fix inline on nested substitutions (#2533)

fixes #2531

lib/compress.js

@@ -2268,6 +2268,10 @@ merge(Compressor.prototype, {
             self.walk(new TreeWalker(function(node) {
                 if (!result) return true;
                 if (node instanceof AST_SymbolRef) {
+                    if (self.inlined) {
+                        result = false;
+                        return true;
+                    }
                     var def = node.definition();
                     if (member(def, self.enclosed)
                         && !self.variables.has(def.name)) {

test/compress/functions.js

@@ -554,3 +554,102 @@ issue_2428: {
         "PASS",
     ]
 }
+
+issue_2531_1: {
+    options = {
+        evaluate: true,
+        inline: true,
+        reduce_funcs: true,
+        reduce_vars: true,
+        unused: true,
+    }
+    input: {
+        function outer() {
+            function inner(value) {
+                function closure() {
+                    return value;
+                }
+                return function() {
+                    return closure();
+                };
+            }
+            return inner("Hello");
+        }
+        console.log("Greeting:", outer()());
+    }
+    expect: {
+        function outer() {
+            return function(value) {
+                return function() {
+                    return value;
+                };
+            }("Hello");
+        }
+        console.log("Greeting:", outer()());
+    }
+    expect_stdout: "Greeting: Hello"
+}
+
+issue_2531_2: {
+    options = {
+        evaluate: true,
+        inline: true,
+        passes: 2,
+        reduce_funcs: true,
+        reduce_vars: true,
+        unused: true,
+    }
+    input: {
+        function outer() {
+            function inner(value) {
+                function closure() {
+                    return value;
+                }
+                return function() {
+                    return closure();
+                };
+            }
+            return inner("Hello");
+        }
+        console.log("Greeting:", outer()());
+    }
+    expect: {
+        function outer() {
+            return function() {
+                return "Hello";
+            };
+        }
+        console.log("Greeting:", outer()());
+    }
+    expect_stdout: "Greeting: Hello"
+}
+
+issue_2531_3: {
+    options = {
+        evaluate: true,
+        inline: true,
+        passes: 2,
+        reduce_funcs: true,
+        reduce_vars: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        function outer() {
+            function inner(value) {
+                function closure() {
+                    return value;
+                }
+                return function() {
+                    return closure();
+                };
+            }
+            return inner("Hello");
+        }
+        console.log("Greeting:", outer()());
+    }
+    expect: {
+        console.log("Greeting:", "Hello");
+    }
+    expect_stdout: "Greeting: Hello"
+}