Parse: __shared and __owned should be contextual keywords

This was a source compatibility regression, someone actually had
an identifier named __shared.

include/swift/Parse/Parser.h

@@ -787,7 +787,10 @@ public:
   bool parseTypeAttributeList(VarDecl::Specifier &Specifier,
                               SourceLoc &SpecifierLoc,
                               TypeAttributes &Attributes) {
-    if (Tok.isAny(tok::at_sign, tok::kw_inout, tok::kw___shared, tok::kw___owned))
+    if (Tok.isAny(tok::at_sign, tok::kw_inout) ||
+        (Tok.is(tok::identifier) &&
+         (Tok.getRawText().equals("__shared") ||
+          Tok.getRawText().equals("__owned"))))
       return parseTypeAttributeListPresent(Specifier, SpecifierLoc, Attributes);
     return false;
   }

include/swift/Parse/Token.h

@@ -179,13 +179,17 @@ public:
   /// used
   bool canBeArgumentLabel() const {
     // Identifiers, escaped identifiers, and '_' can be argument labels.
-    if (is(tok::identifier) || isEscapedIdentifier() || is(tok::kw__))
-      return true;
+    if (is(tok::identifier) || isEscapedIdentifier() || is(tok::kw__)) {
+      // ... except for '__shared' and '__owned'.
+      if (getRawText().equals("__shared") ||
+          getRawText().equals("__owned"))
+        return false;
 
-    // 'let', 'var', 'inout', '__shared', and '__owned'
-    // cannot be argument labels.
-    if (isAny(tok::kw_let, tok::kw_var, tok::kw_inout,
-              tok::kw___owned, tok::kw___shared))
+      return true;
+    }
+
+    // 'let', 'var', and 'inout' cannot be argument labels.
+    if (isAny(tok::kw_let, tok::kw_var, tok::kw_inout))
       return false;
 
     // All other keywords can be argument labels.

include/swift/Syntax/TokenKinds.def

@@ -140,8 +140,6 @@ DECL_KEYWORD(struct)
 DECL_KEYWORD(subscript)
 DECL_KEYWORD(typealias)
 DECL_KEYWORD(var)
-DECL_KEYWORD(__shared)
-DECL_KEYWORD(__owned)
 
 DECL_KEYWORD(fileprivate)
 DECL_KEYWORD(internal)

lib/Parse/ParseDecl.cpp

@@ -1820,19 +1820,22 @@ bool Parser::parseTypeAttributeListPresent(VarDecl::Specifier &Specifier,
                                            SourceLoc &SpecifierLoc,
                                            TypeAttributes &Attributes) {
   Specifier = VarDecl::Specifier::Owned;
-  while (Tok.isAny(tok::kw_inout, tok::kw___shared, tok::kw___owned)) {
+  while (Tok.is(tok::kw_inout) ||
+         (Tok.is(tok::identifier) &&
+          (Tok.getRawText().equals("__shared") ||
+           Tok.getRawText().equals("__owned")))) {
     if (SpecifierLoc.isValid()) {
       diagnose(Tok, diag::parameter_specifier_repeated)
         .fixItRemove(SpecifierLoc);
     } else {
-      if (Tok.is(tok::kw___owned)) {
-        Specifier = VarDecl::Specifier::Owned;
-      } else if (Tok.is(tok::kw_inout)) {
+      if (Tok.is(tok::kw_inout)) {
         Specifier = VarDecl::Specifier::InOut;
-      } else if (Tok.is(tok::kw___shared)) {
-        Specifier = VarDecl::Specifier::Shared;
-      } else {
-        llvm_unreachable("unhandled specifier kind?");
+      } else if (Tok.is(tok::identifier)) {
+        if (Tok.getRawText().equals("__shared")) {
+          Specifier = VarDecl::Specifier::Shared;
+        } else if (Tok.getRawText().equals("__owned")) {
+          Specifier = VarDecl::Specifier::Owned;
+        }
       }
     }
     SpecifierLoc = consumeToken();

lib/Parse/ParsePattern.cpp

@@ -182,15 +182,18 @@ Parser::parseParameterClause(SourceLoc &leftParenLoc,
     
     // ('inout' | 'let' | 'var' | '__shared' | '__owned')?
     bool hasSpecifier = false;
-    while (Tok.isAny(tok::kw_inout, tok::kw_let, tok::kw_var,
-                     tok::kw___shared, tok::kw___owned)) {
+    while (Tok.isAny(tok::kw_inout, tok::kw_let, tok::kw_var) ||
+           (Tok.is(tok::identifier) &&
+            (Tok.getRawText().equals("__shared") ||
+             Tok.getRawText().equals("__owned")))) {
       if (!hasSpecifier) {
         if (Tok.is(tok::kw_inout)) {
           // This case is handled later when mapping to ParamDecls for
           // better fixits.
           param.SpecifierKind = VarDecl::Specifier::InOut;
           param.SpecifierLoc = consumeToken();
-        } else if (Tok.is(tok::kw___shared)) {
+        } else if (Tok.is(tok::identifier) &&
+                   Tok.getRawText().equals("__shared")) {
           // This case is handled later when mapping to ParamDecls for
           // better fixits.
           param.SpecifierKind = VarDecl::Specifier::Shared;

lib/Parse/ParseType.cpp

@@ -175,13 +175,16 @@ ParserResult<TypeRepr> Parser::parseTypeSimple(Diag<> MessageID,
   if (Tok.is(tok::kw_inout)) {
     SpecifierLoc = consumeToken();
     TypeSpecifier = VarDecl::Specifier::InOut;
-  } else if (Tok.is(tok::kw___shared)) {
-    SpecifierLoc = consumeToken();
-    TypeSpecifier = VarDecl::Specifier::Shared;
-  } else if (Tok.is(tok::kw___owned)) {
-    SpecifierLoc = consumeToken();
-    TypeSpecifier = VarDecl::Specifier::Owned;
-
+  } else if (Tok.is(tok::identifier)) {
+    if (Tok.getRawText().equals("__shared")) {
+      assert(false);
+      SpecifierLoc = consumeToken();
+      TypeSpecifier = VarDecl::Specifier::Shared;
+    } else if (Tok.getRawText().equals("__owned")) {
+      assert(false);
+      SpecifierLoc = consumeToken();
+      TypeSpecifier = VarDecl::Specifier::Owned;
+    }
   }
 
   switch (Tok.getKind()) {

test/Compatibility/shared_owned_identifiers.swift

@@ -0,0 +1,10 @@
+// RUN: %target-swift-frontend -typecheck %s
+
+func __shared() {}
+
+func __owned() {}
+
+func foo() {
+  __shared()
+  __owned()
+}

test/SourceKit/CodeComplete/complete_override.swift.response

@@ -1,23 +1,5 @@
 {
   key.results: [
-    {
-      key.kind: source.lang.swift.keyword,
-      key.name: "__owned",
-      key.sourcetext: "__owned",
-      key.description: "__owned",
-      key.typename: "",
-      key.context: source.codecompletion.context.none,
-      key.num_bytes_to_erase: 0
-    },
-    {
-      key.kind: source.lang.swift.keyword,
-      key.name: "__shared",
-      key.sourcetext: "__shared",
-      key.description: "__shared",
-      key.typename: "",
-      key.context: source.codecompletion.context.none,
-      key.num_bytes_to_erase: 0
-    },
     {
       key.kind: source.lang.swift.keyword,
       key.name: "associatedtype",