Given this code:

include <stdio.h>

include <string>

void test()
{
std::string mystr("Hello World");
char c;

c = mystr[1];
printf("char: %c", (int)c);

}

Lint produces this output:

c = mystr[1];

main.cc 9 Info 747: Significant prototype coercion (arg. no. 1) int to
unsigned log

It seems unreasonable for this message to be emitted for a literal. The compiler obviously will convert to the properly sized argument.