fix corner cases in unused (#5075)

fixes #5074

lib/compress.js

@@ -7132,13 +7132,12 @@ merge(Compressor.prototype, {
                         prop_keys = [];
                         prop_map = Object.create(null);
                         value.properties.forEach(function(prop, index) {
-                            if (prop instanceof AST_ObjectSetter) return;
                             if (prop instanceof AST_Spread) return prop_map = false;
                             var key = prop.key;
                             if (key instanceof AST_Node) key = key.evaluate(compressor, true);
                             if (key instanceof AST_Node) {
                                 prop_map = false;
-                            } else if (prop_map) {
+                            } else if (prop_map && !(prop instanceof AST_ObjectSetter)) {
                                 prop_map[key] = prop;
                             }
                             prop_keys[index] = key;
@@ -7184,7 +7183,13 @@ merge(Compressor.prototype, {
                                 if (drop_keys && !(key in drop_keys)) {
                                     if (mapped) {
                                         drop_keys[key] = mapped;
-                                        if (value === null) prop_map[key] = false;
+                                        if (value === null) {
+                                            prop_map[key] = mapped.key instanceof AST_Node
+                                                && make_node(AST_ObjectKeyVal, mapped, {
+                                                    key: mapped.key,
+                                                    value: make_node(AST_Number, mapped, { value: 0 }),
+                                                });
+                                        }
                                     } else {
                                         drop_keys[key] = true;
                                     }
@@ -7201,25 +7206,26 @@ merge(Compressor.prototype, {
                     });
                     value = save_value;
                     drop = save_drop;
-                    if (drop_keys && prop_keys) value.properties = value.properties.filter(function(prop, index) {
+                    if (drop_keys && prop_keys) value.properties = List(value.properties, function(prop, index) {
-                        if (prop instanceof AST_ObjectSetter) return false;
+                        if (prop instanceof AST_Spread) return prop;
-                        if (prop instanceof AST_Spread) return true;
                         var key = prop_keys[index];
-                        if (key instanceof AST_Node) return true;
+                        if (key instanceof AST_Node) return prop;
                         if (key in drop_keys) {
                             var mapped = drop_keys[key];
-                            if (!mapped) return true;
+                            if (!mapped) return prop;
-                            if (mapped === prop) return prop_map[key];
+                            if (mapped === prop) return prop_map[key] || List.skip;
                         } else if (node.rest) {
-                            return true;
+                            return prop;
                         }
                         var trimmed = prop.value.drop_side_effect_free(compressor);
-                        if (!trimmed) {
+                        if (trimmed) {
-                            if (!(prop.key instanceof AST_Node)) return false;
-                            trimmed = make_node(AST_Number, prop, { value: 0 });
-                        }
                             prop.value = trimmed;
-                        return true;
+                            return prop;
+                        }
+                        return prop.key instanceof AST_Node ? make_node(AST_ObjectKeyVal, prop, {
+                            key: prop.key,
+                            value: make_node(AST_Number, prop, { value: 0 }),
+                        }) : List.skip;
                     });
                     if (value && !node.rest) switch (properties.length) {
                       case 0:

test/compress/destructured.js

@@ -1154,7 +1154,7 @@ drop_hole: {
     node_version: ">=6"
 }
 
-keep_key: {
+keep_key_1: {
     options = {
         evaluate: true,
         side_effects: true,
@@ -1174,6 +1174,39 @@ keep_key: {
     node_version: ">=6"
 }
 
+keep_key_2: {
+    options = {
+        evaluate: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        var { 42: a } = { [(console.log("PASS"), 42)](){} };
+    }
+    expect: {
+        var {} = { [(console.log("PASS"), 42)]: 0 };
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+keep_key_2_pure_getters: {
+    options = {
+        evaluate: true,
+        pure_getters: "strict",
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        var { 42: a } = { [(console.log("PASS"), 42)](){} };
+    }
+    expect: {
+        console.log("PASS");
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
 keep_reference: {
     options = {
         reduce_vars: true,
@@ -2816,3 +2849,102 @@ issue_5071_2: {
     expect_stdout: "PASS"
     node_version: ">=6"
 }
+
+issue_5074_getter: {
+    options = {
+        evaluate: true,
+        side_effects: true,
+        unused: true,
+    }
+    input: {
+        ({} = { get [(console.log("PASS"), 42)]() {} });
+    }
+    expect: {
+        ({} = { [(console.log("PASS"), 42)]: 0 });
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+issue_5074_getter_pure_getters: {
+    options = {
+        evaluate: true,
+        pure_getters: "strict",
+        side_effects: true,
+        unused: true,
+    }
+    input: {
+        ({} = { get [(console.log("PASS"), 42)]() {} });
+    }
+    expect: {
+        console.log("PASS");
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+issue_5074_setter: {
+    options = {
+        evaluate: true,
+        side_effects: true,
+        unused: true,
+    }
+    input: {
+        ({} = { set [(console.log("PASS"), 42)](v) {} });
+    }
+    expect: {
+        ({} = { [(console.log("PASS"), 42)]: 0 });
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+issue_5074_setter_pure_getters: {
+    options = {
+        evaluate: true,
+        pure_getters: "strict",
+        side_effects: true,
+        unused: true,
+    }
+    input: {
+        ({} = { set [(console.log("PASS"), 42)](v) {} });
+    }
+    expect: {
+        console.log("PASS");
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+issue_5074_method: {
+    options = {
+        evaluate: true,
+        side_effects: true,
+        unused: true,
+    }
+    input: {
+        ({} = { [(console.log("PASS"), 42)]() {} });
+    }
+    expect: {
+        ({} = { [(console.log("PASS"), 42)]: 0 });
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+issue_5074_method_pure_getters: {
+    options = {
+        evaluate: true,
+        pure_getters: "strict",
+        side_effects: true,
+        unused: true,
+    }
+    input: {
+        ({} = { [(console.log("PASS"), 42)]() {} });
+    }
+    expect: {
+        console.log("PASS");
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}