Parse: Create a trailing where clause even if it was incomplete

Also, store the end location of the where clause explicitly, so that
we can recover it even if there are no requirements.

This fixes one of the failing tests when parser lookup is disabled in
swift-ide-test by ensuring that the source range of the function
extends to the end of the 'where' clause, even though the 'where'
clause has a code completion token in it.

Author: slavapestov

include/swift/AST/GenericParamList.h

@@ -324,6 +324,9 @@ class GenericParamList final :
     if (WhereLoc.isInvalid())
       return SourceRange();
 
+    if (Requirements.empty())
+      return WhereLoc;
+
     auto endLoc = Requirements.back().getSourceRange().End;
     return SourceRange(WhereLoc, endLoc);
   }
@@ -352,16 +355,18 @@ class alignas(RequirementRepr) TrailingWhereClause final :
   friend TrailingObjects;
 
   SourceLoc WhereLoc;
+  SourceLoc EndLoc;
 
   /// The number of requirements. The actual requirements are tail-allocated.
   unsigned NumRequirements;
 
-  TrailingWhereClause(SourceLoc whereLoc,
+  TrailingWhereClause(SourceLoc whereLoc, SourceLoc endLoc,
                       ArrayRef<RequirementRepr> requirements);
 
 public:
   /// Create a new trailing where clause with the given set of requirements.
-  static TrailingWhereClause *create(ASTContext &ctx, SourceLoc whereLoc,
+  static TrailingWhereClause *create(ASTContext &ctx,
+                                     SourceLoc whereLoc, SourceLoc endLoc,
                                      ArrayRef<RequirementRepr> requirements);
 
   /// Retrieve the location of the 'where' keyword.
@@ -379,8 +384,7 @@ class alignas(RequirementRepr) TrailingWhereClause final :
 
   /// Compute the source range containing this trailing where clause.
   SourceRange getSourceRange() const {
-    return SourceRange(WhereLoc,
-                       getRequirements().back().getSourceRange().End);
+    return SourceRange(WhereLoc, EndLoc);
   }
 
   void print(llvm::raw_ostream &OS, bool printWhereKeyword) const;

include/swift/Parse/Parser.h

@@ -1689,8 +1689,9 @@ class Parser {
   parseFreestandingGenericWhereClause(GenericContext *genCtx);
 
   ParserStatus parseGenericWhereClause(
-      SourceLoc &WhereLoc, SmallVectorImpl<RequirementRepr> &Requirements,
-      bool &FirstTypeInComplete, bool AllowLayoutConstraints = false);
+      SourceLoc &WhereLoc, SourceLoc &EndLoc,
+      SmallVectorImpl<RequirementRepr> &Requirements,
+      bool AllowLayoutConstraints = false);
 
   ParserStatus
   parseProtocolOrAssociatedTypeWhereClause(TrailingWhereClause *&trailingWhere,

lib/AST/GenericParamList.cpp

@@ -110,9 +110,9 @@ GenericTypeParamDecl *GenericParamList::lookUpGenericParam(
 }
 
 TrailingWhereClause::TrailingWhereClause(
-                       SourceLoc whereLoc,
+                       SourceLoc whereLoc, SourceLoc endLoc,
                        ArrayRef<RequirementRepr> requirements)
-  : WhereLoc(whereLoc),
+  : WhereLoc(whereLoc), EndLoc(endLoc),
     NumRequirements(requirements.size())
 {
   std::uninitialized_copy(requirements.begin(), requirements.end(),
@@ -122,8 +122,9 @@ TrailingWhereClause::TrailingWhereClause(
 TrailingWhereClause *TrailingWhereClause::create(
                        ASTContext &ctx,
                        SourceLoc whereLoc,
+                       SourceLoc endLoc,
                        ArrayRef<RequirementRepr> requirements) {
   unsigned size = totalSizeToAlloc<RequirementRepr>(requirements.size());
   void *mem = ctx.Allocate(size, alignof(TrailingWhereClause));
-  return new (mem) TrailingWhereClause(whereLoc, requirements);
+  return new (mem) TrailingWhereClause(whereLoc, endLoc, requirements);
 }

lib/Parse/ParseDecl.cpp

@@ -717,13 +717,12 @@ bool Parser::parseSpecializeAttributeArguments(
 
   // Parse the where clause.
   if (Tok.is(tok::kw_where)) {
-    SourceLoc whereLoc;
+    SourceLoc whereLoc, endLoc;
     SmallVector<RequirementRepr, 4> requirements;
-    bool firstTypeInComplete;
-    parseGenericWhereClause(whereLoc, requirements, firstTypeInComplete,
+    parseGenericWhereClause(whereLoc, endLoc, requirements,
                             /* AllowLayoutConstraints */ true);
     TrailingWhereClause =
-        TrailingWhereClause::create(Context, whereLoc, requirements);
+        TrailingWhereClause::create(Context, whereLoc, endLoc, requirements);
   }
   return true;
 }
@@ -1053,12 +1052,12 @@ bool Parser::parseDifferentiableAttributeArguments(
 
   // Parse a trailing 'where' clause if any.
   if (Tok.is(tok::kw_where)) {
-    SourceLoc whereLoc;
+    SourceLoc whereLoc, endLoc;
     SmallVector<RequirementRepr, 4> requirements;
-    bool firstTypeInComplete;
-    parseGenericWhereClause(whereLoc, requirements, firstTypeInComplete,
+    parseGenericWhereClause(whereLoc, endLoc, requirements,
                             /*AllowLayoutConstraints*/ true);
-    whereClause = TrailingWhereClause::create(Context, whereLoc, requirements);
+    whereClause =
+        TrailingWhereClause::create(Context, whereLoc, endLoc, requirements);
   }
   return false;
 }
@@ -4878,19 +4877,17 @@ Parser::parseDeclExtension(ParseDeclOptions Flags, DeclAttributes &Attributes) {
   TrailingWhereClause *trailingWhereClause = nullptr;
   bool trailingWhereHadCodeCompletion = false;
   if (Tok.is(tok::kw_where)) {
-    SourceLoc whereLoc;
+    SourceLoc whereLoc, endLoc;
     SmallVector<RequirementRepr, 4> requirements;
-    bool firstTypeInComplete;
-    auto whereStatus = parseGenericWhereClause(whereLoc, requirements,
-                                               firstTypeInComplete);
+    auto whereStatus = parseGenericWhereClause(whereLoc, endLoc, requirements);
     if (whereStatus.hasCodeCompletion()) {
       if (isCodeCompletionFirstPass())
         return whereStatus;
       trailingWhereHadCodeCompletion = true;
     }
     if (!requirements.empty()) {
-      trailingWhereClause = TrailingWhereClause::create(Context, whereLoc,
-                                                        requirements);
+      trailingWhereClause =
+          TrailingWhereClause::create(Context, whereLoc, endLoc, requirements);
     }
     status |= whereStatus;
   }

lib/Parse/ParseGeneric.cpp

@@ -140,11 +140,11 @@ Parser::parseGenericParameters(SourceLoc LAngleLoc) {
 
   // Parse the optional where-clause.
   SourceLoc WhereLoc;
+  SourceLoc EndLoc;
   SmallVector<RequirementRepr, 4> Requirements;
-  bool FirstTypeInComplete;
   if (Tok.is(tok::kw_where) &&
-      parseGenericWhereClause(WhereLoc, Requirements,
-                              FirstTypeInComplete).isErrorOrHasCompletion()) {
+      parseGenericWhereClause(WhereLoc, EndLoc, Requirements)
+        .isErrorOrHasCompletion()) {
     Invalid = true;
   }
 
@@ -261,16 +261,14 @@ Parser::diagnoseWhereClauseInGenericParamList(const GenericParamList *
 ///   same-type-requirement:
 ///     type-identifier '==' type
 ParserStatus Parser::parseGenericWhereClause(
-               SourceLoc &WhereLoc,
+               SourceLoc &WhereLoc, SourceLoc &EndLoc,
                SmallVectorImpl<RequirementRepr> &Requirements,
-               bool &FirstTypeInComplete,
                bool AllowLayoutConstraints) {
   SyntaxParsingContext ClauseContext(SyntaxContext,
                                      SyntaxKind::GenericWhereClause);
   ParserStatus Status;
   // Parse the 'where'.
   WhereLoc = consumeToken(tok::kw_where);
-  FirstTypeInComplete = false;
   SyntaxParsingContext ReqListContext(SyntaxContext,
                                       SyntaxKind::GenericRequirementList);
   bool HasNextReq;
@@ -283,7 +281,7 @@ ParserStatus Parser::parseGenericWhereClause(
     if (Tok.is(tok::code_complete)) {
       if (CodeCompletion)
         CodeCompletion->completeGenericRequirement();
-      consumeToken(tok::code_complete);
+      EndLoc = consumeToken(tok::code_complete);
       Status.setHasCodeCompletionAndIsError();
       break;
     }
@@ -295,7 +293,6 @@ ParserStatus Parser::parseGenericWhereClause(
     if (FirstType.hasCodeCompletion()) {
       BodyContext->setTransparent();
       Status.setHasCodeCompletionAndIsError();
-      FirstTypeInComplete = true;
     }
 
     if (FirstType.isNull()) {
@@ -383,8 +380,10 @@ ParserStatus Parser::parseGenericWhereClause(
     }
   } while (HasNextReq);
 
-  if (Requirements.empty())
-    WhereLoc = SourceLoc();
+  if (!Requirements.empty())
+    EndLoc = Requirements.back().getSourceRange().End;
+  else if (EndLoc.isInvalid())
+    EndLoc = WhereLoc;
 
   return Status;
 }
@@ -396,31 +395,26 @@ parseFreestandingGenericWhereClause(GenericContext *genCtx) {
   assert(Tok.is(tok::kw_where) && "Shouldn't call this without a where");
 
   SmallVector<RequirementRepr, 4> Requirements;
-  SourceLoc WhereLoc;
-  bool FirstTypeInComplete;
-  auto result = parseGenericWhereClause(WhereLoc, Requirements,
-                                        FirstTypeInComplete);
-  if (result.isErrorOrHasCompletion() || Requirements.empty())
-    return result;
+  SourceLoc WhereLoc, EndLoc;
+  auto result = parseGenericWhereClause(WhereLoc, EndLoc, Requirements);
 
   genCtx->setTrailingWhereClause(
-      TrailingWhereClause::create(Context, WhereLoc, Requirements));
+      TrailingWhereClause::create(Context, WhereLoc, EndLoc, Requirements));
 
-  return ParserStatus();
+  return result;
 }
 
 /// Parse a where clause after a protocol or associated type declaration.
 ParserStatus Parser::parseProtocolOrAssociatedTypeWhereClause(
     TrailingWhereClause *&trailingWhere, bool isProtocol) {
   assert(Tok.is(tok::kw_where) && "Shouldn't call this without a where");
-  SourceLoc whereLoc;
+  SourceLoc whereLoc, endLoc;
   SmallVector<RequirementRepr, 4> requirements;
-  bool firstTypeInComplete;
   auto whereStatus =
-      parseGenericWhereClause(whereLoc, requirements, firstTypeInComplete);
+      parseGenericWhereClause(whereLoc, endLoc, requirements);
   if (whereStatus.isSuccess() && !whereStatus.hasCodeCompletion()) {
     trailingWhere =
-        TrailingWhereClause::create(Context, whereLoc, requirements);
+        TrailingWhereClause::create(Context, whereLoc, endLoc, requirements);
   } else if (whereStatus.hasCodeCompletion()) {
     return whereStatus;
   }