Comparison of integer expression of different signedness.

[TylerBird]

Subject of the issue

Getting a warning caused by comparison of different data types

Your workbench

• STM32
• LoRa ST (EU868
• Wired via I2C
• The power supply is 3V3
• I'm using PlatformIO

Output warning:

.pio\libdeps\disco_l072cz_lrwan1\SparkFun External EEPROM Arduino Library\src\SparkFun_External_EEPROM.cpp: In member function 'void ExternalEEPROM::read(uint32_t, uint8_t*, uint16_t)':
.pio\libdeps\disco_l072cz_lrwan1\SparkFun External EEPROM Arduino Library\src\SparkFun_External_EEPROM.cpp:159:50: warning: comparison of integer expressions of different signedness: 'long unsigned int' and 'int' [-Wsign-compare]
  159 |         if (0xFFFF - (eepromLocation + received) < amtToRead) //0xFFFF - 0xFFFA < 32
      |             ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~

Steps to reproduce

The datatype of amtToRead can be set to uint16_t since the var is initialized with bufferSize-received where bufferSize also is a uint16_t and substracted by another value. So amtToRead could never get bigger then uint16_t

Expected behavior

In file SparkFun_External_EEPROM.cpp in line 148 change the data type from int to uint16_t.

Actual behavior

In case the amtToRead var becomes negative, there is an overflow and an unintended behavior could happen.