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Add workaround for Safari for loop lexical scope bug #567

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merged 4 commits into from Jun 13, 2017
Merged

Add workaround for Safari for loop lexical scope bug #567

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9b61b04
Add workaround for Safari for loop lexical scope bug
btmills Jun 6, 2017
40f0b4c
More idiomatic implementation
btmills Jun 6, 2017
75488d9
More extensive tests
btmills Jun 6, 2017
4665255
Better use path API
btmills Jun 6, 2017
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339 changes: 339 additions & 0 deletions packages/babel-plugin-minify-mangle-names/__tests__/mangle-names-test.js
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Expand Up @@ -1281,4 +1281,343 @@ describe("mangle-names", () => {
`);
expect(transform(source, { topLevel: true }, "module")).toBe(expected);
});

// Safari raises a syntax error for a `let` or `const` declaration in a `for`
// loop initialization that shadows a parent function's parameter.
// https://github.com/babel/babili/issues/559
// https://bugs.webkit.org/show_bug.cgi?id=171041
// https://trac.webkit.org/changeset/217200/webkit/trunk/Source
describe("Safari for loop lexical scope workaround", () => {
it("should permit shadowing in top-level for loops", () => {
const source = unpad(`
var a;

for (a = 0;;);
for (a of x);
for (x of a);
for (a in x);
for (x in a);
for (;; a++);
for (;; a = 1);

for (let b;;);
for (let b of x);
for (const b of x);
for (let b in x);
for (const b in x);
for (let [b, c] of x);
for (const [b, c] of x);
for (let [b, c] in x);
for (const [b, c] in x);
for (let { c: { b: { a } } } = x;;);
for (;; () => {
let a = 1;
});
`);
const expected = unpad(`
var a;

for (a = 0;;);
for (a of x);
for (x of a);
for (a in x);
for (x in a);
for (;; a++);
for (;; a = 1);

for (let a;;);
for (let a of x);
for (const a of x);
for (let a in x);
for (const a in x);
for (let [a, b] of x);
for (const [a, b] of x);
for (let [a, b] in x);
for (const [a, b] in x);
for (let { c: { b: { a: b } } } = x;;);
for (;; () => {
let b = 1;
});
`);
expect(transform(source)).toBe(expected);
});

it("should permit shadowing in nested for loops", () => {
const source = unpad(`
function a(a) {
{
for (a = 0;;);
for (a of x);
for (x of a);
for (a in x);
for (x in a);
for (;; a++);
for (;; a = 1);

for (let a;;);
for (let a of x);
for (const a of x);
for (let a in x);
for (const a in x);
for (let [a, b] of x);
for (const [a, b] of x);
for (let [a, b] in x);
for (const [a, b] in x);
for (let { c: { b: { a } } } = x;;);
for (;; () => {
let a = 1;
});
}
}
`);
const expected = unpad(`
function a(b) {
{
for (b = 0;;);
for (b of x);
for (x of b);
for (b in x);
for (x in b);
for (;; b++);
for (;; b = 1);

for (let b;;);
for (let b of x);
for (const b of x);
for (let b in x);
for (const b in x);
for (let [c, a] of x);
for (const [c, a] of x);
for (let [c, a] in x);
for (const [c, a] in x);
for (let { c: { b: { a: b } } } = x;;);
for (;; () => {
let b = 1;
});
}
}
`);
expect(transform(source)).toBe(expected);
});

it("should not shadow params in function declaration top-level for loops", () => {
const source = unpad(`
function a(a) {
for (a = 0;;);
for (a of x);
for (x of a);
for (a in x);
for (x in a);
for (;; a++);
for (;; a = 1);

for (let b;;);
for (let b of x);
for (const b of x);
for (let b in x);
for (const b in x);
for (let [b, c] of x);
for (const [b, c] of x);
for (let [b, c] in x);
for (const [b, c] in x);
for (let { c: { b: { a } } } = x;;);
for (;; () => {
let a = 1;
});
}
`);
const expected = unpad(`
function a(b) {
for (b = 0;;);
for (b of x);
for (x of b);
for (b in x);
for (x in b);
for (;; b++);
for (;; b = 1);

for (let a;;);
for (let a of x);
for (const a of x);
for (let a in x);
for (const a in x);
for (let [a, d] of x);
for (const [a, d] of x);
for (let [a, d] in x);
for (const [a, d] in x);
for (let { c: { b: { a: c } } } = x;;);
for (;; () => {
let b = 1;
});
}
`);
expect(transform(source)).toBe(expected);
});

it("should not shadow params in function expression top-level for loops", () => {
const source = unpad(`
var a = function (a) {
for (a = 0;;);
for (a of x);
for (x of a);
for (a in x);
for (x in a);
for (;; a++);
for (;; a = 1);

for (let b;;);
for (let b of x);
for (const b of x);
for (let b in x);
for (const b in x);
for (let [b, c] of x);
for (const [b, c] of x);
for (let [b, c] in x);
for (const [b, c] in x);
for (let { c: { b: { a } } } = x;;);
for (;; () => {
let a = 1;
});
};
`);
const expected = unpad(`
var a = function (b) {
for (b = 0;;);
for (b of x);
for (x of b);
for (b in x);
for (x in b);
for (;; b++);
for (;; b = 1);

for (let a;;);
for (let a of x);
for (const a of x);
for (let a in x);
for (const a in x);
for (let [a, d] of x);
for (const [a, d] of x);
for (let [a, d] in x);
for (const [a, d] in x);
for (let { c: { b: { a: c } } } = x;;);
for (;; () => {
let b = 1;
});
};
`);
expect(transform(source)).toBe(expected);
});

it("should not shadow params in arrow function top-level for loops", () => {
const source = unpad(`
var a = (a) => {
for (a = 0;;);
for (a of x);
for (x of a);
for (a in x);
for (x in a);
for (;; a++);
for (;; a = 1);

for (let b;;);
for (let b of x);
for (const b of x);
for (let b in x);
for (const b in x);
for (let [b, c] of x);
for (const [b, c] of x);
for (let [b, c] in x);
for (const [b, c] in x);
for (let { c: { b: { a } } } = x;;);
for (;; () => {
let a = 1;
});
};
`);
const expected = unpad(`
var a = (b) => {
for (b = 0;;);
for (b of x);
for (x of b);
for (b in x);
for (x in b);
for (;; b++);
for (;; b = 1);

for (let a;;);
for (let a of x);
for (const a of x);
for (let a in x);
for (const a in x);
for (let [a, d] of x);
for (const [a, d] of x);
for (let [a, d] in x);
for (const [a, d] in x);
for (let { c: { b: { a: c } } } = x;;);
for (;; () => {
let b = 1;
});
};
`);
expect(transform(source)).toBe(expected);
});

it("should not shadow params in class method top-level for loops", () => {
const source = unpad(`
class a {
a(a) {
for (a = 0;;);
for (a of x);
for (x of a);
for (a in x);
for (x in a);
for (;; a++);
for (;; a = 1);

for (let b;;);
for (let b of x);
for (const b of x);
for (let b in x);
for (const b in x);
for (let [b, c] of x);
for (const [b, c] of x);
for (let [b, c] in x);
for (const [b, c] in x);
for (let { c: { b: { a } } } = x;;);
for (;; () => {
let a = 1;
});
}
}
`);
const expected = unpad(`
class a {
a(b) {
for (b = 0;;);
for (b of x);
for (x of b);
for (b in x);
for (x in b);
for (;; b++);
for (;; b = 1);

for (let a;;);
for (let a of x);
for (const a of x);
for (let a in x);
for (const a in x);
for (let [a, d] of x);
for (const [a, d] of x);
for (let [a, d] in x);
for (const [a, d] in x);
for (let { c: { b: { a: c } } } = x;;);
for (;; () => {
let b = 1;
});
}
}
`);
expect(transform(source)).toBe(expected);
});
});
});
31 changes: 31 additions & 0 deletions packages/babel-plugin-minify-mangle-names/src/scope-tracker.js
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Expand Up @@ -121,6 +121,37 @@ module.exports = class ScopeTracker {
return false;
}

// Safari raises a syntax error for a `let` or `const` declaration in a
// `for` loop initialization that shadows a parent function's parameter.
// https://github.com/babel/babili/issues/559
// https://bugs.webkit.org/show_bug.cgi?id=171041
// https://trac.webkit.org/changeset/217200/webkit/trunk/Source
const maybeDecl = binding.path.parentPath;
const isBlockScoped =
maybeDecl.isVariableDeclaration({ kind: "let" }) ||
maybeDecl.isVariableDeclaration({ kind: "const" });
if (isBlockScoped) {
const maybeFor = maybeDecl.parentPath;
const isForLoopBinding =
maybeFor.isForStatement({ init: maybeDecl.node }) ||
maybeFor.isForXStatement({ left: maybeDecl.node });
if (isForLoopBinding) {
const fnParent = maybeFor.getFunctionParent();
if (fnParent.isFunction({ body: maybeFor.parent })) {
const parentFunctionBinding = this.bindings
.get(fnParent.scope)
.get(next);
if (parentFunctionBinding) {
const parentFunctionHasParamBinding =
parentFunctionBinding.kind === "param";
if (parentFunctionHasParamBinding) {
return false;
}
}
}
}
}

for (let i = 0; i < binding.constantViolations.length; i++) {
const violation = binding.constantViolations[i];
if (tracker.hasBindingOrReference(violation.scope, binding, next)) {
Expand Down