#12628: __GLASGOW_HASKELL_LLVM__ is no longer an Int -------------------------------------+------------------------------------- Reporter: nicolast | Owner: Type: bug | Status: new Priority: normal | Milestone: 8.0.2 Component: Driver | Version: 8.0.1 Resolution: | Keywords: llvm cpp Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: Other | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by nicolast): I considered this as well, and the pre-8.0.1 behaviour is indeed prone to the examples you provided, so simply reverting to the old method may not be the way to go. Proposal: - Consider the 8.0.1 'tuple' value to be a mistake/oversight and use a plain integer anyway - Format {{{__GLASGOW_HASKELL_LLVM__}} similar to {{__GLASGOW_HASKELL__}}}: {{{ __GLASGOW_HASKELL__ For version x.y.z of GHC, the value of __GLASGOW_HASKELL__ is the integer ⟨xyy⟩ (if ⟨y⟩ is a single digit, then a leading zero is added, so for example in version 6.2 of GHC, __GLASGOW_HASKELL__==602). More information in GHC version numbering policy. }}} I believe this encoding should be fine and, in a way, backwards compatible: - *Or* one was using GHC < 8, which has {{{__GLASGOW_HASKELL_LLVM__}}} defined as {{{34}}}, {{{35}}} or whichever other version was ever supported - *Or* one is using GHC 8.0.1, and a specific work-around to handle the tuple case - *Or* one is using GHC > 8.0.1, and (for now) {{{__GLASGOW_HASKELL_LLVM__}}} will be {{{307}}}. *If* one was using the macro value in a conditional, then - Or one was doing an equality check, which will still work out nicely: or it's some old LLVM version, or it's LLVM 3.7 for GHC 8.0.1 (tuple), or it's 307 - Or one was doing a comparison. Again, we can exclude the GHC 8.0.1 case. If one checks whether the LLVM version is, say, 3.5 or lower, then {{{__GLASGOW_HASKELL_LLVM__ <= 35}}} will do 'the right thing' for {{{307}}} or whatever later version. - Similarly, {{{__GLASGOW_HASKELL_LLVM__ > 35}}} will work out nicely for {{{307}}}. As such, I believe that if we make the change (add padding) now, things should be 'morally' backwards compatible. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/12628#comment:3 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler