M4 build with DEBUG=1 gives fatal warning in wiznet5k driver

[dhalbert]

When doing make -j4 BOARD=metro_m4_express DEBUG=1, I get this fatal warning:

../../drivers/wiznet5k/internet/dhcp/dhcp.c: In function 'parseDHCPMSG':
../../drivers/wiznet5k/internet/dhcp/dhcp.c:670:9: error: 'type' may be used uninitialized in this function [-Werror=maybe-uninitialized]
  return type;
         ^~~~
cc1: all warnings being treated as errors
../../py/mkrules.mk:55: recipe for target 'build-metro_m4_express/drivers/wiznet5k/internet/dhcp/dhcp.o' failed

Doesn't fail without DEBUG=1. I got around this temporarily by setting type = 0; in its declaration. But the code logic does seem flawed, I think, based on the outer if statement.

@nickzoic

[nickzoic]

Hiya Dan, You're not wrong, and either is gcc :-)

There's a broken logic there, if the packet received is not from DHCP_SERVER_PORT it skips the whole block which sets type. I think your setting of type=0 as a default is not incorrect ... if the packet received is not a DHCP packet it should return an invalid type which will prevent the DHCP_run state machine from continuing on.

The code is a bit of a mess around there ... I'm happy to say this is the WizNet sample code imported into the project, not stuff I wrote!

Seems like the best rewrite would be to just change the logic in parseDHCPMSG to:

if (svr_port != DHCP_SERVER_PORT) return 0;

[dhalbert]

Fixed by #1573 (a long time ago).