Sema: Don't forget to visit conformances introduced by non-generic types

Even if a nominal type does not have its own generic parameters,
we need to visit its conformances, because it might be defined
in a constrained extension or have a 'where' clause of its own.

Author: slavapestov

lib/Sema/TypeCheckAvailability.cpp

@@ -3070,7 +3070,20 @@ class ProblematicTypeFinder : public TypeDeclFinder {
   Action visitNominalType(NominalType *ty) override {
     visitTypeDecl(ty->getDecl());
 
-    /// FIXME
+    // If some generic parameters are missing, don't check conformances.
+    if (ty->hasUnboundGenericType())
+      return Action::Continue;
+
+    // When the DeclContext parameter to getContextSubstitutionMap()
+    // is a protocol declaration, the receiver must be a concrete
+    // type, so it doesn't make sense to perform this check on
+    // protocol types.
+    if (isa<ProtocolType>(ty))
+      return Action::Continue;
+
+    ModuleDecl *useModule = Where.getDeclContext()->getParentModule();
+    auto subs = ty->getContextSubstitutionMap(useModule, ty->getDecl());
+    (void) diagnoseSubstitutionMapAvailability(Loc, subs, Where);
     return Action::Continue;
   }
 

test/Sema/implementation-only-import-in-decls.swift

@@ -179,6 +179,13 @@ public struct NormalProtoAssocHolder<T: NormalProto> {
 }
 public func testConformanceInBoundGeneric(_: NormalProtoAssocHolder<NormalStruct>) {} // expected-error {{cannot use conformance of 'NormalStruct' to 'NormalProto' here; 'BADLibrary' has been imported as implementation-only}}
 
+public struct OuterGenericHolder<T> {
+  public struct Nested where T : NormalProto {
+    public var value: T.Assoc
+  }
+}
+public func testConformanceInNestedNonGeneric(_: OuterGenericHolder<NormalStruct>.Nested) {} // expected-error {{cannot use conformance of 'NormalStruct' to 'NormalProto' here; 'BADLibrary' has been imported as implementation-only}}
+
 public class SubclassOfNormalClass: NormalClass {}
 
 public func testInheritedConformance(_: NormalProtoAssocHolder<SubclassOfNormalClass>) {} // expected-error {{cannot use conformance of 'NormalClass' to 'NormalProto' here; 'BADLibrary' has been imported as implementation-only}}

test/Sema/spi-in-decls.swift

@@ -213,6 +213,13 @@ public struct NormalProtoAssocHolder<T: NormalProto> {
 }
 public func testConformanceInBoundGeneric(_: NormalProtoAssocHolder<NormalStruct>) {} // expected-error {{cannot use conformance of 'NormalStruct' to 'NormalProto' here; the conformance is declared as SPI}}
 
+public struct OuterGenericHolder<T> {
+  public struct Nested where T : NormalProto {
+    public var value: T.Assoc
+  }
+}
+public func testConformanceInNestedNonGeneric(_: OuterGenericHolder<NormalStruct>.Nested) {} // expected-error {{cannot use conformance of 'NormalStruct' to 'NormalProto' here; the conformance is declared as SPI}}
+
 public class SubclassOfNormalClass: NormalClass {}
 
 public func testInheritedConformance(_: NormalProtoAssocHolder<SubclassOfNormalClass>) {} // expected-error {{cannot use conformance of 'NormalClass' to 'NormalProto' here; the conformance is declared as SPI}}