[cfe-dev] tautological-compare for unsigned chars

[Robert Lytton]

Hi,

Am I right in thinking that char types are not checked for tautological-compare?

I started to look at  SemaChecking.cpp   CheckTrivialUnsignedComparison()
Is this the right place?

example code:
    void test(void) {
      unsigned char c = (unsigned char)-1;
      if(c >= 0) test();
      unsigned int i = (unsigned int)-1;
      if(i >= 0) test();
    }
gives the warning:
    char_signedness.c:6:8: warning: comparison of unsigned expression >= 0 is always true [-Wtautological-compare]
      if(i >= 0) test();
         ~ ^  ~
    1 warning generated.


I'm happy to do the work, but would welcome some input!

robert

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