Fix array and object patterns in DCE (#233)

Related previous fix - #155 does
the same thing except for a different case - the binding.constant is
true for that and for the current fix binding is not referenced but is
an array pattern or an object pattern.

+ (close #232)

packages/babel-plugin-minify-dead-code-elimination/__tests__/dead-code-elimination-test.js

@@ -2105,6 +2105,35 @@ describe("dce-plugin", () => {
     expect(transform(source)).toBe(expected);
   });
 
+  // https://github.com/babel/babili/issues/232
+  it("should fix issue#232 - array patterns and object patterns with non constant init", () => {
+    const source = unpad(`
+      const a = {
+        lol: input => {
+          const [hello, world] = input.split('|');
+          if (hello === 't' || hello === 'top') {
+            return 'top';
+          }
+          return 'bottom';
+        }
+      };
+    `);
+    const expected = source;
+    expect(transform(source)).toBe(expected);
+  });
+
+  // https://github.com/babel/babili/issues/232
+  it("should fix issue#232 - array & object patterns with non-constant init", () => {
+    const source = unpad(`
+      function foo() {
+        const { bar1, bar2 } = baz();
+        return bar1;
+      }
+    `);
+    const expected = source;
+    expect(transform(source)).toBe(expected);
+  });
+
   it("should preserve variabledeclarations(var) after completion statements", () => {
     const source = unpad(`
       function foo() {

packages/babel-plugin-minify-dead-code-elimination/src/index.js

@@ -196,6 +196,10 @@ module.exports = ({ types: t, traverse }) => {
               if (binding.path.parentPath.node.declarations.length !== 1) {
                 continue;
               }
+              // Bail out for ArrayPattern and ObjectPattern
+              if (!binding.path.get("id").isIdentifier()) {
+                continue;
+              }
 
               binding.path.parentPath.replaceWith(binding.path.node.init);
             } else {