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				https://github.com/ethereum/solidity
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			25 lines
		
	
	
		
			779 B
		
	
	
	
		
			Solidity
		
	
	
	
	
	
			
		
		
	
	
			25 lines
		
	
	
		
			779 B
		
	
	
	
		
			Solidity
		
	
	
	
	
	
type U8 is uint8;
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using {add as +} for U8 global;
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function add(U8 x, U8 y) pure returns (U8) {
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    return U8.wrap(U8.unwrap(x) + U8.unwrap(y)); // FIXME: should detect possible overflow here
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}
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contract C {
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    U8 x = U8.wrap(254);
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    function inc() public {
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        x = x + U8.wrap(1); // FIXME: should detect possible overflow here
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    }
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    function check() view public {
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        U8 y = x;
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        assert(U8.unwrap(y) < 256);
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    }
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}
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// ====
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// SMTEngine: all
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// ----
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// Warning 6756: (274-288): User-defined operators are not yet supported by SMTChecker. This invocation of operator + has been ignored, which may lead to incorrect results.
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// Info 1391: CHC: 1 verification condition(s) proved safe! Enable the model checker option "show proved safe" to see all of them.
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