Parse: Don't create PatternBindingDecls with overlapping source ranges

This was happening in the error recovery path when parsing accessors
on a pattern binding declaration that does not bind any variables, eg

let _: Int { 0 }

Author: slavapestov

include/swift/Parse/Parser.h

@@ -1116,7 +1116,7 @@ class Parser {
                            ParsedAccessors &accessors,
                            AbstractStorageDecl *storage,
                            SourceLoc StaticLoc);
-  ParserResult<VarDecl> parseDeclVarGetSet(Pattern *pattern,
+  ParserResult<VarDecl> parseDeclVarGetSet(PatternBindingEntry &entry,
                                            ParseDeclOptions Flags,
                                            SourceLoc StaticLoc,
                                            StaticSpellingKind StaticSpelling,

lib/IDE/SyntaxModel.cpp

@@ -990,7 +990,9 @@ bool ModelASTWalker::walkToDeclPre(Decl *D) {
     if (bracesRange.isValid())
       SN.BodyRange = innerCharSourceRangeFromSourceRange(SM, bracesRange);
     SourceLoc NRStart = VD->getNameLoc();
-    SourceLoc NREnd = NRStart.getAdvancedLoc(VD->getName().getLength());
+    SourceLoc NREnd = (!VD->getName().empty()
+                       ? NRStart.getAdvancedLoc(VD->getName().getLength())
+                       : NRStart);
     SN.NameRange = CharSourceRange(SM, NRStart, NREnd);
     SN.TypeRange = charSourceRangeFromSourceRange(SM,
                                         VD->getTypeSourceRangeForDiagnostics());

lib/Parse/ParseDecl.cpp

@@ -5680,14 +5680,16 @@ ParserStatus Parser::parseGetSet(ParseDeclOptions Flags,
 
 /// Parse the brace-enclosed getter and setter for a variable.
 ParserResult<VarDecl>
-Parser::parseDeclVarGetSet(Pattern *pattern, ParseDeclOptions Flags,
+Parser::parseDeclVarGetSet(PatternBindingEntry &entry, ParseDeclOptions Flags,
                            SourceLoc StaticLoc,
                            StaticSpellingKind StaticSpelling,
                            SourceLoc VarLoc, bool hasInitializer,
                            const DeclAttributes &Attributes,
                            SmallVectorImpl<Decl *> &Decls) {
   bool Invalid = false;
-  
+
+  auto *pattern = entry.getPattern();
+
   // The grammar syntactically requires a simple identifier for the variable
   // name. Complain if that isn't what we got. But for recovery purposes,
   // make an effort to look through other things anyway.
@@ -5730,22 +5732,12 @@ Parser::parseDeclVarGetSet(Pattern *pattern, ParseDeclOptions Flags,
                                     VarDecl::Introducer::Var,
                                     VarLoc, Identifier(),
                                     CurDeclContext);
-    storage->setImplicit(true);
     storage->setInvalid();
 
-    Pattern *pattern =
+    pattern =
       TypedPattern::createImplicit(Context, new (Context) NamedPattern(storage),
                                    ErrorType::get(Context));
-    PatternBindingEntry entry(pattern, /*EqualLoc*/ SourceLoc(),
-                              /*Init*/ nullptr, /*InitContext*/ nullptr);
-    auto binding = PatternBindingDecl::create(Context, StaticLoc,
-                                              StaticSpelling,
-                                              VarLoc, entry, CurDeclContext);
-    binding->setInvalid();
-    storage->setParentPatternBinding(binding);
-
-    Decls.push_back(binding);
-    Decls.push_back(storage);
+    entry.setPattern(pattern);
   }
 
   // Parse getter and setter.
@@ -6157,7 +6149,8 @@ Parser::parseDeclVar(ParseDeclOptions Flags,
     if (Tok.is(tok::l_brace)) {
       HasAccessors = true;
       auto boundVar =
-          parseDeclVarGetSet(pattern, Flags, StaticLoc, StaticSpelling, VarLoc,
+          parseDeclVarGetSet(PBDEntries.back(),
+                             Flags, StaticLoc, StaticSpelling, VarLoc,
                              PatternInit != nullptr, Attributes, Decls);
       if (boundVar.hasCodeCompletion())
         return makeResult(makeParserCodeCompletionStatus());

test/Index/invalid_code.swift

@@ -1,6 +1,5 @@
 // RUN: %target-swift-ide-test -print-indexed-symbols -include-locals -source-filename %s | %FileCheck %s
 
-// CHECK: [[@LINE+1]]:8 | struct/Swift | Int | {{.*}} | Ref | rel: 0
 var _: Int { get { return 1 } }
 
 func test() {

test/Parse/pattern_without_variables.swift

@@ -40,5 +40,4 @@ func testVarLetPattern(a : SimpleEnum) {
 
 class SR10903 {
   static var _: Int { 0 } //expected-error {{getter/setter can only be defined for a single variable}}
-  //expected-error@-1 {{property declaration does not bind any variables}}
 }

test/SourceKit/DocumentStructure/structure.swift.foobar.response

@@ -573,11 +573,10 @@
       key.kind: source.lang.swift.decl.var.global,
       key.accessibility: source.lang.swift.accessibility.internal,
       key.setter_accessibility: source.lang.swift.accessibility.internal,
-      key.name: "Qtys",
       key.offset: 1079,
-      key.length: 15,
-      key.nameoffset: 1089,
-      key.namelength: 4
+      key.length: 3,
+      key.nameoffset: 1079,
+      key.namelength: 0
     },
     {
       key.kind: source.lang.swift.stmt.foreach,

test/SourceKit/DocumentStructure/structure.swift.response

@@ -573,11 +573,10 @@
       key.kind: source.lang.swift.decl.var.global,
       key.accessibility: source.lang.swift.accessibility.internal,
       key.setter_accessibility: source.lang.swift.accessibility.internal,
-      key.name: "Qtys",
       key.offset: 1079,
-      key.length: 15,
-      key.nameoffset: 1089,
-      key.namelength: 4
+      key.length: 3,
+      key.nameoffset: 1079,
+      key.namelength: 0
     },
     {
       key.kind: source.lang.swift.stmt.foreach,