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Attempts to fix issue #266 #317

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Attempts to fix issue #266 #317

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keyehzy
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@keyehzy keyehzy commented May 18, 2021

We do this by treating else ( separately. If else is followed by
a (conditional + block) pattern, maybe the intention was to use an
else if instead and a warning is emitted.

We do this by treating `else (` separately. If `else` is followed by
a (conditional + block) pattern, maybe the intention was to use an
`else if` instead and a warning is emitted.
src/quick-lint-js/error.h Outdated Show resolved Hide resolved
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Included function to check if the expression is side-effect-free,
although I have to check more carefully if the cases are done
correctly.

The cases that explicitly not side-effect-free are: dot, index,
function and named_functions.

From testing I found that arrow functions invalidate placing an `if`,
even if their children are side-effect-free. This case is treated
seperately. Maybe there are more cases where this happens and I must
think it through.
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Hmm, this issue is more complicated than I thought! Lots of edge cases.

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This function has been refactored and tested for edge cases.
src/parse.cpp Outdated
auto entry = ast->object_entry(i);
if (entry.property.has_value()) {
if (this->has_potential_side_effects(*entry.property) ||
this->has_potential_side_effects(entry.value))
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Shouldn't we check entry.value regardless of entry.property.has_value()?

test/test-parse-expression.cpp Outdated Show resolved Hide resolved
}

{
test_parser p(u8"import foo;"_sv);
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Blocking: This has syntax errors. I think you meant this:

import(foo);

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This one is resolved.

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Blocking: if (a) { b; } else (c) { d; } is still an issue (false negative).

Other than that, this commit looks bueno!

TEST(test_parse, else_with_implicit_if) {
{
spy_visitor v;
padded_string code(u8"if (a) { b; } else (c)\n{ d; }"_sv);
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We should check v.visits so we know we recovered from the error correctly.

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src/parse.cpp Outdated
auto entry = ast->object_entry(i);
if (entry.property.has_value()) {
if (has_potential_side_effects(*entry.property) ||
has_potential_side_effects(entry.value))
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Shouldn't we check entry.value regardless of entry.property.has_value()?

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break;
}

this->consume_semicolon();
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Blocking: This looks like it's in the wrong spot. Won't skipping a semicolon here cause the following code to have the error_else_with_conditional_missing_if warning?

if (a) { b; } else (c);
{ d; }

I think we need to consume a semicolon after the check on line 2546.

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Agreed!

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Please add a test for this example.

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Comment on lines +2124 to +2125
return has_potential_side_effects(*entry.property) ||
has_potential_side_effects(entry.value);
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Blocking: You're only checking the first entry which has a value! We should check all entries.

break;
}

this->consume_semicolon();
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Please add a test for this example.

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strager commented Jan 5, 2022

There are merge conflicts because parser::parse_and_visit_if's body has been moved to src/quick-lint-js/parse-statement-inl.h.

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2 participants