Created attachment 977 [details]
Proposed patch

../src/devices/wimax/simple-ofdm-wimax-phy.cc:800:3: error: 
      comparison of unsigned expression >= 0 is always true
      [-Wtautological-compare]
  NS_ASSERT_MSG (m_paddingBits >= 0, "Size of padding bytes < 0");
                 ~~~~~~~~~~~~~ ^  ~

Assertion can never fail - should make the assertion on the subtraction instead of the final value (which is silently cast back to uint.

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../src/devices/wimax/bs-scheduler-simple.cc:168:35: error: ][0.820s]
      comparison of unsigned expression >= 0 is always true
      [-Wtautological-compare]
          while (availableSymbols >= 0 && ...
                 ~~~~~~~~~~~~~~~~ ^  ~

For this one, lines 193-196 may not trigger if availableSymbols overflows. Lines 162 may cause the overflow. The else-block at line 166 cannot overflow - no code branch can decrease availableSymbols to below 0. The 1st while condition on line 168 can therefore be removed.

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../src/devices/wimax/wimax-mac-queue.cc:175:11: error: comparison of
      unsigned expression >= 0 is always true
      [-Wtautological-compare]
          NS_ASSERT_MSG (m_nrDataPackets >= 0,
                         ~~~~~~~~~~~~~~~ ^  ~
(Also on line 182)

Need to swap the decrement operation and the assertion (catch error before overflow)