[cvs-nhc98] Fix many faults in the import/export mechanism.

[Malcolm Wallace]

malcolm: Wed Oct 17 14:57:21 CEST 2001

Update of /usr/src/master/nhc/src/compiler98
In directory hinken:/tmp/cvs-serv28723

Modified Files:
	CaseLib.hs DbgDataTrans.hs DbgDumpSRIDTable.hs 
	DbgDumpSRIDTableC.hs DbgReplaceConstr.hs DbgTrans.hs Export.hs 
	FFITrans.hs FSLib.hs GcodeFix.hs GcodeSpec.hs IExtract.hs 
	Import.hs Info.hs IntState.hs Need.hs ParseI.hs PreImp.hs 
	PreImport.hs Remove1_3.hs Rename.hs RenameLib.hs 
	ReportImports.hs TokenId.hs TokenInt.hs TypeUtil.hs 
Log Message:
Fix many faults in the import/export mechanism.

New features
------------
  * The compiler now treats explicitly named constructors and methods
    correctly, e.g. in
        module M (T(A,B), C(f,g)) where
    or
        import M (T(A,B), C(f,g))
    only the constructors A and B of datatype T, and only the methods f and g
    of class C, are exported/imported.

  * The declaration
        import qualified M (f)
    is now accepted without complaint, whereas previously it needed to be
        import qualified M (M.f)
    in some circumstances.

  * It is now possible to name selectors explicitly in an export/import
    list, provided the type they select over is *not* exported/imported.


Implementation
--------------
The symbol table entries
    InfoConstr, InfoMethod, InfoField
now each have an extra field 'ie' which determines whether an
individual constructor/method/field is to be re-exported, rather than
relying on the corresponding tag of the relevant InfoData/InfoClass
symbol.

The IE type is extended to distinguish the various cases of:
    IEall  - re-export with all constructors/methods  e.g. C(..)
    IEsome - re-export with some constructors/methods  e.g. C(f,g)
    IEabs  - re-export with no constructors/methods  e.g. C() or C
    IEnone - do not re-export
and
    IEsel  - re-export this selected constructor/method individually

The interface file (.hi) now indicates which individual
constructors/methods are actually exported in the {-# NEED {C f g} #-}
annotation.  Most importantly, *all* the actual constructors/methods
are listed in the datatype/class definition that follows, because the
numerical ordering is required to generate correct code.  However, when
importing such a datatype/class, the non-visible constructors/methods
are renamed internally to something like "Unknown.Constructor_n" in
the symbol table, to ensure that they cannot be used.  These new names
will appear any new interface file that is generated due to a further
re-export.