fix corner cases in `templates` (#4610)

1 files changed, 13 insertions, 3 deletions

diff --git a/lib/compress.js b/lib/compress.js
index 7293f9df..dbd3dd35 100644
--- a/lib/compress.js
+++ b/lib/compress.js
@@ -4416,8 +4416,8 @@ merge(Compressor.prototype, {
             }
             var exprs = eval_all(this.expressions, compressor, ignore_side_effects, cached, depth);
             if (!exprs) return this;
-            var ret = decode(this.strings[0]);
             var malformed = false;
+            var ret = decode(this.strings[0]);
             for (var i = 0; i < exprs.length; i++) {
                 ret += exprs[i] + decode(this.strings[i + 1]);
             }
@@ -4426,7 +4426,7 @@ merge(Compressor.prototype, {
             return this;
 
             function decode(str) {
-                return str.replace(/\\(u[0-9a-fA-F]{4}|u\{[0-9a-fA-F]+\}|x[0-9a-fA-F]{2}|[0-9]+|[\s\S])/g, function(match, seq) {
+                return str.replace(/\\(u\{[^}]*\}?|u[\s\S]{0,4}|x[\s\S]{0,2}|[0-9]+|[\s\S])/g, function(match, seq) {
                     var s = decode_escape_sequence(seq);
                     if (typeof s != "string") malformed = true;
                     return s;
@@ -9952,8 +9952,18 @@ merge(Compressor.prototype, {
                     return "\\" + (s == "\r" ? "r" : s);
                 });
                 if (ev.length > node.print_to_string().length + 3) continue;
+                var combined = strs[i] + ev + strs[i + 1];
+                if (typeof make_node(AST_Template, self, {
+                    expressions: [],
+                    strings: [ combined ],
+                    tag: self.tag,
+                }).evaluate(compressor) != typeof make_node(AST_Template, self, {
+                    expressions: [ node ],
+                    strings: strs.slice(i, i + 2),
+                    tag: self.tag,
+                }).evaluate(compressor)) continue;
                 exprs.splice(i, 1);
-                strs.splice(i, 2, strs[i] + ev + strs[i + 1]);
+                strs.splice(i, 2, combined);
             }
         }
         return try_evaluate(compressor, self);