fix corner case in conditionals (#4948)

fixes #4947

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"

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"
+}