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Eric Seidel authored
This patch modifies `error`, `undefined`, and `assertError` to use implicit call-stacks to provide better error messages to users. There are a few knock-on effects: - `GHC.Classes.IP` is now wired-in so it can be used in the wired-in types for `error` and `undefined`. - `TysPrim.tyVarList` has been replaced with a new function `TysPrim.mkTemplateTyVars`. `tyVarList` made it easy to introduce subtle bugs when you need tyvars of different kinds. The naive ``` tv1 = head $ tyVarList kind1 tv2 = head $ tyVarList kind2 ``` would result in `tv1` and `tv2` sharing a `Unique`, thus substitutions would be applied incorrectly, treating `tv1` and `tv2` as the same tyvar. `mkTemplateTyVars` avoids this pitfall by taking a list of kinds and producing a single tyvar of each kind. - The types `GHC.SrcLoc.SrcLoc` and `GHC.Stack.CallStack` now live in ghc-prim. - The type `GHC.Exception.ErrorCall` has a new constructor `ErrorCallWithLocation` that takes two `String`s instead of one, the 2nd one being arbitrary metadata about the error (but usually the call-stack). A bi-directional pattern synonym `ErrorCall` continues to provide the old API. Updates Cabal, array, and haddock submodules. Reviewers: nh2, goldfire, simonpj, hvr, rwbarton, austin, bgamari Reviewed By: simonpj Subscribers: rwbarton, rodlogic, goldfire, maoe, simonmar, carter, liyang, bgamari, thomie Differential Revision: https://phabricator.haskell.org/D861 GHC Trac Issues: #5273
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