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Sema: Small matchPackExpansionTypes cleanup #78320

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Merged
merged 2 commits into from
Jan 2, 2025
Merged

Sema: Small matchPackExpansionTypes cleanup #78320

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352bddd
[NFC] CSSimplify: Small `matchPackExpansionTypes` cleanup
AnthonyLatsis Dec 11, 2024
0b20482
CSSimplify: Continue matching instead of adding constraint in `matchP…
AnthonyLatsis Dec 13, 2024
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49 changes: 20 additions & 29 deletions lib/Sema/CSSimplify.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2405,40 +2405,31 @@ ConstraintSystem::matchPackExpansionTypes(PackExpansionType *expansion1,
}
}

// If both sides are expanded or neither side is, just match them
auto *const pack1 = pattern1->getAs<PackType>();
auto *const pack2 = pattern2->getAs<PackType>();

// If both sides are expanded or neither side is, proceed to matching them
// directly.
if (pattern1->is<PackType>() == pattern2->is<PackType>()) {
return matchTypes(pattern1, pattern2, kind, flags, locator);

// If the right hand side is expanded, we have something like
// Foo<$T0>... vs Pack{Foo<Int>, Foo<String>}...; We're going to
// bind $T0 to Pack{Int, String}.
} else if (!pattern1->is<PackType>() && pattern2->is<PackType>()) {
if (auto *pack2 = pattern2->getAs<PackType>()) {
if (auto *pack1 = replaceTypeVariablesWithFreshPacks(
*this, pattern1, pack2, locator)) {
addConstraint(kind, pack1, pack2, locator);
return getTypeMatchSuccess();
}
// Otherwise, we have something like `Foo<$T0>` vs.
// `Pack{Foo<Int>, Foo<String>}` or vice versa.
// We're going to bind `$T0` to `Pack{Int, String}` and unfold `Foo<$T0>` into
// `Pack{Foo<$T3>, Foo<$T4>} first.
if ((bool)pack1 != (bool)pack2) {
if (pack1) {
pattern2 =
replaceTypeVariablesWithFreshPacks(*this, pattern2, pack1, locator);
} else {
pattern1 =
replaceTypeVariablesWithFreshPacks(*this, pattern1, pack2, locator);
}

return getTypeMatchFailure(locator);

// If the left hand side is expanded, we have something like
// Pack{Foo<Int>, Foo<String>}... vs Foo<$T0>...; We're going to
// bind $T0 to Pack{Int, String}.
} else {
assert(pattern1->is<PackType>() && !pattern2->is<PackType>());
if (auto *pack1 = pattern1->getAs<PackType>()) {
if (auto *pack2 = replaceTypeVariablesWithFreshPacks(
*this, pattern2, pack1, locator)) {
addConstraint(kind, pack1, pack2, locator);
return getTypeMatchSuccess();
}
if (!(pattern1 && pattern2)) {
return getTypeMatchFailure(locator);
}

return getTypeMatchFailure(locator);
}

// Continue matching.
return matchTypes(pattern1, pattern2, kind, flags, locator);
}

/// Check where a representation is a subtype of another.
Expand Down