Revert D70342616: Multisect successfully blamed "D70342616: [Thrift] …

…Merge fbcode and xplat copies of thrift/parse" for one test failure

Summary:
This diff reverts D70342616
D70342616: [Thrift] Merge fbcode and xplat copies of thrift/parse by vitaut causes the following test failure:

Tests affected:
- [cogwheel:cogwheel_blackbird#main](https://www.internalfb.com/intern/test/844424930579139/)

Here's the Multisect link:
https://www.internalfb.com/multisect/21970461
Here are the tasks that are relevant to this breakage:
T191387297: 10+ CI signals unhealthy for blackbird_ingestion_and_detection

The backout may land if someone accepts it.

If this diff has been generated in error, you can Commandeer and Abandon it.

Reviewed By: vitaut

Differential Revision: D70382891

fbshipit-source-id: 1ebacf1498d5c134abe4dd31361c8e556b57c9ba

thrift/compiler/parse/lexer.cc

@@ -169,7 +169,6 @@ const std::unordered_map<std::string_view, tok> keywords = {
     {"const", tok::kw_const},
     {"required", tok::kw_required},
     {"optional", tok::kw_optional},
-    {"as", tok::kw_as},
 };
 
 } // namespace

thrift/compiler/parse/parser.cc

@@ -174,19 +174,15 @@ class parser {
     auto str_range = token_.range;
     consume_token();
     switch (kind) {
-      case tok::kw_include:{
-        auto alias = try_parse_include_alias();
-        actions_.on_include(range, str, alias, str_range);
+      case tok::kw_include:
+        actions_.on_include(range, str, std::nullopt, str_range);
         break;
-      }
-      case tok::kw_cpp_include: {
+      case tok::kw_cpp_include:
         actions_.on_cpp_include(range, str);
         break;
-      }
-      case tok::kw_hs_include: {
+      case tok::kw_hs_include:
         actions_.on_hs_include(range, str);
         break;
-      }
       default:
         assert(false);
     }
@@ -1074,7 +1070,6 @@ class parser {
       case tok::kw_permanent:
       case tok::kw_server:
       case tok::kw_client:
-      case tok::kw_as:
         return identifier{to_string(consume_token().kind), range};
       default:
         return {};
@@ -1093,26 +1088,6 @@ class parser {
     return try_consume_token(',') || try_consume_token(';');
   }
 
-  std::optional<std::string_view> try_parse_include_alias() {
-    if (!try_consume_token(tok::kw_as)) {
-      return std::nullopt;
-    }
-
-    auto alias = try_parse_identifier();
-    if (!alias.has_value()) {
-      if (token_.kind == ';') {
-        report_error("Include alias cannot be empty");
-      } else {
-        const auto invalid_alias = consume_token();
-        report_error(
-            "Invalid include alias '{}'", to_string(invalid_alias.kind.value));
-      }
-      return std::nullopt;
-    }
-
-    return alias.value().str;
-  }
-
  public:
   parser(lexer& lex, parser_actions& actions, diagnostics_engine& diags)
       : lexer_(lex), actions_(actions), diags_(diags) {}