4. Release notes for version 8.4.2

4.1. Highlights

This is a bug-fix release resolving several regressions introduced in 8.4.1.

The highlights, since the 8.4.1 release, are:

  • Fixed a regression causing uses of Control.Exception.evaluate to be incorrectly optimised, resulting in incorrect evaluation behavior (Trac #13930)

  • Fix a regression causing the interpreter to segmentation fault when built with profiling (Trac #14705)

  • DWARF debug information support has been significantly improved (Trac #14894, Trac #14779)

  • A regression in runtime performance of code involving newtypes has been fixed (Trac #14936)

4.2. Full details

In addition to the highlights listed above, this release resolves a number of other issues, described below.

4.2.1. Compiler

  • A bug affecting GHC’s debug output support (-g) which resulted in invalid code being generated for string literals (Trac #13868)

  • Trac #14918, where Read instances for types with field names containing # would fail to parse, has been fixed.

  • Several compiler panics have been resolved (Trac #12158, Trac #15002, Trac #14933, Trac #14959)

  • Fix a regression in which derived Read instances for record data types with field names ending with # (by way of -XMagicHash) would no longer parse valid output.

4.2.2. Runtime system

  • A bug causing panics while running programs with retainer profiling (-hr) was fixed (Trac #14947)

4.2.3. Template Haskell

No changes.

4.2.4. ghc library

No changes.

4.2.5. base library

  • Version bumped to 4.11.1.0 to account for the addition of GHC.IO.FixIOException

  • Add the readFieldHash function to GHC.Read which behaves like readField, but for a field that ends with a # symbol.

4.2.6. integer-gmp library

  • Version bumped to 1.0.2.0 to account for the addition of powModSecInteger.

  • Define powModSecInteger, a “secure” version of powModInteger using the mpz_powm_sec function.

4.2.7. Build system

  • configure now takes a --disable-dtrace flag, allowing workaround of Trac #15040.

  • A bug breaking GHC builds bootstrapped on Darwin has been fixed (Trac #14972)

4.3. 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

 8.4.4

The compiler itself

Cabal

 2.2.0.1

Dependency of ghc-pkg utility

Win32

 2.6.1.0

Dependency of ghc library

array

 0.5.2.0

Dependency of ghc library

base

 4.11.1.0

Core library

binary

 0.8.5.1

Dependency of ghc library

bytestring

 0.10.8.2

Deppendency of ghc library

containers

 0.5.11.0

Dependency of ghc library

deepseq

 1.4.3.0

Dependency of ghc library

directory

 1.3.1.5

Dependency of ghc library

filepath

 1.4.2

Dependency of ghc library

ghc-boot

 8.4.4

Internal compiler library

ghc-compact

 0.1.0.0

Core library

ghc-prim

 0.5.2.0

Core library

ghci

 8.4.4

The REPL interface

haskeline

 0.7.4.2

Dependency of ghci executable

hpc

 0.6.0.3

Dependency of hpc executable

integer-gmp

 1.0.2.0

Core library

mtl

 2.2.2

Dependency of Cabal library

parsec

 3.1.13.0

Dependency of Cabal library

process

 1.6.3.0

Dependency of ghc library

template-haskell

 2.13.0.0

Core library

text

 1.2.3.1

Dependency of Cabal library

time

 1.8.0.2

Dependency of ghc library

transformers

 0.5.5.0

Dependency of ghc library

unix

 2.7.2.2

Dependency of ghc library

xhtml

 3000.2.2.1

Dependency of haddock executable