[GHC] #10508: comipleExpr or :def in GHCi rejects valid multiline expr or accepts invalid expr

[GHC]

#10508: comipleExpr or :def in GHCi rejects valid multiline expr or accepts invalid
expr
-------------------------------------+-------------------------------------
        Reporter:  watashi           |                   Owner:  watashi
            Type:  bug               |                  Status:  new
        Priority:  normal            |               Milestone:
       Component:  GHC API           |                 Version:  7.10.1
      Resolution:                    |                Keywords:
Operating System:  Linux             |            Architecture:  x86
 Type of failure:  GHC rejects       |               Test Case:
  valid program                      |                Blocking:
      Blocked By:                    |  Differential Revisions:  Phab:D974
 Related Tickets:                    |
-------------------------------------+-------------------------------------

Comment (by Simon Marlow <marlowsd@…>):

 In [changeset:"d20031d4c88b256cdae264cb05d9d850e973d956/ghc"]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="d20031d4c88b256cdae264cb05d9d850e973d956"
 Add parseExpr and compileParsedExpr and use them in GHC API and GHCi

 Summary:
 This commit brings following changes and fixes:

  * Implement parseExpr and compileParsedExpr;
  * Fix compileExpr and dynCompilerExpr, which returned `()` for empty
 expr;
  * Fix :def and :cmd, which didn't work if `IO` or `String` is not in
 scope;
  * Use GHCiMonad instead IO in :def and :cmd;
  * Clean PrelInfo: delete dead comment and duplicate entries, add
 assertion.

 See new tests for more details.

 Test Plan: ./validate

 Reviewers: austin, dterei, simonmar

 Reviewed By: simonmar

 Subscribers: thomie, bgamari

 Differential Revision: https://phabricator.haskell.org/D974

 GHC Trac Issues: #10508
 }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10508#comment:2>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler