[GHC] #9370: unfolding info as seen when building a module depends on flags in a previously-compiled module

[GHC]

#9370: unfolding info as seen when building a module depends on flags in a
previously-compiled module
-------------------------------------+-------------------------------------
              Reporter:  carter      |            Owner:
                  Type:  bug         |           Status:  new
              Priority:  high        |        Milestone:  7.10.1
             Component:  Compiler    |          Version:  7.8.3
            Resolution:              |         Keywords:
      Operating System:              |     Architecture:  Unknown/Multiple
  Unknown/Multiple                   |       Difficulty:  Unknown
       Type of failure:  Compile-    |       Blocked By:
  time performance bug               |  Related Tickets:
             Test Case:              |
              Blocking:              |
Differential Revisions:              |
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Comment (by rwbarton):

 I would guess it's to avoid the very code size explosion (inlining 4000
 copies of Text's `fromString`) that Carter encountered that originated
 this ticket. But that doesn't explain the `-fno-case-merge -fno-strictness
 -fno-cse` part. Carter has asked about this on the xmlhtml bug tracker.

 The same scenario could apply in reverse, right? In the actual xmlhtml
 package, `Text.XmlHtml.HTML.Meta` is the first module built and it is
 built with `-O0` so any interface files that are read while compiling that
 module will not have unfoldings attached. Then those modules will not have
 unfoldings during the compilation of any subsequent module either, even
 though those are built with `-O`.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9370#comment:11>
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