Merge pull request ClickHouse#60088 from ClickHouse/remove-formatting…

…-consistency-check-from-the-fuzzer

Remove the check for formatting consistency from the Fuzzer

programs/client/Client.cpp

@@ -845,83 +845,7 @@ bool Client::processWithFuzzing(const String & full_query)
             have_error = true;
         }
 
-        // Check that after the query is formatted, we can parse it back,
-        // format again and get the same result. Unfortunately, we can't
-        // compare the ASTs, which would be more sensitive to errors. This
-        // double formatting check doesn't catch all errors, e.g. we can
-        // format query incorrectly, but to a valid SQL that we can then
-        // parse and format into the same SQL.
-        // There are some complicated cases where we can generate the SQL
-        // which we can't parse:
-        // * first argument of lambda() replaced by fuzzer with
-        //   something else, leading to constructs such as
-        //   arrayMap((min(x) + 3) -> x + 1, ....)
-        // * internals of Enum replaced, leading to:
-        //   Enum(equals(someFunction(y), 3)).
-        // And there are even the cases when we can parse the query, but
-        // it's logically incorrect and its formatting is a mess, such as
-        // when `lambda()` function gets substituted into a wrong place.
-        // To avoid dealing with these cases, run the check only for the
-        // queries we were able to successfully execute.
-        // Another caveat is that sometimes WITH queries are not executed,
-        // if they are not referenced by the main SELECT, so they can still
-        // have the aforementioned problems. Disable this check for such
-        // queries, for lack of a better solution.
-        // There is also a problem that fuzzer substitutes positive Int64
-        // literals or Decimal literals, which are then parsed back as
-        // UInt64, and suddenly duplicate alias substitution starts or stops
-        // working (ASTWithAlias::formatImpl) or something like that.
-        // So we compare not even the first and second formatting of the
-        // query, but second and third.
-        // If you have to add any more workarounds to this check, just remove
-        // it altogether, it's not so useful.
-        if (ast_to_process && !have_error && !queryHasWithClause(*ast_to_process))
-        {
-            ASTPtr ast_2;
-            try
-            {
-                const auto * tmp_pos = query_to_execute.c_str();
-                ast_2 = parseQuery(tmp_pos, tmp_pos + query_to_execute.size(), false /* allow_multi_statements */);
-            }
-            catch (Exception & e)
-            {
-                if (e.code() != ErrorCodes::SYNTAX_ERROR &&
-                    e.code() != ErrorCodes::TOO_DEEP_RECURSION)
-                    throw;
-            }
-
-            if (ast_2)
-            {
-                const auto text_2 = ast_2->formatForErrorMessage();
-                const auto * tmp_pos = text_2.c_str();
-                const auto ast_3 = parseQuery(tmp_pos, tmp_pos + text_2.size(),
-                    false /* allow_multi_statements */);
-                const auto text_3 = ast_3 ? ast_3->formatForErrorMessage() : "";
-
-                if (text_3 != text_2)
-                {
-                    fmt::print(stderr, "Found error: The query formatting is broken.\n");
-
-                    printChangedSettings();
-
-                    fmt::print(stderr,
-                        "Got the following (different) text after formatting the fuzzed query and parsing it back:\n'{}'\n, expected:\n'{}'\n",
-                        text_3, text_2);
-                    fmt::print(stderr, "In more detail:\n");
-                    fmt::print(stderr, "AST-1 (generated by fuzzer):\n'{}'\n", ast_to_process->dumpTree());
-                    fmt::print(stderr, "Text-1 (AST-1 formatted):\n'{}'\n", query_to_execute);
-                    fmt::print(stderr, "AST-2 (Text-1 parsed):\n'{}'\n", ast_2->dumpTree());
-                    fmt::print(stderr, "Text-2 (AST-2 formatted):\n'{}'\n", text_2);
-                    fmt::print(stderr, "AST-3 (Text-2 parsed):\n'{}'\n", ast_3 ? ast_3->dumpTree() : "");
-                    fmt::print(stderr, "Text-3 (AST-3 formatted):\n'{}'\n", text_3);
-                    fmt::print(stderr, "Text-3 must be equal to Text-2, but it is not.\n");
-
-                    _exit(1);
-                }
-            }
-        }
-
-        // The server is still alive so we're going to continue fuzzing.
+        // The server is still alive, so we're going to continue fuzzing.
         // Determine what we're going to use as the starting AST.
         if (have_error)
         {