The following code compiles and prints the message.

#include <stdio.h>

char test_char = 'a';
int test_int = 97;

int main(void)
{
    if (test_char == test_int)
    {
        printf("%s\n", "compared int and char with no issues");
    }
}

Even if we compile it with all possible warnings enabled:

/usr/bin/gcc -Wall -Wextra -Wconversion -Werror -Wfloat-equal -Wmissing-noreturn -Wmissing-prototypes -Wsequence-point -Wshadow -Wstrict-prototypes -Wunreachable-code -pedantic -std=c18 -ggdb3

However, no warning or errors are printed, even though we compare int to char.