Compiling errors with Ubuntu22.04

[Alizyt]

I'm having a bunch of compiling error when using the single header file on Ubuntu 22.04.2 w/ gcc11, most relates to std::chars_format.
Is it now fully supported?

[biojppm]

I tried it, and it works flawlessly, without any compiler warnings:

git clone --recursive https://github.com/biojppm/rapidyaml
cd rapidyaml/samples/singleheader && ./run.sh

The result is

+ cfg=Release
++ dirname ./run.sh
+ cd .
+ cmake -S . -B ./build/Release -DCMAKE_BUILD_TYPE=Release
-- The CXX compiler identification is GNU 11.3.0
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Check for working CXX compiler: /usr/bin/c++ - skipped
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Found Python3: /usr/bin/python3.10 (found version "3.10.6") found components: Interpreter
-- Configuring done
-- Generating done
-- Build files have been written to: /home/jpmag/proj/rapidyaml/samples/singleheader/build/Release
+ cmake --build ./build/Release --config Release --target run
[ 33%] /usr/bin/python3.10 /home/jpmag/proj/rapidyaml/samples/singleheader/../../tools/amalgamate.py /home/jpmag/proj/rapidyaml/samples/singleheader/../../src_singleheader/ryml_all.hpp
[ 66%] Building CXX object CMakeFiles/ryml-quickstart.dir/home/jpmag/proj/rapidyaml/samples/quickstart.cpp.o
[100%] Linking CXX executable ryml-quickstart
[100%] Built target ryml-quickstart
/home/jpmag/proj/rapidyaml/samples/quickstart.cpp:187: OK! tree.is_map(root_id)
/home/jpmag/proj/rapidyaml/samples/quickstart.cpp:188: OK! tree.is_seq(bar_id)
/home/jpmag/proj/rapidyaml/samples/quickstart.cpp:194: OK! root.is_map()
.... # etc

This defaults on cxx_std_11. It works just the same if I set the standard to 17 or 20 (by changing the cmake file).

I suspect something else is at play. How are you compiling it? Do you have any special flags enabled?

[Alizyt]

Hi @biojppm,

Thank you for looking into this. I've tried the sample code compiling on my system and it passed as well. After a little bit further digging into, I found the issue relates to the other header file <boost/format.hpp> included in my project, and the include order matters. I can simply reproduce the error by including <boost/format.hpp> before <ryml_all.hpp> within quickstart.cpp, see diff as below:

diff --git a/samples/quickstart.cpp b/samples/quickstart.cpp
index 0652f9f..785e3ef 100644
--- a/samples/quickstart.cpp
+++ b/samples/quickstart.cpp
@@ -23,6 +23,8 @@

 //-----------------------------------------------------------------------------

+#include <boost/format.hpp>
+
 // ryml can be used as a single header, or as a simple library:
 #if defined(RYML_SINGLE_HEADER) // using the single header directly in the executable
     #define RYML_SINGLE_HDR_DEFINE_NOW

And then the compiling errors will be as below:

+ cfg=Release
++ dirname ./run.sh
+ cd .
+ cmake -S . -B ./build/Release -DCMAKE_BUILD_TYPE=Release
-- Configuring done (0.1s)
-- Generating done (0.1s)
-- Build files have been written to: /home/dev/ali/rapidyaml/samples/singleheader/build/Release
+ cmake --build ./build/Release --config Release --target run
[ 33%] Building CXX object CMakeFiles/ryml-quickstart.dir/home/dev/ali/rapidyaml/samples/quickstart.cpp.o
In file included from /home/dev/ali/rapidyaml/samples/quickstart.cpp:42:
/home/dev/ali/rapidyaml/samples/singleheader/../../src_singleheader/ryml_all.hpp:10781:42: error: ‘chars_format’ is not a member of ‘std’; did you mean ‘fast_float::chars_format’?
10781 | typedef enum : std::underlying_type<std::chars_format>::type {
      |                                          ^~~~~~~~~~~~
In file included from /home/dev/ali/rapidyaml/samples/quickstart.cpp:42:
/home/dev/ali/rapidyaml/samples/singleheader/../../src_singleheader/ryml_all.hpp:7428:6: note: ‘fast_float::chars_format’ declared here
 7428 | enum chars_format {
      |      ^~~~~~~~~~~~
In file included from /home/dev/ali/rapidyaml/samples/quickstart.cpp:42:
/home/dev/ali/rapidyaml/samples/singleheader/../../src_singleheader/ryml_all.hpp:10781:54: error: template argument 1 is invalid
10781 | typedef enum : std::underlying_type<std::chars_format>::type {
      |                                                      ^
/home/dev/ali/rapidyaml/samples/singleheader/../../src_singleheader/ryml_all.hpp:10781:57: error: expected ‘{’ before ‘type’
10781 | typedef enum : std::underlying_type<std::chars_format>::type {
      |                                                         ^~~~
/home/dev/ali/rapidyaml/samples/singleheader/../../src_singleheader/ryml_all.hpp:10781:57: error: typedef ‘c4::type’ is initialized (use ‘decltype’ instead)
/home/dev/ali/rapidyaml/samples/singleheader/../../src_singleheader/ryml_all.hpp:10783:5: error: ‘FTOA_FLOAT’ was not declared in this scope; did you mean ‘MAXFLOAT’?
10783 |     FTOA_FLOAT = static_cast<std::underlying_type<std::chars_format>::type>(std::chars_format::fixed),
      |     ^~~~~~~~~~
      |     MAXFLOAT
/home/dev/ali/rapidyaml/samples/singleheader/../../src_singleheader/ryml_all.hpp:10783:56: error: ‘chars_format’ is not a member of ‘std’; did you mean ‘fast_float::chars_format’?
10783 |     FTOA_FLOAT = static_cast<std::underlying_type<std::chars_format>::type>(std::chars_format::fixed),
      |                                                        ^~~~~~~~~~~~
In file included from /home/dev/ali/rapidyaml/samples/quickstart.cpp:42:
/home/dev/ali/rapidyaml/samples/singleheader/../../src_singleheader/ryml_all.hpp:7428:6: note: ‘fast_float::chars_format’ declared here
 7428 | enum chars_format {
      |      ^~~~~~~~~~~~
In file included from /home/dev/ali/rapidyaml/samples/quickstart.cpp:42:
...... # etc

[biojppm]

Thanks - with your description I now see the error.

It has to do with the amalgamated header, where for some reason std::chars_format is used when it should not be. This only happens with the single header; for example the add_subdirectory sample runs without problems.

I guess some macro in the boost header is throwing off the preprocessor code for charconv method selection, but I have to investigate this.

[biojppm]

Actually, it was down to a filtered #include <charconv> in the amalgamated header. This was fixed (I hope) by updating to the fixed c4core version.

Can you confirm that the current master fixes your problem?

[Alizyt]

Sorry for a delayed response, @biojppm.
I just tried the latest master on my env, and it's working now! BRAVO!!!
One more thing is that I noticed the newly generated single header file is pretty different from the previous one, with more than 3000 lines diff, is it expected?

[biojppm]

Yes, there was an update of the fastfloat library, and also more work on the c4core.

[biojppm]

Closing now. Thanks for reporting!

[Alizyt]

You're very welcome😄