[clang-format] Handle C# 9 `init` accessor specifier.

[curdeius]

Summary

Before, the code:

int Value { get; } = 0;
int Value { init; } = 0;

was formatted incoherently:

int Value { get; } = 0;
int Value { init; }
= 0;

because init was not recognised as an accessor specifier.

[curdeius]

Rename.

[curdeius]

Handle init in same places as get and set.

[curdeius]

clang/lib/Format/TokenAnnotator.cpp

4245

Oops, unrelated change, will revert.

[MyDeveloperDay]

LGTM

clang/lib/Format/FormatToken.h

AdditionalKeywords(IdentifierTable &IdentTable) {
     kw_base = &IdentTable.get("base");
     kw_byte = &IdentTable.get("byte");
     kw_checked = &IdentTable.get("checked");
     kw_decimal = &IdentTable.get("decimal");
     kw_delegate = &IdentTable.get("delegate");
     kw_event = &IdentTable.get("event");
     kw_fixed = &IdentTable.get("fixed");
     kw_foreach = &IdentTable.get("foreach");
+    kw_init = &IdentTable.get("init");
     kw_implicit = &IdentTable.get("implicit");
     kw_internal = &IdentTable.get("internal");
     kw_lock = &IdentTable.get("lock");
     kw_null = &IdentTable.get("null");
     kw_object = &IdentTable.get("object");
     kw_out = &IdentTable.get("out");
     kw_params = &IdentTable.get("params");
     kw_ref = &IdentTable.get("ref");
JsExtraKeywords = std::unordered_set<IdentifierInfo *>(
         {kw_as, kw_async, kw_await, kw_declare, kw_finally, kw_from,
          kw_function, kw_get, kw_import, kw_is, kw_let, kw_module, kw_override,
          kw_readonly, kw_set, kw_type, kw_typeof, kw_var, kw_yield,
          // Keywords from the Java section.
          kw_abstract, kw_extends, kw_implements, kw_instanceof, kw_interface});
 
     CSharpExtraKeywords = std::unordered_set<IdentifierInfo *>(
         {kw_base, kw_byte, kw_checked, kw_decimal, kw_delegate, kw_event,
-         kw_fixed, kw_foreach, kw_implicit, kw_in, kw_interface, kw_internal,
-         kw_is, kw_lock, kw_null, kw_object, kw_out, kw_override, kw_params,
-         kw_readonly, kw_ref, kw_string, kw_stackalloc, kw_sbyte, kw_sealed,
-         kw_uint, kw_ulong, kw_unchecked, kw_unsafe, kw_ushort, kw_when,
-         kw_where,
+         kw_fixed, kw_foreach, kw_implicit, kw_in, kw_init, kw_interface,
+         kw_internal, kw_is, kw_lock, kw_null, kw_object, kw_out, kw_override,
+         kw_params, kw_readonly, kw_ref, kw_string, kw_stackalloc, kw_sbyte,
+         kw_sealed, kw_uint, kw_ulong, kw_unchecked, kw_unsafe, kw_ushort,
+         kw_when, kw_where,
          // Keywords from the JavaScript section.
          kw_as, kw_async, kw_await, kw_declare, kw_finally, kw_from,
          kw_function, kw_get, kw_import, kw_is, kw_let, kw_module, kw_readonly,
          kw_set, kw_type, kw_typeof, kw_var, kw_yield,
          // Keywords from the Java section.
          kw_abstract, kw_extends, kw_implements, kw_instanceof, kw_interface});
   }
 
struct AdditionalKeywords {
   IdentifierInfo *kw_byte;
   IdentifierInfo *kw_checked;
   IdentifierInfo *kw_decimal;
   IdentifierInfo *kw_delegate;
   IdentifierInfo *kw_event;
   IdentifierInfo *kw_fixed;
   IdentifierInfo *kw_foreach;
   IdentifierInfo *kw_implicit;
+  IdentifierInfo *kw_init;
   IdentifierInfo *kw_internal;
 
   IdentifierInfo *kw_lock;
   IdentifierInfo *kw_null;
   IdentifierInfo *kw_object;
   IdentifierInfo *kw_out;
 
   IdentifierInfo *kw_params;

clang/lib/Format/TokenAnnotator.cpp

if ((Style.isJavaScript() || Style.isCSharp()) &&
             Style.isJavaScript()
                 ? Keywords.IsJavaScriptIdentifier(
                       *Current.Previous, /* AcceptIdentifierName= */ true)
                 : Current.Previous->is(tok::identifier);
         if (IsIdentifier ||
             Current.Previous->isOneOf(
                 tok::kw_namespace, tok::r_paren, tok::r_square, tok::r_brace,
                 tok::kw_false, tok::kw_true, Keywords.kw_type, Keywords.kw_get,
-                Keywords.kw_set) ||
+                Keywords.kw_init, Keywords.kw_set) ||
             Current.Previous->Tok.isLiteral()) {
           Current.setType(TT_NonNullAssertion);
           return;
         }
       }
       if (Current.Next &&
           Current.Next->isOneOf(TT_BinaryOperator, Keywords.kw_as)) {
         Current.setType(TT_NonNullAssertion);
if (Style.isCSharp()) {
     const FormatToken *NonComment = Right.getPreviousNonComment();
     if (NonComment &&
         NonComment->isOneOf(
             tok::kw_return, Keywords.kw_yield, tok::kw_continue, tok::kw_break,
             tok::kw_throw, Keywords.kw_interface, Keywords.kw_type,
             tok::kw_static, tok::kw_public, tok::kw_private, tok::kw_protected,
             Keywords.kw_readonly, Keywords.kw_override, Keywords.kw_abstract,
             Keywords.kw_get, Keywords.kw_set, Keywords.kw_async,
             Keywords.kw_await))
       return false; // Otherwise automatic semicolon insertion would trigger.
     if (Right.NestingLevel == 0 &&
         (Left.Tok.getIdentifierInfo() ||
          Left.isOneOf(tok::r_square, tok::r_paren)) &&
         Right.isOneOf(tok::l_square, tok::l_paren))
       return false; // Otherwise automatic semicolon insertion would trigger.
     if (NonComment && NonComment->is(tok::identifier) &&
         NonComment->TokenText == "asserts")

clang/lib/Format/UnwrappedLineParser.cpp

bool UnwrappedLineParser::tryToParsePropertyAccessor() {
   //
   // Record the current tokenPosition so that we can advance and
   // reset the current token. `Next` is not set yet so we need
   // another way to advance along the token stream.
   unsigned int StoredPosition = Tokens->getPosition();
   FormatToken *Tok = Tokens->getNextToken();
 
   // A trivial property accessor is of the form:
-  // { [ACCESS_SPECIFIER] [get]; [ACCESS_SPECIFIER] [set] }
+  // { [ACCESS_SPECIFIER] [get]; [ACCESS_SPECIFIER] [set|init] }
   // Track these as they do not require line breaks to be introduced.
-  bool HasGetOrSet = false;
+  bool HasSpecialAccessor = false;
   bool IsTrivialPropertyAccessor = true;
   while (!eof()) {
     if (Tok->isOneOf(tok::semi, tok::kw_public, tok::kw_private,
                      tok::kw_protected, Keywords.kw_internal, Keywords.kw_get,
-                     Keywords.kw_set)) {
-      if (Tok->isOneOf(Keywords.kw_get, Keywords.kw_set))
-        HasGetOrSet = true;
+                     Keywords.kw_init, Keywords.kw_set)) {
+      if (Tok->isOneOf(Keywords.kw_get, Keywords.kw_init, Keywords.kw_set))
+        HasSpecialAccessor = true;
       Tok = Tokens->getNextToken();
       continue;
     }
     if (Tok->isNot(tok::r_brace))
       IsTrivialPropertyAccessor = false;
     break;
   }
 
-  if (!HasGetOrSet) {
+  if (!HasSpecialAccessor) {
     Tokens->setPosition(StoredPosition);
     return false;
   }
 
   // Try to parse the property accessor:
   // https://docs.microsoft.com/en-us/dotnet/csharp/programming-guide/classes-and-structs/properties
   Tokens->setPosition(StoredPosition);
   if (!IsTrivialPropertyAccessor && Style.BraceWrapping.AfterFunction)
case tok::equal:
         nextToken();
         addUnwrappedLine();
         --Line->Level;
         break;
       }
       nextToken();
       break;
     default:
-      if (FormatTok->isOneOf(Keywords.kw_get, Keywords.kw_set) &&
+      if (FormatTok->isOneOf(Keywords.kw_get, Keywords.kw_init,
+                             Keywords.kw_set) &&
           !IsTrivialPropertyAccessor) {
         // Non-trivial get/set needs to be on its own line.
         addUnwrappedLine();
       }
       nextToken();
     }
   } while (!eof());
 

clang/unittests/Format/FormatTestCSharp.cpp

TEST_F(FormatTestCSharp, CSharpPropertyAccessors) {
   FormatStyle Style = getGoogleStyle(FormatStyle::LK_CSharp);
 
   verifyFormat("int Value { get }", Style);
   verifyFormat("int Value { get; }", Style);
   verifyFormat("int Value { internal get; }", Style);
   verifyFormat("int Value { get; } = 0", Style);
   verifyFormat("int Value { set }", Style);
   verifyFormat("int Value { set; }", Style);
+  verifyFormat("int Value { init; }", Style);
   verifyFormat("int Value { internal set; }", Style);
   verifyFormat("int Value { set; } = 0", Style);
   verifyFormat("int Value { get; set }", Style);
+  verifyFormat("int Value { get; init; }", Style);
   verifyFormat("int Value { set; get }", Style);
   verifyFormat("int Value { get; private set; }", Style);
   verifyFormat("int Value { get; set; }", Style);
   verifyFormat("int Value { get; set; } = 0", Style);
   verifyFormat("int Value { internal get; internal set; }", Style);
 
   // Do not wrap expression body definitions.
   verifyFormat(R"(//
 public string Name {
   get => _name;
   set => _name = value;
 })",
                Style);
+  verifyFormat(R"(//
+public string Name {
+  init => _name = value;
+  get => _name;
+})",
+               Style);
+  verifyFormat(R"(//
+public string Name {
+  set => _name = value;
+  get => _name;
+})",
+               Style);
 
   // Examples taken from
   // https://docs.microsoft.com/en-us/dotnet/csharp/programming-guide/classes-and-structs/properties
   verifyFormat(R"(
 // Expression body definitions
 public class SaleItem {
   public decimal Price {
     get => _cost;