Allow compilation in recent ARDUINO ESP32 RELEASES 2.0.1 and 2.0.2…

[Martin-Laclaustra]

… by excluding AudioGeneratorMIDI
This is a temporary solution that drops MIDI support to make this library available in most recent ESP32-Arduino cores, which have a compiler bug that renders this code incompatible.

(Temporary) Fix for:
#498
#464
#440

[Martin-Laclaustra]

I see that "core_version.h" is not available in all contexts (I verified it was in ESP32 and ESP8266). May be this proposal serves as inspiration for some to find a general solution. (Mine works fine locally in my computer)

[Martin-Laclaustra]

I fixed the error arising from "core_version.h" not being available in all contexts.
Currently some tests fail, but the errors seem unrelated to this pull request.
I hope that this can be merged and this library be made available again for ESP32 in the most recent core releases.

[earlephilhower]

The issue is the GCC version, so why not just use

#if __GNUC__ == 8
// Do not build, GCC8 has a compiler bug
#else
....

That way if V2.0.3 comes out w/the same compiler it's still good.

[earlephilhower]

Oh, and thanks for the PR!

[Martin-Laclaustra]

Done!

[earlephilhower]

Thanks!

[shuai132]

Should we remove the code now? or make it configable.

#if __GNUC__ == 8
// Do not build, GCC8 has a compiler bug
#else
....

Because MIDI works on gcc8.4 patch3. and my esp8266 use gcc8 too. We can't use midi if keep it.

This is esp32:

• framework-arduinoespressif32 @ 3.20004.220818 (2.0.4)
• tool-esptoolpy @ 1.30300.0 (3.3.0)
• toolchain-riscv32-esp @ 8.4.0+2021r2-patch3

And when esp8266 use 10.3, GNUC is equals 8 too!!!

 - framework-arduinoespressif8266 @ 3.30002.0 (3.0.2) 
 - tool-esptool @ 1.413.0 (4.13) 
 - tool-esptoolpy @ 1.30000.201119 (3.0.0) 
 - toolchain-xtensa @ 2.100300.210717 (10.3.0)

 ➜  .platformio packages/toolchain-xtensa/bin/xtensa-lx106-elf-gcc --version
xtensa-lx106-elf-gcc (GCC) 10.3.0
Copyright (C) 2020 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

@earlephilhower

[earlephilhower]

@shuai132, I am not seeing GNUC as 8 in 10.3. Here is my output from the ESP8266 core:

echo | ~/Arduino/hardware/esp8266com/esp8266/tools/xtensa-lx106-elf/bin/xtensa-lx106-elf-gcc -dM -E - | grep GNU
#define __GNUC_PATCHLEVEL__ 0
#define __GNUC__ 10
#define __GNUC_STDC_INLINE__ 1
#define __GNUC_MINOR__ 3

I would be fine adding additional conditions to the #if. Can you run the same command line with your working GCC 8.4 so we can see what defines come out? Maybe we can change it to

#if (__GNUC__ == 8) && (__GNUC_MINOR__ < 4)
// GCC bug prevents compilation
#else
...

[shuai132]

Sorry, 10.3 is correct, it's my IDE(clion) issue(host compiler's notice).
I'm using platformio:
toolchain path: ~/.platformio/packages/toolchain-xtensa/bin

➜  bin echo | ./xtensa-lx106-elf-gcc -dM -E - | grep GNU
#define __GNUC_PATCHLEVEL__ 0
#define __GNUC__ 10
#define __GNUC_STDC_INLINE__ 1
#define __GNUC_MINOR__ 3

BTW:
we do need like this:

#if (__GNUC__ == 8) && (__GNUC_MINOR__ < 4)

I have tested it, it works on my esp32 compiler.

[earlephilhower]

@shuai132 great. Would you like to make the PR adding the && (__GNUC_MINOR__ < 4) to the condition?

[shuai132]

Thanks，my pleasure,
PR: #567