From 5935acdb1302263011c2023d5e7f4ec496c972c0 Mon Sep 17 00:00:00 2001
From: Simon Marlow <marlowsd@gmail.com>
Date: Thu, 28 Sep 2017 13:08:45 -0400
Subject: [PATCH] mkDataConRep: fix bug in strictness signature (#14290)

The strictness signature for a data con wrapper wasn't including any
dictionary arguments, which meant that bangs on the fields of a
constructor with an existential context would be moved to the wrong
fields.  See T14290 for an example.

Test Plan:
* New test T14290
* validate

Reviewers: simonpj, niteria, austin, bgamari, erikd

Reviewed By: simonpj, bgamari

Subscribers: rwbarton, thomie

GHC Trac Issues: #14290

Differential Revision: https://phabricator.haskell.org/D4040
---
 compiler/basicTypes/MkId.hs                  |  6 +++++-
 testsuite/tests/stranal/should_run/T14290.hs | 17 +++++++++++++++++
 testsuite/tests/stranal/should_run/all.T     |  1 +
 3 files changed, 23 insertions(+), 1 deletion(-)
 create mode 100644 testsuite/tests/stranal/should_run/T14290.hs

diff --git a/compiler/basicTypes/MkId.hs b/compiler/basicTypes/MkId.hs
index 03ab04a24c..87e40dd62f 100644
--- a/compiler/basicTypes/MkId.hs
+++ b/compiler/basicTypes/MkId.hs
@@ -530,7 +530,11 @@ mkDataConRep dflags fam_envs wrap_name mb_bangs data_con
 
              wrap_sig = mkClosedStrictSig wrap_arg_dmds (dataConCPR data_con)
 
-             wrap_arg_dmds = map mk_dmd arg_ibangs
+             wrap_arg_dmds =
+               replicate (length theta) topDmd ++ map mk_dmd arg_ibangs
+               -- Don't forget the dictionary arguments when building
+               -- the strictness signature (#14290).
+
              mk_dmd str | isBanged str = evalDmd
                         | otherwise           = topDmd
 
diff --git a/testsuite/tests/stranal/should_run/T14290.hs b/testsuite/tests/stranal/should_run/T14290.hs
new file mode 100644
index 0000000000..7093239d4c
--- /dev/null
+++ b/testsuite/tests/stranal/should_run/T14290.hs
@@ -0,0 +1,17 @@
+{-# LANGUAGE ExistentialQuantification #-}
+module Main (main) where
+
+main :: IO ()
+main = r `seq` return ()
+
+r :: Rec
+r = Rec{ a = error "xxx", b = 3, c = True }
+
+class C t
+instance C Bool
+
+data Rec = forall t. C t => Rec
+  { a :: ()
+  , b :: !Int
+  , c :: t
+  }
diff --git a/testsuite/tests/stranal/should_run/all.T b/testsuite/tests/stranal/should_run/all.T
index 076474608e..dada8176cb 100644
--- a/testsuite/tests/stranal/should_run/all.T
+++ b/testsuite/tests/stranal/should_run/all.T
@@ -15,3 +15,4 @@ test('T11555a', normal, compile_and_run, [''])
 test('T12368', exit_code(1), compile_and_run, [''])
 test('T12368a', exit_code(1), compile_and_run, [''])
 test('T13380', [expect_broken(13380), exit_code(1)], compile_and_run, [''])
+test('T14290', normal, compile_and_run, [''])
-- 
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