[SE-0404] Rebase fixes and better handling of generic superclasses with inferred params

Author: karwa

lib/AST/DeclContext.cpp

@@ -269,6 +269,12 @@ DeclContext *DeclContext::getParentForLookup() const {
     // outer types.
     return getModuleScopeContext();
   }
+  if (isa<ProtocolDecl>(this) && getParent()->isGenericContext()) {
+    // Protocols in generic contexts must not look in to their parents,
+    // as the parents may contain types with inferred implicit
+    // generic parameters not present in the protocol's generic signature.
+    return getModuleScopeContext();
+  }
   if (isa<NominalTypeDecl>(this)) {
     // If we are inside a nominal type that is inside a protocol,
     // skip the protocol.

lib/Sema/TypeCheckDeclPrimary.cpp

@@ -2674,30 +2674,30 @@ class DeclChecker : public DeclVisitor<DeclChecker> {
         NTD->diagnose(diag::tuple_extension_nested_type, NTD);
         return;
       }
-    }
 
-    // We don't support protocols nested in generic contexts.
-    // This includes protocols nested in other protocols.
-    if (isa<ProtocolDecl>(NTD) && NTD->getParent()->isGenericContext()) {
-      if (auto *OuterPD = NTD->getParent()->getSelfProtocolDecl())
-        NTD->diagnose(diag::unsupported_nested_protocol_in_protocol, NTD,
-                      OuterPD);
-      else
-        NTD->diagnose(diag::unsupported_nested_protocol_in_generic, NTD);
+      // We don't support protocols nested in generic contexts.
+      // This includes protocols nested in other protocols.
+      if (isa<ProtocolDecl>(NTD) && DC->isGenericContext()) {
+        if (auto *OuterPD = DC->getSelfProtocolDecl())
+          NTD->diagnose(diag::unsupported_nested_protocol_in_protocol, NTD,
+                        OuterPD);
+        else
+          NTD->diagnose(diag::unsupported_nested_protocol_in_generic, NTD);
 
-      NTD->setInvalid();
-      return;
-    }
+        NTD->setInvalid();
+        return;
+      }
 
-    // We don't support nested types in protocols.
-    if (auto proto = dyn_cast<ProtocolDecl>(parentDecl)) {
-      if (DC->getExtendedProtocolDecl()) {
-        NTD->diagnose(diag::unsupported_type_nested_in_protocol_extension, NTD,
-                      proto);
-      } else {
-        NTD->diagnose(diag::unsupported_type_nested_in_protocol, NTD, proto);
+      // We don't support nested types in protocols.
+      if (auto proto = dyn_cast<ProtocolDecl>(parentDecl)) {
+        if (DC->getExtendedProtocolDecl()) {
+          NTD->diagnose(diag::unsupported_type_nested_in_protocol_extension, NTD,
+                        proto);
+        } else {
+          NTD->diagnose(diag::unsupported_type_nested_in_protocol, NTD, proto);
+        }
+        NTD->setInvalid();
       }
-      NTD->setInvalid();
     }
 
     // We don't support nested types in generic functions yet.
@@ -3189,15 +3189,6 @@ class DeclChecker : public DeclVisitor<DeclChecker> {
     if (!PD->getPrimaryAssociatedTypeNames().empty())
       (void) PD->getPrimaryAssociatedTypes();
 
-    // We cannot compute the requirement signature of a protocol
-    // in a generic context, because superclass constraints
-    // may include implicitly inferred generic arguments that are
-    // not part of the protocol's generic signature.
-    if (PD->getParent()->isGenericContext()) {
-      assert(PD->isInvalid());
-      return;
-    }
-
     // Explicitly compute the requirement signature to detect errors.
     // Do this before visiting members, to avoid a request cycle if
     // a member references another declaration whose generic signature

test/decl/nested/protocol.swift

@@ -163,15 +163,15 @@ struct OuterGeneric<D> {
   protocol InnerProtocol { // expected-error{{protocol 'InnerProtocol' cannot be nested in a generic context}}
     associatedtype Rooster
     func flip(_ r: Rooster)
-    func flop(_ t: D)
+    func flop(_ t: D) // expected-error {{cannot find type 'D' in scope}}
   }
 }
 
 class OuterGenericClass<T> {
   protocol InnerProtocol { // expected-error{{protocol 'InnerProtocol' cannot be nested in a generic context}}
     associatedtype Rooster
     func flip(_ r: Rooster)
-    func flop(_ t: T)
+    func flop(_ t: T) // expected-error {{cannot find type 'T' in scope}}
   }
 }
 
@@ -180,7 +180,7 @@ protocol OuterProtocol {
   protocol InnerProtocol { // expected-error{{protocol 'InnerProtocol' cannot be nested in protocol 'OuterProtocol'}}
     associatedtype Rooster
     func flip(_ r: Rooster)
-    func flop(_ h: Hen)
+    func flop(_ h: Hen) // expected-error {{cannot find type 'Hen' in scope}}
   }
 }
 
@@ -195,37 +195,40 @@ struct ConformsToOuterProtocol : OuterProtocol {
 
 extension OuterProtocol {
   func f() {
-    protocol Invalid_0 {} // expected-error{{protocol 'Invalid_0' cannot be nested in a generic context}}
+    protocol Invalid_0 {} // expected-error{{type 'Invalid_0' cannot be nested in generic function 'f()'}}
 
     struct SomeType { // expected-error{{type 'SomeType' cannot be nested in generic function 'f()'}}
       protocol Invalid_1 {} // expected-error{{protocol 'Invalid_1' cannot be nested in a generic context}}
     }
   }
   func g<T>(_: T) {
-    protocol Invalid_2 {} // expected-error{{protocol 'Invalid_2' cannot be nested in a generic context}}
+    protocol Invalid_2 {} // expected-error{{type 'Invalid_2' cannot be nested in generic function 'g'}}
   }
 }
 
 // 'InnerProtocol' does not inherit the generic parameters of
 // 'OtherGenericClass', so the occurrence of 'OtherGenericClass'
 // in 'InnerProtocol' is not "in context" with implicitly
 // inferred generic arguments <T, U>.
-class OtherGenericClass<T, U> {
+class OtherGenericClass<T, U> { // expected-note {{generic type 'OtherGenericClass' declared here}}
   protocol InnerProtocol : OtherGenericClass { }
-  // expected-error@-1{{protocol 'InnerProtocol' cannot be nested in a generic context}}
+  // expected-error@-1 {{protocol 'InnerProtocol' cannot be nested in a generic context}}
+  // expected-error@-2 {{reference to generic type 'OtherGenericClass' requires arguments in <...>}}
 }
 
 protocol InferredGenericTest {
   associatedtype A
 }
 extension OtherGenericClass {
-  protocol P: InferredGenericTest where Self.A == T {} // expected-error {{protocol 'P' cannot be nested in a generic context}}
+  protocol P: InferredGenericTest where Self.A == T {}
+  // expected-error@-1 {{protocol 'P' cannot be nested in a generic context}}
+  // expected-error@-2 {{cannot find type 'T' in scope}}
 }
 
 // A nested protocol does not satisfy an associated type requirement.
 
 protocol HasAssoc {
-  associatedtype A // expected-note {{protocol requires nested type 'A'; do you want to add it?}}
+  associatedtype A // expected-note {{protocol requires nested type 'A'; add nested type 'A' for conformance}}
 }
 struct ConformsToHasAssoc: HasAssoc { // expected-error {{type 'ConformsToHasAssoc' does not conform to protocol 'HasAssoc'}}
   protocol A {}
@@ -257,12 +260,12 @@ func testLookup<T: OuterForUFI.Inner>(_ x: T) {
 // Protocols cannot be nested inside of generic functions.
 
 func invalidProtocolInGeneric<T>(_: T) {
-  protocol Test {} // expected-error{{protocol 'Test' cannot be nested in a generic context}}
+  protocol Test {} // expected-error{{type 'Test' cannot be nested in generic function 'invalidProtocolInGeneric'}}
 }
 
 struct NestedInGenericMethod<T> {
   func someMethod() {
-    protocol AnotherTest {} // expected-error{{protocol 'AnotherTest' cannot be nested in a generic context}}
+    protocol AnotherTest {} // expected-error{{type 'AnotherTest' cannot be nested in generic function 'someMethod()'}}
   }
 }