v2.8.3 does not compile anymore with gcc 4.8.2 (used by Tasmota for ESP8266)

[s-hadinger]

Version/revision of the library used

v2.8.3

Describe the bug

Tasmota uses gcc 4.8.2 for ESP8266 which does not support __VA_OPT__ extension.

Is there a way to rewrite the COND(<define_to_test>[||/&&<more_define>...], <true_result>, <false_result>) macro without __VA_OPT__?

Below is the first compilation error resported (there are many afterwards):

In file included from lib/lib_basic/IRremoteESP8266/IRremoteESP8266/src/IRtext.cpp:14:0:
lib/lib_basic/IRremoteESP8266/IRremoteESP8266/src/IRmacros.h:22:40: error: pasting ")" and "THING" does not give a valid preprocessing token
 #define VA_TEST_P(a, ...) __VA_OPT__(NO)##THING
                                        ^
lib/lib_basic/IRremoteESP8266/IRremoteESP8266/src/IRmacros.h:23:22: note: in expansion of macro 'VA_TEST_P'
 #define VA_TEST(...) VA_TEST_P(__VA_ARGS__)
                      ^
lib/lib_basic/IRremoteESP8266/IRremoteESP8266/src/IRmacros.h:24:19: note: in expansion of macro 'VA_TEST'
 #define NEGATE(a) VA_TEST(a, a)
                   ^
lib/lib_basic/IRremoteESP8266/IRremoteESP8266/src/IRmacros.h:25:51: note: in expansion of macro 'NEGATE'
 #define COND_P(cond, a, b) STUFF(a, cond)STUFF(b, NEGATE(cond))
                                                   ^
lib/lib_basic/IRremoteESP8266/IRremoteESP8266/src/IRmacros.h:26:33: note: in expansion of macro 'COND_P'
 #define COND(cond, a, b) EXPAND(COND_P(cond, a, b))
                                 ^
lib/lib_basic/IRremoteESP8266/IRremoteESP8266/src/IRtext.cpp:292:5: note: in expansion of macro 'COND'
     COND(DECODE_RC5 || SEND_RC5,

To Reproduce

Compilation error with gcc 4.8.2

Example code used

Expected behaviour

Output of raw data from [IRrecvDumpV2.ino]

What brand/model IR demodulator are you using?

Circuit diagram and hardware used (if applicable)

I have followed the steps in the [Troubleshooting Guide]

Has this library/code previously worked as expected for you?

Yes, 2.8.2 compiled fine

Other useful information

[Jason2866]

@tonhuisman Please have a look, i think EspEasy will fail to compile too.

[tonhuisman]

Best solution would be to upgrade the gcc version, but I assume that's not an option, probably related to the Arduino framework version in use. (same problem at ESPEasy).

Simplest alternative is to add a test if __VA_OPT__ is supported, and define the COND() macro (set) based on that, but that won't give the real solution, as I would have used it like that already.

I can add a different macro PP_NARG() (also from the interwebz) to check if __VA_OPT__ can be used:

#if PP_NARG(__VA_OPT__(,)) != 2
#define COND(cond, a, b) a
#else
...// existing COND definition
#endif

This 'avoids' removing the not available protocols from the protocol-list, and also the check if a protocol is not available, but I assume that is currently only used in ESPEasy, as I designed it for use there.

[s-hadinger]

This would be a good solution. If I understand well, ESP8266 will have the same behavior as before, while ESP32 (with gcc8) will have better features.

I'm not aware of the protocol-list. What is it?

[tonhuisman]

I'm not aware of the protocol-list. What is it?

There is a function to fetch all supported protocols. After using the change I made, it will return ? if a protocol is not available, so you can check if the length is > 1 and only show the enabled protocols (used in ESPEasy to reduce build size by excluding unneeded protocols in a Custom build)

[tonhuisman]

I think I've fixed it (see linked PR), with the side-note/limitation that the list of protocols contains all names, even when not included, but only for older compilers that don't support the __VA_OPT__ macro.

NB: This feature was introduced to reduce code-size as much as possible.

[s-hadinger]

Thanks a lot. I confirm it's compiling fine on both esp8266 and esp32

[crankyoldgit]

v2.8.4 has been released which contains the fix.