#5289: Can't use ghci with a library linked against libstdc++
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Reporter: bos | Owner:
Type: bug | Status: new
Priority: normal | Milestone: 7.2.1
Component: GHCi | Version: 7.0.3
Keywords: | Testcase:
Blockedby: | Difficulty:
Os: Unknown/Multiple | Blocking:
Architecture: Unknown/Multiple | Failure: GHCi crash
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Comment(by hgolden):
Replying to [comment:19 bos]:
> Replying to [comment:17 hgolden]:
>
> > To me, this means that ghci dynamic loader can find libstdc++. Note:
On my system, it is located at /usr/lib/libstdc++.so.5 which is a symlink
to /usr/lib/libstdc++.so.5.0.7.
>
> That's not what {{{ghci}}} is finding. If you run it under {{{strace}}},
you'll find that it is picking up a symlink named {{{libstdc++.so}}}
somewhere else. {{{ghci}}} doesn't search for a shared library by its
extended name, only with the {{{.so}}} suffix.
I was incorrect before about the location of the shared library. Here is
the correct explanation:
{{{dlopen}}} looks in {{{/lib/ld.so.cache}}} for "libstdc++.so" (which is
what {{{ghci}}} asks for when it gets the option "-lstdc++"). It finds the
first entry that corresponds to the particular system in use (for me,
libc6,x86-64). On my system this entry is {{{/usr/lib/gcc/x86_64-pc-linux-
gnu/4.5.2/libstdc++.so}}}. On my system, that is a symlink to
{{{/usr/lib/gcc/x86_64-pc-linux-gnu/4.5.2/libstdc++.so.6.0.14}}}.
In other words, {{{libstdc++.so}}} is NOT a symlink. It is an entry in
{{{/lib/ld.so.cache}}}.
You can see all the {{{/lib/ld.so.cache}}} entries your system has by
using the command "ldconfig -p".
> Right. But that's not my focus here. I might open a separate bug for
that. This one should remain focused on the library finding issue.
I still believe that libstdc++ is being found using {{{dlopen}}}. I
suspect that the reason the initial report couldn't find libstdc++.so was
that the entry in {{{/lib/ld.so.cache}}} (or its OS X equivalent) was
missing. Perhaps later you rebuilt {{{/lib/ld.so.cache}}} which may
explain why you aren't able to reproduce the original error.
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/5289#comment:20>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler
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