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fix: fill_match_arms hangs on a tuple of large enums

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This commit is contained in:
Dawer 2021-05-20 23:50:27 +05:00
parent 63d317c71a
commit 570eff6552
1 changed files with 14 additions and 2 deletions
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16
crates/ide_assists/src/handlers/fill_match_arms.rs
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@ -84,14 +84,26 @@ pub(crate) fn fill_match_arms(acc: &mut Assists, ctx: &AssistContext) -> Option<
};
missing_pats.peekable()
} else if let Some(enum_defs) = resolve_tuple_of_enum_def(&ctx.sema, &expr) {
let mut n_arms = 1;
let variants_of_enums: Vec<Vec<ExtendedVariant>> = enum_defs
.into_iter()
.map(|enum_def| enum_def.variants(ctx.db()))
.inspect(|variants| n_arms *= variants.len())
.collect();
// When calculating the match arms for a tuple of enums, we want
// to create a match arm for each possible combination of enum
// values. The `multi_cartesian_product` method transforms
// Vec<Vec<EnumVariant>> into Vec<(EnumVariant, .., EnumVariant)>
// where each tuple represents a proposed match arm.
let missing_pats = enum_defs
// A number of arms grows very fast on even a small tuple of large enums.
// We skip the assist beyond an arbitrary threshold.
if n_arms > 256 {
return None;
}
let missing_pats = variants_of_enums
.into_iter()
.map(|enum_def| enum_def.variants(ctx.db()))
.multi_cartesian_product()
.map(|variants| {
let patterns =