Thanks for this.
I've improved Note [Order of Coercible Instances] in TcInteract
Generally, it's much better to give an actual, concrete example in the Note, and refer to the ticket for additional background. It took me a few minutes to re-read the long #9117 to reconstruct the example that precisely illustrates the Note.
Simon
| -----Original Message-----
| From: ghc-tickets [mailto:ghc-tickets-bounces@haskell.org] On Behalf Of
| GHC
| Sent: 30 May 2014 01:35
| Cc: ghc-tickets@haskell.org
| Subject: [GHC] #9153: TcCoercible test is failing with context reduction
| stack overflow
|
| #9153: TcCoercible test is failing with context reduction stack overflow
| ------------------------------------+-----------------------------------
| ------------------------------------+--
| Reporter: ezyang | Owner:
| Type: bug | Status: new
| Priority: low | Milestone:
| Component: Test Suite | Version: 7.9
| Keywords: | Operating System:
| Unknown/Multiple
| Architecture: Unknown/Multiple | Type of failure: None/Unknown
| Difficulty: Unknown | Test Case:
| Blocked By: | Blocking:
| Related Tickets: |
| ------------------------------------+-----------------------------------
| ------------------------------------+--
| Here is the error:
|
| {{{
| TcCoercible.hs:62:12:
| Context reduction stack overflow; size = 21
| Use -fcontext-stack=N to increase stack size to N
| Coercible Int Int
| In the expression: coerce
| In the first argument of ‘print’, namely
| ‘(coerce $ (FixEither (Left age) :: FixEither Age) ::
| Either Int (FixEither Int))’
| In a stmt of a 'do' block:
| print
| (coerce $ (FixEither (Left age) :: FixEither Age) ::
| Either Int (FixEither Int))
| }}}
|
| I do not know enough to know if bumping the stack size is correct.
|
| Additionally, when run as GHCi I get:
|
| {{{
| =====> TcCoercible(ghci) 2784 of 3970 [0, 7, 0] cd
| ./typecheck/should_run && '/home/hs01/ezyang/ghc-validate/inplace/bin
| /ghc-stage2' -fforce-re
| comp -dcore-lint -dcmm-lint -dno-debug-output -no-user-package-db -
| rtsopts -fno-ghci-history Tc Coercible.hs --interactive -v0 -ignore-
| dot-ghci +RTS -I0.1 -RTS