AnneW at 16:27, 19 July 2012

2012-07-19T16:27:50Z

Dfaure: Tell people how to debug undefined symbols

2010-09-29T22:30:19Z

Tell people how to debug undefined symbols

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== Abstract ==

This tutorial gives precise steps for debugging issues related to linking of applications and libraries.

== Undefined symbol ==

When the linker says undefined reference to 'Foo', and you don't understand why, follow the following steps:

* Check that the library that is supposed to provide this symbol is actually in the link line. To see the full link line with cmake, use <tt>make VERBOSE=1</tt>. If -lkdecore is the link line, then we're at least asking the linker to link to libkdecore.
* Check that the right version of the library is linked in, rather than one from the wrong place. To see which library is actually used by ld, copy/paste the full link line from <tt>make VERBOSE=1</tt>, and add to it: <tt>-Q -v -Wl,-t</tt>. Somewhere in the verbose output you'll see the full path to each library being used.
* Check that the library actually provides the symbol. <tt>nm -D -C /path/to/lib.so | grep Foo</tt> will tell you. If the symbol shows up with a 'T' or a 'W' in the second column, then it is indeed provided by the library. If it shows up with a 'U' then it is undefined in this library, and is supposed to be provided by another.

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AnneW at 16:27, 19 July 2012

Dfaure: Tell people how to debug undefined symbols