ASTDemangler: Implement unresolved DependentMemberType

The debug mangling emits these when the type parameter only
conforms to one protocol having an associated type with this
name.

Author: slavapestov

include/swift/AST/ASTDemangler.h

@@ -90,6 +90,8 @@ class ASTBuilder {
 
   Type createGenericTypeParameterType(unsigned depth, unsigned index);
 
+  Type createDependentMemberType(StringRef member, Type base);
+
   Type createDependentMemberType(StringRef member, Type base,
                                  ProtocolDecl *protocol);
 

include/swift/Demangling/TypeDecoder.h

@@ -464,7 +464,7 @@ class TypeDecoder {
       auto member = Node->getChild(1)->getText();
       auto assocTypeChild = Node->getChild(1);
       if (assocTypeChild->getNumChildren() < 1)
-        return BuiltType();
+        return Builder.createDependentMemberType(member, base);
 
       auto protocol = decodeMangledProtocolType(assocTypeChild->getChild(0));
       if (!protocol)

include/swift/Reflection/TypeRefBuilder.h

@@ -300,6 +300,13 @@ class TypeRefBuilder {
     return GenericTypeParameterTypeRef::create(*this, depth, index);
   }
 
+  const DependentMemberTypeRef *
+  createDependentMemberType(const std::string &member,
+                            const TypeRef *base) {
+    // Should not have unresolved dependent member types here.
+    return nullptr;
+  }
+
   const DependentMemberTypeRef *
   createDependentMemberType(const std::string &member,
                             const TypeRef *base,

lib/AST/ASTDemangler.cpp

@@ -329,6 +329,14 @@ Type ASTBuilder::createGenericTypeParameterType(unsigned depth,
   return GenericTypeParamType::get(depth, index, Ctx);
 }
 
+Type ASTBuilder::createDependentMemberType(StringRef member,
+                                           Type base) {
+  if (!base->isTypeParameter())
+    return Type();
+
+  return DependentMemberType::get(base, Ctx.getIdentifier(member));
+}
+
 Type ASTBuilder::createDependentMemberType(StringRef member,
                                            Type base,
                                            ProtocolDecl *protocol) {

stdlib/public/runtime/MetadataLookup.cpp

@@ -1164,6 +1164,11 @@ class DecodedMetadataBuilder {
                                       /*proposedWitnesses=*/nullptr).Value;
   }
 
+  BuiltType createDependentMemberType(StringRef name, BuiltType base) const {
+    // Should not have unresolved dependent member types here.
+    return BuiltType();
+  }
+
   BuiltType createDependentMemberType(StringRef name, BuiltType base,
                                       BuiltProtocolDecl protocol) const {
 #if SWIFT_OBJC_INTEROP

test/TypeDecoder/generics.swift

@@ -0,0 +1,109 @@
+// RUN: %empty-directory(%t)
+
+// RUN: %target-build-swift -emit-executable %s -g -o %t/generics -emit-module
+// RUN: sed -ne '/\/\/ *DEMANGLE: /s/\/\/ *DEMANGLE: *//p' < %s > %t/input
+// RUN: %lldb-moduleimport-test %t/generics -type-from-mangled=%t/input | %FileCheck %s
+
+func blackHole(_: Any...) {}
+
+protocol First {
+  associatedtype Assoc : First
+}
+
+protocol Second {
+  associatedtype Assoc : Second
+}
+
+struct OuterFirst<A : First, B : First> {
+  struct Inner<C : First, D : First> {
+    func method(a: A, b: B, c: C, d: D) {
+      do {
+        let fn: (A, A.Assoc, A.Assoc.Assoc) -> () = { _, _, _ in }
+      }
+      do {
+        let fn: (B, B.Assoc, B.Assoc.Assoc) -> () = { _, _, _ in }
+      }
+      do {
+        let fn: (C, C.Assoc, C.Assoc.Assoc) -> () = { _, _, _ in }
+      }
+      do {
+        let fn: (D, D.Assoc, D.Assoc.Assoc) -> () = { _, _, _ in }
+      }
+    }
+  }
+}
+
+struct OuterBoth<A : First & Second, B : First & Second> {
+  struct Inner<C : First & Second, D : First & Second> {
+    func method(a: A, b: B, c: C, d: D) {
+      do {
+        let fn: (A, A.Assoc, A.Assoc.Assoc) -> () = { _, _, _ in }
+      }
+      do {
+        let fn: (B, B.Assoc, B.Assoc.Assoc) -> () = { _, _, _ in }
+      }
+      do {
+        let fn: (C, C.Assoc, C.Assoc.Assoc) -> () = { _, _, _ in }
+      }
+      do {
+        let fn: (D, D.Assoc, D.Assoc.Assoc) -> () = { _, _, _ in }
+      }
+    }
+  }
+}
+
+// DEMANGLE: $sxD
+// DEMANGLE: $s5AssocQzD
+// DEMANGLE: $s5Assoc_AAQZD
+
+// CHECK: τ_0_0
+// CHECK: τ_0_0.Assoc
+// CHECK: τ_0_0.Assoc.Assoc
+
+// DEMANGLE: $sq_D
+// DEMANGLE: $s5AssocQy_D
+// DEMANGLE: $s5Assoc_AAQY_D
+
+// CHECK: τ_0_1
+// CHECK: τ_0_1.Assoc
+// CHECK: τ_0_1.Assoc.Assoc
+
+// DEMANGLE: $sqd__D
+// DEMANGLE: $s5AssocQyd__D
+// DEMANGLE: $s5Assoc_AAQYd__D
+
+// CHECK: τ_1_0
+// CHECK: τ_1_0.Assoc
+// CHECK: τ_1_0.Assoc.Assoc
+
+// DEMANGLE: $sqd_0_D
+// DEMANGLE: $s5AssocQyd_0_D
+// DEMANGLE: $s5Assoc_AAQYd_0_D
+
+// CHECK: τ_1_1
+// CHECK: τ_1_1.Assoc
+// CHECK: τ_1_1.Assoc.Assoc
+
+// DEMANGLE: $s5Assoc8generics5FirstPQzD
+// DEMANGLE: $s5Assoc8generics5FirstP_AaDQZD
+
+// CHECK: τ_0_0.Assoc
+// CHECK: τ_0_0.Assoc.Assoc
+
+// DEMANGLE: $s5Assoc8generics5FirstPQy_D
+// DEMANGLE: $s5Assoc8generics5FirstP_AaDQY_D
+
+// CHECK: τ_0_1.Assoc
+// CHECK: τ_0_1.Assoc.Assoc
+
+// DEMANGLE: $s5Assoc8generics5FirstPQyd__D
+// DEMANGLE: $s5Assoc8generics5FirstP_AaDQYd__D
+
+// CHECK: τ_1_0.Assoc
+// CHECK: τ_1_0.Assoc.Assoc
+
+// DEMANGLE: $s5Assoc8generics5FirstPQyd_0_D
+// DEMANGLE: $s5Assoc8generics5FirstP_AaDQYd_0_D
+
+// CHECK: τ_1_1.Assoc
+// CHECK: τ_1_1.Assoc.Assoc