Fix negative denominator in boost::rational during exponentiation.

ethereum · Nov 5, 2018 · 1530632 · 1530632
1 parent 88aee34
commit 1530632
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diff --git a/libsolidity/ast/Types.cpp b/libsolidity/ast/Types.cpp
@@ -1145,9 +1145,14 @@ TypePointer RationalNumberType::binaryOperatorResult(Token _operator, TypePointe
 
 				if (exp >= 0)
 					value = rational(numerator, denominator);
-				else
+				else {
 					// invert
-					value = rational(denominator, numerator);
+					// due to a bug in certain versions of boost the denominator cannot be negative
+					if (numerator < 0)
+						value = rational(-denominator, -numerator);
+					else
+						value = rational(denominator, numerator);
+				}
 			}
 			break;
 		}

diff --git a/test/libsolidity/syntaxTests/types/rational_negative_numerator_negative_exp.sol b/test/libsolidity/syntaxTests/types/rational_negative_numerator_negative_exp.sol
@@ -0,0 +1,5 @@
+contract C {
+    function f() public pure returns (int) {
+        return (-1 / 2) ** -1;
+    }
+}