[SourceKit] Annotate dynamic Self type in protocol *extensions*

D'oh, forgot to resolve a FIXME in my protocol commit. Now working there
too except that it's giving USRs on the original protocol instead of the
extension.  It's not clear how to get back to the extension from the
archetype though.

rdar://problem/25128561

Author: benlangmuir

lib/AST/ASTPrinter.cpp

@@ -3855,10 +3855,18 @@ class TypePrinter : public TypeVisitor<TypePrinter> {
       if (T->getName().empty())
         Printer << "<anonymous>";
       else {
-        PrintNameContext context = PrintNameContext::Normal;
-        if (T->getSelfProtocol())
-          context = PrintNameContext::GenericParameter;
-        Printer.printName(T->getName(), context);
+        // Print protocol 'Self' as a generic parameter so that it gets
+        // annotated in cursor info.
+        // FIXME: in a protocol extension, we really want the extension, not the
+        // protocol.
+        if (auto *P = T->getSelfProtocol()) {
+          auto *GTD = P->getProtocolSelf();
+          assert(GTD && GTD->isProtocolSelf());
+          Printer.printTypeRef(T, GTD, T->getName());
+          return;
+        }
+
+        Printer.printName(T->getName());
       }
     }
   }

test/SourceKit/SourceDocInfo/cursor_info.swift

@@ -602,10 +602,10 @@ class C7 {
 // RUN: %sourcekitd-test -req=cursor -pos=165:8 %s -- -F %S/../Inputs/libIDE-mock-sdk -I %t.tmp %mcp_opt %s | FileCheck %s -check-prefix=CHECK75
 // CHECK75: source.lang.swift.decl.function.method.instance (165:8-165:18)
 // CHECK75: <Self : P3> (Self) -> (Self) -> Self
-// CHECK75: <Declaration>func f(s: <Type usr="s:tE11cursor_infoPS_2P34SelfMx">Self</Type>) -&gt; Self</Declaration>
+// CHECK75: <Declaration>func f(s: <Type usr="s:tE11cursor_infoPS_2P34SelfMx">Self</Type>) -&gt; <Type usr="s:tP11cursor_info2P34SelfMx">Self</Type></Declaration>
 // CHECK75: <decl.var.parameter.type><ref.generic_type_param usr="s:tE11cursor_infoPS_2P34SelfMx">Self</ref.generic_type_param></decl.var.parameter.type>
-// CHECK75-SAME: <decl.function.returntype><decl.generic_type_param.name>Self</decl.generic_type_param.name></decl.function.returntype>
-// FIXME: Should be ref.generic_type_param
+// CHECK75-SAME: <decl.function.returntype><ref.generic_type_param usr="s:tP11cursor_info2P34SelfMx">Self</ref.generic_type_param></decl.function.returntype>
+// FIXME: the return type gets the USR for the original protocol, rather than the extension.
 
 // RUN: %sourcekitd-test -req=cursor -pos=169:8 %s -- -F %S/../Inputs/libIDE-mock-sdk -I %t.tmp %mcp_opt %s | FileCheck %s -check-prefix=CHECK76
 // CHECK76: source.lang.swift.decl.function.method.instance (169:8-169:11)