Enhance VarPattern to capture a bit indicating whether the pattern was a var or let.

Previously we only used this information in the parser, but Sema needs to know as well.

NFC except in -dump-ast.



Swift SVN r25914

include/swift/AST/Pattern.h

@@ -757,14 +757,18 @@ public:
 /// parsed as expressions referencing existing entities.
 class VarPattern : public Pattern {
   SourceLoc VarLoc;
+  bool IsLet;  // True if this is a let pattern, false if a var pattern.
   Pattern *SubPattern;
 public:
-  VarPattern(SourceLoc loc, Pattern *sub, Optional<bool> implicit = None)
+  VarPattern(SourceLoc loc, bool isLet, Pattern *sub,
-    : Pattern(PatternKind::Var), VarLoc(loc), SubPattern(sub) {
+             Optional<bool> implicit = None)
+    : Pattern(PatternKind::Var), VarLoc(loc), IsLet(isLet), SubPattern(sub) {
     if (implicit.hasValue() ? *implicit : !loc.isValid())
       setImplicit();
   }
 
+  bool isLet() const { return IsLet; }
+  
   SourceLoc getLoc() const { return VarLoc; }
   SourceRange getSourceRange() const {
     SourceLoc EndLoc = SubPattern->getSourceRange().End;

include/swift/Serialization/ModuleFormat.h

@@ -51,7 +51,7 @@ const uint16_t VERSION_MAJOR = 0;
 /// To ensure that two separate changes don't silently get merged into one
 /// in source control, you should also update the comment to briefly
 /// describe what change you made.
-const uint16_t VERSION_MINOR = 177; // Last change: Flag for sib
+const uint16_t VERSION_MINOR = 178; // Last change: VarPattern
 
 using DeclID = Fixnum<31>;
 using DeclIDField = BCFixed<31>;
@@ -1009,6 +1009,7 @@ namespace decls_block {
 
   using VarPatternLayout = BCRecordLayout<
     VAR_PATTERN,
+    BCFixed<1>, // isLet?
     BCFixed<1>  // implicit?
     // The sub-pattern trails the record.
   >;

lib/AST/ASTDumper.cpp

@@ -259,7 +259,7 @@ namespace {
       OS << ')';
     }
     void visitVarPattern(VarPattern *P) {
-      printCommon(P, "pattern_var");
+      printCommon(P, P->isLet() ? "pattern_let" : "pattern_var");
       OS << '\n';
       printRec(P->getSubPattern());
       OS << ')';

lib/AST/ASTPrinter.cpp

@@ -498,7 +498,7 @@ void PrintAST::printPattern(const Pattern *pattern) {
 
   case PatternKind::Var:
     if (!Options.SkipIntroducerKeywords)
-      Printer << "var ";
+      Printer << (cast<VarPattern>(pattern)->isLet() ? "let " : "var ");
     printPattern(cast<VarPattern>(pattern)->getSubPattern());
   }
 }

lib/AST/Pattern.cpp

@@ -390,7 +390,7 @@ Pattern *Pattern::clone(ASTContext &context,
       
   case PatternKind::Var: {
     auto var = cast<VarPattern>(this);
-    result = new(context) VarPattern(var->getLoc(),
+    result = new(context) VarPattern(var->getLoc(), var->isLet(),
                                      var->getSubPattern()->clone(
                                        context,
                                        options|IsVar));
@@ -431,7 +431,7 @@ Pattern *Pattern::cloneForwardable(ASTContext &context, DeclContext *DC,
 
   case PatternKind::Var: {
     auto var = cast<VarPattern>(this);
-    result = new(context) VarPattern(var->getLoc(),
+    result = new(context) VarPattern(var->getLoc(), var->isLet(),
                                      var->getSubPattern()->cloneForwardable(
                                        context, DC, options|IsVar));
     break;

lib/Parse/ParsePattern.cpp

@@ -391,7 +391,8 @@ mapParsedParameters(Parser &parser,
     // If 'var' or 'let' was specified explicitly, create a pattern for it.
     if (specifierKind != Parser::ParsedParameter::InOut &&
         letVarInOutLoc.isValid()) {
-      param = new (ctx) VarPattern(letVarInOutLoc, param);
+      bool isLet = specifierKind == Parser::ParsedParameter::Let;
+      param = new (ctx) VarPattern(letVarInOutLoc, isLet, param);
     }
 
     if (var)
@@ -802,7 +803,8 @@ ParserResult<Pattern> Parser::parsePatternVarOrLet() {
     return makeParserCodeCompletionResult<Pattern>();
   if (subPattern.isNull())
     return nullptr;
-  return makeParserResult(new (Context) VarPattern(varLoc, subPattern.get()));
+  return makeParserResult(new (Context) VarPattern(varLoc, isLet,
+                                                   subPattern.get()));
 }
 
 /// \brief Determine whether this token can start a binding name, whether an
@@ -978,21 +980,22 @@ ParserResult<Pattern> Parser::parseMatchingPattern() {
 
 ParserResult<Pattern> Parser::parseMatchingPatternVarOrVal() {
   assert((Tok.is(tok::kw_let) || Tok.is(tok::kw_var)) && "expects val or var");
-  bool isVal = Tok.is(tok::kw_let);
+  bool isLet = Tok.is(tok::kw_let);
   SourceLoc varLoc = consumeToken();
 
   // 'var' and 'let' patterns shouldn't nest.
   if (InVarOrLetPattern)
-    diagnose(varLoc, diag::var_pattern_in_var, unsigned(isVal));
+    diagnose(varLoc, diag::var_pattern_in_var, unsigned(isLet));
 
   // In our recursive parse, remember that we're in a var/let pattern.
   llvm::SaveAndRestore<decltype(InVarOrLetPattern)>
-    T(InVarOrLetPattern, isVal ? IVOLP_InLet : IVOLP_InVar);
+    T(InVarOrLetPattern, isLet ? IVOLP_InLet : IVOLP_InVar);
 
   ParserResult<Pattern> subPattern = parseMatchingPattern();
   if (subPattern.isNull())
     return nullptr;
-  return makeParserResult(new (Context) VarPattern(varLoc, subPattern.get()));
+  return makeParserResult(new (Context) VarPattern(varLoc, isLet,
+                                                   subPattern.get()));
 }
 
 // matching-pattern ::= 'is' type

lib/Serialization/Deserialization.cpp

@@ -367,12 +367,12 @@ Pattern *ModuleFile::maybeReadPattern() {
     return result;
   }
   case decls_block::VAR_PATTERN: {
-    bool isImplicit;
+    bool isImplicit, isLet;
-    VarPatternLayout::readRecord(scratch, isImplicit);
+    VarPatternLayout::readRecord(scratch, isLet, isImplicit);
     Pattern *subPattern = maybeReadPattern();
     assert(subPattern);
 
-    auto result = new (getContext()) VarPattern(SourceLoc(), subPattern,
+    auto result = new (getContext()) VarPattern(SourceLoc(), isLet, subPattern,
                                                 isImplicit);
     result->setType(subPattern->getType());
     return result;

lib/Serialization/Serialization.cpp

@@ -842,7 +842,7 @@ void Serializer::writePattern(const Pattern *pattern) {
     auto var = cast<VarPattern>(pattern);
 
     unsigned abbrCode = DeclTypeAbbrCodes[VarPatternLayout::Code];
-    VarPatternLayout::emitRecord(Out, ScratchRecord, abbrCode,
+    VarPatternLayout::emitRecord(Out, ScratchRecord, abbrCode, var->isLet(),
                                  var->isImplicit());
     writePattern(var->getSubPattern());
     break;