Implement assumptions defined in the babel/rfcs#5 RFC

- `mutableTemplateObject` and `ignoreToPrimitiveHint` (#12408)
- `setClassMethods` (#12407)
- `setComputedProperties` (#12490)
- `ignoreFunctionLength` (#12491)
- `noDocumentAll` (#12481)
- `iterableIsArray` and `arrayLikeIsIterable` (#12489)
- `pureGetters` (#12504)
- `skipForOfIteratorClosing` (#12496)
- `objectRestNoSymbols`, `setSpreadProperties` and `pureGetters` (#12505)
- `noNewArrows` (#12613, #12793)
- `setPublicClassFields` and `privateFieldsAsProperties` (#12497)
- `constantReexports` and `enumerableModuleMeta` (#12618)
- `constantSuper`, `superIsCallableConstructor` and `noClassCalls` (#12726)

Co-authored-by: Justin Ridgewell <justin@ridgewell.name>
Co-authored-by: Huáng Jùnliàng <JLHwung@users.noreply.github.com>

packages/babel-plugin-transform-destructuring/test/fixtures/assumption-arrayLikeIsIterable/holes/exec.js

@@ -0,0 +1,6 @@
+var o = { 0: "a", 2: "c", length: 3 };
+
+var [...rest] = o;
+
+expect(rest).toEqual(["a", undefined, "c"]);
+expect(1 in rest).toBe(true); // Not holey

packages/babel-plugin-transform-destructuring/test/fixtures/assumption-arrayLikeIsIterable/length-cropped/exec.js

@@ -0,0 +1,6 @@
+var o = { 0: "a", 1: "b", 2: "c", length: 2 };
+
+var [first, ...rest] = o;
+
+expect(first).toBe("a");
+expect(rest).toEqual(["b"]);

packages/babel-plugin-transform-destructuring/test/fixtures/assumption-arrayLikeIsIterable/options.json

@@ -0,0 +1,9 @@
+{
+  "plugins": [
+    ["external-helpers", { "helperVersion": "7.100.0" }],
+    "transform-destructuring"
+  ],
+  "assumptions": {
+    "arrayLikeIsIterable": true
+  }
+}

packages/babel-plugin-transform-destructuring/test/fixtures/assumption-arrayLikeIsIterable/simple/exec.js

@@ -0,0 +1,6 @@
+var o = { 0: "a", 1: "b", 2: "c", length: 3 };
+
+var [first, ...rest] = o;
+
+expect(first).toBe("a");
+expect(rest).toEqual(["b", "c"]);

packages/babel-plugin-transform-destructuring/test/fixtures/assumption-arrayLikeIsIterable/simple/input.js

@@ -0,0 +1 @@
+var [first, ...rest] = o;

packages/babel-plugin-transform-destructuring/test/fixtures/assumption-arrayLikeIsIterable/simple/output.js

@@ -0,0 +1,4 @@
+var _o = o,
+    _o2 = babelHelpers.maybeArrayLike(babelHelpers.toArray, _o),
+    first = _o2[0],
+    rest = _o2.slice(1);

packages/babel-plugin-transform-destructuring/test/fixtures/assumption-iterableIsArray/basic/input.js

@@ -0,0 +1 @@
+let [foo, bar] = baz;

packages/babel-plugin-transform-destructuring/test/fixtures/assumption-iterableIsArray/basic/output.js

@@ -0,0 +1,3 @@
+let _baz = baz,
+    foo = _baz[0],
+    bar = _baz[1];

packages/babel-plugin-transform-destructuring/test/fixtures/assumption-iterableIsArray/for-in/input.js

@@ -0,0 +1,7 @@
+for (var [name, value] in obj) {
+  print("Name: " + name + ", Value: " + value);
+}
+
+for ([name, value] in obj) {
+  print("Name: " + name + ", Value: " + value);
+}

packages/babel-plugin-transform-destructuring/test/fixtures/assumption-iterableIsArray/for-in/output.js

@@ -0,0 +1,11 @@
+for (var _ref in obj) {
+  var name = _ref[0];
+  var value = _ref[1];
+  print("Name: " + name + ", Value: " + value);
+}
+
+for (var _ref2 in obj) {
+  name = _ref2[0];
+  value = _ref2[1];
+  print("Name: " + name + ", Value: " + value);
+}

packages/babel-plugin-transform-destructuring/test/fixtures/assumption-iterableIsArray/options.json

@@ -0,0 +1,9 @@
+{
+  "plugins": [
+    ["external-helpers", { "helperVersion": "7.100.0" }],
+    "transform-destructuring"
+  ],
+  "assumptions": {
+    "iterableIsArray": true
+  }
+}

packages/babel-plugin-transform-destructuring/test/fixtures/assumption-objectRestNoSymbols/options.json

@@ -0,0 +1,9 @@
+{
+  "plugins": [
+    ["external-helpers", { "helperVersion": "7.100.0"}],
+    "transform-destructuring"
+  ],
+  "assumptions": {
+    "objectRestNoSymbols": true
+  }
+}

packages/babel-plugin-transform-destructuring/test/fixtures/assumption-objectRestNoSymbols/rest-assignment-expression/input.js

@@ -0,0 +1 @@
+({ a, b, ...c } = obj);

packages/babel-plugin-transform-destructuring/test/fixtures/assumption-objectRestNoSymbols/rest-assignment-expression/output.js

@@ -0,0 +1,5 @@
+var _obj = obj;
+a = _obj.a;
+b = _obj.b;
+c = babelHelpers.objectWithoutPropertiesLoose(_obj, ["a", "b"]);
+_obj;

packages/babel-plugin-transform-destructuring/test/fixtures/assumption-objectRestNoSymbols/rest-computed/input.js

@@ -0,0 +1 @@
+let { [a]: b, ...c } = obj;

packages/babel-plugin-transform-destructuring/test/fixtures/assumption-objectRestNoSymbols/rest-computed/output.js

@@ -0,0 +1,4 @@
+let _obj = obj,
+    _a = a,
+    b = _obj[_a],
+    c = babelHelpers.objectWithoutPropertiesLoose(_obj, [_a].map(babelHelpers.toPropertyKey));

packages/babel-plugin-transform-destructuring/test/fixtures/assumption-objectRestNoSymbols/rest-ignore-symbols/exec.js

@@ -0,0 +1,7 @@
+let sym = Symbol();
+
+let { a, ...r } = { a: 1, b: 2, [sym]: 3 };
+
+expect(a).toBe(1);
+expect(r.b).toBe(2);
+expect(sym in r).toBe(false);

packages/babel-plugin-transform-destructuring/test/fixtures/assumption-objectRestNoSymbols/rest-nested/input.js

@@ -0,0 +1 @@
+let { a, nested: { b, c, ...d }, e } = obj;

packages/babel-plugin-transform-destructuring/test/fixtures/assumption-objectRestNoSymbols/rest-nested/output.js

@@ -0,0 +1,7 @@
+let _obj = obj,
+    a = _obj.a,
+    _obj$nested = _obj.nested,
+    b = _obj$nested.b,
+    c = _obj$nested.c,
+    d = babelHelpers.objectWithoutPropertiesLoose(_obj$nested, ["b", "c"]),
+    e = _obj.e;

packages/babel-plugin-transform-destructuring/test/fixtures/assumption-objectRestNoSymbols/rest-var-declaration/input.js

@@ -0,0 +1 @@
+var { a, b, ...c } = obj;

packages/babel-plugin-transform-destructuring/test/fixtures/assumption-objectRestNoSymbols/rest-var-declaration/output.js

@@ -0,0 +1,4 @@
+var _obj = obj,
+    a = _obj.a,
+    b = _obj.b,
+    c = babelHelpers.objectWithoutPropertiesLoose(_obj, ["a", "b"]);