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 4.16.3.0.

  • 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

9.2.6

The compiler itself

Cabal

3.6.3.0

Dependency of ghc-pkg utility

Win32

2.12.0.1

Dependency of ghc library

array

0.5.4.0

Dependency of ghc library

base

4.16.4.0

Core library

binary

0.8.9.0

Dependency of ghc library

bytestring

0.11.4.0

Dependency of ghc library

containers

0.6.5.1

Dependency of ghc library

deepseq

1.4.6.1

Dependency of ghc library

directory

1.3.6.2

Dependency of ghc library

exceptions

0.10.4

Dependency of ghc and haskeline library

filepath

1.4.2.2

Dependency of ghc library

ghc-boot-th

9.2.6

Internal compiler library

ghc-boot

9.2.6

Internal compiler library

ghc-compact

0.1.0.0

Core library

ghc-heap

9.2.6

GHC heap-walking library

ghc-prim

0.8.0

Core library

ghci

9.2.6

The REPL interface

haskeline

0.8.2

Dependency of ghci executable

hpc

0.6.1.0

Dependency of hpc executable

integer-gmp

1.1

Core library

libiserv

9.2.6

Internal compiler library

mtl

2.2.2

Dependency of Cabal library

parsec

3.1.15.0

Dependency of Cabal library

pretty

1.1.3.6

Dependency of ghc library

process

1.6.16.0

Dependency of ghc library

stm

2.5.0.2

Dependency of haskeline library

template-haskell

2.18.0.0

Core library

terminfo

0.4.1.5

Dependency of haskeline library

text

1.2.5.0

Dependency of Cabal library

time

1.11.1.1

Dependency of ghc library

transformers

0.5.6.2

Dependency of ghc library

unix

2.7.2.2

Dependency of ghc library

xhtml

3000.2.2.1

Dependency of haddock executable