[Bug c++/91493] New: g++ 9.2.1 crashes compiling clickhouse

[rafaeldtinoco at ubuntu dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91493

            Bug ID: 91493
           Summary: g++ 9.2.1 crashes compiling clickhouse
           Product: gcc
           Version: 9.2.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: rafaeldtinoco at ubuntu dot com
  Target Milestone: ---

The following function:

std::string toString(const ColumnDefaultKind kind)
{
    static const std::unordered_map<ColumnDefaultKind, std::string> map{
        { ColumnDefaultKind::Default, AliasNames::DEFAULT },
        { ColumnDefaultKind::Materialized, AliasNames::MATERIALIZED },
        { ColumnDefaultKind::Alias, AliasNames::ALIAS }
    };

    const auto it = map.find(kind);
    return it != std::end(map) ? it->second : throw Exception{"Invalid
ColumnDefaultKind", ErrorCodes::LOGICAL_ERROR};
}

causes gcc9 (with attached dump) to crash while other similar function (in
related syntax):

ColumnDefaultKind columnDefaultKindFromString(const std::string & str)
{
    static const std::unordered_map<std::string, ColumnDefaultKind> map{
        { AliasNames::DEFAULT, ColumnDefaultKind::Default },
        { AliasNames::MATERIALIZED, ColumnDefaultKind::Materialized },
        { AliasNames::ALIAS, ColumnDefaultKind::Alias }
    };

    const auto it = map.find(str);
    return it != std::end(map) ? it->second : throw Exception{"Unknown column
default specifier: " + str, ErrorCodes::LOGICAL_ERROR};
}

does not. Changing the syntax to:

std::string toString(const ColumnDefaultKind kind)
{
    static const std::unordered_map<ColumnDefaultKind, std::string> map{
        { ColumnDefaultKind::Default, AliasNames::DEFAULT },
        { ColumnDefaultKind::Materialized, AliasNames::MATERIALIZED },
        { ColumnDefaultKind::Alias, AliasNames::ALIAS }
    };

    const auto it = map.find(kind);

    if (it != std::end(map))
        throw Exception{"Invalid ColumnDefaultKind",
ErrorCodes::LOGICAL_ERROR};

    return it->second;
}

fixes the issue.