[GHC] #11380: Compiling a 10.000 line file exhausts memory (was: `cabal repl` exhausts memory)

[GHC]

#11380: Compiling a 10.000 line file exhausts memory
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        Reporter:  kennethb          |                Owner:
            Type:  bug               |               Status:  new
        Priority:  high              |            Milestone:
       Component:  Compiler          |              Version:  7.10.3
      Resolution:                    |             Keywords:
Operating System:  Linux             |         Architecture:  x86_64
 Type of failure:  Compile-time      |  (amd64)
  performance bug                    |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Changes (by thomie):

 * failure:  Compile-time crash => Compile-time performance bug


Comment:

 Compiling (instead of interpreting) the generated Parser.hs with
 ghc-7.10.3 (wihout optimizations) doesn't complete either, when only 3GB
 of RAM is available (tested with `ulimit -v 3000000`). The problems seem
 to begin in the desugaring phase:

 {{{
 *** Parser:
 *** Renamer/typechecker:
 *** Desugar:
 ghc: out of memory (requested 2097152 bytes)
 }}}

 The generated parser is huge (10.000 lines). But it is about the same size
 as GHC's own parser, which GHC //is// able to compile with reasonable
 memory.

 I tried making the Parser smaller a bit, but didn't find any obvious rule
 that might be triggering the problem.

 Could you try with other version of GHC (say 7.8.4 and 8.0.1)? Is it a
 regression, or maybe already fixed?

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11380#comment:4>
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