charlit.c: (in function f)
charlit.c:3:11: Variable x initialized to type char, expects int: 'a'
  A character constant is used as an int. Use +charintliteral to allow
  character constants to be used as ints.  (This is safe since the actual type
  of a char constant is int.)
charlit.c:6:7: Incompatible types for + (int, char): x + 'c'
charlit.c:8:10: Return value type char does not match declared type int: 'a'
charlit.c:12:14: Variable u initialized to type int, expects unsigned int: -3
  To ignore signs in type comparisons use +ignoresigns

Finished checking --- 4 code warnings, as expected

charlit.c: (in function f)
charlit.c:3:11: Variable x initialized to type char, expects int: 'a'
  A character constant is used as an int. Use +charintliteral to allow
  character constants to be used as ints.  (This is safe since the actual type
  of a char constant is int.)
charlit.c:4:14: Variable z initialized to type int, expects double: 3
  An int literal is used as any numeric type (including float and long long).
  Use +numliteral to allow int literals to be used as any numeric type.
charlit.c:6:7: Incompatible types for + (int, char): x + 'c'
charlit.c:8:10: Return value type char does not match declared type int: 'a'
charlit.c:11:18: Initial value of s[1] is type int, expects short int: -1
  To ignore type qualifiers in type comparisons use +ignorequals.
charlit.c:12:14: Variable u initialized to type int, expects unsigned int: -3
  To ignore signs in type comparisons use +ignoresigns

Finished checking --- 6 code warnings, as expected

charlit.c: (in function f)
charlit.c:6:3: Assignment of double to int: x = x + 'c' + 2 + z
  To allow all numeric types to match, use +relaxtypes.

Finished checking --- 1 code warning, as expected