cpan install error for XML::LibXML::Node

BradV has asked for the wisdom of the Perl Monks concerning the following question:

I'm running on RHEL 6.9. I have installed libxml2 and libxml2-devel. The xml2 libraries are under /usr/lib64. Zlib is installed and is under /lib64. So, I changed makepl_arg as:

o conf makepl_arg "INC=-I/usr/include -I/usr/local/include -I/usr/incl
+ude/libxml2/libxml LIBS=-L/usr/lib64 -L/usr/lib -L/usr/local/lib -L/l
+ib64 -llibxml2 -lm"
o conf commit
[download]

When I run cpan XML::LibXML::Node, I get:

...
Checking for ability to link against xml2...no
Checking for ability to link against libxml2...libxml2, zlib, and/or t
+he Math library (-lm) have not been found.
[download]

I'm not sure what math library it is referring to. I have been searching on the Internet, but nothing is really popping out. Any clues what I may be missing?

Comment on cpan install error for XML::LibXML::Node Select or Download Code

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Re: cpan install error for XML::LibXML::Node by Corion (Patriarch) on May 31, 2017 at 11:51 UTC
The easy approach is to run `Makefile.PL` yourself: `cpan cpan> look XML::LibXML /path/to/build/dir/for/XML-LibXML-123.456> perl Makefile.PL INC=... LI +BS=... /path/to/build/dir/for/XML-LibXML-123.456> make /path/to/build/dir/for/XML-LibXML-123.456> make test` [download] Hopefully you see more output of which library the Makefile.PL run is missing. If the Makefile.PL is not verbose enough, consider adding `print` statements to it to see what it does and which libraries it tests for.	[reply] [d/l] [select]
Re^2: cpan install error for XML::LibXML::Node by BradV (Sexton) on May 31, 2017 at 12:46 UTC
I added DEBUG=1 to the line. It is complaining about not being able to find all of the headers under /usr/include/libxml2/libxml. I included that with '-I.' So, not sure why it can't find them? I checked and all of the files and the path down have world readability. Does the order of the includes matter?	[reply]
Re: cpan install error for XML::LibXML::Node by hippo (Archbishop) on May 31, 2017 at 12:44 UTC
`conf makepl_arg "INC=-I/usr/include -I/usr/local/include -I/usr/include/libxml2/libxml LIBS=-L/usr/lib64 -L/usr/lib -L/usr/local/lib -L/lib64 -llibxml2 -lm"` The penultimate term looks wrong. Surely it should be `-lxml2` instead?	[reply] [d/l] [select]
Re^2: cpan install error for XML::LibXML::Node by BradV (Sexton) on May 31, 2017 at 12:53 UTC
I tried that and get the same results. I'm not an experienced compiler. I'm assuming the '-l' is just passed to gcc? The libxml2 library is: `/usr/lib64/libxml2.so.2.7.6 /usr/lib64/libxml2.so.2 -> libxml2.so.2.7.6` [download] that is why I used libxml2. Maybe I should make it libxml2.so.2?	[reply] [d/l]
Re^3: cpan install error for XML::LibXML::Node by hippo (Archbishop) on May 31, 2017 at 13:11 UTC
Nope, definitely `-lxml2`. `$ xml2-config --libs -lxml2 -lz -lm` [download]	[reply] [d/l] [select]
Re^4: cpan install error for XML::LibXML::Node by BradV (Sexton) on May 31, 2017 at 13:36 UTC
Re^5: cpan install error for XML::LibXML::Node by hippo (Archbishop) on May 31, 2017 at 13:48 UTC
Some notes below your chosen depth have not been shown here
Re: cpan install error for XML::LibXML::Node by stevieb (Canon) on May 31, 2017 at 12:14 UTC
It is referring to the standard C math library. I doubt this is what is actually causing the issue, but you can verify this specifically if what Corion said doesn't lead you to the root problem. Create a basic C file: `// test.c #include <math.h> int main (){ return 0; }` [download] Then compile it: `gcc test.c -lm` [download] If you don't get errors (which I highly expect you won't), the problem is due to finding the libxml libraries and you'll have to focus there.	[reply] [d/l] [select]
Re^2: cpan install error for XML::LibXML::Node by BradV (Sexton) on May 31, 2017 at 12:36 UTC
yes, the compile worked without complaint. I see the math header under /usr/include as part of the glibc-headers rpm. Thanks! Will take a shot at the 'look' method.	[reply]