1. 08 Mar, 2005 3 commits
  2. 07 Feb, 2005 1 commit
    • simonpj's avatar
      [project @ 2005-02-07 12:07:21 by simonpj] · 233b831b
      simonpj authored
      ------------------------------
      	Improve unused-import warnings
      	------------------------------
      
      	Merge to STABLE
      
      This commit improves the warning messages for unused imports, in the
      case where the 'module A' form is used in an export list.
      
      In doing this, I've realised that the unused-import checking is deficient
      in several ways.  At least
      
      	a) it doesn't recognise that there might be several import statements
      	   for the same module (TcRnTypes.imp_mods has only one entry per
      	   module
      
      	b) it doesn't understand about qualified modules at all
      
      	c) even more fundamentally, it starts from the used Names,
      	   but if the module mentions (say) aliases M.f and N.f for
      	   the same Name, then two imports might be necessary for it
      
      I'm not going to fix these problems now; this message just records them.
      233b831b
  3. 27 Jan, 2005 1 commit
    • simonpj's avatar
      [project @ 2005-01-27 10:44:00 by simonpj] · 508a505e
      simonpj authored
      --------------------------------------------
                Replace hi-boot files with hs-boot files
        	--------------------------------------------
      
      This major commit completely re-organises the way that recursive modules
      are dealt with.
      
        * It should have NO EFFECT if you do not use recursive modules
      
        * It is a BREAKING CHANGE if you do
      
      ====== Warning: .hi-file format has changed, so if you are
      ======		updating into an existing HEAD build, you'll
      ======		need to make clean and re-make
      
      
      The details:  [documentation still to be done]
      
      * Recursive loops are now broken with Foo.hs-boot (or Foo.lhs-boot),
        not Foo.hi-boot
      
      * An hs-boot files is a proper source file.  It is compiled just like
        a regular Haskell source file:
      	ghc Foo.hs		generates Foo.hi, Foo.o
      	ghc Foo.hs-boot		generates Foo.hi-boot, Foo.o-boot
      
      * hs-boot files are precisely a subset of Haskell. In particular:
      	- they have the same import, export, and scoping rules
      	- errors (such as kind errors) in hs-boot files are checked
        You do *not* need to mention the "original" name of something in
        an hs-boot file, any more than you do in any other Haskell module.
      
      * The Foo.hi-boot file generated by compiling Foo.hs-boot is a machine-
        generated interface file, in precisely the same format as Foo.hi
      
      * When compiling Foo.hs, its exports are checked for compatibility with
        Foo.hi-boot (previously generated by compiling Foo.hs-boot)
      
      * The dependency analyser (ghc -M) knows about Foo.hs-boot files, and
        generates appropriate dependencies.  For regular source files it
        generates
      	Foo.o : Foo.hs
      	Foo.o : Baz.hi		-- Foo.hs imports Baz
      	Foo.o : Bog.hi-boot	-- Foo.hs source-imports Bog
      
        For a hs-boot file it generates similar dependencies
      	Bog.o-boot : Bog.hs-boot
      	Bog.o-boot : Nib.hi	-- Bog.hs-boto imports Nib
      
      * ghc -M is also enhanced to use the compilation manager dependency
        chasing, so that
      	ghc -M Main
        will usually do the job.  No need to enumerate all the source files.
      
      * The -c flag is no longer a "compiler mode". It simply means "omit the
        link step", and synonymous with -no-link.
      508a505e
  4. 18 Jan, 2005 1 commit
    • simonpj's avatar
      [project @ 2005-01-18 12:18:11 by simonpj] · ac80e0de
      simonpj authored
      ------------------------
          Reorganisation of hi-boot files
        	------------------------
      
      The main point of this commit is to arrange that in the Compilation
      Manager's dependendency graph, hi-boot files are proper nodes. This
      is important to make sure that we compile everything in the right
      order.  It's a step towards hs-boot files.
      
      * The fundamental change is that CompManager.ModSummary has a new
        field, ms_boot :: IsBootInterface
      
        I also tided up CompManager a bit.  No change to the Basic Plan.
      
        ModSummary is now exported abstractly from CompManager (was concrete)
      
      * Hi-boot files now have import declarations.  The idea is they are
        compulsory, so that the dependency analyser can find them
      
      * I changed an invariant: the Compilation Manager used to ensure that
        hscMain was given a HomePackageTable only for the modules 'below' the
        one being compiled.  This was really only important for instances and
        rules, and it was a bit inconvenient.  So I moved the filter to the
        compiler itself: see HscTypes.hptInstances and hptRules.
      
      * Module Packages.hs now defines
          data PackageIdH
          = HomePackage 		-- The "home" package is the package
       				-- curently being compiled
          | ExtPackage PackageId	-- An "external" package is any other package
      
         It was just a Maybe type before, so this makes it a bit clearer.
      
      * I tried to add a bit better location info to the IfM monad, so that
        errors in interfaces come with a slightly more helpful error message.
        See the if_loc field in TcRnTypes --- and follow-on consequences
      
      * Changed Either to Maybes.MaybeErr in a couple of places (more perspicuous)
      ac80e0de
  5. 02 Dec, 2004 1 commit
    • simonpj's avatar
      [project @ 2004-12-02 17:18:15 by simonpj] · 759739c6
      simonpj authored
      Sorry for the fact that there are overlapping three commits in here...
      
      1.  Make -fno-monomorphism-restriction 
          and -fno-implicit-prelude reversible, like other flags
      
      2.  Fix a wibble in the new ImportAvails story, in RnNames.mkExportAvails
      
      3.  Fix a Template Haskell bug that meant that top-level names created
          with newName were not made properly unique.
      759739c6
  6. 29 Nov, 2004 1 commit
    • simonpj's avatar
      [project @ 2004-11-29 16:25:03 by simonpj] · b3fe66bb
      simonpj authored
      ---------------------
      	Simplify ImportAvails
      	---------------------
      
      Every Name has, for some while, contained its "parent";
      the type or class inside which it is defined.  But the rest
      of the renamer wasn't using this information as much as it 
      could do.  In particular, the ImportAvails type was more elaborate
      than necessary.
      
      This commit combines these two fields of ImportAvails:
      	imp_env :: AvailEnv
      	imp_qual :: ModuleEnv AvailEnv
      into one
      	imp_env :: ModuleEnv NameSet 
      
      This is quite a bit simpler.  Less redundancy and, I think, less
      code.
      b3fe66bb
  7. 26 Nov, 2004 1 commit
    • simonmar's avatar
      [project @ 2004-11-26 16:19:45 by simonmar] · ef5b4b14
      simonmar authored
      Further integration with the new package story.  GHC now supports
      pretty much everything in the package proposal.
      
        - GHC now works in terms of PackageIds (<pkg>-<version>) rather than
          just package names.  You can still specify package names without
          versions on the command line, as long as the name is unambiguous.
      
        - GHC understands hidden/exposed modules in a package, and will refuse
          to import a hidden module.  Also, the hidden/eposed status of packages
          is taken into account.
      
        - I had to remove the old package syntax from ghc-pkg, backwards
          compatibility isn't really practical.
      
        - All the package.conf.in files have been rewritten in the new syntax,
          and contain a complete list of modules in the package.  I've set all
          the versions to 1.0 for now - please check your package(s) and fix the
          version number & other info appropriately.
      
        - New options:
      
      	-hide-package P    sets the expose flag on package P to False
      	-ignore-package P  unregisters P for this compilation
      
      	For comparison, -package P sets the expose flag on package P
              to True, and also causes P to be linked in eagerly.
      
              -package-name is no longer officially supported.  Unofficially, it's
      	a synonym for -ignore-package, which has more or less the same effect
      	as -package-name used to.
      
      	Note that a package may be hidden and yet still be linked into
      	the program, by virtue of being a dependency of some other package.
      	To completely remove a package from the compiler's internal database,
              use -ignore-package.
      
      	The compiler will complain if any two packages in the
              transitive closure of exposed packages contain the same
              module.
      
      	You *must* use -ignore-package P when compiling modules for
              package P, if package P (or an older version of P) is already
              registered.  The compiler will helpfully complain if you don't.
      	The fptools build system does this.
      
         - Note: the Cabal library won't work yet.  It still thinks GHC uses
           the old package config syntax.
      
      Internal changes/cleanups:
      
         - The ModuleName type has gone away.  Modules are now just (a
           newtype of) FastStrings, and don't contain any package information.
           All the package-related knowledge is in DynFlags, which is passed
           down to where it is needed.
      
         - DynFlags manipulation has been cleaned up somewhat: there are no
           global variables holding DynFlags any more, instead the DynFlags
           are passed around properly.
      
         - There are a few less global variables in GHC.  Lots more are
           scheduled for removal.
      
         - -i is now a dynamic flag, as are all the package-related flags (but
           using them in {-# OPTIONS #-} is Officially Not Recommended).
      
         - make -j now appears to work under fptools/libraries/.  Probably
           wouldn't take much to get it working for a whole build.
      ef5b4b14
  8. 20 Oct, 2004 1 commit
    • simonpj's avatar
      [project @ 2004-10-20 13:34:04 by simonpj] · f4c9d2b2
      simonpj authored
      ---------------------------------
      	Fix a bug in usage recording
      	---------------------------------
      
      As a result of the new stuff on hi-boot-file consistency checking, I
      accidentally caused Foo.hi to record a usage line for module Foo, and
      this in turn caused rather nasty bad things to happen.  In particular,
      there were occasional crashes of form
      
      ghc-6.3: panic! (the `impossible' happened, GHC version 6.3.20041017):
              forkM Constructor Var.TcTyVar{d r1B9}
      
      At least I think that's why the crash happened.
      
      Anyway, it was certainly a bug, and this commit fixes it.  The main
      payload of this fix is in Desugar.lhs;  the rest is comments and
      tidying.
      f4c9d2b2
  9. 04 Oct, 2004 1 commit
  10. 01 Oct, 2004 2 commits
    • simonpj's avatar
      [project @ 2004-10-01 13:42:04 by simonpj] · 837824d2
      simonpj authored
      ------------------------------------
      	Simplify the treatment of newtypes
      	Complete hi-boot file consistency checking
      	------------------------------------
      
      In the representation of types, newtypes used to have a special constructor
      all to themselves, very like TyConApp, called NewTcApp.    The trouble is
      that means we have to *know* when a newtype is a newtype, and in an hi-boot
      context we may not -- the data type might be declared as
      	data T
      in the hi-boot file, but as
      	newtype T = ...
      in the source file.  In GHCi, which accumulates stuff from multiple compiles,
      this makes a difference.
      
      So I've nuked NewTcApp.  Newtypes are represented using TyConApps again. This
      turned out to reduce the total amount of code, and simplify the Type data type,
      which is all to the good.
      
      
      This commit also fixes a few things in the hi-boot consistency checking
      stuff.
      837824d2
    • simonpj's avatar
      [project @ 2004-10-01 10:08:49 by simonpj] · da95f4a0
      simonpj authored
      -----------------------------------
      	Do simple checking on hi-boot files
      	-----------------------------------
      
      This commit arranges that, when compiling A.hs, we compare
      the types we infer with those in A.hi-boot, if the latter 
      exists.  (Or, more accurately, if anything A.hs imports in
      turn imports A.hi-boot, directly or indirectly.)
      
      This has been on the to-do list forever.
      da95f4a0
  11. 30 Sep, 2004 1 commit
    • simonpj's avatar
      [project @ 2004-09-30 10:35:15 by simonpj] · 23f40f0e
      simonpj authored
      ------------------------------------
      	Add Generalised Algebraic Data Types
      	------------------------------------
      
      This rather big commit adds support for GADTs.  For example,
      
          data Term a where
       	  Lit :: Int -> Term Int
      	  App :: Term (a->b) -> Term a -> Term b
      	  If  :: Term Bool -> Term a -> Term a
      	  ..etc..
      
          eval :: Term a -> a
          eval (Lit i) = i
          eval (App a b) = eval a (eval b)
          eval (If p q r) | eval p    = eval q
          		    | otherwise = eval r
      
      
      Lots and lots of of related changes throughout the compiler to make
      this fit nicely.
      
      One important change, only loosely related to GADTs, is that skolem
      constants in the typechecker are genuinely immutable and constant, so
      we often get better error messages from the type checker.  See
      TcType.TcTyVarDetails.
      
      There's a new module types/Unify.lhs, which has purely-functional
      unification and matching for Type. This is used both in the typechecker
      (for type refinement of GADTs) and in Core Lint (also for type refinement).
      23f40f0e
  12. 02 Sep, 2004 1 commit
  13. 26 Aug, 2004 1 commit
    • simonpj's avatar
      [project @ 2004-08-26 15:44:50 by simonpj] · bb88e732
      simonpj authored
      -------------------------------
      	Print built-in sytax right
      	-------------------------------
      
      Built-in syntax, like (:) and [], is not "in scope" via the GlobalRdrEnv
      in the usual way.  When we print it out, we should also print it in unqualified
      form, even though it's not in the environment.
      
      I've finally bitten the (not very big) bullet, and added to Name the information
      about whether or not a name is one of these built-in ones.  That entailed changing
      the calls to mkWiredInName, but those are exactly the places where you have to
      decide whether it's built-in or not, which is fine.
      
      
      Built-in syntax => It's a syntactic form, not "in scope" (e.g. [])
      
      Wired-in thing  => The thing (Id, TyCon) is fully known to the compiler,
      		   not read from an interface file.
      		   E.g. Bool, True, Int, Float, and many others
      
      All built-in syntax is for wired-in things.
      bb88e732
  14. 17 Aug, 2004 1 commit
    • simonpj's avatar
      [project @ 2004-08-17 15:23:47 by simonpj] · 59c796f8
      simonpj authored
      -------------------------------
      	Use merge-sort not quicksort
      	Nuke quicksort altogether
      	-------------------------------
      
      Quicksort has O(n**2) behaviour worst case, and this occasionally bites.
      In particular, when compiling large files consisting only of static data,
      we get loads of top-level delarations -- and that led to more than half the
      total compile time being spent in the strongly connected component analysis
      for the occurrence analyser.  Switching to merge sort completely solved the
      problem.
      
      I've nuked quicksort altogether to make sure this does not happen again.
      59c796f8
  15. 16 Aug, 2004 1 commit
    • simonpj's avatar
      [project @ 2004-08-16 09:53:47 by simonpj] · 4e325538
      simonpj authored
      -------------------------------
      	Add instance information to :i
       	Get rid of the DeclPool
      	-------------------------------
      
      
      1.  Add instance information to :info command.  GHCi now prints out
          which instances a type or class belongs to, when you use :i
      
      2.  Tidy up printing of unqualified names in user output.
          Previously Outputable.PrintUnqualified was
      	type PrintUnqualified = Name -> Bool
          but it's now
      	type PrintUnqualified = ModuleName -> OccName -> Bool
          This turns out to be tidier even for Names, and it's now also usable
          when printing IfaceSyn stuff in GHCi, eliminating a grevious hack.
      
      3.  On the way to doing this, Simon M had the great idea that we could
          get rid of the DeclPool holding pen, which held declarations read from
          interface files but not yet type-checked.   We do this by eagerly
          populating the TypeEnv with thunks what, when poked, do the type
          checking.   This is just a logical continuation of lazy import
          mechanism we've now had for some while.
      
      The InstPool and RulePool still exist, but I plan to get rid of them in
      the same way.  The new scheme does mean that more rules get sucked in than
      before, because previously the TypeEnv was used to mean "this thing was needed"
      and hence to control which rules were sucked in.  But now the TypeEnv is
      populated more eagerly => more rules get sucked in.  However this problem
      will go away when I get rid of the Inst and Rule pools.
      
      I should have kept these changes separate, but I didn't.  Change (1)
      affects mainly
      	TcRnDriver, HscMain, CompMan, InteractiveUI
      whereas change (3) is more wide ranging.
      4e325538
  16. 22 Jun, 2004 1 commit
    • simonpj's avatar
      [project @ 2004-06-22 11:03:42 by simonpj] · 20410577
      simonpj authored
      -----------------------------------------------
             Improve reporting of TH reify out-of-scope errors
      	-----------------------------------------------
      
      No change to functionality, just better error reports.
      20410577
  17. 20 Jun, 2004 1 commit
  18. 25 May, 2004 1 commit
    • simonpj's avatar
      [project @ 2004-05-25 08:09:37 by simonpj] · c6713d35
      simonpj authored
      -----------------------------------------------
      	Improve location info on unused-import warnings
      	-----------------------------------------------
      
      Improving the location involves plumbing the location of the import a bit
      more assiduously -- hence change to imp_mods in TcRnTypes
      c6713d35
  19. 10 May, 2004 1 commit
  20. 07 May, 2004 1 commit
  21. 26 Feb, 2004 2 commits
  22. 24 Feb, 2004 1 commit
    • simonpj's avatar
      [project @ 2004-02-24 15:57:52 by simonpj] · 53fe9413
      simonpj authored
      ---------------------------------------
        	 Record dependency on Template Haskell package
      	  ---------------------------------------
      
      An unforseen consequence of making the Template Haskell package separate
      is that we need to record dependency on the package, even if no TH module
      is imported.  So we carry round (another) mutable variable tcg_th_used in
      the tyepchecker monad, and zap it when $(...) and [| ... |] are used.
      
      I did a little tidy-up and documentation in ListSetOps too
      53fe9413
  23. 05 Jan, 2004 2 commits
    • simonpj's avatar
      [project @ 2004-01-05 12:11:42 by simonpj] · 3721dd37
      simonpj authored
      ---------------------------------------
      	  Don't expose constructors as vigorously
      	  ---------------------------------------
      
      GHC used to expose the constructors of a data type in the interface file,
      even if (a) we were not optimising, and (b) the constructors are not exported.
      
      In practice this isn't really necessary, and it's bad because it forces too
      much recompilation.  I've been meaning to fix this for some while.
      
      Now the data cons are hidden, even in the interface file, if both (a) and (b)
      are true.  That means less interface file wobbling.
      
      Mind you, the interface file still changes, because the to/from functions for
      generic type classes change their types.  But provided you don't use them, you'll
      get "compilation not required".
      
      We could play the same game for classes (by hiding their class ops) but that'd
      mean we'd have to change the data type for IfaceClassDecl, and I can't be
      bothered to do that today.  It's unusual to have a class which exports none
      of its methods anyway.
      
      
      
      On the way, I changed the representation of tcg_exports and mg_exports (from
      Avails to NameSet), but that should be externally invisible.
      3721dd37
    • simonpj's avatar
      [project @ 2004-01-05 08:20:39 by simonpj] · d191be5d
      simonpj authored
      Dont report deprecations arising from uses in the export list
      d191be5d
  24. 31 Dec, 2003 1 commit
    • simonpj's avatar
      [project @ 2003-12-31 08:23:25 by simonpj] · 7473349e
      simonpj authored
      -----------------------------
              Improve deprecation reporting
      	-----------------------------
      
      	[PS: the 1.31 commit of basicTypes/RdrName.lhs
      	 also belongs in this commit.]
      
      Up to now, deprecated functions are only reported when imported
      from the module defining them, but not when re-exporting.  This
      seems wrong -- often a "root" module gathers exports from sub-modules.
      
      It turned out that there was a structural problem: the deprectaions
      were getting put in the GlobalRdrEnv, and it simply doesn't have
      the defining-module's interface to hand.
      
      So this commit removes gre_deprec from GRE, and moves deprecation
      reporting from the individual occurrences (RnEnv.lookupGreRn) to
      RnNames.reportUnusedNames.  In many ways this is a better place for it,
      because there we get a global view of the entire module.  For example,
      repeated use of a single deprecated thing will only give rise to one
      warning instead of multiple warnings.
      
      So here's what we now get:
      
        Foo.hs:3:0:
          Warning: Deprecated use of Variable `withObject'
      	     (imported from Foreign.Marshal, but defined in Foreign.Marshal.Utils)
      	     use `with' instead
      7473349e
  25. 30 Dec, 2003 1 commit
    • simonpj's avatar
      [project @ 2003-12-30 16:29:17 by simonpj] · f714e6b6
      simonpj authored
      ----------------------------
              Re-do kind inference (again)
      	----------------------------
      
         [WARNING: interface file binary representation has
         (as usual) changed slightly; recompile your libraries!]
      
      Inspired by the lambda-cube, for some time GHC has used
      	type Kind = Type
      That is, kinds were represented by the same data type as types.
      
      But GHC also supports unboxed types and unboxed tuples, and these
      complicate the kind system by requiring a sub-kind relationship.
      Notably, an unboxed tuple is acceptable as the *result* of a
      function but not as an *argument*.  So we have the following setup:
      
      		 ?
      		/ \
      	       /   \
      	      ??   (#)
      	     /  \
                  *   #
      
      where	*    [LiftedTypeKind]   means a lifted type
      	#    [UnliftedTypeKind] means an unlifted type
      	(#)  [UbxTupleKind]     means unboxed tuple
      	??   [ArgTypeKind]      is the lub of *,#
      	?    [OpenTypeKind]	means any type at all
      
      In particular:
      
        error :: forall a:?. String -> a
        (->)  :: ?? -> ? -> *
        (\(x::t) -> ...)	Here t::?? (i.e. not unboxed tuple)
      
      All this has beome rather difficult to accommodate with Kind=Type, so this
      commit splits the two.
      
        * Kind is a distinct type, defined in types/Kind.lhs
      
        * IfaceType.IfaceKind disappears: we just re-use Kind.Kind
      
        * TcUnify.unifyKind is a distinct unifier for kinds
      
        * TyCon no longer needs KindCon and SuperKindCon variants
      
        * TcUnify.zapExpectedType takes an expected Kind now, so that
          in TcPat.tcMonoPatBndr we can express that the bound variable
          must have an argTypeKind (??).
      
      The big change is really that kind inference is much more systematic and
      well behaved.  In particular, a kind variable can unify only with a
      "simple kind", which is built from * and (->).  This deals neatly
      with awkward questions about how we can combine sub-kinding with type
      inference.
      
      Lots of small consequential changes, especially to the kind-checking
      plumbing in TcTyClsDecls.  (We played a bit fast and loose before, and
      now we have to be more honest, in particular about how kind inference
      works for type synonyms.  They can have kinds like (* -> #), so
      
      This cures two long-standing SourceForge bugs
      
      * 753777 (tcfail115.hs), which used erroneously to pass,
        but crashed in the code generator
            type T a = Int -> (# Int, Int #)
            f :: T a -> T a
            f t = \x -> case t x of r -> r
      
      * 753780 (tc167.hs), which used erroneously to fail
            f :: (->) Int# Int#
      
      
      Still, the result is not entirely satisfactory.  In particular
      
      * The error message from tcfail115 is pretty obscure
      
      * SourceForge bug 807249 (Instance match failure on openTypeKind)
        is not fixed.  Alas.
      f714e6b6
  26. 19 Dec, 2003 1 commit
    • simonpj's avatar
      [project @ 2003-12-19 10:34:51 by simonpj] · 3674a5cc
      simonpj authored
      ---------------------------------------
        Precise locations for duplicate imports
        ---------------------------------------
      
      As a displacment activity I added reporting for duplicate imports
      And more precise locations for the imports themselves.  For example:
      
        module T where
      
        import Maybe (isJust,isJust)
        import Maybe (isJust)
      
      gives
      
      Foo.hs:
          Warning: `isJust' is imported more than once:
      	       imported from Maybe at Foo.hs:4:16-21
      	       imported from Maybe at Foo.hs:3:23-28
      	       imported from Maybe at Foo.hs:3:16-21
      3674a5cc
  27. 16 Dec, 2003 1 commit
  28. 10 Dec, 2003 2 commits
    • simonmar's avatar
      [project @ 2003-12-10 17:25:12 by simonmar] · c7b38930
      simonmar authored
      Cleanups:
      
      - Move the collect* functions from HsSyn into HsUtils.  Check that we
        have a clean separation of utilties over HsSyn, with the generic
        versions in HsUtils, and the specific versions in RdrHsSyn, RnHsSyn
        and TcHsSyn as appropriate.
      
      - Remove the RdrBinding data type, which was really just a nested list
        with O(1) append, and use OrdList instead.  This makes it much clearer
        that there's nothing strange going on.
      
      - Various other minor cleanups.
      c7b38930
    • simonmar's avatar
      [project @ 2003-12-10 14:15:16 by simonmar] · 55042138
      simonmar authored
      Add accurate source location annotations to HsSyn
      -------------------------------------------------
      
      Every syntactic entity in HsSyn is now annotated with a SrcSpan, which
      details the exact beginning and end points of that entity in the
      original source file.  All honest compilers should do this, and it was
      about time GHC did the right thing.
      
      The most obvious benefit is that we now have much more accurate error
      messages; when running GHC inside emacs for example, the cursor will
      jump to the exact location of an error, not just a line somewhere
      nearby.  We haven't put a huge amount of effort into making sure all
      the error messages are accurate yet, so there could be some tweaking
      still needed, although the majority of messages I've seen have been
      spot-on.
      
      Error messages now contain a column number in addition to the line
      number, eg.
      
         read001.hs:25:10: Variable not in scope: `+#'
      
      To get the full text span info, use the new option -ferror-spans.  eg.
      
         read001.hs:25:10-11: Variable not in scope: `+#'
      
      I'm not sure whether we should do this by default.  Emacs won't
      understand the new error format, for one thing.
      
      In a more elaborate editor setting (eg. Visual Studio), we can arrange
      to actually highlight the subexpression containing an error.  Eventually
      this information will be used so we can find elements in the abstract
      syntax corresponding to text locations, for performing high-level editor
      functions (eg. "tell me the type of this expression I just highlighted").
      
      Performance of the compiler doesn't seem to be adversely affected.
      Parsing is still quicker than in 6.0.1, for example.
      
      Implementation:
      
      This was an excrutiatingly painful change to make: both Simon P.J. and
      myself have been working on it for the last three weeks or so.  The
      basic changes are:
      
       - a new datatype SrcSpan, which represents a beginning and end position
         in a source file.
      
       - To reduce the pain as much as possible, we also defined:
      
            data Located e = L SrcSpan e
      
       - Every datatype in HsSyn has an equivalent Located version.  eg.
      
            type LHsExpr id = Located (HsExpr id)
      
         and pretty much everywhere we used to use HsExpr we now use
         LHsExpr.  Believe me, we thought about this long and hard, and
         all the other options were worse :-)
      
      
      Additional changes/cleanups we made at the same time:
      
        - The abstract syntax for bindings is now less arcane.  MonoBinds
          and HsBinds with their built-in list constructors have gone away,
          replaced by HsBindGroup and HsBind (see HsSyn/HsBinds.lhs).
      
        - The various HsSyn type synonyms have now gone away (eg. RdrNameHsExpr,
          RenamedHsExpr, and TypecheckedHsExpr are now HsExpr RdrName,
          HsExpr Name, and HsExpr Id respectively).
      
        - Utilities over HsSyn are now collected in a new module HsUtils.
          More stuff still needs to be moved in here.
      
        - MachChar now has a real Char instead of an Int.  All GHC versions that
          can compile GHC now support 32-bit Chars, so this was a simplification.
      55042138
  29. 03 Nov, 2003 1 commit
  30. 09 Oct, 2003 1 commit
    • simonpj's avatar
      [project @ 2003-10-09 11:58:39 by simonpj] · 98688c6e
      simonpj authored
      -------------------------
      		GHC heart/lung transplant
      		-------------------------
      
      This major commit changes the way that GHC deals with importing
      types and functions defined in other modules, during renaming and
      typechecking.  On the way I've changed or cleaned up numerous other
      things, including many that I probably fail to mention here.
      
      Major benefit: GHC should suck in many fewer interface files when
      compiling (esp with -O).  (You can see this with -ddump-rn-stats.)
      
      It's also some 1500 lines of code shorter than before.
      
      **	So expect bugs!  I can do a 3-stage bootstrap, and run
      **	the test suite, but you may be doing stuff I havn't tested.
      ** 	Don't update if you are relying on a working HEAD.
      
      
      In particular, (a) External Core and (b) GHCi are very little tested.
      
      	But please, please DO test this version!
      
      
      	------------------------
      		Big things
      	------------------------
      
      Interface files, version control, and importing declarations
      ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      * There is a totally new data type for stuff that lives in interface files:
      	Original names			IfaceType.IfaceExtName
      	Types				IfaceType.IfaceType
      	Declarations (type,class,id)	IfaceSyn.IfaceDecl
      	Unfoldings			IfaceSyn.IfaceExpr
        (Previously we used HsSyn for type/class decls, and UfExpr for unfoldings.)
        The new data types are in iface/IfaceType and iface/IfaceSyn.  They are
        all instances of Binary, so they can be written into interface files.
        Previous engronkulation concering the binary instance of RdrName has
        gone away -- RdrName is not an instance of Binary any more.  Nor does
        Binary.lhs need to know about the ``current module'' which it used to,
        which made it specialised to GHC.
      
        A good feature of this is that the type checker for source code doesn't
        need to worry about the possibility that we might be typechecking interface
        file stuff.  Nor does it need to do renaming; we can typecheck direct from
        IfaceSyn, saving a whole pass (module TcIface)
      
      * Stuff from interface files is sucked in *lazily*, rather than being eagerly
        sucked in by the renamer. Instead, we use unsafeInterleaveIO to capture
        a thunk for the unfolding of an imported function (say).  If that unfolding
        is every pulled on, TcIface will scramble over the unfolding, which may
        in turn pull in the interface files of things mentioned in the unfolding.
      
        The External Package State is held in a mutable variable so that it
        can be side-effected by this lazy-sucking-in process (which may happen
        way later, e.g. when the simplifier runs).   In effect, the EPS is a kind
        of lazy memo table, filled in as we suck things in.  Or you could think
        of it as a global symbol table, populated on demand.
      
      * This lazy sucking is very cool, but it can lead to truly awful bugs. The
        intent is that updates to the symbol table happen atomically, but very bad
        things happen if you read the variable for the table, and then force a
        thunk which updates the table.  Updates can get lost that way. I regret
        this subtlety.
      
        One example of the way it showed up is that the top level of TidyPgm
        (which updates the global name cache) to be much more disciplined about
        those updates, since TidyPgm may itself force thunks which allocate new
        names.
      
      * Version numbering in interface files has changed completely, fixing
        one major bug with ghc --make.  Previously, the version of A.f changed
        only if A.f's type and unfolding was textually different.  That missed
        changes to things that A.f's unfolding mentions; which was fixed by
        eagerly sucking in all of those things, and listing them in the module's
        usage list.  But that didn't work with --make, because they might have
        been already sucked in.
      
        Now, A.f's version changes if anything reachable from A.f (via interface
        files) changes.  A module with unchanged source code needs recompiling
        only if the versions of any of its free variables changes. [This isn't
        quite right for dictionary functions and rules, which aren't mentioned
        explicitly in the source.  There are extensive comments in module MkIface,
        where all version-handling stuff is done.]
      
      * We don't need equality on HsDecls any more (because they aren't used in
        interface files).  Instead we have a specialised equality for IfaceSyn
        (eqIfDecl etc), which uses IfaceEq instead of Bool as its result type.
        See notes in IfaceSyn.
      
      * The horrid bit of the renamer that tried to predict what instance decls
        would be needed has gone entirely.  Instead, the type checker simply
        sucks in whatever instance decls it needs, when it needs them.  Easy!
      
        Similarly, no need for 'implicitModuleFVs' and 'implicitTemplateHaskellFVs'
        etc.  Hooray!
      
      
      Types and type checking
      ~~~~~~~~~~~~~~~~~~~~~~~
      * Kind-checking of types is far far tidier (new module TcHsTypes replaces
        the badly-named TcMonoType).  Strangely, this was one of my
        original goals, because the kind check for types is the Right Place to
        do type splicing, but it just didn't fit there before.
      
      * There's a new representation for newtypes in TypeRep.lhs.  Previously
        they were represented using "SourceTypes" which was a funny compromise.
        Now they have their own constructor in the Type datatype.  SourceType
        has turned back into PredType, which is what it used to be.
      
      * Instance decl overlap checking done lazily.  Consider
      	instance C Int b
      	instance C a Int
        These were rejected before as overlapping, because when seeking
        (C Int Int) one couldn't tell which to use.  But there's no problem when
        seeking (C Bool Int); it can only be the second.
      
        So instead of checking for overlap when adding a new instance declaration,
        we check for overlap when looking up an Inst.  If we find more than one
        matching instance, we see if any of the candidates dominates the others
        (in the sense of being a substitution instance of all the others);
        and only if not do we report an error.
      
      
      
      	------------------------
      	     Medium things
      	------------------------
      
      * The TcRn monad is generalised a bit further.  It's now based on utils/IOEnv.lhs,
        the IO monad with an environment.  The desugarer uses the monad too,
        so that anything it needs can get faulted in nicely.
      
      * Reduce the number of wired-in things; in particular Word and Integer
        are no longer wired in.  The latter required HsLit.HsInteger to get a
        Type argument.  The 'derivable type classes' data types (:+:, :*: etc)
        are not wired in any more either (see stuff about derivable type classes
        below).
      
      * The PersistentComilerState is now held in a mutable variable
        in the HscEnv.  Previously (a) it was passed to and then returned by
        many top-level functions, which was painful; (b) it was invariably
        accompanied by the HscEnv.  This change tidies up top-level plumbing
        without changing anything important.
      
      * Derivable type classes are treated much more like 'deriving' clauses.
        Previously, the Ids for the to/from functions lived inside the TyCon,
        but now the TyCon simply records their existence (with a simple boolean).
        Anyone who wants to use them must look them up in the environment.
      
        This in turn makes it easy to generate the to/from functions (done
        in types/Generics) using HsSyn (like TcGenDeriv for ordinary derivings)
        instead of CoreSyn, which in turn means that (a) we don't have to figure
        out all the type arguments etc; and (b) it'll be type-checked for us.
        Generally, the task of generating the code has become easier, which is
        good for Manuel, who wants to make it more sophisticated.
      
      * A Name now says what its "parent" is. For example, the parent of a data
        constructor is its type constructor; the parent of a class op is its
        class.  This relationship corresponds exactly to the Avail data type;
        there may be other places we can exploit it.  (I made the change so that
        version comparison in interface files would be a bit easier; but in
        fact it tided up other things here and there (see calls to
        Name.nameParent).  For example, the declaration pool, of declararations
        read from interface files, but not yet used, is now keyed only by the 'main'
        name of the declaration, not the subordinate names.
      
      * New types OccEnv and OccSet, with the usual operations.
        OccNames can be efficiently compared, because they have uniques, thanks
        to the hashing implementation of FastStrings.
      
      * The GlobalRdrEnv is now keyed by OccName rather than RdrName.  Not only
        does this halve the size of the env (because we don't need both qualified
        and unqualified versions in the env), but it's also more efficient because
        we can use a UniqFM instead of a FiniteMap.
      
        Consequential changes to Provenance, which has moved to RdrName.
      
      * External Core remains a bit of a hack, as it was before, done with a mixture
        of HsDecls (so that recursiveness and argument variance is still inferred),
        and IfaceExprs (for value declarations).  It's not thoroughly tested.
      
      
      	------------------------
      	     Minor things
      	------------------------
      
      * DataCon fields dcWorkId, dcWrapId combined into a single field
        dcIds, that is explicit about whether the data con is a newtype or not.
        MkId.mkDataConWorkId and mkDataConWrapId are similarly combined into
        MkId.mkDataConIds
      
      * Choosing the boxing strategy is done for *source* type decls only, and
        hence is now in TcTyDecls, not DataCon.
      
      * WiredIn names are distinguished by their n_sort field, not by their location,
        which was rather strange
      
      * Define Maybes.mapCatMaybes :: (a -> Maybe b) -> [a] -> [b]
        and use it here and there
      
      * Much better pretty-printing of interface files (--show-iface)
      
      Many, many other small things.
      
      
      	------------------------
      	     File changes
      	------------------------
      * New iface/ subdirectory
      * Much of RnEnv has moved to iface/IfaceEnv
      * MkIface and BinIface have moved from main/ to iface/
      * types/Variance has been absorbed into typecheck/TcTyDecls
      * RnHiFiles and RnIfaces have vanished entirely.  Their
        work is done by iface/LoadIface
      * hsSyn/HsCore has gone, replaced by iface/IfaceSyn
      * typecheck/TcIfaceSig has gone, replaced by iface/TcIface
      * typecheck/TcMonoType has been renamed to typecheck/TcHsType
      * basicTypes/Var.hi-boot and basicTypes/Generics.hi-boot have gone altogether
      98688c6e
  31. 23 Sep, 2003 1 commit
  32. 23 Jun, 2003 1 commit
    • simonpj's avatar
      [project @ 2003-06-23 10:35:15 by simonpj] · d28ba8c8
      simonpj authored
      -------------------
      	Dealing with 'main'
      	-------------------
      
      1.  In GHC 6.0, a module with no "module Main ... where" header
          elicited an error "main is not in scope" if 'main' is not defined.  We
          don't want this behaviour in GHCi.  This happened because the parser
          expanded the (absent) header to "module Main( main ) where", and the
          'main' in the export list isn't.
      
      Solution: elaborate HsModule to record whether the 'module ..." header was
      given explicitly by the user or not.
      
      
      2.  Add a -main-is flag, and document it, so that you can have a 'main' function
      that is not Main.main.  Summary of changes
      
      * The -main-is flag nominates what the main function is to be (see the documentation).
      	No -main-is flag 	says that the main function is Main.main
      	-main-is Foo.baz	says that the main function is Foo.baz
      	-main-is Foo		says that the main function is Foo.main
      	-main-is baz		says that the main function is Main.baz
      
        Let's say  you say -main-is Foo.baz
      
      * TcRnDriver injects the extra definition
      	$Mian.main :: IO t
      	$Main.main = baz
        in the module Foo.   Note the naming, which is a bit different than before;
        previously the extra defn was for Main.$main.  The RTS invokes zdMain_main_closure.
      
      * CodeGen injects an extra initialisation block into module Foo, thus
      	stginit_zdMain {
      		stginit_Foo
      	}
        That ensures that the RTS can initialise stginit_zdMain.
      d28ba8c8
  33. 02 Jun, 2003 1 commit
  34. 06 May, 2003 1 commit
    • simonpj's avatar
      [project @ 2003-05-06 10:25:32 by simonpj] · e4abae1d
      simonpj authored
      -------------------------------------
      		Main module exports
      	-------------------------------------
      
      Make it so that
      
         	    module Main where ....
      
      exports everything defined in Main, as the report says it should.
      e4abae1d