Small message types for Mail objects cause errors?

[SakuGlumoff]

Description

• Type: Bug | Question

Target
NUCLEO_F429ZI

I am using a Mail object for one of my threads for inter-thread communications.
The message type struct basically contains two enums (result and command).

typedef enum {
  MESSAGE_ERROR = -1,

  MESSAGE_OK = 0
} MessageResult;

typedef enum {
  COMMAND_ACTION_1,
  COMMAND_ACTION_2,
  COMMAND_ACTION_3
} MessageCommand;

typedef struct {
   MessageResult result;
   MessageCommand command;
} message_t;

I have been testing the functionality in the online compiler where my main() function is very simple as to just show that the program runs without problems:

static Mail<message_t, 10> mailBox;
int main() {
    
    int i = 0;
    while (1) {
        printf("asd %d\r\n", i++);
    }
    
    return 0;
}

However, when I compile the program (mbed online compiler), the program output to the serial port is:

mbed assertation failed: _id, file: /extras/mbed-os.lib/rtos/MemoryPool.h, line 58

Now, when I add some padding to lengthen the message struct like this:

typedef struct {
   MessageResult result;
   MessageCommand command;
   union {
       bool val;
       uint16_t val2;
   } padding;
} message_t;

The program runs correctly with output:

asd 5966
asd 5967
asd 5968
asd 5969
asd 5970
asd 5971
...

Do you have any idea as to what causes this?
I have also tested this with the offline compiler using the GCC_ARM toolchain - same results, although the serial output is:

Memory Pool 0x0 error -10

[SenRamakri]

I'm able to reproduce this issue, looking into this.

[SakuGlumoff]

Thank you.

[bulislaw]

Should be fixed internally in #4941

[bulislaw]

Closing as #4941 was merged. Please reopen if you still have issues.