[5.5] [IDE] Fix superclass constraint handling for extension merging

lib/IDE/IDETypeChecking.cpp

@@ -306,6 +306,8 @@ struct SynthesizedExtensionAnalyzer::Implementation {
           continue;
 
         if (!BaseType->isExistentialType()) {
+          // Apply any substitutions we need to map the requirements from a
+          // a protocol extension to an extension on the conforming type.
           First = First.subst(subMap);
           Second = Second.subst(subMap);
 
@@ -317,11 +319,12 @@ struct SynthesizedExtensionAnalyzer::Implementation {
           }
         }
 
+        assert(!First->hasArchetype() && !Second->hasArchetype());
         switch (Kind) {
         case RequirementKind::Conformance: {
           auto *M = DC->getParentModule();
           auto *Proto = Second->castTo<ProtocolType>()->getDecl();
-          if (!First->isTypeParameter() && !First->is<ArchetypeType>() &&
+          if (!First->isTypeParameter() &&
               M->conformsToProtocol(First, Proto).isInvalid())
             return true;
           if (M->conformsToProtocol(First, Proto).isInvalid())
@@ -330,11 +333,27 @@ struct SynthesizedExtensionAnalyzer::Implementation {
         }
 
         case RequirementKind::Superclass:
-          if (!Second->isBindableToSuperclassOf(First)) {
-            return true;
-          } else if (!Second->isExactSuperclassOf(Second)) {
+          // If the subject type of the requirement is still a type parameter,
+          // we need to check if the contextual type could possibly be bound to
+          // the superclass. If not, this extension isn't applicable.
+          if (First->isTypeParameter()) {
+            if (!Target->mapTypeIntoContext(First)->isBindableTo(
+                    Target->mapTypeIntoContext(Second))) {
+              return true;
+            }
             MergeInfo.addRequirement(GenericSig, First, Second, Kind);
+            break;
           }
+
+          // If we've substituted in a concrete type for the subject, we can
+          // check for an exact superclass match, and disregard the extension if
+          // it missed.
+          // FIXME: What if it ends being something like `C<U> : C<Int>`?
+          // Arguably we should allow that to be mirrored with a U == Int
+          // constraint.
+          if (!Second->isExactSuperclassOf(First))
+            return true;
+
           break;
 
         case RequirementKind::SameType:

test/IDE/print_synthesized_extensions.swift

@@ -15,6 +15,8 @@
 // RUN: %FileCheck %s -check-prefix=CHECK12 < %t.syn.txt
 // RUN: %FileCheck %s -check-prefix=CHECK13 < %t.syn.txt
 // RUN: %FileCheck %s -check-prefix=CHECK14 < %t.syn.txt
+// RUN: %FileCheck %s -check-prefix=CHECK15 < %t.syn.txt
+// RUN: %FileCheck %s -check-prefix=CHECK16 < %t.syn.txt
 
 public protocol P1 {
   associatedtype T1
@@ -339,3 +341,60 @@ extension S13 : P5 {
 // CHECK14-NEXT: <decl:Func>/// This should not crash
 // CHECK14-NEXT:     public func <loc>foo5()</loc></decl>
 // CHECK14-NEXT: }</synthesized>
+
+// rdar://76868074: Make sure we print the extensions for C.
+public class C<T> {}
+public class D {}
+public class E {}
+
+extension C where T : D {
+  public func foo() {}
+}
+
+public protocol P8 {
+  associatedtype T
+}
+
+extension P8 where T : D {
+  public func bar() {}
+}
+
+extension P8 where T : E {
+  public func baz() {}
+}
+
+extension C : P8 {}
+
+// CHECK15:      <decl:Class>public class <loc>C<<decl:GenericTypeParam>T</decl>></loc> {
+// CHECK15-NEXT: }</decl>
+
+// CHECK15:      <decl:Extension>extension <loc><ref:Class>C</ref></loc> : <ref:module>print_synthesized_extensions</ref>.<ref:Protocol>P8</ref> {
+// CHECK15-NEXT: }</decl>
+
+// CHECK15:      <decl:Extension>extension <loc><ref:Class>C</ref></loc> where <ref:GenericTypeParam>T</ref> : <ref:module>print_synthesized_extensions</ref>.<ref:Class>D</ref> {
+// CHECK15-NEXT:   <decl:Func>public func <loc>foo()</loc></decl></decl>
+// CHECK15-NEXT:   <decl:Func>public func <loc>bar()</loc></decl>
+// CHECK15-NEXT: }</synthesized>
+
+// CHECK15:      <synthesized>extension <ref:Class>C</ref> where <ref:GenericTypeParam>T</ref> : <ref:Class>E</ref> {
+// CHECK15-NEXT:   <decl:Func>public func <loc>baz()</loc></decl>
+// CHECK15-NEXT: }</synthesized>
+
+// CHECK15:      <decl:Extension>extension <loc><ref:Protocol>P8</ref></loc> where <ref:GenericTypeParam>Self</ref>.<ref:AssociatedType>T</ref> : <ref:module>print_synthesized_extensions</ref>.<ref:Class>D</ref> {
+// CHECK15-NEXT:   <decl:Func>public func <loc>bar()</loc></decl>
+// CHECK15-NEXT: }</decl>
+
+// CHECK15:      <decl:Extension>extension <loc><ref:Protocol>P8</ref></loc> where <ref:GenericTypeParam>Self</ref>.<ref:AssociatedType>T</ref> : <ref:module>print_synthesized_extensions</ref>.<ref:Class>E</ref> {
+// CHECK15-NEXT:   <decl:Func>public func <loc>baz()</loc></decl>
+// CHECK15-NEXT: }</decl>
+
+// For this class, make sure we mirror the extension P8 where T : D, but not
+// the extension P8 where T : E.
+public class F<T : D> {}
+extension F : P8 {}
+
+// CHECK16:      <synthesized>extension <ref:Class>F</ref> where <ref:GenericTypeParam>T</ref> : <ref:Class>D</ref> {
+// CHECK16-NEXT:   <decl:Func>public func <loc>bar()</loc></decl>
+// CHECK16-NEXT: }</synthesized>
+
+// CHECK16-NOT: <synthesized>extension <ref:Class>F</ref> where <ref:GenericTypeParam>T</ref> : <ref:Class>E</ref> {

test/IDE/print_synthesized_extensions_generics.swift

@@ -0,0 +1,87 @@
+// RUN: %empty-directory(%t)
+// RUN: %target-swift-frontend -emit-module-path %t/print_synthesized_extensions_generics.swiftmodule -emit-module-doc -emit-module-doc-path %t/print_synthesized_extensions_generics.swiftdoc %s
+// RUN: %target-swift-ide-test -print-module -synthesize-extension -print-interface -no-empty-line-between-members -module-to-print=print_synthesized_extensions_generics -I %t -source-filename=%s | %FileCheck %s
+
+public protocol P1 {
+  associatedtype T
+  associatedtype U
+}
+
+public class A {}
+public class B<T> : A {}
+
+extension P1 where T : B<U> {
+  public func qux() {}
+}
+extension P1 where T : B<Int> {
+  public func flob() {}
+}
+
+public class C<T : A, U> {}
+extension C : P1 {}
+// CHECK:      extension C where T : B<U> {
+// CHECK-NEXT:   func qux()
+// CHECK-NEXT: }
+
+// CHECK:      extension C where T : B<Int> {
+// CHECK-NEXT:   func flob()
+// CHECK-NEXT: }
+
+public class D<U> {}
+extension D : P1 {
+  public typealias T = B<U>
+}
+// CHECK:      class D<U> {
+// CHECK-NEXT:   func qux()
+// CHECK-NEXT: }
+
+// FIXME: Arguably we should support this
+// CHECK-NOT: extension D where U == Int
+
+public class E {}
+extension E: P1 {
+  public typealias T = B<U>
+  public typealias U = Int
+}
+// CHECK:      class E {
+// CHECK-NEXT:   func qux()
+// CHECK-NEXT:   func flob()
+// CHECK-NEXT: }
+
+public class F {}
+extension F : P1 {
+  public typealias T = B<U>
+  public typealias U = String
+}
+// CHECK:      class F {
+// CHECK-NEXT:   func qux()
+// CHECK-NEXT: }
+
+// CHECK-NOT: extension F where T : B<Int>
+
+public protocol P2 {
+  associatedtype T : P1
+}
+
+extension P2 where T.T : A {
+  public func blah() {}
+}
+
+public class G<T : P1> {}
+extension G : P2 {}
+
+// CHECK:      extension G where T.T : A {
+// CHECK-NEXT:   func blah()
+// CHECK-NEXT: }
+
+// CHECK:      extension P1 where Self.T : print_synthesized_extensions_generics.B<Self.U> {
+// CHECK-NEXT:   func qux()
+// CHECK-NEXT: }
+
+// CHECK:      extension P1 where Self.T : print_synthesized_extensions_generics.B<Int> {
+// CHECK-NEXT:   func flob()
+// CHECK-NEXT: }
+
+// CHECK:      extension P2 where Self.T.T : print_synthesized_extensions_generics.A {
+// CHECK-NEXT:   func blah()
+// CHECK-NEXT: }

test/SourceKit/DocSupport/Inputs/module_with_class_extension.swift

@@ -0,0 +1,25 @@
+
+public class C<T> {}
+public class D {}
+public class E {}
+
+extension C where T : D {
+  public func foo() {}
+}
+
+public protocol P8 {
+  associatedtype T
+}
+
+extension P8 where T : D {
+  public func bar() {}
+}
+
+extension P8 where T : E {
+  public func baz() {}
+}
+
+extension C : P8 {}
+
+public class F<T : D> {}
+extension F : P8 {}

test/SourceKit/DocSupport/doc_swift_module_class_extension.swift

@@ -0,0 +1,6 @@
+// RUN: %empty-directory(%t.mod)
+// RUN: %swift -emit-module -o %t.mod/module_with_class_extension.swiftmodule %S/Inputs/module_with_class_extension.swift -parse-as-library
+// RUN: %sourcekitd-test -req=doc-info -module module_with_class_extension -- -Xfrontend -disable-implicit-concurrency-module-import -I %t.mod > %t.response
+// RUN: %diff -u %s.response %t.response
+
+// rdar://76868074: Make sure we print the extensions for C.