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	8.4.3	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	8.4.3	Internal compiler library
ghc-compact	0.1.0.0	Core library
ghc-prim	0.5.2.0	Core library
ghci	8.4.3	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	1.2.3.0	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