fix `inline` on duplicate argument names (#2698)

2 files changed, 26 insertions, 1 deletions

diff --git a/lib/compress.js b/lib/compress.js
index 604371fb..56176e55 100644
--- a/lib/compress.js
+++ b/lib/compress.js
@@ -4012,7 +4012,7 @@ merge(Compressor.prototype, {
             for (var len = fn.argnames.length, i = len; --i >= 0;) {
                 var name = fn.argnames[i];
                 var value = self.args[i];
-                if (name.__unused) {
+                if (name.__unused || scope.var_names()[name.name]) {
                     if (value) {
                         expressions.unshift(value);
                     }
diff --git a/test/compress/functions.js b/test/compress/functions.js
index 888c6e3c..e6c4301c 100644
--- a/test/compress/functions.js
+++ b/test/compress/functions.js
@@ -1646,3 +1646,28 @@ issue_2663_3: {
         "reset",
     ]
 }
+
+duplicate_argnames: {
+    options = {
+        inline: true,
+        reduce_vars: true,
+        side_effects: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        var a = "PASS";
+        function f(b, b, b) {
+            b && (a = "FAIL");
+        }
+        f(0, console);
+        console.log(a);
+    }
+    expect: {
+        var a = "PASS";
+        console, b && (a = "FAIL");
+        var b;
+        console.log(a);
+    }
+    expect_stdout: "PASS"
+}