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<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif;mso-fareast-language:EN-US">Great question.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif;mso-fareast-language:EN-US">And just to add: I _<i>really</i>_ appreciate the fact that you make small examples. Thank you.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif;mso-fareast-language:EN-US">Simon<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif">From:</span></b><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif"> ghc-devs [mailto:ghc-devs-bounces@haskell.org]
<b>On Behalf Of </b>Eric Crockett<br>
<b>Sent:</b> 26 October 2016 05:27<br>
<b>To:</b> ghc-devs <ghc-devs@haskell.org><br>
<b>Subject:</b> Tool for minimizing examples<o:p></o:p></span></p>
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Devs: as I'm sure you know, the hardest part of reporting a GHC bug is finding a minimal example that triggers the bug. When I initially trigger a bug in my large code base, my workflow is something like:<o:p></o:p></p>
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1. write a driver that triggers the bug<o:p></o:p></p>
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2. do manual dead code elimination by removing unused files and functions<o:p></o:p></p>
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3. "human required" step to figure out what can be trimmed to further minimize<o:p></o:p></p>
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4. go to step 2 until example is simple enouogh<o:p></o:p></p>
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Since I work on a large library (>60 modules) and also report a fair number of bugs, I spend a nontrivial amount of time on step 2, which is completely mechanical. It would be nice to have a tool that can help out. Specifically, something that takes a "driver"
file, and produces a copy of the code contents to a new directory sans unimported files, and unused functions from imported files.<o:p></o:p></p>
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Ideally, this tool would make a "closed universe" assumption so that exported functions can also be eliminated as dead, if they are never used elsewhere. A bonus feature would be to remove unused imports, and even unused build-depends from the cabal file.<o:p></o:p></p>
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Are there any tools out there that can do any portion of this process for me? Perhaps it is possible to output contents after the compiler does a DCE pass?<o:p></o:p></p>
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Regards,<o:p></o:p></p>
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Eric Crockett<o:p></o:p></p>
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