<div dir="ltr">Why don't we use the DWARF information instead? It has no runtime overhead so it can actually be turned on always. It also integrates with all the standard open source tooling.</div><div class="gmail_extra"><br><div class="gmail_quote">On Tue, Dec 2, 2014 at 10:04 AM, Simon Peyton Jones <span dir="ltr"><<a href="mailto:simonpj@microsoft.com" target="_blank">simonpj@microsoft.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
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+1, as I don't see a downside. However, I don't think this change is a sufficient change as long as stack traces are only available for profiled builds. I still wish something like rewrite-with-location[1], which even addresses explicit stack traces directly[2].
IIRC, last time that feature was brought up for discussion, it stalled due to disagreements on the right design.<u></u><u></u></p>
</span><p class="MsoNormal"><span style="font-family:"Calibri","sans-serif"">I think we have something of a consensus forming around
<a href="https://ghc.haskell.org/trac/ghc/wiki/ExplicitCallStack/ImplicitLocations" target="_blank">
https://ghc.haskell.org/trac/ghc/wiki/ExplicitCallStack/ImplicitLocations</a>, see #9049. It’s simple, non-invasive, and predicatable. It does need someone to implement it though. Simon Hengel is thinking about implementing it. (He is the one who also
suggested “rewrite with location”).<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-family:"Calibri","sans-serif""><u></u> <u></u></span></p>
<p class="MsoNormal"><span style="font-family:"Calibri","sans-serif"">So I think we are stalled not so much on design but on implementation.<u></u><u></u></span></p>
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<p class="MsoNormal"><span style="font-family:"Calibri","sans-serif"">Simon<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-family:"Calibri","sans-serif""><u></u> <u></u></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""> Libraries [mailto:<a href="mailto:libraries-bounces@haskell.org" target="_blank">libraries-bounces@haskell.org</a>]
<b>On Behalf Of </b>Michael Snoyman<br>
<b>Sent:</b> 01 December 2014 05:33<br>
<b>To:</b> Christopher Allen; Mark Wotton<br>
<b>Cc:</b> Haskell Libraries<br>
<b>Subject:</b> Re: replace definition of error with errorWithStackTrace<u></u><u></u></span></p>
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+1, as I don't see a downside. However, I don't think this change is a sufficient change as long as stack traces are only available for profiled builds. I still wish something like rewrite-with-location[1], which even addresses explicit stack traces directly[2].
IIRC, last time that feature was brought up for discussion, it stalled due to disagreements on the right design.<u></u><u></u></p>
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<u></u> <u></u></p>
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[1] <a href="https://github.com/sol/rewrite-with-location" target="_blank">https://github.com/sol/rewrite-with-location</a><u></u><u></u></p>
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[2] <a href="https://github.com/sol/rewrite-with-location#explicit-call-stacks" target="_blank">https://github.com/sol/rewrite-with-location#explicit-call-stacks</a><u></u><u></u></p>
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On Mon Dec 01 2014 at 6:39:25 AM Christopher Allen <<a href="mailto:cma@bitemyapp.com" target="_blank">cma@bitemyapp.com</a>> wrote:<u></u><u></u></p>
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+1 - I would be very happy if this happened.<u></u><u></u></p>
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<u></u> <u></u></p>
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On Sun, Nov 30, 2014 at 10:09 PM, Mark Wotton <<a href="mailto:mwotton@gmail.com" target="_blank">mwotton@gmail.com</a>> wrote:<u></u><u></u></p>
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having just spent a day tracking down a really uninformative error in Cabal, I'm all for this.<u></u><u></u></p>
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On Mon Dec 01 2014 at 11:08:35 Carter Schonwald <<a href="mailto:carter.schonwald@gmail.com" target="_blank">carter.schonwald@gmail.com</a>> wrote:<u></u><u></u></p>
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<a href="http://hackage.haskell.org/package/base-4.7.0.1/docs/GHC-Stack.html#v:errorWithStackTrace" target="_blank">http://hackage.haskell.org/package/base-4.7.0.1/docs/GHC-Stack.html#v:errorWithStackTrace</a> <u></u><u></u></p>
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has been in GHC for for >=1 major version,<u></u><u></u></p>
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and for normal builds, acts just like error, BUT, when an error is thrown in a profiled build, it appends a stack trace with some basic source location data to the end of the error message!<u></u><u></u></p>
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<u></u> <u></u></p>
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I think this change would benefit many!<u></u><u></u></p>
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My current understanding is that the DWARF based approach to stack traces wont make it into GHC 7.10 , and while this variant would only provide extra info in profiling builds (and strictly less than the dwarf work), its something that can definitely be done
in a single small patch that could easily be swapped out for that improved approach once it lands.<u></u><u></u></p>
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<u></u> <u></u></p>
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<u></u> <u></u></p>
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discussion period: 2 weeks unless theres a clear unanimous agreement to make the change ASAP, OR if the stack trace error stuff is landing in 7.10 and I'm misinformed!<u></u><u></u></p>
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<u></u> <u></u></p>
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cheers<u></u><u></u></p>
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-Carter<u></u><u></u></p>
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<u></u> <u></u></p>
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