[SMTChecker] Support unary inc/dec for array/mapping access

test/libsolidity/smtCheckerTests/operators/unary_add.sol

@@ -0,0 +1,17 @@
+pragma experimental SMTChecker;
+
+contract C
+{
+	function f() public pure {
+		uint x = 2;
+		uint a = ++x;
+		assert(x == 3);
+		assert(a == 3);
+		uint b = x++;
+		assert(x == 4);
+		// Should fail.
+		assert(b < 3);
+	}
+}
+// ----
+// Warning: (194-207): Assertion violation happens here

test/libsolidity/smtCheckerTests/operators/unary_add_array.sol

@@ -0,0 +1,18 @@
+pragma experimental SMTChecker;
+
+contract C
+{
+	uint[] array;
+	function f(uint x) public {
+		array[x] = 2;
+		uint a = ++array[x];
+		assert(array[x] == 3);
+		assert(a == 3);
+		uint b = array[x]++;
+		assert(array[x] == 4);
+		// Should fail.
+		assert(b < 3);
+	}
+}
+// ----
+// Warning: (240-253): Assertion violation happens here

test/libsolidity/smtCheckerTests/operators/unary_add_mapping.sol

@@ -0,0 +1,18 @@
+pragma experimental SMTChecker;
+
+contract C
+{
+	mapping (uint => uint) map;
+	function f(uint x) public {
+		map[x] = 2;
+		uint a = ++map[x];
+		assert(map[x] == 3);
+		assert(a == 3);
+		uint b = map[x]++;
+		assert(map[x] == 4);
+		// Should fail.
+		assert(b < 3);
+	}
+}
+// ----
+// Warning: (244-257): Assertion violation happens here

test/libsolidity/smtCheckerTests/operators/unary_sub.sol

@@ -0,0 +1,17 @@
+pragma experimental SMTChecker;
+
+contract C
+{
+	function f() public pure {
+		uint x = 5;
+		uint a = --x;
+		assert(x == 4);
+		assert(a == 4);
+		uint b = x--;
+		assert(x == 3);
+		// Should fail.
+		assert(b > 4);
+	}
+}
+// ----
+// Warning: (194-207): Assertion violation happens here

test/libsolidity/smtCheckerTests/operators/unary_sub_array.sol

@@ -0,0 +1,18 @@
+pragma experimental SMTChecker;
+
+contract C
+{
+	uint[] array;
+	function f(uint x) public {
+		array[x] = 5;
+		uint a = --array[x];
+		assert(array[x] == 4);
+		assert(a == 4);
+		uint b = array[x]--;
+		assert(array[x] == 3);
+		// Should fail.
+		assert(b > 4);
+	}
+}
+// ----
+// Warning: (240-253): Assertion violation happens here

test/libsolidity/smtCheckerTests/operators/unary_sub_mapping.sol

@@ -0,0 +1,18 @@
+pragma experimental SMTChecker;
+
+contract C
+{
+	mapping (uint => uint) map;
+	function f(uint x) public {
+		map[x] = 5;
+		uint a = --map[x];
+		assert(map[x] == 4);
+		assert(a == 4);
+		uint b = map[x]--;
+		assert(map[x] == 3);
+		// Should fail.
+		assert(b > 4);
+	}
+}
+// ----
+// Warning: (244-257): Assertion violation happens here