Add Layout Requirements To AST

Layout Requirements aren't a fully-exposed part of the language, but
we do need some representation for them.

Author: CodaFi

lib/Parse/ParseGeneric.cpp

@@ -298,10 +298,11 @@ ParserStatus Parser::parseGenericWhereClause(
     if (Tok.is(tok::colon)) {
       // A conformance-requirement.
       SourceLoc ColonLoc = consumeToken();
-      BodyContext->setCreateSyntax(SyntaxKind::ConformanceRequirement);
       if (Tok.is(tok::identifier) &&
           getLayoutConstraint(Context.getIdentifier(Tok.getText()), Context)
               ->isKnownLayout()) {
+        BodyContext->setCreateSyntax(SyntaxKind::LayoutRequirement);
+
         // Parse a layout constraint.
         Identifier LayoutName;
         auto LayoutLoc = consumeIdentifier(LayoutName,
@@ -323,6 +324,7 @@ ParserStatus Parser::parseGenericWhereClause(
               LayoutConstraintLoc(Layout, LayoutLoc)));
         }
       } else {
+        BodyContext->setCreateSyntax(SyntaxKind::ConformanceRequirement);
         // Parse the protocol or composition.
         ParserResult<TypeRepr> Protocol = parseType();
         Status |= Protocol;

utils/gyb_syntax_support/GenericNodes.py

@@ -15,7 +15,7 @@
          element_name='GenericRequirement'),
 
     # generic-requirement ->
-    #     (same-type-requirement|conformance-requirement) ','?
+    #     (same-type-requirement|conformance-requirement|layout-requirement) ','?
     Node('GenericRequirement', kind='Syntax',
          traits=['WithTrailingComma'],
          children=[
@@ -25,6 +25,8 @@
                              kind='SameTypeRequirement'),
                        Child('ConformanceRequirement',
                              kind='ConformanceRequirement'),
+                       Child('LayoutRequirement',
+                             kind='LayoutRequirement'),
                    ]),
              Child('TrailingComma', kind='CommaToken',
                    is_optional=True),
@@ -44,6 +46,23 @@
              Child('RightTypeIdentifier', kind='Type'),
          ]),
 
+    # layout-requirement -> type-name : layout-constraint
+    # layout-constraint -> identifier '('? integer-literal? ','? integer-literal? ')'?
+    Node('LayoutRequirement', kind='Syntax',
+         children=[
+             Child('TypeIdentifier', kind='Type'),
+             Child('Colon', kind='ColonToken'),
+             Child('LayoutConstraint', kind='IdentifierToken'),
+             Child('LeftParen', kind='LeftParenToken',
+                   is_optional=True),
+             Child('Size', kind='IntegerLiteralToken', is_optional=True),
+             Child('Comma', kind='CommaToken',
+                   is_optional=True),
+             Child('Alignment', kind='IntegerLiteralToken', is_optional=True),
+             Child('RightParen', kind='RightParenToken',
+                   is_optional=True),
+         ]),
+
     Node('GenericParameterList', kind='SyntaxCollection',
          element='GenericParameter'),
 

utils/gyb_syntax_support/NodeSerializationCodes.py

@@ -166,7 +166,7 @@
     'AvailabilityVersionRestriction': 161,
     'VersionTuple': 162,
     'CodeBlockItemList': 163,
-    # removed: 'FunctionCallArgumentList': 164,
+    'LayoutRequirement': 164,
     'TupleExprElementList': 165,
     'ArrayElementList': 166,
     'DictionaryElementList': 167,