[GHC] #10021: Add "Error:" prefix for error-messages

[GHC]

#10021: Add "Error:" prefix for error-messages
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              Reporter:  k-bx        |             Owner:
                  Type:  feature     |            Status:  new
  request                            |         Milestone:  7.12.1
              Priority:  normal      |           Version:  7.8.4
             Component:  Compiler    |  Operating System:  Unknown/Multiple
              Keywords:              |   Type of failure:  None/Unknown
          Architecture:              |        Blocked By:
  Unknown/Multiple                   |   Related Tickets:
             Test Case:              |
              Blocking:              |
Differential Revisions:              |
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 Similar to what we have for "Warning:".

 E.g., we have:

 {{{
 ➜ cat test.hs
 main = putStrLn "Hello!"
 ➜ ghc --make -fforce-recomp -Wall ./test.hs
 [1 of 1] Compiling Main             ( test.hs, test.o )

 test.hs:1:1: Warning:
     Top-level binding with no type signature: main :: IO ()
 Linking test ...
 ➜ cat test2.hs
 main = foo
 ➜ ghc --make -fforce-recomp -Wall ./test2.hs
 [1 of 1] Compiling Main             ( test2.hs, test2.o )

 test2.hs:1:8: Not in scope: ‘foo’
 }}}

 And I propose having:

 {{{
 ➜ cat test2.hs
 main = foo
 ➜ ghc --make -fforce-recomp -Wall ./test2.hs
 [1 of 1] Compiling Main             ( test2.hs, test2.o )

 test2.hs:1:8: Error: Not in scope: ‘foo’
 }}}

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10021>
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