Re^3: Device::USB gives "Use of uninitialized value in concatenation" error

[Eliya]

My guess would be that it's complaining about undefined CFLAGS / CPPFLAGS / LDFLAGS environment variables (see line 19 and 20). Line numbers reported are not always precise when a statement stretches over multiple lines.

Try setting those env variables to nothing, i.e. export CFLAGS= etc., and see what happens...

[holandes777]

  9 use Inline (
  10         C => "DATA",
  11         ($ENV{LIBUSB_LIBDIR}
  12             ? ( LIBS => "-L\"$ENV{LIBUSB_LIBDIR}\" " .
  13                         ($^O eq 'MSWin32' ? ' -llibusb -L\"$ENV{W
+INDDK}\\lib\\crt\\i386\" -lmsvcrt ' : '-lusb') )
  14             : ( LIBS => '-lusb', )
  15         ),
  16         ($ENV{LIBUSB_INCDIR} ? ( INC => "-I\"$ENV{LIBUSB_INCDIR}\
+"" ) : () ),
  17         NAME => 'Device::USB',
  18         VERSION => '0.35',
  19         CCFLAGS => "$Config{ccflags} $ENV{CFLAGS} $ENV{CPPFLAGS}"
+,
  20         LDDLFLAGS => "$Config{lddlflags} $ENV{LDFLAGS}",
  21    );
  22 print "CCFLAGS =>|$Config{ccflags}|$ENV{CFLAGS}|$ENV{CPPFLAGS}|\n
+";
  23 print "LDDLFLAGS =>|$Config{lddlflags}|$ENV{LDFLAGS}|\n";

this gave the following errors and output:

root@gk-kubuntu-dev:~/dav/Nevada# perl kk.pl
Use of uninitialized value in concatenation (.) or string at /usr/lib/
+perl5/Device/USB.pm line 10.
Use of uninitialized value in concatenation (.) or string at /usr/lib/
+perl5/Device/USB.pm line 10.
Use of uninitialized value in concatenation (.) or string at /usr/lib/
+perl5/Device/USB.pm line 10.
Use of uninitialized value in concatenation (.) or string at /usr/lib/
+perl5/Device/USB.pm line 22.
Use of uninitialized value in concatenation (.) or string at /usr/lib/
+perl5/Device/USB.pm line 22.
CCFLAGS =>|-D_REENTRANT -D_GNU_SOURCE -DDEBIAN -fstack-protector -fno-
+strict-aliasing -pipe -I/usr/local/include -D_LARGEFILE_SOURCE -D_FIL
+E_OFFSET_BITS=64|||
Use of uninitialized value in concatenation (.) or string at /usr/lib/
+perl5/Device/USB.pm line 23.
LDDLFLAGS =>|-shared -L/usr/local/lib -fstack-protector||

This indicates $ENV{CFLAGS},$ENV{CPPFLAGS} and $ENV{LDFLAGS} are uninitialized. I'll need to determine what they are supposed to be. There is not much useful I can find. I wonder why the package did not set the variables it needed. Could it be the botched cpan install? Frankly I have no idea what those things should be. I will try defining them as '' or some value

 9 $ENV{CFLAGS} = 'A';
  10 $ENV{CPPFLAGS} = 'B';
  11 $ENV{LDFLAGS} = 'C';
  12 $ENV{LIBUSB_LIBDIR} = 'D';
  13 $ENV{WINDDK} = 'E';
  14 $ENV{LIBUSB__INCDIR} = 'F';
  15 use Inline ( 
  16         C => "DATA",
  17         ($ENV{LIBUSB_LIBDIR}
  18             ? ( LIBS => "-L\"$ENV{LIBUSB_LIBDIR}\" " .
  19                         ($^O eq 'MSWin32' ? ' -llibusb -L\"$ENV{W
+INDDK}\\lib\\crt\\i386\" -lmsvcrt ' : '-lusb') )
  20             : ( LIBS => '-lusb', )
  21         ),
  22         ($ENV{LIBUSB_INCDIR} ? ( INC => "-I\"$ENV{LIBUSB_INCDIR}\
+"" ) : () ),
  23         NAME => 'Device::USB',
  24         VERSION => '0.35',
  25         CCFLAGS => "$Config{ccflags} $ENV{CFLAGS} $ENV{CPPFLAGS}"
+,
  26         LDDLFLAGS => "$Config{lddlflags} $ENV{LDFLAGS}",
  27    ); 
  28 print "CCFLAGS =>|$Config{ccflags}|$ENV{CFLAGS}|$ENV{CPPFLAGS}|\n
+";
  29 print "LDDLFLAGS =>|$Config{lddlflags}|$ENV{LDFLAGS}|\n";

gives the following errors and output

Use of uninitialized value in concatenation (.) or string at /usr/lib/
+perl5/Device/USB.pm line 16.
Use of uninitialized value in concatenation (.) or string at /usr/lib/
+perl5/Device/USB.pm line 16.
Use of uninitialized value in concatenation (.) or string at /usr/lib/
+perl5/Device/USB.pm line 16.
CCFLAGS =>|-D_REENTRANT -D_GNU_SOURCE -DDEBIAN -fstack-protector -fno-
+strict-aliasing -pipe -I/usr/local/include -D_LARGEFILE_SOURCE -D_FIL
+E_OFFSET_BITS=64|A|B|
LDDLFLAGS =>|-shared -L/usr/local/lib -fstack-protector|C|

from what I can tell, every ENV variable is assigned something, Why are there still 3 concatenation errors?

[Eliya]

I'll need to determine what they are supposed to be.

I don't think they have to be set to anything. The idea presumably is that in case they are set they should be appended to whatever CCFLAGS / LDDLFLAGS options have been determined via %Config...

IMHO, the code should either test if those vars are defined before interpolating them, or disable warnings :)

As for your update:

from what I can tell, every ENV variable is assigned something, Why are there still 3 concatenation errors?

If you set them within the Perl source, you'll need to set them in a BEGIN { } block, because due to the use Inine (...) statement, they're being evaluated at compile time of the Perl code.

...
BEGIN {
  $ENV{CFLAGS} = '';
  $ENV{CPPFLAGS} = '';
  $ENV{LDFLAGS} = '';
}
use Inline (
        ...
        ... 
    );
...

[holandes777]

I don't know if the warnings have anything to do with it, but this code:

  1 use Device::USB;
  2 
  3   $usb = Device::USB->new();
  4   $dev = $usb->find_device('0403', '6001');
  5   printf("Device: %04X:%04X\n", $dev->idVendor(), $dev->idProduct(
+));
  6   $dev->open();
  7   print "Manufactured by: $dev->manufacturer()\n";
  8   print "Product: $dev->product()\n";

gives the concatenation warnings plus:

Can't call method "idVendor" on an undefined value at kk.pl line 5, <D
+ATA> line 1.

Here is the part of dmesg that applies

[349416.436284] usb 4-2: new full-speed USB device number 3 using uhci
+_hcd
[349416.634282] usb 4-2: New USB device found, idVendor=0403, idProduc
+t=6001
[349416.634294] usb 4-2: New USB device strings: Mfr=1, Product=2, Ser
+ialNumber=3
[349416.634302] usb 4-2: Product: FT232R USB UART
[349416.634309] usb 4-2: Manufacturer: FTDI
[349416.634316] usb 4-2: SerialNumber: A100X16Z
[349416.642482] ftdi_sio 4-2:1.0: FTDI USB Serial Device converter det
+ected
[349416.642595] usb 4-2: Detected FT232RL
[349416.642603] usb 4-2: Number of endpoints 2
[349416.642610] usb 4-2: Endpoint 1 MaxPacketSize 64
[349416.642618] usb 4-2: Endpoint 2 MaxPacketSize 64
[349416.642624] usb 4-2: Setting MaxPacketSize 64
[349416.644397] usb 4-2: FTDI USB Serial Device converter now attached
+ to ttyUSB0

OK, SLAM ON THE BRAKES: I jumped onto my Ubuntu 13.04 box and ran the same code. It asked for Device::USB. I installed it correcly by using apt-get install libdevice-usb-perl. The warnings went away and all I still have left is the error: "Can't call method "idVendor" on an undefined value at kk.pl line 5, <DATA> line 1." which is probably due to my lack of knowledge so I have to go study this. Thanks for your help and the lesson here is: IF YOU'RE USING UBUNTU, AVOID CPAN!!"