Linear types (#15981)

This is the first step towards implementation of the linear types proposal
(https://github.com/ghc-proposals/ghc-proposals/pull/111).

It features

* A language extension -XLinearTypes
* Syntax for linear functions in the surface language
* Linearity checking in Core Lint, enabled with -dlinear-core-lint
* Core-to-core passes are mostly compatible with linearity
* Fields in a data type can be linear or unrestricted; linear fields
  have multiplicity-polymorphic constructors.
  If -XLinearTypes is disabled, the GADT syntax defaults to linear fields

The following items are not yet supported:

* a # m -> b syntax (only prefix FUN is supported for now)
* Full multiplicity inference (multiplicities are really only checked)
* Decent linearity error messages
* Linear let, where, and case expressions in the surface language
  (each of these currently introduce the unrestricted variant)
* Multiplicity-parametric fields
* Syntax for annotating lambda-bound or let-bound with a multiplicity
* Syntax for non-linear/multiple-field-multiplicity records
* Linear projections for records with a single linear field
* Linear pattern synonyms
* Multiplicity coercions (test LinearPolyType)

A high-level description can be found at
https://ghc.haskell.org/trac/ghc/wiki/LinearTypes/Implementation
Following the link above you will find a description of the changes made to Core.
This commit has been authored by

* Richard Eisenberg
* Krzysztof Gogolewski
* Matthew Pickering
* Arnaud Spiwack

With contributions from:

* Mark Barbone
* Alexander Vershilov

Updates haddock submodule.

1 files changed, 2 insertions, 1 deletions

diff --git a/compiler/GHC/ByteCode/InfoTable.hs b/compiler/GHC/ByteCode/InfoTable.hs
index 73f55f63cc..b02683d10f 100644
--- a/compiler/GHC/ByteCode/InfoTable.hs
+++ b/compiler/GHC/ByteCode/InfoTable.hs
@@ -19,6 +19,7 @@ import GHC.Types.Name       ( Name, getName )
 import GHC.Types.Name.Env
 import GHC.Core.DataCon     ( DataCon, dataConRepArgTys, dataConIdentity )
 import GHC.Core.TyCon       ( TyCon, tyConFamilySize, isDataTyCon, tyConDataCons )
+import GHC.Core.Multiplicity     ( scaledThing )
 import GHC.Types.RepType
 import GHC.StgToCmm.Layout  ( mkVirtConstrSizes )
 import GHC.StgToCmm.Closure ( tagForCon, NonVoid (..) )
@@ -58,7 +59,7 @@ make_constr_itbls hsc_env cons =
   mk_itbl dcon conNo = do
      let rep_args = [ NonVoid prim_rep
                     | arg <- dataConRepArgTys dcon
-                    , prim_rep <- typePrimRep arg ]
+                    , prim_rep <- typePrimRep (scaledThing arg) ]
 
          (tot_wds, ptr_wds) =
              mkVirtConstrSizes dflags rep_args