Merge pull request swiftlang#74522 from mateusrodriguesxyz/trailing-comma

Author: ahoppen

include/swift/Basic/Features.def

@@ -398,6 +398,9 @@ EXPERIMENTAL_FEATURE(SE427NoInferenceOnExtension, true)
 
 EXPERIMENTAL_FEATURE(Extern, true)
 
+// Enable trailing comma for comma-separated lists.
+EXPERIMENTAL_FEATURE(TrailingComma, false)
+
 #undef EXPERIMENTAL_FEATURE_EXCLUDED_FROM_MODULE_INTERFACE
 #undef EXPERIMENTAL_FEATURE
 #undef UPCOMING_FEATURE

include/swift/Parse/Parser.h

@@ -1986,6 +1986,8 @@ class Parser {
   /// expression can be parsed.
   bool isStartOfStmt(bool preferExpr);
 
+  bool isStartOfConditionalStmtBody();
+
   bool isTerminatorForBraceItemListKind(BraceItemListKind Kind,
                                         ArrayRef<ASTNode> ParsedDecls);
   ParserResult<Stmt> parseStmt(bool fromASTGen = false);

lib/AST/FeatureSet.cpp

@@ -224,6 +224,7 @@ UNINTERESTING_FEATURE(Sensitive)
 UNINTERESTING_FEATURE(DebugDescriptionMacro)
 UNINTERESTING_FEATURE(ReinitializeConsumeInMultiBlockDefer)
 UNINTERESTING_FEATURE(SE427NoInferenceOnExtension)
+UNINTERESTING_FEATURE(TrailingComma)
 
 // ----------------------------------------------------------------------------
 // MARK: - FeatureSet

lib/ASTGen/Sources/ASTGen/SourceFile.swift

@@ -67,6 +67,7 @@ extension Parser.ExperimentalFeatures {
     mapFeature(.DoExpressions, to: .doExpressions)
     mapFeature(.NonescapableTypes, to: .nonescapableTypes)
     mapFeature(.SendingArgsAndResults, to: .sendingArgsAndResults)
+    mapFeature(.TrailingComma, to: .trailingComma)
   }
 }