From 0c3cd458773f2fa416dbb3448b0976e1ab178476 Mon Sep 17 00:00:00 2001
From: John Hodge <tpg@mutabah.net>
Date: Sat, 29 Oct 2016 11:52:53 +0800
Subject: Parse - Convert `<Foo>::BAR` into `<Foo as _>::BAR`

---
 src/parse/expr.cpp       | 22 +++++-----------------
 src/parse/paths.cpp      |  6 ++++--
 src/resolve/absolute.cpp |  2 +-
 3 files changed, 10 insertions(+), 20 deletions(-)

diff --git a/src/parse/expr.cpp b/src/parse/expr.cpp
index ddac8a2b..018000db 100644
--- a/src/parse/expr.cpp
+++ b/src/parse/expr.cpp
@@ -1066,23 +1066,10 @@ ExprNodeP Parse_ExprVal(TokenStream& lex)
     
     // UFCS
     case TOK_DOUBLE_LT:
-        PUTBACK(TOK_LT, lex);
-    case TOK_LT: {
-        TypeRef ty = Parse_Type(lex);
-        if( GET_TOK(tok, lex) == TOK_RWORD_AS ) {
-            auto trait = Parse_Path(lex, PATH_GENERIC_TYPE);
-            GET_CHECK_TOK(tok, lex, TOK_GT);
-            GET_CHECK_TOK(tok, lex, TOK_DOUBLE_COLON);
-            path = AST::Path(AST::Path::TagUfcs(), ty, trait, Parse_PathNodes(lex, PATH_GENERIC_EXPR));
-        }
-        else {
-            PUTBACK(tok, lex);
-            GET_CHECK_TOK(tok, lex, TOK_GT);
-            // TODO: Terminating the "path" here is sometimes valid
-            GET_CHECK_TOK(tok, lex, TOK_DOUBLE_COLON);
-            path = AST::Path(AST::Path::TagUfcs(), ty, Parse_PathNodes(lex, PATH_GENERIC_EXPR));
-        }
-        }
+    case TOK_LT:
+        PUTBACK(tok, lex);
+        path = Parse_Path(lex, PATH_GENERIC_EXPR);
+        // Skip down to method
         if(0)
     case TOK_RWORD_SELF:
         {
@@ -1116,6 +1103,7 @@ ExprNodeP Parse_ExprVal(TokenStream& lex)
         if(0)
     case TOK_DOUBLE_COLON:
         path = Parse_Path(lex, true, PATH_GENERIC_EXPR);
+        // SKIP TARGET
         switch( GET_TOK(tok, lex) )
         {
         case TOK_PAREN_OPEN:
diff --git a/src/parse/paths.cpp b/src/parse/paths.cpp
index ecfdf7dd..c952d977 100644
--- a/src/parse/paths.cpp
+++ b/src/parse/paths.cpp
@@ -45,7 +45,7 @@ AST::Path Parse_Path(TokenStream& lex, eParsePathGenericMode generic_mode)
     case TOK_DOUBLE_LT:
         lex.putback( Token(TOK_LT) );
     case TOK_LT: {
-        TypeRef ty = Parse_Type(lex, false);    // Don't allow un-parenthesied trait objects
+        TypeRef ty = Parse_Type(lex, true);  // Allow trait objects without parens
         if( GET_TOK(tok, lex) == TOK_RWORD_AS ) {
             ::AST::Path trait;
             if( GET_TOK(tok, lex) == TOK_DOUBLE_COLON ) {
@@ -64,7 +64,9 @@ AST::Path Parse_Path(TokenStream& lex, eParsePathGenericMode generic_mode)
             GET_CHECK_TOK(tok, lex, TOK_GT);
             // TODO: Terminating the "path" here is sometimes valid?
             GET_CHECK_TOK(tok, lex, TOK_DOUBLE_COLON);
-            return AST::Path(AST::Path::TagUfcs(), ty, Parse_PathNodes(lex, generic_mode));
+            // NOTE: <Foo>::BAR is actually `<Foo as _>::BAR` (in mrustc parleance)
+            //return AST::Path(AST::Path::TagUfcs(), ty, Parse_PathNodes(lex, generic_mode));
+            return AST::Path(AST::Path::TagUfcs(), ty, AST::Path(), Parse_PathNodes(lex, generic_mode));
         }
         throw ""; }
     
diff --git a/src/resolve/absolute.cpp b/src/resolve/absolute.cpp
index d8b167c4..7f69f02d 100644
--- a/src/resolve/absolute.cpp
+++ b/src/resolve/absolute.cpp
@@ -1388,7 +1388,7 @@ void Resolve_Absolute_Path(/*const*/ Context& context, const Span& sp, Context::
     (UFCS,
         DEBUG("- UFCS");
         Resolve_Absolute_Type(context, *e.type);
-        if( e.trait ) {
+        if( e.trait && *e.trait != ::AST::Path() ) {
             Resolve_Absolute_Path(context, sp, Context::LookupMode::Type, *e.trait);
         }
         
-- 
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