From a9d0ddea9d6812ede67a1c318dc8a7f8d9a764a4 Mon Sep 17 00:00:00 2001
From: "Alex Lam S.L" <alexlamsl@gmail.com>
Date: Wed, 23 Feb 2022 21:04:04 +0000
Subject: [PATCH] fix corner case in `directives` & `expression` (#5369)

fixes #5368
---
 lib/compress.js             | 31 ++++++++++++++++---------------
 test/compress/directives.js | 29 +++++++++++++++++++++++++++++
 2 files changed, 45 insertions(+), 15 deletions(-)

diff --git a/lib/compress.js b/lib/compress.js
index 3e5e9194b7..998626ab19 100644
--- a/lib/compress.js
+++ b/lib/compress.js
@@ -227,9 +227,7 @@ Compressor.prototype.exposed = function(def) {
 Compressor.prototype.compress = function(node) {
     node = node.resolve_defines(this);
     node.hoist_exports(this);
-    if (this.option("expression")) {
-        node.process_expression(true);
-    }
+    if (this.option("expression")) node.process_expression(true);
     var merge_vars = this.options.merge_vars;
     var passes = +this.options.passes || 1;
     var min_count = 1 / 0;
@@ -261,9 +259,7 @@ Compressor.prototype.compress = function(node) {
             }
         }
     }
-    if (this.option("expression")) {
-        node.process_expression(false);
-    }
+    if (this.option("expression")) node.process_expression(false);
     return node;
 };
 
@@ -308,12 +304,19 @@ Compressor.prototype.compress = function(node) {
     AST_Scope.DEFMETHOD("process_expression", function(insert, transform) {
         var self = this;
         var tt = new TreeTransformer(function(node) {
-            if (insert && node instanceof AST_SimpleStatement) {
-                return transform ? transform(node) : make_node(AST_Return, node, { value: node.body });
-            }
-            if (!insert && node instanceof AST_Return) {
-                return transform ? transform(node) : make_node(AST_SimpleStatement, node, {
-                    body: node.value || make_node(AST_UnaryPrefix, node, {
+            if (insert) {
+                if (node instanceof AST_Directive) node = make_node(AST_SimpleStatement, node, {
+                    body: make_node(AST_String, node, node),
+                });
+                if (node instanceof AST_SimpleStatement) {
+                    return transform ? transform(node) : make_node(AST_Return, node, { value: node.body });
+                }
+            } else if (node instanceof AST_Return) {
+                if (transform) return transform(node);
+                var value = node.value;
+                if (value instanceof AST_String) return make_node(AST_Directive, node, value);
+                return make_node(AST_SimpleStatement, node, {
+                    body: value || make_node(AST_UnaryPrefix, node, {
                         operator: "void",
                         expression: make_node(AST_Number, node, { value: 0 }),
                     }),
@@ -334,9 +337,7 @@ Compressor.prototype.compress = function(node) {
                 }
             } else if (node instanceof AST_If) {
                 node.body = node.body.transform(tt);
-                if (node.alternative) {
-                    node.alternative = node.alternative.transform(tt);
-                }
+                if (node.alternative) node.alternative = node.alternative.transform(tt);
             } else if (node instanceof AST_With) {
                 node.body = node.body.transform(tt);
             }
diff --git a/test/compress/directives.js b/test/compress/directives.js
index 6c85fded70..6e3fd13138 100644
--- a/test/compress/directives.js
+++ b/test/compress/directives.js
@@ -129,3 +129,32 @@ valid_after_invalid_2: {
     }
     expect_stdout: "undefined"
 }
+
+issue_5368_1: {
+    options = {
+        directives: true,
+        expression: true,
+    }
+    input: {
+        "foo";
+    }
+    expect: {
+        "foo";
+    }
+}
+
+issue_5368_2: {
+    options = {
+        directives: true,
+        expression: true,
+    }
+    input: {
+        "foo";
+        (function() {
+            "bar";
+        })();
+    }
+    expect: {
+        (function() {})();
+    }
+}