cores: replace max and min macros with imports from std

[yoursunny]

fixes #1734

[yoursunny]

TravisCI is unhappy. I tried the two examples from AzureIoT library locally (Arduino IDE 1.8.5 on Windows), and they all build correctly. I couldn't figure out what's wrong.

[stickbreaker]

Looks like the problem is a redefinition of round() in Arduino.h

/home/travis/build/espressif/arduino-esp32/tools/xtensa-esp32-elf/xtensa-esp32-elf/include/c++/5.2.0/bits/random.tcc: In member function 'void std::poisson_distribution<_IntType>::param_type::_M_initialize()':
/home/travis/arduino_ide/hardware/espressif/esp32/cores/esp32/Arduino.h:78:22: error: expected unqualified-id before '(' token
#define round(x) ((x)>=0?(long)((x)+0.5):(long)((x)-0.5))

[yoursunny]

There's a usage of std::round.
https://github.com/jmattsson/nodemcu-prebuilt-toolchains/blob/3f4f3890f97fe01870770dd5a624ee0823d71a13/esp32/xtensa-esp32-elf/include/c%2B%2B/5.2.0/bits/random.tcc#L1408

Looks like I also need to replace #define round with using std::round.

[yoursunny]

I’ve completed the round changes. Hopefully this can be reviewed soon.

[me-no-dev]

Hey! Thanks for going through this :) It was somewhere on the list of things to do...

[radiumray]

hi, we got this issue, the test code is below:

uint8_t a = 2;
uint16_t b = 6;
uint16_t c = 0;
void setup() {
  // put your setup code here, to run once:
  Serial.begin(115200);
  c = min(a, b);
  Serial.println(c);
}

void loop() {
  // put your main code here, to run repeatedly:
}

this code will got error:
no matching function for call to 'min(uint8_t&, uint16_t&)'

we think this change cause this issue:
1e4bf14#diff-50967a1be7f16cc780e7a8501c5d6c34

[yoursunny]

no matching function for call to 'min(uint8_t&, uint16_t&)'

In C++, std::min requires both argument to have the same type. Otherwise, it cannot select an overload propery. See https://en.cppreference.com/w/cpp/algorithm/min
In your case, you should write: c = std::min<uint16_t>(a, b); or c = std::min(static_cast<uint16t_t>(a), b);