AST: Improve TypeRefinementContext debug descriptions.

When printing the source ranges for nodes that represent an expansion within a
source file, print the range from the original source file and include a
description of the kind of expansion.

Author: tshortli

include/swift/Basic/SourceManager.h

@@ -55,6 +55,7 @@ class GeneratedSourceInfo {
   enum Kind {
 #define MACRO_ROLE(Name, Description) Name##MacroExpansion,
 #include "swift/Basic/MacroRoles.def"
+#undef MACRO_ROLE
 
     /// A new function body that is replacing an existing function body.
     ReplacedFunctionBody,
@@ -66,6 +67,23 @@ class GeneratedSourceInfo {
     DefaultArgument,
   } kind;
 
+  static StringRef kindToString(GeneratedSourceInfo::Kind kind) {
+    switch (kind) {
+#define MACRO_ROLE(Name, Description)                                          \
+  case Name##MacroExpansion:                                                   \
+    return #Name "MacroExpansion";
+#include "swift/Basic/MacroRoles.def"
+#undef MACRO_ROLE
+    case ReplacedFunctionBody:
+      return "ReplacedFunctionBody";
+    case PrettyPrinted:
+      return "PrettyPrinted";
+    case DefaultArgument:
+      return "DefaultArgument";
+    }
+    llvm_unreachable("Invalid kind");
+  }
+
   /// The source range in the enclosing buffer where this source was generated.
   ///
   /// This could point at a macro expansion or at the implicit location at

lib/AST/TypeRefinementContext.cpp

@@ -404,7 +404,24 @@ void TypeRefinementContext::print(raw_ostream &OS, SourceManager &SrcMgr,
   auto R = getSourceRange();
   if (R.isValid()) {
     OS << " src_range=";
-    R.print(OS, SrcMgr, /*PrintText=*/false);
+
+    if (getReason() != Reason::Root) {
+      R.print(OS, SrcMgr, /*PrintText=*/false);
+    } else if (auto info = SrcMgr.getGeneratedSourceInfo(
+                   Node.getAsSourceFile()->getBufferID())) {
+      info->originalSourceRange.print(OS, SrcMgr, /*PrintText=*/false);
+    } else {
+      OS << "<unknown>";
+    }
+  }
+
+  if (getReason() == Reason::Root) {
+    if (auto info = SrcMgr.getGeneratedSourceInfo(
+            Node.getAsSourceFile()->getBufferID())) {
+      OS << " generated_kind=" << GeneratedSourceInfo::kindToString(info->kind);
+    } else {
+      OS << " file=" << Node.getAsSourceFile()->getFilename().str();
+    }
   }
 
   if (!ExplicitAvailabilityInfo.isAlwaysAvailable())