#12935: Object code produced by GHC is non-deterministic -------------------------------------+------------------------------------- Reporter: bgamari | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.2 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by nh2): I'm looking into doing this. First a remark: Instead of hashing for extra stability, we could also just use the increasing `[1 of 3] Compiling A` numbers for unique namespacing. But I noticed that the order of those is currently not stable: In a project with modules `A, B, C, Main`, `A` imports nothing, `B` and `C` both import `A`, `Main` imports `C` and `D`, sometimes you will get a different output of which of these modules is `[3 of 4]`. Example: {{{ % touch B.hs && /raid/src/ghc/git-8.2.1/inplace/bin/ghc-stage2 --make Main.hs [3 of 4] Compiling B ... }}} {{{ % touch C.hs && /raid/src/ghc/git-8.2.1/inplace/bin/ghc-stage2 --make Main.hs [3 of 4] Compiling C ... }}} That is because in `GhcMake.upsweep'` the `mod_index` is just counting up `+1`, but over `sccs :: [SCC ModSummary]` the order of which is somehow influenced by the file mtime (I haven't found yet how the mtime makes it to be a more significant field than the module name). -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/12935#comment:14 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler