[AST Printer] Associate "Self == Self.Foo requirements with "Foo".

Author: DougGregor

lib/AST/ASTPrinter.cpp

@@ -1300,7 +1300,9 @@ bestRequirementPrintLocation(ProtocolDecl *proto, const Requirement &req) {
     // Self.T.U == Self should go on T (third condition).
     auto rhsBetterDirect =
         !lhsResult.second && rhsResult.second && rhsResult.first != proto;
-    if (lhsDoesntExist || rhsBetterDirect)
+    auto rhsOfSelfToAssoc = lhsResult.first == proto && rhsResult.first;
+    // e.g. Self == Self.T.U
+    if (lhsDoesntExist || rhsBetterDirect || rhsOfSelfToAssoc)
       bestDecl = rhsResult.first;
 
     // Same-type requirements can only occur in where clauses

test/IDE/print_ast_tc_decls.swift

@@ -1339,13 +1339,13 @@ protocol ProtocolWithWhereClause : QuxProtocol where Qux == Int, Self : FooProto
 // PREFER_TYPE_REPR_PRINTING: protocol ProtocolWithWhereClause : QuxProtocol where Self : FooProtocol, Self.Qux == Int {
 
 protocol ProtocolWithWhereClauseAndAssoc : QuxProtocol where Qux == Int, Self : FooProtocol {
-// PREFER_TYPE_REPR_PRINTING-DAG: protocol ProtocolWithWhereClauseAndAssoc : QuxProtocol where Self : FooProtocol, Self == Self.A2.Qux, Self.Qux == Int {
+// PREFER_TYPE_REPR_PRINTING-DAG: protocol ProtocolWithWhereClauseAndAssoc : QuxProtocol where Self : FooProtocol, Self.Qux == Int {
   associatedtype A1 : QuxProtocol where A1 : FooProtocol, A1.Qux : QuxProtocol, Int == A1.Qux.Qux
 // PREFER_TYPE_REPR_PRINTING-DAG: {{^}}  associatedtype A1 : QuxProtocol where Self.A1 : FooProtocol, Self.A1.Qux : QuxProtocol, Self.A1.Qux.Qux == Int{{$}}
 
   // FIXME: this same type requirement with Self should be printed here
   associatedtype A2 : QuxProtocol where A2.Qux == Self
-// PREFER_TYPE_REPR_PRINTING-DAG: {{^}}  associatedtype A2 : QuxProtocol{{$}}
+// PREFER_TYPE_REPR_PRINTING-DAG: {{^}}  associatedtype A2 : QuxProtocol where Self == Self.A2.Qux{{$}}
 }
 
 #if true