Merge pull request #6371 from ethereum/smt_variable_usage_function_calls

[SMTChecker] Merge SSA state vars properly

test/libsolidity/smtCheckerTests/functions/function_inside_branch_modify_state_var.sol

@@ -0,0 +1,19 @@
+pragma experimental SMTChecker;
+
+contract C
+{
+	uint x;
+	function f() internal {
+		require(x < 10000);
+		x = x + 1;
+	}
+	function g(bool b) public {
+		x = 0;
+		if (b)
+			f();
+		// Should fail for `b == true`.
+		assert(x == 0);
+	}
+}
+// ----
+// Warning: (209-223): Assertion violation happens here

test/libsolidity/smtCheckerTests/functions/function_inside_branch_modify_state_var_2.sol

@@ -0,0 +1,18 @@
+pragma experimental SMTChecker;
+
+contract C
+{
+	uint x;
+	function f() internal {
+		require(x < 10000);
+		x = x + 1;
+	}
+	function g(bool b) public {
+		x = 0;
+		if (b)
+			f();
+		else
+			f();
+		assert(x == 1);
+	}
+}

test/libsolidity/smtCheckerTests/functions/function_inside_branch_modify_state_var_3.sol

@@ -0,0 +1,28 @@
+pragma experimental SMTChecker;
+
+contract C
+{
+	uint x;
+	function f() internal {
+		require(x < 10000);
+		x = x + 1;
+	}
+	function g(bool b) public {
+		x = 0;
+		if (b)
+			f();
+		// Should fail for `b == true`.
+		assert(x == 0);
+	}
+	function h(bool b) public {
+		x = 0;
+		if (!b)
+			f();
+		// Should fail for `b == false`.
+		assert(x == 0);
+	}
+
+}
+// ----
+// Warning: (209-223): Assertion violation happens here
+// Warning: (321-335): Assertion violation happens here