2.4. Version 9.2.4

The significant changes to the various parts of the compiler are listed in the following sections.

The LLVM backend of this release is to be used with LLVM 9, 10, 11, or 12.

2.4.1. Compiler

  • The flag -ddump-llvm doesn’t imply -fllvm any more (#21776).
  • Fix a compiler panic due to a bug in the simplifier (#21694).
  • Fix a bug where the flag Werror=unrecognised-warning-flags did not behave as expected (#21682).
  • Fix miscompilations on AArch64 (#21624, #21773, #20735).
  • Fix a miscompilation bug that manifests due to improper handling of name shadowing during common subexpression elimination (#21685).
  • Fix a space leak that may manifest using the extendMG function (#21818).
  • Ensure types from record dot syntax are stored in the HIE file AST (#21797).
  • Fix a compiler panic when importing “wrapper” with -XCApiFFI (#20272).
  • Enable -Wunicode-bidirectional-format-characters by default. This was meant to be enabled previously but was not due to a botched backport (#21865).

2.4.2. Runtime system

  • Fix segfaults that may arise due to a bug in the implementation of the keepAlive# primop. This may regress performance for certain programs which use this primop or functions which use the primop, such as withForeignPtr. These regressions are mostly small, but can be larger in certain edge cases. Judicious use of unsafeWithForeignPtr when its argument is known not to statically diverge can mitigate these in many cases. It is our judgement that the critical correctness issues justify the regression in performance and that it is important to get a release out with the fix while we work on a better approach which will improve performance for future releases (#21708).
  • Fix a segfault that may arise using LDV profiling (#21880).
  • Fix a bug in the nonmoving GC which resulted in segfaults due to early GC (#21885).
  • Fix accounting for copied bytes during sequential garbage collections (#21745).
  • Allow passing``-po`` flag to set output during non-profiled builds (#21445).
  • Respect the -po flag to set output while heap profiling (#21446).

2.4.3. GHCi

  • Allow CApi FFI calls in GHCi (#7388).
  • Fix behaviour of Ctrl-C on Windows in GHCi (#21889).

2.4.4. Core libraries

  • Bump base to
  • Ensure hGetBufNonBlocking doesn’t block on Windows (#21665).

2.4.5. Build system and packaging

  • Don’t override linker on Darwin during configure (#21712).
  • Fix a hadrian bug to do with building profiled executables without corresponding libraries (#19624).
  • Fix a panic on FreeBSD when building with hadrian due to incorrect arch triple (#15718).

2.4.6. 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.

Package Version Reason for inclusion
ghc 9.2.8 The compiler itself
Cabal Dependency of ghc-pkg utility
Win32 Dependency of ghc library
array Dependency of ghc library
base Core library
binary Dependency of ghc library
bytestring Dependency of ghc library
containers Dependency of ghc library
deepseq Dependency of ghc library
directory Dependency of ghc library
exceptions 0.10.4 Dependency of ghc and haskeline library
filepath Dependency of ghc library
ghc-boot-th 9.2.8 Internal compiler library
ghc-boot 9.2.8 Internal compiler library
ghc-compact Core library
ghc-heap 9.2.8 GHC heap-walking library
ghc-prim 0.8.0 Core library
ghci 9.2.8 The REPL interface
haskeline 0.8.2 Dependency of ghci executable
hpc Dependency of hpc executable
integer-gmp 1.1 Core library
libiserv 9.2.8 Internal compiler library
mtl 2.2.2 Dependency of Cabal library
parsec Dependency of Cabal library
pretty Dependency of ghc library
process Dependency of ghc library
stm Dependency of haskeline library
template-haskell Core library
terminfo Dependency of haskeline library
text Dependency of Cabal library
time Dependency of ghc library
transformers Dependency of ghc library
unix Dependency of ghc library
xhtml 3000.2.2.1 Dependency of haddock executable