[bug] Crash in String Matcher

[opmtk]

Describe the bug

The following

        try {
            std::string a{ "string" };
            std::string const expected{ "string" };
            REQUIRE_THAT(a, Matches(expected));
        }
        catch (std::exception const& e) {
            std::cerr << std::format("caught '{}'\n", e.what());
        }

works as expected. If I get a bigger expected string (e.g. ~110kByte) it crashes with

...
[ctest] due to a fatal error condition:
[ctest]   SIGSEGV - Segmentation violation signal

The problem is related to the Matches matcher - the following doesn't crash:

        // Catch2's matchers haven't support for string_view
        std::string const expected_str{ csv_data::CsvSV };

        try {
            std::string a{ "string" };
            REQUIRE_THAT(expected_str, Matches(a));
        }
        catch (std::exception const& e) {
            std::cerr << std::format("caught '{}'\n", e.what());
        }

Expected behavior
I must not crash in that way, even I've a try/catch block/scope!

Reproduction steps

See above.

Platform information:

• OS: Windows NT with devcontainer in VS Code running Ubuntu24.04
• Compiler+version: gcc version 13.2.0 (Ubuntu 13.2.0-23ubuntu4)
• Catch version: 3.4.0-1build1 amd64

Additional context

• How can I ignore line endings with matchers? My reference data contains 16 rows with 161 columns in lines.

constexpr std::string_view const CsvSV =
R"(0,0.999994607194946,...
...
...,0.783392372240895
)";

• How can a make a diff of the strings compared? E.g. only give the line number of difference?

[horenmar]

I can't reproduce this locally, nor on CE.

Are you sure that the segfault comes from the StringMatcher?

[opmtk]

I'm still working on it (with breaks), but I did some tests and I'm not still sure about it. Note, I use C++20.

I'm redirecting ostream:

class StreamBufSentry {
    std::ostream& ostream;
    std::streambuf* rdbufBak;

public:
    ~StreamBufSentry() { ostream.rdbuf(rdbufBak); }
    StreamBufSentry(StreamBufSentry const&) = delete;
    StreamBufSentry(StreamBufSentry&&) = delete;

    StreamBufSentry(std::ostream& ostream)
        : ostream{ ostream }
        , rdbufBak{ ostream.rdbuf() }
    {
    }
};

and using it:

...
extern std::string_view const ActuatorLengthCsvSV; // test_csv_data.cpp
...
        ...
        StreamBufSentry sentry{ std::cout };
        std::ostringstream os;
        std::cout.rdbuf(os.rdbuf());

        CsvReader<double> csvReader{};
        ...
        csvReader.readFile(...);
         std::cout << csvReader << '\n';
         ...
        std::string const expected_str{ ActuatorLengthCsvSV };
        REQUIRE_THAT(expected_str, Matches(os.str()));         // boom
        ...        
)

//  test_csv_data.cpp
constexpr std::string_view const ActuatorLengthCsvSV = R"(0,0.999994607194946,....)";

[opmtk]

I'll try to reduce it to a compile-able file