replace %defer with errdefer

See #632

now we have 1 less sigil

src/parser.cpp

@@ -1495,7 +1495,7 @@ static AstNode *ast_parse_break_expr(ParseContext *pc, size_t *token_index) {
 }
 
 /*
-Defer(body) = option("%") "defer" body
+Defer(body) = ("defer" | "errdefer") body
 */
 static AstNode *ast_parse_defer_expr(ParseContext *pc, size_t *token_index) {
     Token *token = &pc->tokens->at(*token_index);
@@ -1503,15 +1503,10 @@ static AstNode *ast_parse_defer_expr(ParseContext *pc, size_t *token_index) {
     NodeType node_type;
     ReturnKind kind;
 
-    if (token->id == TokenIdPercent) {
-        Token *next_token = &pc->tokens->at(*token_index + 1);
-        if (next_token->id == TokenIdKeywordDefer) {
-            kind = ReturnKindError;
-            node_type = NodeTypeDefer;
-            *token_index += 2;
-        } else {
-            return nullptr;
-        }
+    if (token->id == TokenIdKeywordErrdefer) {
+        kind = ReturnKindError;
+        node_type = NodeTypeDefer;
+        *token_index += 1;
     } else if (token->id == TokenIdKeywordDefer) {
         kind = ReturnKindUnconditional;
         node_type = NodeTypeDefer;

src/tokenizer.cpp

@@ -118,6 +118,7 @@ static const struct ZigKeyword zig_keywords[] = {
     {"defer", TokenIdKeywordDefer},
     {"else", TokenIdKeywordElse},
     {"enum", TokenIdKeywordEnum},
+    {"errdefer", TokenIdKeywordErrdefer},
     {"error", TokenIdKeywordError},
     {"export", TokenIdKeywordExport},
     {"extern", TokenIdKeywordExtern},
@@ -1514,6 +1515,7 @@ const char * token_name(TokenId id) {
         case TokenIdKeywordDefer: return "defer";
         case TokenIdKeywordElse: return "else";
         case TokenIdKeywordEnum: return "enum";
+        case TokenIdKeywordErrdefer: return "errdefer";
         case TokenIdKeywordError: return "error";
         case TokenIdKeywordExport: return "export";
         case TokenIdKeywordExtern: return "extern";

src/tokenizer.hpp

@@ -57,6 +57,7 @@ enum TokenId {
     TokenIdKeywordDefer,
     TokenIdKeywordElse,
     TokenIdKeywordEnum,
+    TokenIdKeywordErrdefer,
     TokenIdKeywordError,
     TokenIdKeywordExport,
     TokenIdKeywordExtern,