Compilation warnings in re2 with -Wpedantic

[krlmlr]

What happens?

Building duckdb v0.10.2 with -Wpedantic gives four warnings in re2:

  duckdb/third_party/re2/re2/prog.h:148:14: warning: ISO C++ prohibits anonymous structs [-Wpedantic]
  duckdb/third_party/re2/re2/prog.h:426:12: warning: ISO C++ prohibits anonymous structs [-Wpedantic]
  duckdb/third_party/re2/re2/dfa.cc:124:25: warning: ISO C++ forbids flexible array member ‘next_’ [-Wpedantic]
  duckdb/third_party/re2/re2/onepass.cc:146:12: warning: ISO C++ forbids flexible array member ‘action’ [-Wpedantic]

This affects the R package because CRAN checks this: https://www.r-project.org/nosvn/R.check/r-devel-linux-x86_64-fedora-gcc/duckdb-00check.html

To Reproduce

Compile duckdb with gcc13 and -Wpedantic .

OS:

Linux

DuckDB Version:

v0.10.2

DuckDB Client:

R

Full Name:

Kirill Müller

Affiliation:

cynkra GmbH

What is the latest build you tested with? If possible, we recommend testing with the latest nightly build.

I have tested with a source build

Did you include all relevant data sets for reproducing the issue?

Not applicable - the reproduction does not require a data set

Did you include all code required to reproduce the issue?

• Yes, I have

Did you include all relevant configuration (e.g., CPU architecture, Python version, Linux distribution) to reproduce the issue?

• Yes, I have

[krlmlr]

@szarnyasg: Thanks for looking into it.

In gcc14, there are even more warnings:

    /usr/local/gcc14/include/c++/14.0.1/bits/move.h:221:11: warning: '((__vector(2) long unsigned int*)this)[1]' is used uninitialized [-Wuninitialized]
    /usr/local/gcc14/include/c++/14.0.1/bits/move.h:221:11: warning: '*(__vector(2) long unsigned int*)this' is used uninitialized [-Wuninitialized]
    /usr/local/gcc14/include/c++/14.0.1/bits/move.h:221:11: warning: '((void (**)(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >))this)[2]' is used uninitialized [-Wuninitialized]
    /usr/local/gcc14/include/c++/14.0.1/bits/move.h:221:11: warning: '((duckdb::FileBuffer**)this)[2]' is used uninitialized [-Wuninitialized]

Check results: https://cran.r-project.org/web/checks/check_results_duckdb.html

[hannes]

The first two issues are easily fixable, but found this comment:

// Work around the bug affecting flexible array members in GCC 6.x (for x >= 1).
// (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70932)
#if !defined(__clang__) && defined(__GNUC__) && __GNUC__ == 6 && __GNUC_MINOR__ >= 1
    std::atomic<State*> next_[0];   // Outgoing arrows from State,
#else
    std::atomic<State*> next_[];    // Outgoing arrows from State,
#endif

So this seems intentional to work around a GCC bug?

[hannes]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70932

[hannes]

PR for first part is here: #11956

[hannes]

The re2 package on CRAN has this fixed, will copy their fix over.

[hannes]

second PR is here: #11978

[hannes]

@krlmlr do we have a CI run already that would have found those?

[krlmlr]

Yes. Easiest when that PR is merged and vendored here.

[hannes]

Fixed in upstream

[krlmlr]

Looks super-green now: https://github.com/duckdb/duckdb-r/actions/runs/9162129815/job/25188491799 .

Filed the clang-asan problem: #12142 .

The atlas check is not a problem.

I don't understand why valgrind still finds problems. Investigating.