[commit: ghc] master: Remove redundant kind check (4431e48)

[git at git.haskell.org]

Repository : ssh://git@git.haskell.org/ghc

On branch  : master
Link       : http://ghc.haskell.org/trac/ghc/changeset/4431e48e6dc0a0e47328b6d0ed34a9b8503be4b0/ghc

>---------------------------------------------------------------

commit 4431e48e6dc0a0e47328b6d0ed34a9b8503be4b0
Author: Simon Peyton Jones <simonpj at microsoft.com>
Date:   Thu Nov 24 13:57:04 2016 +0000

    Remove redundant kind check
    
    The invariants for CTyEqCan mean that this check isn't needed.
    Turn it into an ASSERT.


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4431e48e6dc0a0e47328b6d0ed34a9b8503be4b0
 compiler/typecheck/TcFlatten.hs | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/compiler/typecheck/TcFlatten.hs b/compiler/typecheck/TcFlatten.hs
index 3adbee1..4fc8414 100644
--- a/compiler/typecheck/TcFlatten.hs
+++ b/compiler/typecheck/TcFlatten.hs
@@ -1457,8 +1457,9 @@ unflatten tv_eqs funeqs
                         -- NB: unlike unflattenFmv, filling a fmv here /does/
                         --     bump the unification count; it is "improvement"
                         -- Note [Unflattening can force the solver to iterate]
-      , tyVarKind tv `eqType` typeKind rhs
-      = do { is_filled <- isFilledMetaTyVar tv
+      = ASSERT2( tyVarKind tv `eqType` typeKind rhs, ppr ct )
+           -- CTyEqCan invariant should ensure this is true
+        do { is_filled <- isFilledMetaTyVar tv
            ; elim <- case is_filled of
                False -> do { traceTcS "unflatten_eq 2" (ppr ct)
                            ; tryFill      ev eq_rel       tv rhs }