[Parse] Reorder precedence of '&' operator in type parsing

Now 'P1 & P2.Type' is parsed as (composition P1, (metatype P2))
instead of (metatype (composition P1, P2)).

For now, parsing inheritance clause accepts any TypeRepr, that is not allowed
in current Swift grammer. Diagnostic logic will be added in later commits.

Also, in Swift3, (composition P1, (metatype P2)) should be fixed to
(metatype (composition P1, P2)) for source compatibility.

include/swift/Parse/Parser.h

@@ -837,6 +837,11 @@ public:
   parseTypeIdentifierWithRecovery(Diag<> MessageID,
                                   Diag<TypeLoc> NonIdentifierTypeMessageID);
 
+  ParserResult<TypeRepr> parseTypeSimpleOrComposition();
+  ParserResult<TypeRepr>
+    parseTypeSimpleOrComposition(Diag<> MessageID,
+                                 bool HandleCodeCompletion = true);
+
   ParserResult<TypeRepr> parseTypeSimple();
   ParserResult<TypeRepr> parseTypeSimple(Diag<> MessageID,
                                          bool HandleCodeCompletion = true);
@@ -845,7 +850,6 @@ public:
                              SourceLoc &RAngleLoc);
 
   ParserResult<TypeRepr> parseTypeIdentifier();
-  ParserResult<TypeRepr> parseTypeIdentifierOrTypeComposition();
   ParserResult<TypeRepr> parseOldStyleProtocolComposition();
   ParserResult<CompositionTypeRepr> parseAnyType();
 

lib/Parse/ParseDecl.cpp

@@ -2415,10 +2415,10 @@ ParserStatus Parser::parseInheritance(SmallVectorImpl<TypeLoc> &Inherited,
     bool usesDeprecatedCompositionSyntax = Tok.is(tok::kw_protocol) && startsWithLess(peekToken());
     bool isAny = Tok.is(tok::kw_Any); // We allow (redundant) inheritance from Any
 
-    auto ParsedTypeResult = parseTypeIdentifierOrTypeComposition();
+    auto ParsedTypeResult = parseTypeSimpleOrComposition();
     Status |= ParsedTypeResult;
 
-    // Cannot inherit from composition
+    // Recover and emit nice diagnostic for composition.
     if (auto Composition = dyn_cast_or_null<CompositionTypeRepr>(
           ParsedTypeResult.getPtrOrNull())) {
       // Record the protocols inside the composition.

lib/Parse/ParseGeneric.cpp

@@ -71,7 +71,7 @@ Parser::parseGenericParameters(SourceLoc LAngleLoc) {
       ParserResult<TypeRepr> Ty;
       
       if (Tok.isAny(tok::identifier, tok::code_complete, tok::kw_protocol, tok::kw_Any)) {
-        Ty = parseTypeIdentifierOrTypeComposition();
+        Ty = parseTypeSimpleOrComposition();
       } else if (Tok.is(tok::kw_class)) {
         diagnose(Tok, diag::unexpected_class_constraint);
         diagnose(Tok, diag::suggest_anyobject, Name)
@@ -267,7 +267,7 @@ ParserStatus Parser::parseGenericWhereClause(
       SourceLoc ColonLoc = consumeToken();
 
       // Parse the protocol or composition.
-      ParserResult<TypeRepr> Protocol = parseTypeIdentifierOrTypeComposition();
+      ParserResult<TypeRepr> Protocol = parseTypeSimpleOrComposition();
       
       if (Protocol.isNull()) {
         Status.setIsParseError();

lib/Parse/ParseType.cpp

@@ -14,6 +14,7 @@
 //
 //===----------------------------------------------------------------------===//
 
+#include "swift/Basic/Fallthrough.h"
 #include "swift/Parse/Parser.h"
 #include "swift/AST/Attr.h"
 #include "swift/AST/TypeLoc.h"
@@ -42,13 +43,14 @@ ParserResult<TypeRepr> Parser::parseTypeSimple() {
 ///   type-simple:
 ///     type-identifier
 ///     type-tuple
-///     type-composition
+///     type-composition-deprecated
 ///     'Any'
 ///     type-simple '.Type'
 ///     type-simple '.Protocol'
 ///     type-simple '?'
 ///     type-simple '!'
 ///     type-collection
+///     type-array
 ParserResult<TypeRepr> Parser::parseTypeSimple(Diag<> MessageID,
                                                bool HandleCodeCompletion) {
   ParserResult<TypeRepr> ty;
@@ -57,13 +59,16 @@ ParserResult<TypeRepr> Parser::parseTypeSimple(Diag<> MessageID,
   consumeIf(tok::kw_inout, InOutLoc);
 
   switch (Tok.getKind()) {
-  case tok::kw_Self:
-    ty = parseTypeIdentifier();
-    break;
-  case tok::identifier:
   case tok::kw_protocol:
+    if (startsWithLess(peekToken())) {
+      ty = parseOldStyleProtocolComposition();
+      break;
+    }
+    SWIFT_FALLTHROUGH;
+  case tok::kw_Self:
   case tok::kw_Any:
-    ty = parseTypeIdentifierOrTypeComposition();
+  case tok::identifier:
+    ty = parseTypeIdentifier();
     break;
   case tok::l_paren:
     ty = parseTypeTupleBody();
@@ -89,12 +94,17 @@ ParserResult<TypeRepr> Parser::parseTypeSimple(Diag<> MessageID,
     ty = parseTypeCollection();
     break;
   default:
-    checkForInputIncomplete();
     diagnose(Tok, MessageID);
+    if (Tok.isKeyword() && !Tok.isAtStartOfLine()) {
+      ty = makeParserErrorResult(new (Context) ErrorTypeRepr(Tok.getLoc()));
+      consumeToken();
+      return ty;
+    }
+    checkForInputIncomplete();
     return nullptr;
   }
   
-  // '.Type', '.Protocol', '?', and '!' still leave us with type-simple.
+  // '.Type', '.Protocol', '?', '!', and '[]' still leave us with type-simple.
   while (ty.isNonNull()) {
     if ((Tok.is(tok::period) || Tok.is(tok::period_prefix))) {
       if (peekToken().isContextualKeyword("Type")) {
@@ -122,6 +132,11 @@ ParserResult<TypeRepr> Parser::parseTypeSimple(Diag<> MessageID,
         ty = parseTypeImplicitlyUnwrappedOptional(ty.get());
         continue;
       }
+      // Parse legacy array types for migration.
+      if (Tok.is(tok::l_square)) {
+        ty = parseTypeArray(ty.get());
+        continue;
+      }
     }
     break;
   }
@@ -140,11 +155,11 @@ ParserResult<TypeRepr> Parser::parseType() {
 
 /// parseType
 ///   type:
+///     attribute-list type-composition
 ///     attribute-list type-function
-///     attribute-list type-array
 ///
 ///   type-function:
-///     type-simple '->' type
+///     type-composition '->' type
 ///
 ParserResult<TypeRepr> Parser::parseType(Diag<> MessageID,
                                          bool HandleCodeCompletion) {
@@ -159,7 +174,8 @@ ParserResult<TypeRepr> Parser::parseType(Diag<> MessageID,
     generics = maybeParseGenericParams().getPtrOrNull();
   }
 
-  ParserResult<TypeRepr> ty = parseTypeSimple(MessageID, HandleCodeCompletion);
+  ParserResult<TypeRepr> ty =
+    parseTypeSimpleOrComposition(MessageID, HandleCodeCompletion);
   if (ty.hasCodeCompletion())
     return makeParserCodeCompletionResult<TypeRepr>();
 
@@ -215,15 +231,6 @@ ParserResult<TypeRepr> Parser::parseType(Diag<> MessageID,
     diagnose(brackets.Start, diag::generic_non_function);
   }
 
-  // Parse legacy array types for migration.
-  while (ty.isNonNull() && !Tok.isAtStartOfLine()) {
-    if (Tok.is(tok::l_square)) {
-      ty = parseTypeArray(ty.get());
-    } else {
-      break;
-    }
-  }
-
   if (ty.isNonNull() && !ty.hasCodeCompletion()) {
     ty = makeParserResult(applyAttributeToType(ty.get(), attrs));
   }
@@ -392,47 +399,57 @@ ParserResult<TypeRepr> Parser::parseTypeIdentifier() {
   return makeParserResult(Status, ITR);
 }
 
-/// parseTypeIdentifierOrTypeComposition
-/// - Identifiers and compositions both start with the same identifier
-///   token, parse it and continue constructing a composition if the
-///   next token is '&'
+ParserResult<TypeRepr> Parser::parseTypeSimpleOrComposition() {
+  return parseTypeSimpleOrComposition(diag::expected_identifier_for_type);
+}
+
+/// parseTypeSimpleOrComposition
 ///
 ///   type-composition:
-///     type-identifier ('&' type-identifier)*
-///     type-composition-deprecated
-///
-///   type-composition-list-deprecated:
-///     type-identifier (',' type-identifier)*
-ParserResult<TypeRepr> Parser::parseTypeIdentifierOrTypeComposition() {
-  if (Tok.is(tok::kw_protocol) && startsWithLess(peekToken()))
-    return parseOldStyleProtocolComposition();
-
-  SourceLoc FirstTypeLoc = Tok.getLoc();
-  
+///     type-simple
+///     type-composition '&' type-simple
+ParserResult<TypeRepr>
+Parser::parseTypeSimpleOrComposition(Diag<> MessageID,
+                                     bool HandleCodeCompletion) {
   // Parse the first type
-  ParserResult<TypeRepr> FirstType = parseTypeIdentifier();
-  if (!Tok.isContextualPunctuator("&"))
+  ParserResult<TypeRepr> FirstType = parseTypeSimple(MessageID,
+                                                     HandleCodeCompletion);
+  if (FirstType.hasCodeCompletion())
+    return makeParserCodeCompletionResult<TypeRepr>();
+  if (FirstType.isNull() || !Tok.isContextualPunctuator("&"))
     return FirstType;
   
-  SmallVector<TypeRepr *, 4> Protocols;
-  ParserStatus Status;
+  SmallVector<TypeRepr *, 4> Types;
+  ParserStatus Status(FirstType);
+  SourceLoc FirstTypeLoc = FirstType.get()->getStartLoc();
+  SourceLoc FirstAmpersandLoc = Tok.getLoc();
 
-  // If it is not 'Any', add it to the protocol list
-  if (auto *ident = dyn_cast_or_null<IdentTypeRepr>(FirstType.getPtrOrNull()))
-    Protocols.push_back(ident);
-  Status |= FirstType;
-  auto FirstAmpersandLoc = Tok.getLoc();
+  auto addType = [&](TypeRepr *T) {
+    if (!T) return;
+    if (auto Comp = dyn_cast<CompositionTypeRepr>(T)) {
+      // Accept protocol<P1, P2> & P3; explode it.
+      auto TyRs = Comp->getTypes();
+      if (!TyRs.empty()) // If empty, is 'Any'; igone.
+        Types.append(TyRs.begin(), TyRs.end());
+      return;
+    }
+    Types.push_back(T);
+  };
+
+  addType(FirstType.get());
   
   while (Tok.isContextualPunctuator("&")) {
     consumeToken(); // consume '&'
-    ParserResult<TypeRepr> Protocol = parseTypeIdentifier();
-    Status |= Protocol;
-    if (auto *ident = dyn_cast_or_null<IdentTypeRepr>(Protocol.getPtrOrNull()))
-      Protocols.push_back(ident);
+    ParserResult<TypeRepr> ty =
+      parseTypeSimple(diag::expected_identifier_for_type, HandleCodeCompletion);
+    if (ty.hasCodeCompletion())
+      return makeParserCodeCompletionResult<TypeRepr>();
+    Status |= ty;
+    addType(ty.getPtrOrNull());
   };
   
   return makeParserResult(Status, CompositionTypeRepr::create(
-    Context, Protocols, FirstTypeLoc, {FirstAmpersandLoc, PreviousLoc}));
+    Context, Types, FirstTypeLoc, {FirstAmpersandLoc, PreviousLoc}));
 }
 
 ParserResult<CompositionTypeRepr> Parser::parseAnyType() {
@@ -442,10 +459,12 @@ ParserResult<CompositionTypeRepr> Parser::parseAnyType() {
 
 /// parseOldStyleProtocolComposition
 ///   type-composition-deprecated:
-///     'protocol' '<' type-composition-list-deprecated? '>'
+///     'protocol' '<' '>'
+///     'protocol' '<' type-composition-list-deprecated '>'
 ///
 ///   type-composition-list-deprecated:
-///     type-identifier (',' type-identifier)*
+///     type-identifier
+///     type-composition-list-deprecated ',' type-identifier
 ParserResult<TypeRepr> Parser::parseOldStyleProtocolComposition() {
   assert(Tok.is(tok::kw_protocol) && startsWithLess(peekToken()));
 
@@ -482,7 +501,7 @@ ParserResult<TypeRepr> Parser::parseOldStyleProtocolComposition() {
     RAngleLoc = skipUntilGreaterInTypeList(/*protocolComposition=*/true);
   }
 
-  auto composition = ProtocolCompositionTypeRepr::create(
+  auto composition = CompositionTypeRepr::create(
     Context, Protocols, ProtocolLoc, {LAngleLoc, RAngleLoc});
 
   if (Status.isSuccess()) {
@@ -491,7 +510,7 @@ ParserResult<TypeRepr> Parser::parseOldStyleProtocolComposition() {
     if (Protocols.empty()) {
       replacement = "Any";
     } else {
-      auto extractText = [&](IdentTypeRepr *Ty) -> StringRef {
+      auto extractText = [&](TypeRepr *Ty) -> StringRef {
         auto SourceRange = Ty->getSourceRange();
         return SourceMgr.extractText(
           Lexer::getCharSourceRangeFromSourceRange(SourceMgr, SourceRange));