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repl: do not cause side effects in tab completion · nodejs/node@0340fe9 · GitHub

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Commit 0340fe9

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addaleax
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targos
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repl: do not cause side effects in tab completion
A number of recent changes to the REPL tab completion logic have introduced the ability for completion to cause side effects, specifically, calling arbitrary functions or variable assignments/updates. This was first introduced in 0722023 and the problem exacerbated in 8ba66c5. Our team noticed this because our tests started failing when attempting to update to Node.js 20.19.5. Some recent commits, such as 1093f38 or 6945337, have messages or PR descriptions that imply the intention to avoid side effects, which I can can generally be agreed upon is in line with the expectations that a user has of autocomplete functionality. However, some of the tests introduced in those commts specifically verify that side effects *can* happen under specific circunmstances. I am assuming here that this is unintentional, and the corresponding tests have been removed/replaced in this commit. Fixes: #59731 Fixes: #58903 Refs: #58709 Refs: #58775 Refs: #57909 Refs: #58891 PR-URL: #59774 Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de> Reviewed-By: Michaël Zasso <targos@protonmail.com> Reviewed-By: Dario Piotrowicz <dario.piotrowicz@gmail.com>
1 parent 68732cf commit 0340fe9

4 files changed

Lines changed: 73 additions & 8 deletions

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‎lib/repl.js‎

Lines changed: 16 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -1754,10 +1754,25 @@ function findExpressionCompleteTarget(code) {
17541754
return findExpressionCompleteTarget(argumentCode);
17551755
}
17561756

1757+
// Walk the AST for the current block of code, and check whether it contains any
1758+
// statement or expression type that would potentially have side effects if evaluated.
1759+
let isAllowed = true;
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const disallow = () => isAllowed = false;
1761+
acornWalk.simple(lastBodyStatement, {
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ForInStatement: disallow,
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ForOfStatement: disallow,
1764+
CallExpression: disallow,
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AssignmentExpression: disallow,
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UpdateExpression: disallow,
1767+
});
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if (!isAllowed) {
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return null;
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}
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// If any of the above early returns haven't activated then it means that
17581773
// the potential complete target is the full code (e.g. the code represents
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// a simple partial identifier, a member expression, etc...)
1760-
return code;
1775+
return code.slice(lastBodyStatement.start, lastBodyStatement.end);
17611776
}
17621777

17631778
/**

‎test/parallel/test-repl-completion-on-getters-disabled.js‎

Lines changed: 0 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -61,10 +61,6 @@ describe('REPL completion in relation of getters', () => {
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test(`completions are generated for properties that don't trigger getters`, () => {
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runCompletionTests(
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`
64-
function getFooKey() {
65-
return "foo";
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}
67-
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const fooKey = "foo";
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const keys = {
@@ -90,7 +86,6 @@ describe('REPL completion in relation of getters', () => {
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["objWithGetters[keys['foo key']].b", ["objWithGetters[keys['foo key']].bar"]],
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['objWithGetters[fooKey].b', ['objWithGetters[fooKey].bar']],
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["objWithGetters['f' + 'oo'].b", ["objWithGetters['f' + 'oo'].bar"]],
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['objWithGetters[getFooKey()].b', ['objWithGetters[getFooKey()].bar']],
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]);
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});
9691

‎test/parallel/test-repl-tab-complete-getter-error.js‎

Lines changed: 1 addition & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -27,7 +27,6 @@ async function runTest() {
2727

2828
await new Promise((resolve, reject) => {
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replServer.eval(`
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const getNameText = () => "name";
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const foo = { get name() { throw new Error(); } };
3231
`, replServer.context, '', (err) => {
3332
if (err) {
@@ -38,7 +37,7 @@ async function runTest() {
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});
3938
});
4039

41-
['foo.name.', 'foo["name"].', 'foo[getNameText()].'].forEach((test) => {
40+
['foo.name.', 'foo["name"].'].forEach((test) => {
4241
replServer.complete(
4342
test,
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common.mustCall((error, data) => {

‎test/parallel/test-repl-tab-complete-nosideeffects.js‎

Lines changed: 56 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,56 @@
1+
'use strict';
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const common = require('../common');
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const ArrayStream = require('../common/arraystream');
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const { describe, it } = require('node:test');
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const assert = require('assert');
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8+
const repl = require('repl');
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function prepareREPL() {
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const input = new ArrayStream();
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const replServer = repl.start({
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prompt: '',
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input,
15+
output: process.stdout,
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allowBlockingCompletions: true,
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});
18+
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// Some errors are passed to the domain, but do not callback
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replServer._domain.on('error', assert.ifError);
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return { replServer, input };
23+
}
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function getNoResultsFunction() {
26+
return common.mustSucceed((data) => {
27+
assert.deepStrictEqual(data[0], []);
28+
});
29+
}
30+
31+
describe('REPL tab completion without side effects', () => {
32+
const setup = [
33+
'globalThis.counter = 0;',
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'function incCounter() { return counter++; }',
35+
'const arr = [{ bar: "baz" }];',
36+
];
37+
// None of these expressions should affect the value of `counter`
38+
for (const code of [
39+
'incCounter().',
40+
'a=(counter+=1).foo.',
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'a=(counter++).foo.',
42+
'for((counter)of[1])foo.',
43+
'for((counter)in{1:1})foo.',
44+
'arr[incCounter()].b',
45+
]) {
46+
it(`does not evaluate with side effects (${code})`, async () => {
47+
const { replServer, input } = prepareREPL();
48+
input.run(setup);
49+
50+
replServer.complete(code, getNoResultsFunction());
51+
52+
assert.strictEqual(replServer.context.counter, 0);
53+
replServer.close();
54+
});
55+
}
56+
});

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