9. Release notes for version 8.10.7 — Glasgow Haskell Compiler 8.10.7 User's Guide

# Glasgow Haskell Compiler User's Guide

# 9. Release notes for version 8.10.7

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 versions 9 through 12.

## 9.1. Portability fixes

- Actually fix a linking portability issue on macOS that resulted in undefined symbol errors for `___darwin_check_fd_set_overflow` (#19950), working around a bug in certain versions of XCode 11. We claimed to have fixed this in GHC 8.10.6, but alas this wasn’t the case. The fix was originally tested on the master branch, which uses a different build configuration from the 8.10 branch. We have now tested the fix on the GHC 8.10 branch and finally squashed the bug.

## 9.2. Known issues

- A long-standing bug (#16893) which can cause some applications of `unsafeCoerce` to segmentation fault is only partially fixed in this release. This release only avoids this issue in the uses of `unsafeCoerce` in `Data.Typeable.Internal`, which was the proximate cause of #16893.

  However, it is possible that this bug could manifest in user-code using `unsafeCoerce` to perform dynamic type checks. See the ticket for details.

  We expect that this issue will be fixed in the next major release of GHC.

- A long-standing bug (#17760) where some uses of the `touch#` primop can be dropped by the simplifier is present in this release. This bug will be fixed in GHC 9.0.1. In the meantime, see the ticket for mitigations.

## 9.3. 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 | 8.10.7 | The compiler itself
Cabal | 3.2.1.0 | Dependency of `ghc-pkg` utility
Win32 | 2.6.2.1 | Dependency of `ghc` library
array | 0.5.4.0 | Dependency of `ghc` library
base | 4.14.3.0 | Core library
binary | 0.8.8.0 | Dependency of `ghc` library
bytestring | 0.10.12.0 | Dependency of `ghc` library
containers | 0.6.5.1 | Dependency of `ghc` library
deepseq | 1.4.4.0 | Dependency of `ghc` library
directory | 1.3.6.0 | Dependency of `ghc` library
exceptions | 0.10.4 | Dependency of `haskeline` library
filepath | 1.4.2.1 | Dependency of `ghc` library
ghc-boot-th | 8.10.7 | Internal compiler library
ghc-boot | 8.10.7 | Internal compiler library
ghc-compact | 0.1.0.0 | Core library
ghc-heap | 8.10.7 | GHC heap-walking library
ghc-prim | 0.6.1 | Core library
ghci | 8.10.7 | The REPL interface
haskeline | 0.8.2 | Dependency of `ghci` executable
hpc | 0.6.1.0 | Dependency of `hpc` executable
integer-gmp | 1.0.3.0 | Core library
libiserv | 8.10.7 | Internal compiler library
mtl | 2.2.2 | Dependency of `Cabal` library
parsec | 3.1.14.0 | Dependency of `Cabal` library
pretty | 1.1.3.6 | Dependency of `ghc` library
process | 1.6.13.2 | Dependency of `ghc` library
stm | 2.5.0.1 | Dependency of `haskeline` library
template-haskell | 2.16.0.0 | Core library
terminfo | 0.4.1.4 | Dependency of `haskeline` library
text | 1.2.4.1 | Dependency of `Cabal` library
time | 1.9.3 | 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