ESP8266 Community Forum

- Sun Jan 31, 2016 4:40 am #40046 Hi there,

I'm (java expert, no c++ expert) trying to port a library from avr arduino to esp8266 arduino.

The library makes more or leass heavily use of static variables and class instances (singleton pattern).

I faced two problems:

1) duplicate method definition using templaes

I got the error:

Code: Select allerror: duplicate explicit instantiation of 'e_KnxDeviceStatus KnxDevice::read(byte, T&) [with T = unsigned char; byte = unsigned char]' [-fpermissive]
 template e_KnxDeviceStatus KnxDevice::read <unsigned char>(byte objectIndex, unsigned char& returnedValue);

Adding "-fpermissive" to the flags in platform.txt solved the issue:

compiler.cpreprocessor.flags=-fpermissive -D__ets__ -DICACHE_FLASH -U__STRICT_ANSI__ "-I{compiler.sdk.path}/include"

Maybe the code can be modified to overcome this issue without adding the permissive flag. but as the avr arduino had no problems with it: How about adding this flag by default to the platform?

2) After solving the issue with the duplicate error, I faced this error:

/tmp/buildbb4fcaf6d0d53941d44b612db42cc988.tmp/sketch/KnxDevice_PushButton_with_Programming.ino.cpp.o:(.text._Z9knxEventsh+0x10): undefined reference to `e_KnxDeviceStatus KnxDevice::write<bool>(unsigned char, bool)'
/tmp/buildbb4fcaf6d0d53941d44b612db42cc988.tmp/sketch/KnxDevice_PushButton_with_Programming.ino.cpp.o: In function `knxEvents(unsigned char)':
/tmp/arduino_bb4fcaf6d0d53941d44b612db42cc988/KnxDevice_PushButton_with_Programming.ino:35: undefined reference to `e_KnxDeviceStatus KnxDevice::write<bool>(unsigned char, bool)'
/tmp/buildbb4fcaf6d0d53941d44b612db42cc988.tmp/libraries/KonnektingDeviceLibrary/KnxTpUart.cpp.o:(.text._ZN9KnxTpUart6RXTaskEv+0x14): undefined reference to `__cxa_guard_acquire'
/tmp/buildbb4fcaf6d0d53941d44b612db42cc988.tmp/libraries/KonnektingDeviceLibrary/KnxTpUart.cpp.o:(.text._ZN9KnxTpUart6RXTaskEv+0x18): undefined reference to `__cxa_guard_release'
/tmp/buildbb4fcaf6d0d53941d44b612db42cc988.tmp/libraries/KonnektingDeviceLibrary/KnxTpUart.cpp.o:(.text._ZN9KnxTpUart6RXTaskEv+0x37): undefined reference to `__cxa_guard_acquire'
/tmp/buildbb4fcaf6d0d53941d44b612db42cc988.tmp/libraries/KonnektingDeviceLibrary/KnxTpUart.cpp.o: In function `KnxTpUart::RXTask()':
/media/bigdisk/Programming/Arduino/Sketchbook/libraries/KonnektingDeviceLibrary/KnxTpUart.cpp:515: undefined reference to `__cxa_guard_release'
collect2: error: ld returned 1 exit status

I alread create an issue on github for both problems: https://github.com/esp8266/Arduino/issues/1498

User Links2004 pointed me to issue #500: https://github.com/esp8266/Arduino/issues/500

I compared the code example with my library, but did not find an exact pattern match.
I followed a link to related issue #574 where Links2004 suggested:

yes, replace all places where static is initialized by an function / or class in a function.
like this:

Code: Select allint EthernetClass::begin(uint8_t *mac_address)
{
  static DhcpClass s_dhcp;
in this specific case this will work:

static DhcpClass s_dhcp;
int EthernetClass::begin(uint8_t *mac_address)
{

but how to rework it can be different from static case to static case.

Changing the library accoring to this hint, would be equal to re-write the library. And that is not really practical.
Back on issue #500: User iggr stated.

Actually the original code is fine — C++ standard guarantees that local static initializer will be called exactly once, first time the function is executed. We just need to add __cxa_guard* implementations.

As I said at the beginning: I'm a Java expert, with little knowledge in C/C++. I have no idea what this "__cxa_guard* implementation" is about. All I found out: Those methods are defined in cxxabi.h, and a few of them are "dummy-implemented" in abi.cpp (https://github.com/esp8266/Arduino/blob ... 66/abi.cpp). Almost all of them will result in a "panic()" call... So, do they work? Or will the just throw a panic?

So, for my issue nr. 2): Is there a chance to get this solved (implement these methods to get the library working)? I would be glad if so. I even would donate to get this solved.

All further details can be found on my github issue: https://github.com/esp8266/Arduino/issues/1498

And if there is some information/detail missing: please let me know.

Best regards,
Alex

- Tue Feb 02, 2016 9:28 am #40266 Any expert here who can comment on this?

- Mon Feb 08, 2016 4:02 am #40671 The guard-issue is fixed: https://github.com/esp8266/Arduino/pull/1586
Donation is on the way

- Mon Feb 08, 2016 5:22 am #40672 Issue #1 is also fixed, but this time by myself...

the code uses "boolean" and not "bool". Changing the code from "boolean" to "bool" fixed the error. No idea why, but it works now.