Merge branch 'master' into feature/codeql

CHANGELOG.md

@@ -1,5 +1,9 @@
 # Changelog
 
+## v5.25.0
+ - Regex properties added to reserved property mangler (#1471)
+ - `pure_new` option added to drop unused `new` expressions.
+
 ## v5.24.0
  - Improve formatting performance in V8 by keeping a small work string and a large output string
 

README.md

@@ -820,6 +820,9 @@ If you happen to need the source map as a raw object, set `sourceMap.asObject` t
   Specify `"strict"` to treat `foo.bar` as side-effect-free only when
   `foo` is certain to not throw, i.e. not `null` or `undefined`.
 
+- `pure_new` (default: `false`) -- Set to `true` to assume `new X()` never has
+  side effects.
+
 - `reduce_vars` (default: `true`) -- Improve optimization on variables assigned with and
   used as constant values.
 

lib/compress/index.js

@@ -251,6 +251,7 @@ class Compressor extends TreeWalker {
             properties    : !false_by_default,
             pure_getters  : !false_by_default && "strict",
             pure_funcs    : null,
+            pure_new      : false,
             reduce_funcs  : !false_by_default,
             reduce_vars   : !false_by_default,
             sequences     : !false_by_default,

lib/compress/inference.js

@@ -828,6 +828,9 @@ AST_Call.DEFMETHOD("is_callee_pure", function(compressor) {
             return true;
         }
     }
+    if ((this instanceof AST_New) && compressor.option("pure_new")) {
+        return true;
+    }
     return !!has_annotation(this, _PURE) || !compressor.pure_funcs(this);
 });
 

package.json

@@ -4,7 +4,7 @@
   "homepage": "https://terser.org",
   "author": "Mihai Bazon <mihai.bazon@gmail.com> (http://lisperator.net/)",
   "license": "BSD-2-Clause",
-  "version": "5.24.0",
+  "version": "5.25.0",
   "engines": {
     "node": ">=10"
   },

test/compress/new.js

@@ -116,3 +116,22 @@ dot_parenthesis_2: {
     expect_exact: "console.log(typeof new function(){Math.random()}.constructor);"
     expect_stdout: "function"
 }
+
+new_pure: {
+    options = {
+        pure_new: true,
+        defaults: true,
+    }
+    input: {
+        new function() {};
+        (new function() {
+            this.pass = () => console.log("PASS");
+        }).pass();
+    }
+    expect: {
+        (new function() {
+            this.pass = () => console.log("PASS");
+        }).pass();
+    }
+    expect_stdout: "PASS"
+}

tools/terser.d.ts

@@ -50,6 +50,7 @@ export interface CompressOptions {
     passes?: number;
     properties?: boolean;
     pure_funcs?: string[];
+    pure_new?: boolean;
     pure_getters?: boolean | 'strict';
     reduce_funcs?: boolean;
     reduce_vars?: boolean;