[Bug 1557852] Re: [needs-packaging] juju-mongodb3.2 in xenial, wily, and trusty

[Michael Hudson-Doyle]

Something very odd is going on with the problem offset-outside-of-
bounds.patch is addressing. I hacked the offending source file down to
http://paste.ubuntu.com/15573220/.

This fails to compile with -O2:

ubuntu at promonarchy-remi:~/xenial-mongodb-3.2$ g++ -o foo.o -c -O2 -Werror -std=c++11 -Ibuild/opt -Isrc src/mongo/bson/bson_obj_test.cpp 
In file included from src/mongo/db/jsobj.h:49:0,
                 from src/mongo/bson/bson_obj_test.cpp:28:
src/mongo/bson/bsonelement.h: In member function ‘virtual void {anonymous}::UnitTest__BSONObj__getFields::_doTest()’:
src/mongo/bson/bsonelement.h:231:23: error: offset outside bounds of constant string [-Werror]
         return data + 1;
                       ^
cc1plus: all warnings being treated as errors

It succeeds with -O1 though. It _also_ succeeds with -O1 and all the
-fxxx flags that -O2 implies on top of -O1. It _also_ succeeds if almost
any line is removed from the file. But if you remove a few lines and
change it to -O3, it fails again. So I guess some threshold-based
optimization eventually transforms the code in the file into something
that triggers the warning. I'm not quite confident enough to call this a
compiler bug, but it's certainly user hostile.

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Title:
  [needs-packaging] juju-mongodb3.2 in xenial, wily, and trusty

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