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Diagnose Circular Typealiases in Protocols #138

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Merged
merged 2 commits into from
Dec 7, 2015
Merged

Diagnose Circular Typealiases in Protocols #138

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11cce3b
Diagnose circular type aliases in protocol declarations
CodaFi Dec 4, 2015
9b68f5f
Bump decl bits
CodaFi Dec 4, 2015
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13 changes: 12 additions & 1 deletion include/swift/AST/Decl.h
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Original file line number Diff line number Diff line change
Expand Up @@ -573,8 +573,11 @@ class alignas(1 << DeclAlignInBits) Decl {
unsigned : NumTypeDeclBits;

unsigned Recursive : 1;

/// Whether or not this declaration is currently being type-checked.
unsigned BeingTypeChecked : 1;
};
enum { NumAssociatedTypeDeclBits = NumTypeDeclBits + 1 };
enum { NumAssociatedTypeDeclBits = NumTypeDeclBits + 2 };
static_assert(NumAssociatedTypeDeclBits <= 32, "fits in an unsigned");

class ImportDeclBitfields {
Expand Down Expand Up @@ -2605,6 +2608,14 @@ class AssociatedTypeDecl : public AbstractTypeParamDecl {
void setIsRecursive() { AssociatedTypeDeclBits.Recursive = true; }
bool isRecursive() { return AssociatedTypeDeclBits.Recursive; }

/// Whether the declaration is currently being validated.
bool isBeingTypeChecked() { return AssociatedTypeDeclBits.BeingTypeChecked; }

/// Toggle whether or not the declaration is being validated.
void setIsBeingTypeChecked(bool ibt = true) {
AssociatedTypeDeclBits.BeingTypeChecked = ibt;
}

static bool classof(const Decl *D) {
return D->getKind() == DeclKind::AssociatedType;
}
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17 changes: 16 additions & 1 deletion lib/Sema/TypeCheckDecl.cpp
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Expand Up @@ -3173,7 +3173,7 @@ class DeclChecker : public DeclVisitor<DeclChecker> {
TAD->getUnderlyingTypeLoc().setInvalidType(TC.Context);
} else if (TAD->getDeclContext()->isGenericContext()) {
TAD->setInterfaceType(
TC.getInterfaceTypeFromInternalType(TAD->getDeclContext(),
TC.getInterfaceTypeFromInternalType(TAD->getDeclContext(),
TAD->getType()));
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Unnecessary whitespace change here.

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I would go as far as saying that white space had meaning and now is gone. It was enforcing that getInterfaceTypeFromInternalType is an argument passed to setInterfaceType.
It's merged now but would you oppose adding this space back in? I'm not one for PR (just to correct this) with such minimal changes but...

}

Expand All @@ -3192,6 +3192,19 @@ class DeclChecker : public DeclVisitor<DeclChecker> {
}

void visitAssociatedTypeDecl(AssociatedTypeDecl *assocType) {
if (assocType->isBeingTypeChecked()) {

if (!assocType->hasType()) {
assocType->setInvalid();
assocType->overwriteType(ErrorType::get(TC.Context));
}

TC.diagnose(assocType->getLoc(), diag::circular_type_alias, assocType->getName());
return;
}

assocType->setIsBeingTypeChecked();

TC.checkDeclAttributesEarly(assocType);
if (!assocType->hasAccessibility())
assocType->setAccessibility(assocType->getProtocol()->getFormalAccess());
Expand All @@ -3205,6 +3218,8 @@ class DeclChecker : public DeclVisitor<DeclChecker> {
defaultDefinition.setInvalidType(TC.Context);
}
TC.checkDeclAttributes(assocType);

assocType->setIsBeingTypeChecked(false);
}

bool checkUnsupportedNestedGeneric(NominalTypeDecl *NTD) {
Expand Down
4 changes: 4 additions & 0 deletions test/decl/protocol/req/recursion.swift
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Expand Up @@ -16,3 +16,7 @@ public struct S<A: P where A.T == S<A>> {}
class X<T where T == X> { // expected-error{{same-type requirement makes generic parameter 'T' non-generic}}
var type: T { return self.dynamicType } // expected-error{{use of undeclared type 'T'}}
}

protocol Y {
typealias Z = Z // expected-error{{type alias 'Z' circularly references itself}}
}