net: Fix `-Wmissing-braces` #34090

hebasto commented at 2:53 PM on December 17, 2025: member

On some non-POSIX platforms, Clang emits -Wmissing-braces warnings for the IN6ADDR_ANY_INIT and IN6ADDR_LOOPBACK_INIT macros. For example, on OpenIndiana / illumos:

$ uname -srv
SunOS 5.11 illumos-325e0fc8bb
$ clang --version
clang version 21.1.7 (https://github.com/OpenIndiana/oi-userland.git 36a81bf5e5d307d4e85893422600678d46328010)
Target: x86_64-pc-solaris2.11
Thread model: posix
InstalledDir: /usr/clang/21/bin
$ cmake -B build -DCMAKE_GENERATOR=Ninja -DCMAKE_C_COMPILER=clang -DCMAKE_CXX_COMPILER=clang++ -DENABLE_IPC=OFF -DAPPEND_CXXFLAGS='-Wno-unused-command-line-argument'
$ cmake --build build
[284/573] Building CXX object src/CMakeFiles/bitcoin_node.dir/net.cpp.o
/export/home/hebasto/dev/bitcoin/src/net.cpp:3309:42: warning: suggest braces around initialization of subobject [-Wmissing-braces]
 3309 |         const CService ipv6_any{in6_addr(IN6ADDR_ANY_INIT), GetListenPort()}; // ::
      |                                          ^~~~~~~~~~~~~~~~
/usr/include/netinet/in.h:479:32: note: expanded from macro 'IN6ADDR_ANY_INIT'
  479 | #define IN6ADDR_ANY_INIT            {   0, 0, 0, 0,     \
      |                                         ^~~~~~~~~~~~~~~~~
  480 |                                         0, 0, 0, 0,     \
      |                                         ~~~~~~~~~~~~~~~~~
  481 |                                         0, 0, 0, 0,     \
      |                                         ~~~~~~~~~~~~~~~~~
  482 |                                         0, 0, 0, 0 }
      |                                         ~~~~~~~~~~
1 warning generated.
[467/573] Building CXX object src/test/CMakeFiles/test_bitcoin.dir/i2p_tests.cpp.o
/export/home/hebasto/dev/bitcoin/src/test/i2p_tests.cpp:116:34: warning: suggest braces around initialization of subobject [-Wmissing-braces]
  116 |     const CService addr{in6_addr(IN6ADDR_LOOPBACK_INIT), /*port=*/7656};
      |                                  ^~~~~~~~~~~~~~~~~~~~~
/usr/include/netinet/in.h:484:37: note: expanded from macro 'IN6ADDR_LOOPBACK_INIT'
  484 | #define IN6ADDR_LOOPBACK_INIT       {   0, 0, 0, 0,     \
      |                                         ^~~~~~~~~~~~~~~~~
  485 |                                         0, 0, 0, 0,     \
      |                                         ~~~~~~~~~~~~~~~~~
  486 |                                         0, 0, 0, 0,     \
      |                                         ~~~~~~~~~~~~~~~~~
  487 |                                         0, 0, 0, 0x1U }
      |                                         ~~~~~~~~~~~~~
/export/home/hebasto/dev/bitcoin/src/test/i2p_tests.cpp:159:38: warning: suggest braces around initialization of subobject [-Wmissing-braces]
  159 |         const CService addr{in6_addr(IN6ADDR_LOOPBACK_INIT), /*port=*/7656};
      |                                      ^~~~~~~~~~~~~~~~~~~~~
/usr/include/netinet/in.h:484:37: note: expanded from macro 'IN6ADDR_LOOPBACK_INIT'
  484 | #define IN6ADDR_LOOPBACK_INIT       {   0, 0, 0, 0,     \
      |                                         ^~~~~~~~~~~~~~~~~
  485 |                                         0, 0, 0, 0,     \
      |                                         ~~~~~~~~~~~~~~~~~
  486 |                                         0, 0, 0, 0,     \
      |                                         ~~~~~~~~~~~~~~~~~
  487 |                                         0, 0, 0, 0x1U }
      |                                         ~~~~~~~~~~~~~
2 warnings generated.
[483/573] Building CXX object src/test/CMakeFiles/test_bitcoin.dir/netbase_tests.cpp.o
/export/home/hebasto/dev/bitcoin/src/test/netbase_tests.cpp:505:36: warning: suggest braces around initialization of subobject [-Wmissing-braces]
  505 |         CService(CNetAddr(in6_addr(IN6ADDR_LOOPBACK_INIT)), 0 /* port */),
      |                                    ^~~~~~~~~~~~~~~~~~~~~
/usr/include/netinet/in.h:484:37: note: expanded from macro 'IN6ADDR_LOOPBACK_INIT'
  484 | #define IN6ADDR_LOOPBACK_INIT       {   0, 0, 0, 0,     \
      |                                         ^~~~~~~~~~~~~~~~~
  485 |                                         0, 0, 0, 0,     \
      |                                         ~~~~~~~~~~~~~~~~~
  486 |                                         0, 0, 0, 0,     \
      |                                         ~~~~~~~~~~~~~~~~~
  487 |                                         0, 0, 0, 0x1U }
      |                                         ~~~~~~~~~~~~~
/export/home/hebasto/dev/bitcoin/src/test/netbase_tests.cpp:510:36: warning: suggest braces around initialization of subobject [-Wmissing-braces]
  510 |         CService(CNetAddr(in6_addr(IN6ADDR_LOOPBACK_INIT)), 0x00f1 /* port */),
      |                                    ^~~~~~~~~~~~~~~~~~~~~
/usr/include/netinet/in.h:484:37: note: expanded from macro 'IN6ADDR_LOOPBACK_INIT'
  484 | #define IN6ADDR_LOOPBACK_INIT       {   0, 0, 0, 0,     \
      |                                         ^~~~~~~~~~~~~~~~~
  485 |                                         0, 0, 0, 0,     \
      |                                         ~~~~~~~~~~~~~~~~~
  486 |                                         0, 0, 0, 0,     \
      |                                         ~~~~~~~~~~~~~~~~~
  487 |                                         0, 0, 0, 0x1U }
      |                                         ~~~~~~~~~~~~~
/export/home/hebasto/dev/bitcoin/src/test/netbase_tests.cpp:515:36: warning: suggest braces around initialization of subobject [-Wmissing-braces]
  515 |         CService(CNetAddr(in6_addr(IN6ADDR_LOOPBACK_INIT)), 0xf1f2 /* port */),
      |                                    ^~~~~~~~~~~~~~~~~~~~~
/usr/include/netinet/in.h:484:37: note: expanded from macro 'IN6ADDR_LOOPBACK_INIT'
  484 | #define IN6ADDR_LOOPBACK_INIT       {   0, 0, 0, 0,     \
      |                                         ^~~~~~~~~~~~~~~~~
  485 |                                         0, 0, 0, 0,     \
      |                                         ~~~~~~~~~~~~~~~~~
  486 |                                         0, 0, 0, 0,     \
      |                                         ~~~~~~~~~~~~~~~~~
  487 |                                         0, 0, 0, 0x1U }
      |                                         ~~~~~~~~~~~~~
3 warnings generated.
[573/573] Linking CXX executable bin/test_bitcoin

The same issue is observed on Windows. For further details, see #31507.

DrahtBot added the label P2P on Dec 17, 2025

DrahtBot commented at 2:53 PM on December 17, 2025: contributor

The following sections might be updated with supplementary metadata relevant to reviewers and maintainers.

Code Coverage & Benchmarks

For details see: https://corecheck.dev/bitcoin/bitcoin/pulls/34090.

Reviews

See the guideline for information on the review process.

Type	Reviewers
ACK	bensig, maflcko, vasild, sedited

If your review is incorrectly listed, please copy-paste <code></code> into the comment that the bot should ignore.

Conflicts

Reviewers, this pull request conflicts with the following ones:

#31507 (build: Use clang-cl to build on Windows natively by hebasto)

If you consider this pull request important, please also help to review the conflicting pull requests. Ideally, start with the one that should be merged first.

hebasto force-pushed on Dec 17, 2025

DrahtBot added the label CI failed on Dec 17, 2025

fanquake commented at 3:10 PM on December 17, 2025: member

https://github.com/bitcoin/bitcoin/actions/runs/20307057596/job/58327346295?pr=34090#step:11:495:

   net_processing.cpp
  netgroup.cpp
D:\a\bitcoin\bitcoin\src\net.cpp(3309,41): error C2440: '<function-style-cast>': cannot convert from 'initializer list' to 'in6_addr' [D:\a\bitcoin\bitcoin\build\src\bitcoin_node.vcxproj]
      D:\a\bitcoin\bitcoin\src\net.cpp(3309,41):
      'in6_addr::in6_addr': no overloaded function could convert all the argument types
          C:\Program Files (x86)\Windows Kits\10\Include\10.0.26100.0\shared\in6addr.h(30,1):
          could be 'in6_addr::in6_addr(in6_addr &&)'
              D:\a\bitcoin\bitcoin\src\net.cpp(3309,41):
              'in6_addr::in6_addr(in6_addr &&)': cannot convert argument 1 from 'initializer list' to 'in6_addr &&'
                  D:\a\bitcoin\bitcoin\src\net.cpp(3309,42):
                  Reason: cannot convert from 'initializer list' to 'in6_addr'
                  D:\a\bitcoin\bitcoin\src\net.cpp(3309,42):
                  Invalid aggregate initialization
                      D:\a\bitcoin\bitcoin\src\net.cpp(3309,42):
                      'initializing': cannot convert from 'initializer list' to 'UCHAR'
                          D:\a\bitcoin\bitcoin\src\net.cpp(3309,42):
                          Too many braces around initializer for 'UCHAR'
          C:\Program Files (x86)\Windows Kits\10\Include\10.0.26100.0\shared\in6addr.h(30,1):
          or       'in6_addr::in6_addr(const in6_addr &)'
              D:\a\bitcoin\bitcoin\src\net.cpp(3309,41):
              'in6_addr::in6_addr(const in6_addr &)': cannot convert argument 1 from 'initializer list' to 'const in6_addr &'
                  D:\a\bitcoin\bitcoin\src\net.cpp(3309,42):
                  Reason: cannot convert from 'initializer list' to 'const in6_addr'
                  D:\a\bitcoin\bitcoin\src\net.cpp(3309,42):
                  Invalid aggregate initialization
                      D:\a\bitcoin\bitcoin\src\net.cpp(3309,42):
                      'initializing': cannot convert from 'initializer list' to 'UCHAR'
                          D:\a\bitcoin\bitcoin\src\net.cpp(3309,42):
                          Too many braces around initializer for 'UCHAR'
          D:\a\bitcoin\bitcoin\src\net.cpp(3309,41):
          while trying to match the argument list '(initializer list)'

hebasto force-pushed on Dec 17, 2025

net: Fix `-Wmissing-braces` f46e3ec0f9

hebasto force-pushed on Dec 17, 2025

DrahtBot removed the label CI failed on Dec 17, 2025

hebasto commented at 7:13 PM on December 17, 2025: member

https://github.com/bitcoin/bitcoin/actions/runs/20307057596/job/58327346295?pr=34090#step:11:495:

CI is green now.

bensig commented at 12:01 AM on January 4, 2026: contributor

ACK f46e3ec0f9567a19ad9c111f264d395341327e4a

Builds clean, netbase_tests and i2p_tests pass. Clean fix using compat layer for platform-specific brace style in IN6ADDR_*_INIT macros.

maflcko commented at 7:00 PM on January 19, 2026: member

Would it not make sense to enable /we5246, and possibly have a CI output for /w15246 for reviewers? Otherwise, this may regress in the future before switching to clang?

hebasto commented at 9:47 PM on January 19, 2026: member

Would it not make sense to enable /we5246, and possibly have a CI output for /w15246 for reviewers?

MSVC has C5246 disabled by default for a reason. It emits tons of false positives: https://github.com/hebasto/bitcoin/actions/runs/21151989194/job/60829717946

Otherwise, this may regress in the future before switching to clang?

This can be handled by a new job in nightly builds.

maflcko commented at 5:30 PM on January 20, 2026: member

review ACK f46e3ec0f9567a19ad9c111f264d395341327e4a 👭

<details><summary>Show signature</summary>

Signature:

untrusted comment: signature from minisign secret key on empty file; verify via: minisign -Vm "${path_to_any_empty_file}" -P RWTRmVTMeKV5noAMqVlsMugDDCyyTSbA3Re5AkUrhvLVln0tSaFWglOw -x "${path_to_this_whole_four_line_signature_blob}"
RUTRmVTMeKV5npGrKx1nqXCw5zeVHdtdYURB/KlyA/LMFgpNCs+SkW9a8N95d+U4AP1RJMi+krxU1A3Yux4bpwZNLvVBKy0wLgM=
trusted comment: review ACK  f46e3ec0f9567a19ad9c111f264d395341327e4a 👭
R8gcVtWz4Hq5O4AZb4/fvGw/YL86f2x5J00GirFlx1SOBvguF/o6tOuZfLwiwz5fZ+ZS4ukncI4Ol7jzxIr/Cg==

</details>

hebasto commented at 5:22 PM on January 21, 2026: member

Friendly ping @vasild :)

vasild approved

vasild commented at 10:13 AM on January 22, 2026: contributor

ACK f46e3ec0f9567a19ad9c111f264d395341327e4a

Not tested.

sedited approved

sedited commented at 11:21 AM on January 22, 2026: contributor

utACK f46e3ec0f9567a19ad9c111f264d395341327e4a

sedited merged this on Jan 22, 2026

sedited closed this on Jan 22, 2026

hebasto deleted the branch on Jan 22, 2026