AST: Fix crash when attempting typo correction on class-bound archetype

Also clean up some of the badness here just a little bit.

Fixes <rdar://problem/31093620>.

lib/AST/LookupVisibleDecls.cpp

@@ -493,7 +493,7 @@ static void lookupVisibleMemberDeclsImpl(
     VisitedSet &Visited) {
   // Just look through l-valueness.  It doesn't affect name lookup.
   assert(BaseTy && "lookup into null type");
-  BaseTy = BaseTy->getRValueType();
+  assert(!BaseTy->isLValueType());
 
   // Handle metatype references, as in "some_type.some_member".  These are
   // special and can't have extensions.
@@ -674,7 +674,10 @@ public:
 
   OverrideFilteringConsumer(Type BaseTy, const DeclContext *DC,
                             LazyResolver *resolver)
-      : BaseTy(BaseTy->getRValueType()), DC(DC), TypeResolver(resolver) {
+      : BaseTy(BaseTy), DC(DC), TypeResolver(resolver) {
+    assert(!BaseTy->isLValueType());
+    if (auto *MetaTy = BaseTy->getAs<AnyMetatypeType>())
+      BaseTy = MetaTy->getInstanceType();
     assert(DC && BaseTy);
   }
 
@@ -724,11 +727,24 @@ public:
     }
 
     // Does it make sense to substitute types?
-    bool shouldSubst = !BaseTy->hasUnboundGenericType() &&
-                       !BaseTy->is<AnyMetatypeType>() &&
-                       !BaseTy->isExistentialType() &&
+
+    // Don't pass UnboundGenericType here. If you see this assertion
+    // being hit, fix the caller, don't remove it.
+    assert(!BaseTy->hasUnboundGenericType());
+
+    // If the base type is AnyObject, we might be doing a dynamic
+    // lookup, so the base type won't match the type of the member's
+    // context type.
+    //
+    // If the base type is not a nominal type, we can't substitute
+    // the member type.
+    //
+    // If the member is a free function and not a member of a type,
+    // don't substitute either.
+    bool shouldSubst = (!BaseTy->isAnyObject() &&
                         !BaseTy->hasTypeVariable() &&
-                       VD->getDeclContext()->isTypeContext();
+                        BaseTy->getNominalOrBoundGenericNominal() &&
+                        VD->getDeclContext()->isTypeContext());
     ModuleDecl *M = DC->getParentModule();
 
     auto FoundSignature = VD->getOverloadSignature();
@@ -860,7 +876,7 @@ void swift::lookupVisibleDecls(VisibleDeclConsumer &Consumer,
       if (ExtendedType)
         BaseDecl = ExtendedType->getNominalOrBoundGenericNominal();
     } else if (auto ND = dyn_cast<NominalTypeDecl>(DC)) {
-      ExtendedType = ND->getDeclaredType();
+      ExtendedType = ND->getDeclaredTypeInContext();
       BaseDecl = ND;
     }
 

lib/IDE/CodeCompletion.cpp

@@ -3113,14 +3113,14 @@ public:
     NeedLeadingDot = !HaveDot;
 
     // This is horrible
+    ExprType = ExprType->getRValueType();
     this->ExprType = ExprType;
     if (ExprType->hasTypeParameter()) {
       DeclContext *DC;
       if (VD) {
         DC = VD->getInnermostDeclContext();
         this->ExprType = DC->mapTypeIntoContext(ExprType);
-      } else if (auto NTD = ExprType->getRValueType()->getRValueInstanceType()
-          ->getAnyNominal()) {
+      } else if (auto NTD = ExprType->getRValueInstanceType()->getAnyNominal()) {
         DC = NTD;
         this->ExprType = DC->mapTypeIntoContext(ExprType);
       }
@@ -3138,7 +3138,7 @@ public:
         Done = true;
       }
     }
-    if (auto *TT = ExprType->getRValueType()->getAs<TupleType>()) {
+    if (auto *TT = ExprType->getAs<TupleType>()) {
       getTupleExprCompletions(TT);
       Done = true;
     }

test/Sema/typo_correction.swift

@@ -84,3 +84,38 @@ _ = [Any]().withUnsafeBufferPointer { (buf) -> [Any] in
   guard let base = buf.baseAddress else { return [] }
   return (base ..< base + buf.count).m // expected-error {{value of type 'CountableRange<_>' has no member 'm'}}
 }
+
+// Typo correction with class-bound archetypes.
+class SomeClass {
+  func match1() {}
+  // expected-note@-1 {{did you mean 'match1'?}}
+}
+
+func takesSomeClassArchetype<T : SomeClass>(_ t: T) {
+  t.match0()
+  // expected-error@-1 {{value of type 'T' has no member 'match0'}}
+}
+
+// Typo correction of unqualified lookup from generic context.
+struct Generic<T> {
+  func match1() {}
+  // expected-note@-1 {{did you mean 'match1'?}}
+
+  class Inner {
+    func doStuff() {
+      match0()
+      // expected-error@-1 {{use of unresolved identifier 'match0'}}
+    }
+  }
+}
+
+// Typo correction with AnyObject.
+func takesAnyObject(_ t: AnyObject) {
+  _ = t.rawPointer
+  // expected-error@-1 {{value of type 'AnyObject' has no member 'rawPointer'}}
+}
+
+func takesAnyObjectArchetype<T : AnyObject>(_ t: T) {
+  _ = t.rawPointer
+  // expected-error@-1 {{value of type 'T' has no member 'rawPointer'}}
+}