.. _release-9-2-2:
Version 9.2.2
==============
The significant changes to the various parts of the compiler are listed in the
following sections.
The :ghc-flag:`LLVM backend <-fllvm>` of this release is to be used with LLVM
9, 10, 11, or 12.
Compiler
--------
- Numerous improvements in compiler performance.
- A fix for GHC's handling of the XDG Base Directory Specification
(:ghc-ticket:`6077`, :ghc-ticket:`20684`, :ghc-ticket:`20669`,
:ghc-ticket:`20660`):
- For the package database previously in `~/.ghc/<arch-ver>`, we
will continue to use the old path if it exists. For example, if the
`~/.ghc/x86_64-linux-9.4.1` directory exists, GHC will use that for its
user package database. If this directory does not exist, we will use
`$XDG_DATA_HOME/ghc/x86_64-linux-9.4.1`. This is in order to give tooling like
cabal time to migrate
- For GHCi configuration files previously located in `~/.ghc/` like
`ghci.conf` and `ghci_history`, we will first check if they exist in
`~/.ghc` and use those if they do. However, we will create new files like
`ghci_history` only in `$XDG_DATA_HOME/ghc`. So if you don't have a previous
GHC installation which created `~/.ghc/ghci_history`, the history file will be
written to `$XDG_DATA_HOME/ghc`. If you already have an older GHC installation which
wrote `~/.ghc/ghci_history`, then GHC will continue to write the history to
that file.
- Fix bug in CPR analysis's treatment of join points which may result in
runtime crashes (:ghc-ticket:`18824`).
- Link against ``libatomic`` for atomic operations on platforms where this is
necessary (:ghc-ticket:`19119`).
- Fix bootstrapping of compiler with GHC 9.2 and later (:ghc-ticket:`19631`)
- Silence non-actionable warnings regarding missed specialisations of class
methods (:ghc-ticket:`19592`).
- Fix a race condition in the registration of ticky-ticky profiling
counters, potentially resulting in hangs when ticky-ticky is used in a
threaded application (:ghc-ticket:`20451`).
- Introduce a flag, :ghc-flag:`-Wunicode-bidirectional-format-characters`, to
warn if Unicode bidirectional formatting are found in Haskell source files.
- Improve the pattern match checker's handling of unlifted data types, eliminating
spurious warnings from impossible branches (:ghc-ticket:`20631`).
- Fix a compiler crash due to incorrect in-scope set (:ghc-ticket:`20639`)
- Don't use implicit lifting when deriving a ``Lift`` instances, fixing
:ghc-ticket:`20688`.
- Unbox unlifted datatypes fields (:ghc-ticket:`20663`).
- Introduce a flag, :ghc-flag:`-fcheck-prim-bounds`, which adds dynamic bounds
checks in the code generated for array primops (:ghc-ticket:`20769`).
- Ensure that the ``indexWord8ArrayAs<Type>#`` family of array primops are
lowered correctly on platforms which do not support unaligned memory access
(:ghc-ticket:`21015`, :ghc-ticket:`20987`).
- Fix a potential bug where common-block elimination may common-up incompatible
load operations (:ghc-ticket:`21016`)
- Eliminate the ``ghc`` library's dependence on ``parsec`` (:ghc-ticket:`21033`).
- Introduced :ghc-flag:`-fcompact-unwind` , enabling the generation of compact
unwinding information on Apple Darwin targets (:ghc-ticket:`11829`).
- Fix a bug where some exception closures could be inappropriately garbage
collected, resulting in crashes (:ghc-ticket:`21141`)
- Fix a variety of bugs in the AArch64 code generator's handling of
sub-word-size values (:ghc-ticket:`19993`, :ghc-ticket:`20637`,
:ghc-ticket:`20638`).
GHCi
----
- Fix bug in handling of GHC environment files which lead to unintentional
resetting of GHCi's package state (:ghc-ticket:`19650`)
Core libraries
--------------
- Fix a few bugs in WinIO which might result in heap corruption (:ghc-ticket:`21048`).
- Fix an interaction between WinIO and deadlock detection, resulting in
programs potentially hanging in IO (:ghc-ticket:`18382`)
- Add ``CTYPE`` pragmas to all foreign type wrappers (e.g.
``Foreign.C.Types``), ensuring that correct signatures are generated for
``capi`` foreign imports (:ghc-ticket:`15531`).
- Fix incorrect implementation of ``Data.Type.Ord.<:`` (TODO)
- Bump ``stm`` to release 2.5.0.2 (:ghc-ticket:`20575`)
- Avoid using Apple Darwin's broken one-shot kqueue implementation (:ghc-ticket:`20662`)
Build system and packaging
--------------------------
- Fix generation of binary distribution for cross-compilers with Hadrian (:ghc-ticket:`20267`)
- Don't rely on non-POSIX ``realpath`` utility in Hadrian's binary distribution
installation ``Makefile`` (:ghc-ticket:`19963`)
Runtime system
--------------
- :ghc-ticket:`20577`
- Teach runtime linker to resolve special ``iconv_`` symbols on FreeBSD (:ghc-ticket:`20354`)
- Fix garbage collector statistics produced when run :rts-flag:`-qn 1 <-qn
⟨x⟩>` (:ghc-ticket:`19685`).
- Fix the reporting of elapsed GC time when using the :rts-flag:`non-moving
garbage collector <--nonmoving-gc>`. (:ghc-ticket:`20751`)
- Fix a bug where the memory-mapping base address was not updated after creating
a mapping, resulting in linking failures (:ghc-ticket:`20734`)
- Eliminate a case in the linker which would result in memory mappings that
were simultaneously writable and executable (:ghc-ticket:`20814`).
- Seed ``environ`` in the runtime system's symbol table, ensuring that
environment is correctly propagated to loaded objects (:ghc-ticket:`20861`
and related tickets)
- Introduce a new flag, :rts-flag:`--null-eventlog-writer`, allowing the
eventlog to be enabled while suppressing the usual ``.eventlog`` file output.
This can be useful when running programs with a :ref:`custom eventlog writer
<event_log_output_api>`.
Included libraries
------------------
The package database provided with this distribution also contains a number of
packages other than GHC itself. See the changelogs provided with these packages
for further change information.
.. ghc-package-list::
libraries/array/array.cabal: Dependency of ``ghc`` library
libraries/base/base.cabal: Core library
libraries/binary/binary.cabal: Dependency of ``ghc`` library
libraries/bytestring/bytestring.cabal: Dependency of ``ghc`` library
libraries/Cabal/Cabal/Cabal.cabal: Dependency of ``ghc-pkg`` utility
libraries/containers/containers/containers.cabal: Dependency of ``ghc`` library
libraries/deepseq/deepseq.cabal: Dependency of ``ghc`` library
libraries/directory/directory.cabal: Dependency of ``ghc`` library
libraries/exceptions/exceptions.cabal: Dependency of ``ghc`` and ``haskeline`` library
libraries/filepath/filepath.cabal: Dependency of ``ghc`` library
compiler/ghc.cabal: The compiler itself
libraries/ghci/ghci.cabal: The REPL interface
libraries/ghc-boot/ghc-boot.cabal: Internal compiler library
libraries/ghc-boot-th/ghc-boot-th.cabal: Internal compiler library
libraries/ghc-compact/ghc-compact.cabal: Core library
libraries/ghc-heap/ghc-heap.cabal: GHC heap-walking library
libraries/ghc-prim/ghc-prim.cabal: Core library
libraries/haskeline/haskeline.cabal: Dependency of ``ghci`` executable
libraries/hpc/hpc.cabal: Dependency of ``hpc`` executable
libraries/integer-gmp/integer-gmp.cabal: Core library
libraries/libiserv/libiserv.cabal: Internal compiler library
libraries/mtl/mtl.cabal: Dependency of ``Cabal`` library
libraries/parsec/parsec.cabal: Dependency of ``Cabal`` library
libraries/pretty/pretty.cabal: Dependency of ``ghc`` library
libraries/process/process.cabal: Dependency of ``ghc`` library
libraries/stm/stm.cabal: Dependency of ``haskeline`` library
libraries/template-haskell/template-haskell.cabal: Core library
libraries/terminfo/terminfo.cabal: Dependency of ``haskeline`` library
libraries/text/text.cabal: Dependency of ``Cabal`` library
libraries/time/time.cabal: Dependency of ``ghc`` library
libraries/transformers/transformers.cabal: Dependency of ``ghc`` library
libraries/unix/unix.cabal: Dependency of ``ghc`` library
libraries/Win32/Win32.cabal: Dependency of ``ghc`` library
libraries/xhtml/xhtml.cabal: Dependency of ``haddock`` executable