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3a5a540b4c
Extend GenericSignature to be able to answer queries about the requirements placed on dependent types, e.g, are the class-bound, to what protocols must they conform, etc. Implement this using a lazily-created ArchetypeBuilder on the canonical generic signature. NFC and as-yet-untested; this is staging for reducing our dependence on the "all archetypes" list. Swift SVN r32340
477 lines
16 KiB
C++
477 lines
16 KiB
C++
//===--- GenericSignature.cpp - Generic Signature AST ---------------------===//
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//
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// This source file is part of the Swift.org open source project
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//
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// Copyright (c) 2014 - 2015 Apple Inc. and the Swift project authors
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// Licensed under Apache License v2.0 with Runtime Library Exception
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//
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// See http://swift.org/LICENSE.txt for license information
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// See http://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
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//
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//===----------------------------------------------------------------------===//
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//
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// This file implements the GenericSignature class.
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//
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//===----------------------------------------------------------------------===//
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#include "swift/AST/GenericSignature.h"
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#include "swift/AST/ASTContext.h"
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#include "swift/AST/Decl.h"
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#include "swift/AST/Module.h"
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#include "swift/AST/Types.h"
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using namespace swift;
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GenericSignature::GenericSignature(ArrayRef<GenericTypeParamType *> params,
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ArrayRef<Requirement> requirements,
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bool isKnownCanonical)
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: NumGenericParams(params.size()), NumRequirements(requirements.size()),
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CanonicalSignatureOrASTContext()
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{
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auto paramsBuffer = getGenericParamsBuffer();
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for (unsigned i = 0; i < NumGenericParams; ++i) {
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paramsBuffer[i] = params[i];
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}
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auto reqtsBuffer = getRequirementsBuffer();
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for (unsigned i = 0; i < NumRequirements; ++i) {
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reqtsBuffer[i] = requirements[i];
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}
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if (isKnownCanonical)
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CanonicalSignatureOrASTContext = &getASTContext(params, requirements);
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}
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ArrayRef<GenericTypeParamType *>
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GenericSignature::getInnermostGenericParams() const {
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auto params = getGenericParams();
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// Find the point at which the depth changes.
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unsigned depth = params.back()->getDepth();
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for (unsigned n = params.size(); n > 0; --n) {
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if (params[n-1]->getDepth() != depth) {
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return params.slice(n);
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}
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}
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// All parameters are at the same depth.
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return params;
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}
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ASTContext &GenericSignature::getASTContext(
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ArrayRef<swift::GenericTypeParamType *> params,
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ArrayRef<swift::Requirement> requirements) {
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// The params and requirements cannot both be empty.
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if (!params.empty())
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return params.front()->getASTContext();
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else
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return requirements.front().getFirstType()->getASTContext();
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}
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ArchetypeBuilder *GenericSignature::getArchetypeBuilder(ModuleDecl &mod) {
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// The archetype builder is associated with the canonical signature.
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if (!isCanonical())
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return getCanonicalSignature()->getArchetypeBuilder(mod);
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// Archetype builders are stored on the ASTContext.
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return getASTContext().getOrCreateArchetypeBuilder(CanGenericSignature(this),
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&mod);
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}
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bool GenericSignature::isCanonical() const {
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if (CanonicalSignatureOrASTContext.is<ASTContext*>()) return true;
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return getCanonicalSignature() == this;
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}
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CanGenericSignature GenericSignature::getCanonical(
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ArrayRef<GenericTypeParamType *> params,
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ArrayRef<Requirement> requirements) {
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// Canonicalize the parameters and requirements.
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SmallVector<GenericTypeParamType*, 8> canonicalParams;
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canonicalParams.reserve(params.size());
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for (auto param : params) {
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canonicalParams.push_back(cast<GenericTypeParamType>(param->getCanonicalType()));
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}
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SmallVector<Requirement, 8> canonicalRequirements;
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canonicalRequirements.reserve(requirements.size());
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for (auto &reqt : requirements) {
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canonicalRequirements.push_back(Requirement(reqt.getKind(),
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reqt.getFirstType()->getCanonicalType(),
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reqt.getSecondType().getCanonicalTypeOrNull()));
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}
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auto canSig = get(canonicalParams, canonicalRequirements,
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/*isKnownCanonical=*/true);
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return CanGenericSignature(canSig);
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}
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CanGenericSignature
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GenericSignature::getCanonicalSignature() const {
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// If we haven't computed the canonical signature yet, do so now.
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if (CanonicalSignatureOrASTContext.isNull()) {
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// Compute the canonical signature.
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CanGenericSignature canSig = getCanonical(getGenericParams(),
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getRequirements());
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// Record either the canonical signature or an indication that
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// this is the canonical signature.
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if (canSig != this)
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CanonicalSignatureOrASTContext = canSig;
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else
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CanonicalSignatureOrASTContext = &getGenericParams()[0]->getASTContext();
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// Return the canonical signature.
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return canSig;
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}
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// A stored ASTContext indicates that this is the canonical
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// signature.
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if (CanonicalSignatureOrASTContext.is<ASTContext*>())
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// TODO: CanGenericSignature should be const-correct.
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return CanGenericSignature(const_cast<GenericSignature*>(this));
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// Otherwise, return the stored canonical signature.
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return CanGenericSignature(
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CanonicalSignatureOrASTContext.get<GenericSignature*>());
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}
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/// Canonical ordering for dependent types in generic signatures.
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static int compareDependentTypes(const CanType *pa, const CanType *pb) {
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auto a = *pa, b = *pb;
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// Fast-path check for equality.
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if (a == b)
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return 0;
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// Ordering is as follows:
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// - Generic params
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if (auto gpa = dyn_cast<GenericTypeParamType>(a)) {
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if (auto gpb = dyn_cast<GenericTypeParamType>(b)) {
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// - by depth, so t_0_n < t_1_m
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if (int compareDepth = gpa->getDepth() - gpb->getDepth())
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return compareDepth;
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// - by index, so t_n_0 < t_n_1
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return gpa->getIndex() - gpb->getIndex();
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}
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return -1;
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}
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// - Dependent members
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if (auto dma = dyn_cast<DependentMemberType>(a)) {
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if (isa<GenericTypeParamType>(b))
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return +1;
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if (auto dmb = dyn_cast<DependentMemberType>(b)) {
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// - by base, so t_0_n.`P.T` < t_1_m.`P.T`
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auto abase = dma.getBase();
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auto bbase = dmb.getBase();
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if (int compareBases = compareDependentTypes(&abase, &bbase))
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return compareBases;
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// - by protocol, so t_n_m.`P.T` < t_n_m.`Q.T` (given P < Q)
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auto protoa = dma->getAssocType()->getProtocol();
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auto protob = dmb->getAssocType()->getProtocol();
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if (int compareProtocols
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= ProtocolType::compareProtocols(&protoa, &protob))
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return compareProtocols;
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// - by name, so t_n_m.`P.T` < t_n_m.`P.U`
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return dma->getAssocType()->getName().str().compare(
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dmb->getAssocType()->getName().str());
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}
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return -1;
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}
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// - Other types.
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//
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// There should only ever be one of these in a set of constraints related to
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// a dependent type, so the ordering among other types does not matter.
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if (isa<GenericTypeParamType>(b) || isa<DependentMemberType>(b))
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return +1;
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return 0;
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}
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CanGenericSignature
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GenericSignature::getCanonicalManglingSignature(ModuleDecl &M) const {
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// Start from the elementwise-canonical signature.
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auto canonical = getCanonicalSignature();
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auto &Context = canonical->getASTContext();
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// See if we cached the mangling signature.
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auto cached = Context.ManglingSignatures.find({canonical, &M});
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if (cached != Context.ManglingSignatures.end()) {
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return cached->second;
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}
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// Otherwise, we need to compute it.
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// Dump the generic signature into an ArchetypeBuilder that will figure out
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// the minimal set of requirements.
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std::unique_ptr<ArchetypeBuilder> builder(new ArchetypeBuilder(M,
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Context.Diags));
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builder->addGenericSignature(canonical, /*adoptArchetypes*/ false,
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/*treatRequirementsAsExplicit*/ true);
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// Sort out the requirements.
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struct DependentConstraints {
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CanType baseClass;
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SmallVector<CanType, 2> protocols;
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};
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SmallVector<CanType, 2> depTypes;
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llvm::DenseMap<CanType, DependentConstraints> constraints;
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llvm::DenseMap<CanType, SmallVector<CanType, 2>> sameTypes;
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builder->enumerateRequirements([&](RequirementKind kind,
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ArchetypeBuilder::PotentialArchetype *archetype,
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llvm::PointerUnion<Type, ArchetypeBuilder::PotentialArchetype *> type,
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RequirementSource source) {
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CanType depTy
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= archetype->getDependentType(*builder, false)->getCanonicalType();
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// Filter out redundant requirements.
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switch (source.getKind()) {
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case RequirementSource::Explicit:
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// The requirement was explicit and required, keep it.
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break;
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case RequirementSource::Protocol:
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// Keep witness markers.
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if (kind == RequirementKind::WitnessMarker)
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break;
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return;
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case RequirementSource::Redundant:
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case RequirementSource::Inferred:
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// The requirement was inferred or redundant, drop it.
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return;
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case RequirementSource::OuterScope:
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llvm_unreachable("shouldn't have an outer scope!");
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}
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switch (kind) {
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case RequirementKind::WitnessMarker: {
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// Introduce the dependent type into the constraint set, to ensure we
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// have a record for every dependent type.
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depTypes.push_back(depTy);
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return;
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}
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case RequirementKind::Conformance: {
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assert(std::find(depTypes.begin(), depTypes.end(),
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depTy) != depTypes.end()
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&& "didn't see witness marker first?");
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// Organize conformance constraints, sifting out the base class
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// requirement.
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auto &depConstraints = constraints[depTy];
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auto constraintType = type.get<Type>()->getCanonicalType();
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if (constraintType->isExistentialType()) {
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depConstraints.protocols.push_back(constraintType);
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} else {
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assert(depConstraints.baseClass.isNull()
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&& "multiple base class constraints?!");
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depConstraints.baseClass = constraintType;
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}
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return;
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}
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case RequirementKind::SameType:
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// Collect the same-type constraints by their representative.
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CanType repTy;
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if (auto concreteTy = type.dyn_cast<Type>()) {
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// Maybe we were equated to a concrete type...
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repTy = concreteTy->getCanonicalType();
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} else {
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// ...or to a representative dependent type that was in turn equated
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// to a concrete type.
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auto representative
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= type.get<ArchetypeBuilder::PotentialArchetype *>();
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if (representative->isConcreteType())
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repTy = representative->getConcreteType()->getCanonicalType();
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else
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repTy = representative->getDependentType(*builder, false)
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->getCanonicalType();
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}
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sameTypes[repTy].push_back(depTy);
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return;
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}
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});
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// Order the dependent types canonically.
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llvm::array_pod_sort(depTypes.begin(), depTypes.end(), compareDependentTypes);
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// Build a new set of minimized requirements.
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// Emit the conformance constraints.
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SmallVector<Requirement, 4> minimalRequirements;
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for (auto depTy : depTypes) {
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minimalRequirements.push_back(Requirement(RequirementKind::WitnessMarker,
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depTy, Type()));
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auto foundConstraints = constraints.find(depTy);
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if (foundConstraints != constraints.end()) {
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const auto &depConstraints = foundConstraints->second;
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if (depConstraints.baseClass)
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minimalRequirements.push_back(Requirement(RequirementKind::Conformance,
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depTy,
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depConstraints.baseClass));
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for (auto protocol : depConstraints.protocols)
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minimalRequirements.push_back(Requirement(RequirementKind::Conformance,
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depTy, protocol));
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}
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}
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// Collect the same type constraints.
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unsigned sameTypeBegin = minimalRequirements.size();
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for (auto &group : sameTypes) {
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// Sort the types in the set.
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auto types = std::move(group.second);
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types.push_back(group.first);
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llvm::array_pod_sort(types.begin(), types.end(), compareDependentTypes);
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// Form constraints with the greater type on the right (which will be the
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// concrete type, if one).
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auto rhsType = types.pop_back_val();
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for (auto lhsType : types)
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minimalRequirements.push_back(Requirement(RequirementKind::SameType,
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lhsType, rhsType));
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}
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// Sort the same-types by LHS, then by RHS.
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std::sort(minimalRequirements.begin() + sameTypeBegin, minimalRequirements.end(),
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[](const Requirement &a, const Requirement &b) -> bool {
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assert(a.getKind() == b.getKind()
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&& a.getKind() == RequirementKind::SameType
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&& "not same type constraints");
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CanType aLHS(a.getFirstType()), bLHS(b.getFirstType());
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if (int compareLHS = compareDependentTypes(&aLHS, &bLHS))
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return compareLHS < 0;
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CanType aRHS(a.getSecondType()), bRHS(b.getSecondType());
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return compareDependentTypes(&aRHS, &bRHS);
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});
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// Build the minimized signature.
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auto manglingSig = GenericSignature::get(canonical->getGenericParams(),
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minimalRequirements,
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/*isKnownCanonical=*/true);
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CanGenericSignature canSig(manglingSig);
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// Cache the result.
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Context.ManglingSignatures.insert({{canonical, &M}, canSig});
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Context.setArchetypeBuilder(canSig, &M, std::move(builder));
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return canSig;
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}
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ASTContext &GenericSignature::getASTContext() const {
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// Canonical signatures store the ASTContext directly.
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if (auto ctx = CanonicalSignatureOrASTContext.dyn_cast<ASTContext *>())
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return *ctx;
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// For everything else, just get it from the generic parameter.
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return getASTContext(getGenericParams(), getRequirements());
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}
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TypeSubstitutionMap
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GenericSignature::getSubstitutionMap(ArrayRef<Substitution> args) const {
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TypeSubstitutionMap subs;
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// An empty parameter list gives an empty map.
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if (getGenericParams().empty()) {
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assert(args.empty() && "substitutions but no generic params?!");
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return subs;
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}
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// Seed the type map with pre-existing substitutions.
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for (auto sub : args) {
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subs[sub.getArchetype()] = sub.getReplacement();
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}
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for (auto depTy : getAllDependentTypes()) {
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auto replacement = args.front().getReplacement();
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args = args.slice(1);
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if (auto subTy = depTy->getAs<SubstitutableType>()) {
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subs[subTy] = replacement;
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}
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else if (auto dTy = depTy->getAs<DependentMemberType>()) {
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subs[dTy] = replacement;
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}
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}
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assert(args.empty() && "did not use all substitutions?!");
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return subs;
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}
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bool GenericSignature::requiresClass(Type type, ModuleDecl &mod) {
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if (!type->isTypeParameter()) return false;
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auto &builder = *getArchetypeBuilder(mod);
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auto pa = builder.resolveArchetype(type);
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if (!pa) return false;
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pa = pa->getRepresentative();
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// If this type was mapped to a concrete type, then there is no
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// requirement.
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if (pa->isConcreteType()) return false;
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// If there is a superclass bound, then obviously it must be a class.
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if (pa->getSuperclass()) return true;
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// If any of the protocols are class-bound, then it must be a class.
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for (auto proto : pa->getConformsTo()) {
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if (proto.first->requiresClass()) return true;
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}
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return false;
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}
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/// Determine the superclass bound on the given dependent type.
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Type GenericSignature::getSuperclassBound(Type type, ModuleDecl &mod) {
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if (!type->isTypeParameter()) return nullptr;
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auto &builder = *getArchetypeBuilder(mod);
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auto pa = builder.resolveArchetype(type);
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if (!pa) return nullptr;
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pa = pa->getRepresentative();
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// If this type was mapped to a concrete type, then there is no
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// requirement.
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if (pa->isConcreteType()) return nullptr;
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// Retrieve the superclass bound.
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return pa->getSuperclass();
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}
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/// Determine the set of protocols to which the given dependent type
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/// must conform.
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SmallVector<ProtocolDecl *, 2> GenericSignature::getConformsTo(Type type,
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ModuleDecl &mod) {
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if (!type->isTypeParameter()) return { };
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auto &builder = *getArchetypeBuilder(mod);
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auto pa = builder.resolveArchetype(type);
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if (!pa) return { };
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pa = pa->getRepresentative();
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// If this type was mapped to a concrete type, then there are no
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// requirements.
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if (pa->isConcreteType()) return { };
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// Retrieve the protocols to which this type conforms.
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SmallVector<ProtocolDecl *, 2> result;
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for (auto proto : pa->getConformsTo())
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result.push_back(proto.first);
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return result;
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}
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