Fix the case when DataType parser may have exponential complexity

src/Parsers/ParserDataType.cpp

@@ -32,8 +32,10 @@ private:
         const char * operators[] = {"=", "equals", nullptr};
         ParserLeftAssociativeBinaryOperatorList enum_parser(operators, std::make_unique<ParserLiteral>());
 
-        return nested_parser.parse(pos, node, expected)
-            || enum_parser.parse(pos, node, expected)
+        if (pos->type == TokenType::BareWord && std::string_view(pos->begin, pos->size()) == "Nested")
+            return nested_parser.parse(pos, node, expected);
+
+        return enum_parser.parse(pos, node, expected)
             || literal_parser.parse(pos, node, expected)
             || data_type_parser.parse(pos, node, expected);
     }

tests/queries/0_stateless/01691_parser_data_type_exponential.sh

+#!/usr/bin/env bash
+
+CURDIR=$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)
+# shellcheck source=../shell_config.sh
+. "$CURDIR"/../shell_config.sh
+
+# Check that DataType parser does not have exponential complexity in the case found by fuzzer.
+for _ in {1..10}; do ${CLICKHOUSE_CLIENT} -n --testmode --query "SELECT CAST(1 AS A2222222222222222222222222222222222222222222222222teFuncpion(groupBitmap, 222222222222222ggregateFuncpion(groupBitmap2222222222222222222222222222222222222222222222222222222222222222ggregateF222222222222222222222222222222222222222222222222222222222teFuncpion(groupBitmap, 222222222222222ggregateFuncpion(groupBitmap2222222222222222222222222222222222222222222222222222222222222222222222ggregateFuncpion(groupBitmapp, 222222222222222ggregateFuncpion(groupBitmap2222222222222222222222222222222222222222222222222222222222222222222222ggregateF222222222222222222222222222222222222222222222222222222222teFuncpion(groupBitmap, 222222222222223ggregateFuncpion(groupBitmap2222222222222222222222222222222222222222222222222222222222222222222222ggregateFuncpion(groupBitmap, 00000000000000000000000000000000000000000000000000000000000000000000000000000001841416382, 222222222222222ggregateFuncpion(groupBitmap22222222222222222222222222222222222222222222222222220000000000000000000000000000000000000000000000000000000000000000000000000000002260637443813394204222222222222222222ggregateFuncpion(groupBitmapp, 222222222222222ggregateFuncpion(groupBitmap2222222222222222222222222222222222222222222222222222222222222222222222ggregateF222222222222222222222222222222222222222222222222222222222teFuncpion(groupBitmap, 222222222222223ggregateFuncpio22222222ggregateFuncpion(groupBitmap2222222222222222222222222222222222222222222222222222222222222222222222ggregateF222222222222222222222222222222222222222222222222222222222teFuncpion(groupBitmap, 222222222222222ggregateFuncpion(groupBitmap2222222222222222222222222222222222222222222222222222222222222222ggregateF222222222222222222222222222222222222222222222222222222222teFuncpion(groupBitmap, 222222222222222ggregateFuncpion(groupBitmap2222222222222ggregateFuncpion(groupBitmapp, 222222222222222ggregateFuncpion(groupBitmap2222222222222222222222222222222222222222222222222222222222222222222222ggregateF222222222222222222222222222222222222222222222222222222222teFuncpion(groupBitmap, 222222222222223ggregateFuncpion(groupBitmap2222222222222222222222222222222222222222222222222222222222222222222222ggre222222222222222222222222222222222222222222222222222teFuncpion(groupBitmap, 22222222222222222ggregateFuncpion(groupBitmap2222222222222222222222222222222222222222222222222222222222222222222222ggregateF222222222222222222222222222222222222222222222222222222222teFuncpion(groupBitmap, 2222222222222eFuncpion(groupBitmap, 00000000000000000000000000000000000000000000000000000000000000000000000000000001841416382, 222222222222222ggregateFuncpion(groupBitmap22222222222222222222222222222222222222222222222222222222222222222222222200000000000000000000178859639454016722222222222222222222222222222222222222222222222222222222222ggregateFuncpion(groupBitmapp, 222222222222222ggregateFuncpion(groupBitmap2222222222222222222222222222222222222222222222222222222222222222222222ggregateF222222222222222222222222222222222222222222222222222222222teFuncpion(groupBitmap, 222222222222223ggregateFuncpio22222222ggregateFuncpion(groupBitmap2222222222222222222222222222222222222222222222222222222222222222222222ggregateF222222222222222222222222222222222222222222222222222222222teFuncpion(groupBitmap, 222222222222222ggregateFuncpion(groupBitmap2222222222222222222222222222222222222222222222222222222222222222ggregateF222222222222222222222222222222222222222222222222222222222teFuncpion(groupBitmap, 222222222222222ggregateFuncpion(groupBitmap2222222222222222222222222222222222222222222222222222222222222222222222ggregateFuncpion(groupBitmapp, 222222222222222ggregateFuncpion(groupBitmap2222222222222222222222222222222222222222222222222222222222222222222222ggregateF222222222222222222222222222222222222222222222222222222222teFuncpion(groupBitmap, 222222222222223ggregateFuncpion(groupBitmap2222222222222222222222222222222222222222222222222222222222222222222222ggregateFuncpion(groupBitmap, 00000000000000000000000000000000000000000000000000000000000000000000000000000001841416382, 222222222222222ggregateFuncpion(groupBitmap22222222222222222222222222222222222222222222222222222222222222222222222200000000000000000000178859639454016722222222222222222222222222222222222222222222222222222222222ggregateFuncpion(groupBitmapp, 222222222222222ggregateFuncpion(groupBitmap2222222222222222222222222222222222222222222222222222222222222222222222ggregateF222222222222222222222222222222222222222222222222222222222teFuncpion(groupBitmap, 222222222222223ggregateFuncpion(groupBitmap2222222222222222222222222222222222222222222222222222222222222222222222ggregateFuncpion(groupBitmap, 22222222222222222222222222222222222222222222222222222222222222222222222222222222222222222, 222222222222222ggregateFuncpion(groupBitmap222222222222222222222222222222222222222222222222222222222222222222222222000000000000000000001788596394540167623222222222222222222ggregateFu22222222222222222222222222222222222, UInt33)); -- { clientError 62 }"; done