Changelog for Cabal-hooks

3.18.1.0 — July 2026

• Stop exposing constructors of RuleCommands #11461 #11771

  The constructors of the SetupHooks RuleCommands are no longer exposed from Distribution.Simple.SetupHooks. These were rather gnarly internal constructors; the intended public API is via staticRule and dynamicRule.

• Make Cabal-hooks library more self-sufficient #11772

  The Distribution.Simple.SetupHooks module from Cabal-hooks now re-exports a lot of the functionality that is commonly needed when writing SetupHooks:

  • File-path related functionality from Distribution.Utils.Path.
  • Functionality related to the program database: lookupProgram, runProgramCwd.
  • IO utilities such as warn, createDirectoryIfMissingVerbose, and rewriteFileEx.
  • Various types frequently used in pre-build rules, such as Binary, ModuleName.
  • Functions that extract information from LocalBuildInfo such as localPkgDescr, mbWorkDirLBI, withPrograms, interpretSymbolicPathLBI and componentBuildInfo.

  In addition, new file monitoring helper functions findAndMonitorDirFileGlob and findAndMonitorSourceDirsFileExts have been added. These make it very simple and convenient to search for a file glob or files with a particular extension in the source directories, for pre-build rules.

• Recompilation checking for SetupHooks pre-build rules #11730 #11731

  Pre-build rules are now only re-run when stale, according to the conditions described in the SetupHooks API. That is, a rule is re-run if any of the following conditions are satisfied:

  • The rule is new, or
  • A dependency of the rule is stale. That is, either we have re-run another rule that this rule depends on, or one of the file inputs to the rule is newer than the oldest output of the rule (or the rule output doesn't exist at all), or
  • The rule itself has changed, e.g. the parameters stored in RuleData have changed.

  In particular, Cabal will now write per-component caches of pre-build rules in order to compute which rules have changed between runs, with file name "setup-hooks-rules.cache".

• Pre-build rules can generate extra sources and bundled libraries #10791 #11607 #11573

  It is now possible to write pre-build rules that generate source files other than Haskell files, as well as extra bundled library files.

  Because there is no counterpart to autogen-modules for non-Haskell source files, you will need to proceed in two steps:

  1. In a per-component pre-configure hook, add the files you want to generate to the relevant fields, e.g. the cSources field of BuildInfo for a C source file.

     These files must be relative to autogenCompModulesDir.

  2. Pre-build rules generating these files will now be demanded. This avoids getting an error message "The following pre-build rules are not demanded and will not be run".

  Note that include files (such as .h files) are a bit different: any files listed under includes/autogen-includes are required at configure time. This gives SetupHooks authors two choices: either list the include files in autogen-includes but generate them in a pre-configure hook, or don't list them there and generate them in a pre-build rule, relying on the files getting picked up from included directories (this may be brittle).

• Fixed binary format mismatch resulting in runRuleDynDepsCmd build error #12053 #12054

  A build containing a dynamicRule would fail with the following error:

  Error: [Cabal-7125]
  Failed to build hooks-0.1.0.0. The exception was:
  Missing ByteString argument in 'ruleExecCmd'.
  Run 'runRuleDynDepsCmd' on the rule to obtain this data.
  

  This was caused by a mismatch between the binary formats used to encode and decode the rules. The hook produced a result of type ([Dependency], LBS.ByteString), which was then encoded into a Binary blob. However, hooks-exe decoded this data as Maybe ([Dependency], LBS.ByteString), causing the build error.

3.16.1 – December 2025

• No changes

3.16.0 – July 2025

• No changes

3.14.2 – April 2025

• No changes

3.14 – November 2024

• Initial release of the Hooks API.