From 4a19575e74beaf4c934581623c3372d084ebfeb7 Mon Sep 17 00:00:00 2001
From: "Alex Lam S.L" <alexlamsl@gmail.com>
Date: Thu, 20 May 2021 11:08:22 +0100
Subject: [PATCH] fix corner case in `conditionals` (#4948)

fixes #4947
---
 lib/compress.js                  |  1 +
 test/compress/optional-chains.js | 30 ++++++++++++++++++++++++++++++
 2 files changed, 31 insertions(+)

diff --git a/lib/compress.js b/lib/compress.js
index 7b8e17b8..8975f47b 100644
--- a/lib/compress.js
+++ b/lib/compress.js
@@ -11412,6 +11412,7 @@ merge(Compressor.prototype, {
 
         function is_tail_equivalent(consequent, alternative) {
             if (consequent.TYPE != alternative.TYPE) return;
+            if (consequent.optional != alternative.optional) return;
             if (consequent instanceof AST_Call) {
                 if (arg_diff(consequent, alternative) != -1) return;
                 return consequent.TYPE != "Call"
diff --git a/test/compress/optional-chains.js b/test/compress/optional-chains.js
index 7f61263c..ced841d2 100644
--- a/test/compress/optional-chains.js
+++ b/test/compress/optional-chains.js
@@ -275,3 +275,33 @@ issue_4928: {
     expect_stdout: "undefined"
     node_version: ">=14"
 }
+
+issue_4947_1: {
+    options = {
+        conditionals: true,
+    }
+    input: {
+        console.log(console.foo ? 42..p : console.bar?.p);
+    }
+    expect: {
+        console.log(console.foo ? 42..p : console.bar?.p);
+    }
+    expect_stdout: "undefined"
+    node_version: ">=14"
+}
+
+issue_4947_2: {
+    options = {
+        conditionals: true,
+    }
+    input: {
+        var log = console.log, fail;
+        log("PASS") ? log(42) : fail?.(42);
+    }
+    expect: {
+        var log = console.log, fail;
+        log("PASS") ? log(42) : fail?.(42);
+    }
+    expect_stdout: "PASS"
+    node_version: ">=14"
+}