Allow build using -Wshadow option.

[fghoussen]

I use mcap/2.0.2 packaged by conan.

When I include mcap files like so:

diff --git a/app/test.cpp b/app/test.cpp
index a8a213e..1388176 100644
--- a/app/test.cpp
+++ b/app/test.cpp
@@ -2,6 +2,19 @@
 
 #include "libraries/logger_rtmaps/sink.h"
 
+// MCap.
+#define MCAP_IMPLEMENTATION
+#include "mcap/mcap.hpp"
+#include <mcap/writer.hpp>
+
+// Protobuf.
+#include <google/protobuf/descriptor.pb.h>
+
+// Foxglove.
+#include "foxglove/PointCloud.pb.h"
+#include "foxglove/FrameTransforms.pb.h"

I get a bunch of warnings like this:

>> CMAKE_CXX_FLAGS="-Wshadow" cmake ..; make
...
~/.conan/data/mcap/2.0.2/moris/local/package/d6b3e20343f42ea32c60d1ca7cbdf67fe16da986/include/mcap/intervaltree.hpp: In lambda function:
~/.conan/data/mcap/2.0.2/moris/local/package/d6b3e20343f42ea32c60d1ca7cbdf67fe16da986/include/mcap/intervaltree.hpp:173:40: warning: declaration of ‘interval’ shadows a member of ‘mcap::internal::IntervalTree<Scalar, Value>’ [-Wshadow]
  173 |     auto filterF = [&](const interval& interval) {
      |                        ~~~~~~~~~~~~~~~~^~~~~~~~
~/.conan/data/mcap/2.0.2/moris/local/package/d6b3e20343f42ea32c60d1ca7cbdf67fe16da986/include/mcap/intervaltree.hpp:45:9: note: shadowed declaration is here
   45 |   using interval = Interval<Scalar, Value>;
      |         ^~~~~~~~
      
~/.conan/data/mcap/2.0.2/moris/local/package/d6b3e20343f42ea32c60d1ca7cbdf67fe16da986/include/mcap/reader.inl:1221:86: warning: declaration of ‘endOffset’ shadows a member of ‘mcap::RecordReader’ [-Wshadow]
 1221 | RecordReader::RecordReader(IReadable& dataSource, ByteOffset startOffset, ByteOffset endOffset)
      |                                                                           ~~~~~~~~~~~^~~~~~~~~
~/.conan/data/mcap/2.0.2/moris/local/package/d6b3e20343f42ea32c60d1ca7cbdf67fe16da986/include/mcap/reader.hpp:509:14: note: shadowed declaration is here
  509 |   ByteOffset endOffset;
      |              ^~~~~~~~~

These are only warnings but prevent from having a clean / strict set of compilation options.

My understanding is that the conan packaging is OK and that the related causes are indeed in the mcap library.

Is there a plan to patch mcap to pass -Wshadow in a coming future?

[jtbandes]

Which compiler are you using? I am not seeing these warnings in clang...

[fghoussen]

I use g++-13.3.0 with a conan1 (not yet conan2) recipe that packaged mcap. The recipe is inspired from https://github.com/foxglove/mcap/blob/main/cpp/mcap/conanfile.py with minor changes needed to integrate our workflow (adding -Wshadow on the fly to g++).

At first, I believed the problem may be in connection with the conan integration, but, after looking at it closely the errors sounds indeed valid. I attach the full log that lists warnings to be fixed in mcap AFAIU.

Would be great to compile mcap with gcc without warnings using these flags: -Wall -Wextra -Wshadow -Wpointer-arith -Werror -fno-strict-aliasing.

mcap.log

[jtbandes]

Should be fixed by: #1465

However, in working on this I discovered the CONAN_SYSTEM_INCLUDES setting, which I would probably recommend you turn on to avoid warnings from third-party libraries.

[fghoussen]

Great! ;) When is the next release planned? I'll have a look at CONAN_SYSTEM_INCLUDES.