Fix eval when types do not match between the lhs and rhs

Fixes #4306.

influxql/ast.go

@@ -3644,16 +3644,16 @@ func evalBinaryExpr(expr *BinaryExpr, m map[string]interface{}) interface{} {
 	// Evaluate if both sides are simple types.
 	switch lhs := lhs.(type) {
 	case bool:
-		rhs, _ := rhs.(bool)
+		rhs, ok := rhs.(bool)
 		switch expr.Op {
 		case AND:
-			return lhs && rhs
+			return ok && (lhs && rhs)
 		case OR:
-			return lhs || rhs
+			return ok && (lhs || rhs)
 		case EQ:
-			return lhs == rhs
+			return ok && (lhs == rhs)
 		case NEQ:
-			return lhs != rhs
+			return ok && (lhs != rhs)
 		}
 	case float64:
 		// Try the rhs as a float64 or int64

influxql/ast_test.go

@@ -1013,10 +1013,12 @@ func TestEval(t *testing.T) {
 		// Boolean literals.
 		{in: `true AND false`, out: false},
 		{in: `true OR false`, out: true},
+		{in: `false = 4`, out: false},
 
 		// String literals.
 		{in: `'foo' = 'bar'`, out: false},
 		{in: `'foo' = 'foo'`, out: true},
+		{in: `'' = 4`, out: false},
 
 		// Regex literals.
 		{in: `'foo' =~ /f.*/`, out: true},