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Handle incorrect destructuring in for loops at parse time #2190

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Merged
gbrail merged 5 commits into from
Dec 7, 2025
Merged

Handle incorrect destructuring in for loops at parse time #2190

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ee13285
Handle incorrect destructuring in for loops at parse time
Dec 2, 2025
cdf9649
spotless
Dec 2, 2025
e0b7485
Dummy commit to trigger the CI
Dec 2, 2025
9e6e590
Added a test case for `let` as well
Dec 3, 2025
84ee3cc
Added more tests
Dec 3, 2025
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10 changes: 10 additions & 0 deletions rhino/src/main/java/org/mozilla/javascript/Parser.java
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Original file line number Diff line number Diff line change
Expand Up @@ -1677,6 +1677,16 @@ && matchToken(Token.NAME, true)
markDestructuring(init);
cond = expr(false); // object over which we're iterating
} else { // ordinary for-loop
// For ordinary for loops, destructuring declarations must have initializers
if (init instanceof VariableDeclaration) {
VariableDeclaration varDecl = (VariableDeclaration) init;
for (VariableInitializer vi : varDecl.getVariables()) {
if (vi.isDestructuring() && vi.getInitializer() == null) {
reportError("msg.destruct.assign.no.init");
}
}
}

mustMatchToken(Token.SEMI, "msg.no.semi.for", true);
if (peekToken() == Token.SEMI) {
// no loop condition
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7 changes: 7 additions & 0 deletions tests/src/test/java/org/mozilla/javascript/tests/ParserTest.java
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Expand Up @@ -1490,6 +1490,13 @@ public void oomOnInvalidInput() {
expectParseErrors("`\\u{8", new String[] {"syntax error"});
}

@Test
public void errorOnInvalidDestructuringDeclaration() {
expectParseErrors(
"for(var {};;) {}",
new String[] {"Missing = in destructuring declaration", "syntax error"});
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@rbri rbri Dec 6, 2025

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As a reader of error messages i like this form more - not sure why the french version has the ' and the english not.

Missing '=' in destructuring declaration

}

private void expectParseErrors(String string, String[] errors) {
parse(string, errors, null, false);
}
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4 changes: 4 additions & 0 deletions tests/testsrc/jstests/harmony/destructuring.js
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Expand Up @@ -29,5 +29,9 @@ assertEquals(obj.b, 345);

assertThrows("(1 ? {} : 490) = 1", SyntaxError);
assertThrows("(1 ? [] : 490) = 1", SyntaxError);
assertThrows("for (var {};;) {}", SyntaxError);
assertThrows("for (let {};;) {}", SyntaxError);
assertThrows("for (var {a};;) {}", SyntaxError);
assertThrows("for (let {a};;) {}", SyntaxError);

"success";