compress `RegExp()` in `unsafe` (#2735)

1 files changed, 21 insertions, 0 deletions

diff --git a/lib/compress.js b/lib/compress.js
index 0f15eb7e..28d6a1c4 100644
--- a/lib/compress.js
+++ b/lib/compress.js
@@ -3869,6 +3869,27 @@ merge(Compressor.prototype, {
                     operator: "!"
                 }).optimize(compressor);
                 break;
+              case "RegExp":
+                var params = [];
+                if (all(self.args, function(arg) {
+                    var value = arg.evaluate(compressor);
+                    params.unshift(value);
+                    return arg !== value;
+                })) {
+                    try {
+                        return best_of(compressor, self, make_node(AST_RegExp, self, {
+                            value: RegExp.apply(RegExp, params),
+                        }));
+                    } catch (ex) {
+                        compressor.warn("Error converting {expr} [{file}:{line},{col}]", {
+                            expr: self.print_to_string(),
+                            file: self.start.file,
+                            line: self.start.line,
+                            col: self.start.col
+                        });
+                    }
+                }
+                break;
             } else if (exp instanceof AST_Dot) switch(exp.property) {
               case "toString":
                 if (self.args.length == 0) return make_node(AST_Binary, self, {