I’m trying to upgrade the MacPorts ghc install to the latest 8.8.2. The build fails with:

error: use of undeclared identifier 'TAG_MASK' :info:build return (StgWord)p & TAG_MASK;

This is an error observed with previous ghc versions and on other systems, so I do not believe it is macOS-specific. Also, the MacPorts build process simply follows the ghc Build & Install instructions: https://github.com/ghc/ghc/blob/master/README.md#building--installing Is there a simple fix by adding an extra flag somewhere? Logs:

:info:build In file included from compiler/ghci/keepCAFsForGHCi.c:1:0: error: :info:build In file included from includes/Rts.h:191:0: error: :info:build includes/rts/storage/ClosureMacros.h:211:25: error: :info:build error: use of undeclared identifier 'TAG_MASK' :info:build return (StgWord)p & TAG_MASK; :info:build ^ :info:build | :info:build 211 | return (StgWord)p & TAG_MASK; :info:build | ^ :info:build includes/rts/storage/ClosureMacros.h:217:40: error: :info:build error: use of undeclared identifier 'TAG_MASK' :info:build return (StgClosure*)((StgWord)p & ~TAG_MASK); :info:build ^ :info:build | :info:build 217 | return (StgClosure*)((StgWord)p & ~TAG_MASK); :info:build | ^ :info:build includes/rts/storage/ClosureMacros.h:223:46: error: :info:build error: use of undeclared identifier 'TAG_MASK' :info:build return (const StgClosure*)((StgWord)p & ~TAG_MASK); :info:build ^