g together with -gdwarf-2, -gdwarf-3 or -gdwarf-4.

New Languages and Language specific improvements

• GCC 11 adds support for non-rectangular loop nests in OpenMP constructs and the allocator routines of OpenMP 5.0, including initial allocate clause support in C/C++. The OMP_TARGET_OFFLOAD environment variable and the active-levels routines are now supported. For C/C++, the declare variant and map support has been extended. For Fortran, OpenMP 4.5 is now fully supported and OpenMP 5.0 support has been extended, including the following features which were before only available in C and C++: order(concurrent), device_type, memorder-clauses for flush, lastprivate with conditional modifier, atomic construct and reduction clause extensions of OpenMP 5.0, if clause with simd and cancel modifiers, target data without map clause, and limited support for the requires construct.

C family

• New attributes:
  • The no_stack_protector attribute has been added to mark functions which should not be instrumented with stack protection (-fstack-protector).
  • The existing malloc attribute has been extended so that it can be used to identify allocator/deallocator API pairs. A pair of new -Wmismatched-dealloc and -Wmismatched-new-delete warnings will complain about mismatched calls, and -Wfree-nonheap-object about deallocation calls with pointers not obtained from allocation functions. Additionally, the static analyzer will use these attributes when checking for leaks, double-frees, use-after-frees, and similar issues.
• New warnings:
  • -Wmismatched-dealloc, enabled by default, warns about calls to deallocation functions with pointers returned from mismatched allocation functions.
  • -Wsizeof-array-div, enabled by -Wall, warns about divisions of two sizeof operators when the first one is applied to an array and the divisor does not equal the size of the array element.
  • -Wstringop-overread, enabled by default, warns about calls to string functions reading past the end of the arrays passed to them as arguments. In prior GCC releases most instances of his warning are diagnosed by -Wstringop-overflow.
  • -Wtsan, enabled by default, warns about unsupported features in ThreadSanitizer (currently std::atomic_thread_fence).
• Enhancements to existing warnings:
  • -Wfree-nonheap-object detects many more instances of calls to deallocation functions with pointers not returned from a dynamic memory allocation function.
  • -Wmaybe-uninitialized diagnoses passing pointers or references to uninitialized memory to functions taking const-qualified arguments.
  • -Wuninitialized detects reads from uninitialized dynamically allocated memory.

• For ELF targets that support the GNU or FreeBSD OSABIs, the used attribute will now save the symbol declaration it is applied to from linker garbage collection.

  To support this behavior, used symbols that have not been placed in specific sections (e.g. with the section attribute, or the -f{function,data}-sections options) will be placed in new, unique sections.

  This functionality requires Binutils version 2.36 or later.

• A series of conditional expressions that compare the same variable can be transformed into a switch statement if each of them contains a comparison expression. Example: This statement can be transformed into a switch statement and then expanded into a bit-test.
• New command-line options:
  • -fbit-tests, enabled by default, can be used to enable or disable switch expansion using bit-tests.
• GCOV data file format outputs smaller files by representing zero counters in a more compact way.
• Some short options of the gcov tool have been renamed: -i to -j and -j to -H.

C

• Several new features from the upcoming C2X revision of the ISO C standard are supported with -std=c2x and -std=gnu2x. Some of these features are also supported as extensions when compiling for older language versions. In addition to the features listed, some features previously supported as extensions and now added to the C standard are enabled by default in C2X mode and not diagnosed with -std=c2x -Wpedantic.
  • The BOOL_MAX and BOOL_WIDTH macros are provided in <limits.h>.
  • As in C++, function definitions no longer need to give names for unused function parameters.
  • The expansions of the true and false macros in <stdbool.h> have changed so that they have type bool.
  • The [[nodiscard]] standard attribute is now supported.
  • The __has_c_attribute preprocessor operator is now supported.
  • Macros INFINITY, NAN, FLT_SNAN, DBL_SNAN, LDBL_SNAN, DEC_INFINITY, DEC_NAN, and corresponding signaling NaN macros for _FloatN, _FloatNx and _DecimalN types, are provided in <float.h>. There are also corresponding built-in functions __builtin_nansdN for decimal signaling NaNs.
  • Macros FLT_IS_IEC_60559, DBL_IS_IEC_60559 and LDBL_IS_IEC_60559 are provided in <float.h>.
  • The feature test macro __STDC_WANT_IEC_60559_EXT__ is supported by <float.h>.
  • Labels may appear before declarations and at the end of a compound statement.
• New warnings:
  • -Warray-parameter, enabled by -Wall, warns about redeclarations of functions with ordinary array arguments declared using inconsistent forms. The warning also enables the detection of the likely out of bounds accesses in calls to such functions with smaller arrays.
  • -Wvla-parameter, enabled by -Wall, warns redeclarations of functions with variable length array arguments declared using inconsistent forms or with mismatched bounds. The warning also enables the detection of the likely out of bounds accesses in calls to such functions with smaller arrays.

C++

• The default mode has been changed to -std=gnu++17.
• Several C++20 features have been implemented:
  • the compiler now supports consteval virtual functions
  • P2082R1, Fixing CTAD for aggregates
  • P0593R6, Pseudo-destructors end object lifetimes
  • P1907R1, Inconsistencies with non-type template parameters (complete implementation)
  • P1975R0, Fixing the wording of parenthesized aggregate-initialization
  • P1009R2, Array size deduction in new-expressions
  • P1099R5, using enum
  • Modules, Requires -fmodules-ts and some aspects are incomplete. Refer to C++ 20 Status
• The C++ front end has experimental support for some of the upcoming C++23 draft features with the -std=c++23, -std=gnu++23, -std=c++2b or -std=gnu++2b flags, including
  • P0330R8, Literal Suffix for (signed) size_t.
  For a full list of new features, see the C++ status page.
• Several C++ Defect Reports have been resolved, e.g.:
  • DR 625, Use of auto as a template-argument
  • DR 1512, Pointer comparison vs qualification conversions
  • DR 1722, Should lambda to function pointer conversion function be noexcept?
  • DR 1914, Duplicate standard attributes
  • DR 2032, Default template-arguments of variable templates
  • DR 2289, Uniqueness of decomposition declaration names
  • DR 2237, Can a template-id name a constructor?
  • DR 2303, Partial ordering and recursive variadic inheritance
  • DR 2369, Ordering between constraints and substitution
  • DR 2450, braced-init-list as a template-argument
• G++ now performs better access checking in templates (PR41437).
• reinterpret_casts in constexpr evaluation are now checked more completely (PR95307).
• The diagnostic for static_assert has been improved: the compiler now shows the expression including its template arguments (if there were any), and can point to the failing clause if the condition comprised of any logical AND operators (PR97518).
• New warnings:
  • -Wctad-maybe-unsupported, disabled by default, warns about performing class template argument deduction on a type with no deduction guides.
  • -Wrange-loop-construct, enabled by -Wall, warns when a range-based for-loop is creating unnecessary and expensive copies.
  • -Wdeprecated-enum-enum-conversion, enabled by default in C++20, warns about deprecated arithmetic conversions on operands of enumeration types, as outlined in [depr.arith.conv.enum].
  • -Wdeprecated-enum-float-conversion, enabled by default in C++20, warns about deprecated arithmetic conversions on operands where one is of enumeration type and the other is of a floating-point type, as outlined in [depr.arith.conv.enum].
  • -Wmismatched-new-delete, enabled by -Wall, warns about calls to C++ operator delete with pointers returned from mismatched forms of operator new or from other mismatched allocation functions.
  • -Wvexing-parse, enabled by default, warns about the most vexing parse rule: the cases when a declaration looks like a variable definition, but the C++ language requires it to be interpreted as a function declaration.
• Enhancements to existing warnings:
  • -Wnonnull considers the implicit this argument of every C++ nonstatic member function to have been implicitly declared with attribute nonnull and triggers warnings for calls where the pointer is null.

Gcc For Mac Os X

Runtime Library (libstdc++)

• Improved C++17 support, including:
  • std::from_chars and std::to_chars for floating-point types.
• Improved experimental C++20 support, including:
  • Calendar additions to <chrono>. Thanks to Cassio Neri for optimizations.
  • std::bit_cast
  • std::source_location
  • Atomic wait and notify operations.
  • <barrier>, <latch>, and <semaphore>
  • <syncstream>
  • Efficient access to basic_stringbuf's buffer.
• Experimental C++23 support, including:
  • contains member functions for strings, thanks to Paul Fee.
  • std::to_underlying, std::is_scoped_enum
• Experimental support for quality when originally added in GCC 5. Given that we have maintained API and ABI compatibility since then and it is in use by various projects, we have removed that caveat.
• libgccjit can now be built for MinGW
• The libgccjit API gained 10 new entry points:
  • 9 entrypoints for directly embedding asm statements into a compile, analogous to inline asm in the C front end

New Targets and Target Specific Improvements

AArch64 & arm

• A number of new CPUs are supported through arguments to the -mcpu and -mtune options in both the arm and aarch64 backends (GCC identifiers in parentheses):
  • Arm Cortex-A78 (cortex-a78).
  • Arm Cortex-A78AE (cortex-a78ae).
  • Arm Cortex-A78C (cortex-a78c).
  • Arm Cortex-X1 (cortex-x1).
  • Arm Neoverse V1 (neoverse-v1).
  • Arm Neoverse N2 (neoverse-n2).
• GCC can now auto-vectorize operations performing addition, subtraction, multiplication and the accumulate/subtract variants on complex numbers, taking advantage of the Advanced SIMD instructions in the Armv8.3-a (AArch64/AArch32), SVE (AArch64), SVE2 (AArch64) and MVE (AArch32 M-profile) instruction sets.

AArch64

• In addition to the above, the following AArch64-only CPUs are now supported:
  • Fujitsu A64FX (a64fx).
  • Arm Cortex-R82 (cortex-r82).
• The AArch64 Armv8-R architecture is now supported through the -march=armv8-r option.
• Mitigation against the Straight-line Speculation vulnerability is supported with the -mharden-sls= option. Please refer to the documentation for usage instructions.
• The availability of Advanced SIMD intrinsics available through the arm_neon.h header is improved and GCC 11 supports the full set of intrinsics defined by ACLE Q3 2020.

AMD Radeon (GCN)

• Initial support for gfx908 GPUs has been added.

arm

• Initial auto-vectorization is now available when targeting the MVE instruction set.
• GCC can now make use of the Low Overhead Branch instruction in Armv8.1-M to optimize loop counters and checks.
• The -mcpu=cortex-m55 option now supports the extensions +nomve and +nomve.fp to control generation of MVE and MVE floating-point instructions.

IA-32/x86-64

• New ISA extension support for Intel TSXLDTRK was added to GCC. TSXLDTRK intrinsics are available via the -mtsxldtrk compiler switch.
• New ISA extension support for Intel SERIALIZE was added to GCC. SERIALIZE intrinsics are available via the -mserialize compiler switch.
• New ISA extension support for Intel HRESET was added to GCC. HRESET intrinsics are available via the -mhreset compiler switch.
• New ISA extension support for Intel UINTR was added to GCC. UINTR intrinsics are available via the -muintr compiler switch.
• New ISA extension support for Intel KEYLOCKER was added to GCC. KEYLOCKER intrinsics are available via the -mkeylocker compiler switch.
• New ISA extension support for Intel AMX-TILE, AMX-INT8, AMX-BF16 was added to GCC. AMX-TILE, AMX-INT8, AMX-BF16 intrinsics are available via the -mamx-tile, -mamx-int8, -mamx-bf16 compiler switches.
• New ISA extension support for Intel AVX-VNNI was added to GCC. AVX-VNNI intrinsics are available via the -mavxvnni compiler switch.
• GCC now supports the Intel CPU named Sapphire Rapids through -march=sapphirerapids. The switch enables the MOVDIRI, MOVDIR64B, AVX512VP2INTERSECT, ENQCMD, CLDEMOTE, SERIALIZE, PTWRITE, WAITPKG, TSXLDTRK, AMT-TILE, AMX-INT8, AMX-BF16, and AVX-VNNI ISA extensions.
• GCC now supports the Intel CPU named Alderlake through -march=alderlake. The switch enables the CLDEMOTE, PTWRITE, WAITPKG, SERIALIZE, KEYLOCKER, AVX-VNNI, and HRESET ISA extensions.

Nios II

• The options -mcustom-insn=N no longer produce compiler warnings if the custom instruction is not generated due to missing optimization options such as -fno-math-errno, -ffinite-math-only, or -funsafe-math-optimizations. These warnings were not consistently emitted for all custom instructions.
• The -mcustom-fpu-cfg=fph2 option has been added to enable the custom instructions supported by the Nios II Floating Point Hardware 2 Component.

NVPTX

• The -misa default has changed from sm_30 to sm_35.
• The -m32 compiler switch has been removed.
• The -msoft-stack-reserve-local format has been fixed. Previously, it accepted -msoft-stack-reserve-local<n>. It now accepts -msoft-stack-reserve-local=<n>.

S/390, System z, IBM Z Systems

• The behavior when compiling with -fexcess-precision=standard (e.g., implied by -std=c99) on s390(x) targets can now be controlled at configure time with the flag --enable-s390-excess-float-precision. When enabled, GCC will maintain previous behavior and evaluate float expressions in double precision, which aligns with the definition of float_t as double. With the flag disabled, GCC will always evaluate float expressions in single precision. In native builds and cross compiles that have target libc headers, GCC will by default match the definition of float_t in the installed glibc.

Operating Systems

AIX

• GCC for AIX can be built as a 64 bit application and the runtimeis built as FAT libraries containing both 32 bit and 64 bit objects.
• Support AIX Vector Extended ABI with -mabi=vec-extabi.
• Thread-Local uninitiated data placed in local common section.
• Use thread-safe access in ctype.
• Link with libc128.a when long-double-128 enabled.

Improvements to Static Analyzer

• The implementation of how program state is tracked within -fanalyzer has been completely rewritten for GCC 11, fixing numerous bugs, and allowing for the analyzer to scale to larger C source files.
• The analysis of allocations and deallocations has been generalized beyond malloc and free.
  • As preliminary work towards eventually supporting C++, the malloc/free checking will also check new/delete and new[]/delete[]. However, C++ is not yet properly supported by -fanalyzer (for example, exception-handling is unimplemented).
  • As noted above, the existing malloc attribute has been extended so that it can be used to identify allocator/deallocator API pairs. The analyzer will use these attributes when checking for leaks, double-frees, use-after-frees, and similar issues.
  • A new -Wanalyzer-mismatching-deallocation warning has been added, covering such mismatches as using scalar delete rather vector delete[].
• The analyzer has gained warnings -Wanalyzer-shift-count-negative, -Wanalyzer-shift-count-overflow, -Wanalyzer-write-to-const, and -Wanalyzer-write-to-string-literal, all enabled by default when -fanalyzer is enabled.
• The analyzer can now be extended by GCC plugins, allowing for domain-specific path-sensitive warnings. An example of using a GCC plugin to check for misuses of CPython's global interpreter lock can be seen in the test suite
• The analyzer has gained new debugging options -fdump-analyzer-json and -fno-analyzer-feasibility.

Other significant improvements

• GCC has gained a new environment variable GCC_EXTRA_DIAGNOSTIC_OUTPUT which can be used by IDEs to request machine-readable fix-it hints without needing to adjust build flags.

For questions related to the use of GCC,please consult these web pages and theGCC manuals. If that fails,the gcc-help@gcc.gnu.orgmailing list might help.Comments on these web pages and the development of GCC are welcome on ourdeveloper list at gcc@gcc.gnu.org.All of our listshave public archives.

Copyright (C)Free Software Foundation, Inc.Verbatim copying and distribution of this entire article ispermitted in any medium, provided this notice is preserved.

These pages aremaintained by the GCC team.Last modified 2021-03-25.