2.4. Version 9.2.4¶
The significant changes to the various parts of the compiler are listed in the following sections.
LLVM backend of this release is to be used with LLVM
9, 10, 11, or 12.
DeepSubsumptionlanguage extension which reverses the effects of the Simplified Subsumption Proposal introduced in GHC 9.0. This is an attempt to make GHC 9.2.4 more backwards compatible with GHC 8.10 and eases migration for users who depended on this feature.
This extension is enabled by default with the
Haskell98languages but disabled with the
GHC2021language originally introduced in GHC 9.2.1.
See the Deep Subsumption Proposal for more details.
- The flag
-fllvmany more (#21776).
- Fix a compiler panic due to a bug in the simplifier (#21694).
- Fix a bug where the flag
Werror=unrecognised-warning-flagsdid 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
- Ensure types from record dot syntax are stored in the HIE file AST (#21797).
- Fix a compiler panic when importing “wrapper” with
-Wunicode-bidirectional-format-charactersby 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
unsafeWithForeignPtrwhen 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
-poflag to set output while heap profiling (#21446).
2.4.4. Core libraries¶
hGetBufNonBlockingdoesn’t block on Windows (#21665).
2.4.5. Build system and packaging¶
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||9.2.5||The compiler itself|
|ghc-boot-th||9.2.5||Internal compiler library|
|ghc-boot||9.2.5||Internal compiler library|
|ghc-heap||9.2.5||GHC heap-walking library|
|ghci||9.2.5||The REPL interface|
|libiserv||9.2.5||Internal compiler library|