LookupVisibleDecls: Remove RestateFilteringConsumer

It's no longer needed after the previous set of changes, and removing it
fixes a crash.

Fixes <rdar://problem/46853611>.

Author: slavapestov

lib/Sema/LookupVisibleDecls.cpp

@@ -466,92 +466,6 @@ lookupVisibleMemberDeclsImpl(Type BaseTy, VisibleDeclConsumer &Consumer,
                              GenericSignatureBuilder *GSB,
                              VisitedSet &Visited);
 
-// Filters out restated declarations from a protocol hierarchy
-// or equivalent requirements from protocol composition types.
-class RestateFilteringConsumer : public VisibleDeclConsumer {
-  LazyResolver *resolver;
-
-  using FoundDecl = std::pair<ValueDecl*, DeclVisibilityKind>;
-  using NameAndType = std::pair<DeclName, CanType>;
-
-  llvm::DenseMap<DeclName, FoundDecl> foundVars;
-  llvm::DenseMap<NameAndType, FoundDecl> foundFuncs;
-  llvm::MapVector<ValueDecl*, DeclVisibilityKind> declsToReport;
-
-  template <typename K>
-  void addDecl(llvm::DenseMap<K, FoundDecl> &Map, K Key, FoundDecl FD) {
-    // Add the declaration if we haven't found an equivalent yet, otherwise
-    // replace the equivalent if the found decl has a higher access level.
-    auto existingDecl = Map.find(Key);
-
-    if ((existingDecl == Map.end()) ||
-        (Map[Key].first->getFormalAccess() < FD.first->getFormalAccess())) {
-      if (existingDecl != Map.end())
-        declsToReport.erase({existingDecl->getSecond().first});
-      Map[Key] = FD;
-      declsToReport.insert(FD);
-    }
-  }
-
-  CanType stripSelfRequirementsIfNeeded(ValueDecl *VD,
-                                        GenericFunctionType *GFT) const {
-    // Preserve the generic signature if this is a subscript, which are uncurried,
-    // or if we have generic params other than Self. Otherwise, use
-    // the resultType of the curried function type.
-    // When we keep the generic signature, we remove the requirements
-    // from Self to make sure they don't prevent us from recognizing restatements.
-    auto params = GFT->getGenericParams();
-    if (params.size() == 1 && !isa<SubscriptDecl>(VD)) {
-      return GFT->getResult()->getCanonicalType();
-    }
-    auto Self = VD->getDeclContext()->getSelfInterfaceType();
-    SmallVector<Requirement, 4> newReqs;
-    for (auto req: GFT->getRequirements()) {
-      if (!Self->isEqual(req.getFirstType()))
-        newReqs.push_back(req);
-    }
-    auto newSig = GenericSignature::get(params, newReqs, false);
-
-    return GenericFunctionType::get(newSig, GFT->getParams(),
-                                    GFT->getResult(), GFT->getExtInfo())
-      ->getCanonicalType();
-  }
-
-public:
-  RestateFilteringConsumer(Type baseTy, const DeclContext *DC,
-                           LazyResolver *resolver)
-  : resolver(resolver) {
-    assert(DC && baseTy && !baseTy->hasLValueType());
-  }
-
-  void foundDecl(ValueDecl *VD, DeclVisibilityKind Reason) override {
-    assert(VD);
-    // If this isn't a protocol context, don't look further into the decl.
-    if (!isa<ProtocolDecl>(VD->getDeclContext())) {
-      declsToReport.insert({VD, Reason});
-      return;
-    }
-    if (resolver)
-      resolver->resolveDeclSignature(VD);
-
-    if (!VD->hasInterfaceType()) {
-      declsToReport.insert({VD, Reason});
-      return;
-    }
-    if (auto GFT = VD->getInterfaceType()->getAs<GenericFunctionType>()) {
-      auto type = stripSelfRequirementsIfNeeded(VD, GFT);
-      addDecl(foundFuncs, {VD->getFullName(), type}, {VD, Reason});
-      return;
-    }
-    addDecl(foundVars, VD->getFullName(), {VD, Reason});
-  }
-
-  void feedResultsToConsumer(VisibleDeclConsumer &Consumer) const {
-    for (const auto entry: declsToReport)
-      Consumer.foundDecl(entry.first, entry.second);
-  }
-};
-
 static void
   lookupVisibleProtocolMemberDecls(Type BaseTy, ProtocolType *PT,
                                    VisibleDeclConsumer &Consumer,
@@ -911,13 +825,11 @@ static void lookupVisibleMemberDecls(
     LookupState LS, DeclVisibilityKind Reason, LazyResolver *TypeResolver,
     GenericSignatureBuilder *GSB) {
   OverrideFilteringConsumer overrideConsumer(BaseTy, CurrDC, TypeResolver);
-  RestateFilteringConsumer restateConsumer(BaseTy, CurrDC, TypeResolver);
   VisitedSet Visited;
-  lookupVisibleMemberDeclsImpl(BaseTy, restateConsumer, CurrDC, LS, Reason,
+  lookupVisibleMemberDeclsImpl(BaseTy, overrideConsumer, CurrDC, LS, Reason,
                                TypeResolver, GSB, Visited);
 
   // Report the declarations we found to the real consumer.
-  restateConsumer.feedResultsToConsumer(overrideConsumer);
   for (const auto &DeclAndReason : overrideConsumer.DeclsToReport)
     Consumer.foundDecl(DeclAndReason.D, DeclAndReason.Reason);
 }

test/Sema/typo_correction.swift

@@ -113,10 +113,12 @@ struct Generic<T> {
 }
 
 protocol P { // expected-note {{'P' previously declared here}}
+  // expected-note@-1 {{did you mean 'P'?}}
   typealias a = Generic
 }
 
 protocol P {} // expected-error {{invalid redeclaration of 'P'}}
+// expected-note@-1 {{did you mean 'P'?}}
 
 func hasTypo() {
   _ = P.a.a // expected-error {{type 'P.a' (aka 'Generic') has no member 'a'}}
@@ -170,7 +172,7 @@ class CircularValidationWithTypo {
 // Crash with invalid extension that has not been bound -- https://bugs.swift.org/browse/SR-8984
 protocol PP {}
 
-func boo() { // expected-note {{did you mean 'boo'?}}
+func boo() {
   extension PP { // expected-error {{declaration is only valid at file scope}}
     func g() {
       booo() // expected-error {{use of unresolved identifier 'booo'}}
@@ -197,3 +199,22 @@ func testFwdRef() {
   let _ = forward_refX + 1 // expected-error {{use of unresolved identifier 'forward_refX'}}
   let forward_ref1 = 4
 }
+
+// Crash with protocol members.
+protocol P1 {
+  associatedtype A1
+  associatedtype A2
+}
+
+protocol P2 {
+  associatedtype A1
+  associatedtype A2
+
+  func method<T: P1>(_: T) where T.A1 == A1, T.A2 == A2
+}
+
+extension P2 {
+  func f() { // expected-note {{did you mean 'f'?}}
+    _ = a // expected-error {{use of unresolved identifier 'a'}}
+  }
+}