Marge Bot pushed to branch master at Glasgow Haskell Compiler / GHC

Commits:

• 2157db2d
  by sterni at 2025-08-08T15:32:39-04:00

  hadrian: enable terminfo if --with-curses-* flags are given
  
  The GHC make build system used to support WITH_TERMINFO in ghc.mk which
  allowed controlling whether to build GHC with terminfo or not. hadrian
  has replaced this with a system where this is effectively controlled by
  the cross-compiling setting (the default WITH_TERMINFO value was bassed
  on CrossCompiling, iirc).
  
  This behavior is undesireable in some cases and there is not really a
  good way to work around it. Especially for downstream packagers,
  modifying this via UserSettings is not really feasible since such a
  source file has to be kept in sync with Settings/Default.hs manually
  since it can't import Settings.Default or any predefined Flavour
  definitions.
  
  To avoid having to add a new setting to cfg/system.config and/or a new
  configure flag (though I'm happy to implement both if required), I've
  chosen to take --with-curses-* being set explicitly as an indication
  that the user wants to have terminfo enabled. This would work for
  Nixpkgs which sets these flags [1] as well as haskell.nix [2] (which
  goes to some extreme measures [3] [4] to force terminfo in all scenarios).
  
  In general, I'm an advocate for making the GHC build be the same for
  native and cross insofar it is possible since it makes packaging GHC and
  Haskell related things while still supporting cross much less
  compilicated. A more minimal GHC with reduced dependencies should
  probably be a specific flavor, not the default.
  
  Partially addresses #26288 by forcing terminfo to be built if the user
  explicitly passes configure flags related to it. However, it isn't built
  by default when cross-compiling yet nor is there an explicit way to
  control the package being built.
  
  [1]: https://github.com/NixOS/nixpkgs/blob/3a7266fcefcb9ce353df49ba3f292d06443760bb/pkgs/development/compilers/ghc/common-hadrian.nix#L513-L515
  [2]: https://github.com/input-output-hk/haskell.nix/blob/6eaafcdf04bab7be745d1aa4f74d2cc85700042b/compiler/ghc/default.nix#L185
  [3]: https://github.com/input-output-hk/haskell.nix/blob/6eaafcdf04bab7be745d1aa4f74d2cc85700042b/compiler/ghc/default.nix#L678-L682
  [4]: https://github.com/input-output-hk/haskell.nix/blob/6eaafcdf04bab7be745d1aa4f74d2cc85700042b/compiler/ghc/default.nix#L772-L773
  

2 changed files:

• hadrian/src/Settings/Default.hs
• hadrian/src/Settings/Packages.hs

Changes:

 stage0Packages :: Action [Package]

 stage0Packages = do

     cross <- flag CrossCompiling

+    haveCurses <- any (/= "") <$> traverse setting [ CursesIncludeDir, CursesLibDir ]

     return $ [ cabalSyntax

              , cabal

              , compiler

              -- that confused Hadrian, so we must make those a stage0 package as well.

              -- Once we drop `Win32`/`unix` it should be possible to drop those too.

              ]

-          ++ [ terminfo | not windowsHost, not cross ]

-          ++ [ timeout  | windowsHost                ]

+          ++ [ terminfo | not windowsHost, (not cross || haveCurses) ]

+          ++ [ timeout  | windowsHost                                ]

 -- | Packages built in 'Stage1' by default. You can change this in "UserSettings".

 stage1Packages :: Action [Package]

         -- immediately and may lead to cyclic dependencies.

         -- See: https://gitlab.haskell.org/ghc/ghc/issues/16809.

         cross = flag CrossCompiling

+        haveCurses = any (/= "") <$> traverse setting [ CursesIncludeDir, CursesLibDir ]

         -- Check if the bootstrap compiler has the same version as the one we

         -- are building. This is used to build cross-compilers

             -- backends at the moment, so we might as well disable it

             -- for cross GHC.

             [ andM [expr (ghcWithInterpreter stage), notCross] `cabalFlag` "internal-interpreter"

-            , notM cross `cabalFlag` "terminfo"

+            , orM [ notM cross, haveCurses ]  `cabalFlag` "terminfo"

             , arg "-build-tool-depends"

             , flag UseLibzstd `cabalFlag` "with-libzstd"

             -- ROMES: While the boot compiler is not updated wrt -this-unit-id

         -------------------------------- ghcPkg --------------------------------

         , package ghcPkg ?

-          builder (Cabal Flags) ? notM cross `cabalFlag` "terminfo"

+          builder (Cabal Flags) ? orM [ notM cross, haveCurses ] `cabalFlag` "terminfo"

         -------------------------------- ghcBoot ------------------------------

         , package ghcBoot ?

         , package haskeline ?

           builder (Cabal Flags) ? arg "-examples"

         -- Don't depend upon terminfo when cross-compiling to avoid unnecessary

-        -- dependencies.

-        -- TODO: Perhaps the user should rather be responsible for this?

+        -- dependencies unless the user provided ncurses explicitly.

+        -- TODO: Perhaps the user should be able to explicitly enable/disable this.

         , package haskeline ?

-          builder (Cabal Flags) ? notM cross `cabalFlag` "terminfo"

+          builder (Cabal Flags) ? orM [ notM cross, haveCurses ] `cabalFlag` "terminfo"

         -------------------------------- terminfo ------------------------------

         , package terminfo ?