account for eval & with in reduce_vars (#2441)

fixes #2440

lib/compress.js

@@ -317,7 +317,7 @@ merge(Compressor.prototype, {
                         d.fixed = false;
                     } else if (d.fixed) {
                         var value = node.fixed_value();
-                        if (unused && value && d.references.length == 1) {
+                        if (value && ref_once(d)) {
                             if (value instanceof AST_Lambda) {
                                 d.single_use = d.scope === node.scope
                                         && !(d.orig[0] instanceof AST_SymbolFunarg)
@@ -385,7 +385,7 @@ merge(Compressor.prototype, {
                     } else {
                         d.fixed = node;
                         mark(d, true);
-                        if (unused && d.references.length == 1) {
+                        if (ref_once(d)) {
                             d.single_use = d.scope === d.references[0].scope
                                 || node.is_constant_expression(d.references[0].scope);
                         }
@@ -564,7 +564,7 @@ merge(Compressor.prototype, {
         function reset_def(def) {
             def.direct_access = false;
             def.escaped = false;
-            if (def.scope.uses_eval) {
+            if (def.scope.uses_eval || def.scope.uses_with) {
                 def.fixed = false;
             } else if (!compressor.exposed(def)) {
                 def.fixed = undefined;
@@ -576,6 +576,10 @@ merge(Compressor.prototype, {
             def.single_use = undefined;
         }
 
+        function ref_once(def) {
+            return unused && !def.scope.uses_eval && !def.scope.uses_with && def.references.length == 1;
+        }
+
         function is_immutable(value) {
             if (!value) return false;
             return value.is_constant()
@@ -4237,10 +4241,7 @@ merge(Compressor.prototype, {
             if (fixed instanceof AST_Defun) {
                 d.fixed = fixed = make_node(AST_Function, fixed, fixed);
             }
-            if (compressor.option("unused")
-                && fixed
-                && d.references.length == 1
-                && d.single_use) {
+            if (fixed && d.single_use) {
                 var value = fixed.optimize(compressor);
                 return value === fixed ? fixed.clone(true) : value;
             }

test/compress/reduce_vars.js

@@ -3542,3 +3542,115 @@ issue_2423_6: {
         "2",
     ]
 }
+
+issue_2440_eval_1: {
+    options = {
+        reduce_vars: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        function foo() {
+            return bar();
+        }
+        baz = {
+            quux: foo
+        };
+        exec = function() {
+            return eval("foo()");
+        };
+    }
+    expect: {
+        function foo() {
+            return bar();
+        }
+        baz = {
+            quux: foo
+        };
+        exec = function() {
+            return eval("foo()");
+        };
+    }
+}
+
+issue_2440_eval_2: {
+    options = {
+        reduce_vars: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        baz = {
+            quux: foo
+        };
+        exec = function() {
+            return eval("foo()");
+        };
+        function foo() {
+            return bar();
+        }
+    }
+    expect: {
+        baz = {
+            quux: foo
+        };
+        exec = function() {
+            return eval("foo()");
+        };
+        function foo() {
+            return bar();
+        }
+    }
+}
+
+issue_2440_with_1: {
+    options = {
+        reduce_vars: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        function foo() {
+            return bar();
+        }
+        baz = {
+            quux: foo
+        };
+        with (o) whatever();
+    }
+    expect: {
+        function foo() {
+            return bar();
+        }
+        baz = {
+            quux: foo
+        };
+        with (o) whatever();
+    }
+}
+
+issue_2440_with_2: {
+    options = {
+        reduce_vars: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        baz = {
+            quux: foo
+        };
+        with (o) whatever();
+        function foo() {
+            return bar();
+        }
+    }
+    expect: {
+        baz = {
+            quux: foo
+        };
+        with (o) whatever();
+        function foo() {
+            return bar();
+        }
+    }
+}