Not compiling on Win10 with Cygwin

[frankkopp]

In file included from ..../_GITHUB/spdlog/src/spdlog.cpp:12:0:
..../_GITHUB/spdlog/include/spdlog/details/os-inl.h: In function 'void spdlog::details::os::prevent_child_fd(FILE*)':
..../_GITHUB/spdlog/include/spdlog/details/os-inl.h:139:15: error: 'fileno' was not declared in this scope
auto fd = fileno(f);

fileno is unknown.

Cygwin 3.0.7
CMake 3.15.3

Also copying headers to other project only works for "master" branch. 1.x branch does not work:
#includes are not working. I found a workaround by changing the #inclide paths.

[tt4g]

FYI.

There is not defined _WIN32 by CMake if using Cygwin compier.
If the target platform is Windows OS, You can define _WIN32 by specifying set(CMAKE_LEGACY_CYGWIN_WIN32 1) in CMakeLists.txt.

• https://stackoverflow.com/questions/28683365/how-to-disable-warning-in-cmake-3-1-about-cygwin-win32-not-being-defined
• https://stackoverflow.com/questions/50723567/set-clion-on-windows-10

Another way is to specify -std=gnu++11 as a compiler option.

• https://stackoverflow.com/questions/18784112/googletest-1-6-with-cygwin-1-7-compile-error-fileno-was-not-declared-in-this

[gabime]

Also copying headers to other project only works for "master" branch. 1.x branch does not work:
#includes are not working. I found a workaround by changing the #inclide paths.

@frankkopp Please provide more details what is the problem and what is the workaround

[gabime]

@tt4g I think I will fix spdlog's CMakeLists.txt and addset(CMAKE_LEGACY_CYGWIN_WIN32 =1) if built under cygwin (and mingw?)

[tt4g]

I think I will fix spdlog's CMakeLists.txt and addset(CMAKE_LEGACY_CYGWIN_WIN32 =1) if built under cygwin (and mingw?)

@gabime I can't decide if that is a good solution.

I have used MinGW a little with MSYS2.
MinGW library did not work on Windows OS unless the PATH environment variable was set. Because it links with MinGW library. Therefore, the release for Windows OS felt complicated.
This problem also seems to be in Cygwin.

• Cygwin not working on Windows 10 (even after added to system's PATH) - Stack Overflow

Also, I think MinGW and Cygwin have an ABI compatibility problem with the MSVC library.

• windows - What is the difference between Cygwin and MinGW? - Stack Overflow
• shared libraries - Crosscompiler Binary compatibility in C - Stack Overflow
• visual c++ - Is this interface binary compatible between MSVC and mingw? - Stack Overflow

However, MSYS2 provides the MSYS2_PATH_TYPE=inherit option that takes over Windows environment variables and allows to use the Windows API with MinGW.

Based on these facts, I believe that the developer decides whether to use the POSIX API or the Windows API, depending on which platform the library built with MinGW or Cygwin is used.

Fortunately, CMake can specify command line option -DCMAKE_LEGACY_CYGWIN_WIN32=0 or 1 when building.
I can't answer meson because I'm not familiar with it.

[frankkopp]

Also copying headers to other project only works for "master" branch. 1.x branch does not work:
#includes are not working. I found a workaround by changing the #inclide paths.

@frankkopp Please provide more details what is the problem and what is the workaround

I'm using CLION and cygwin (newest version incl. cmake and compiler).
There I have a project which compiles fine.
I have copied the spdlog header files from the "master" branch and it works fine

When I use the header files from the 1.x branch (or release tag 1.4.2) I get errors saying the include files are not found.

I'm not very proficient in CMAKE - but docu says "just copy header files".

Here the diff for my changes so my project compiles with the spdlog headers:
patch.diff.txt

[tt4g]

Here the diff for my changes so my project compiles with the spdlog headers:

There are a few things I noticed.

Some files do not exist in the current master branch, Such as spdlog/details/os-inl.h.
Do you know which commit in master the source file refers to?

And most of the differences in pach.diff.txt show that the include path has been changed to a relative path.
It may be affected by the order of header paths specified to the compiler.
If there is a header file with the same name, it is possible that an unintended file is included.

[frankkopp]

@tt4g I think I will fix spdlog's CMakeLists.txt and addset(CMAKE_LEGACY_CYGWIN_WIN32 =1) if built under cygwin (and mingw?)

I'm not very proficient in CMAKE and platform topics.

But I know the CYGWIN defines __CYGWIN__.

Googletest for example uses this:
#ifdef __CYGWIN__
....

So I think the issue is not CMAKE or CYGWIN but it is in the *.h files.
I guess the solution would be to support CYGWIN in the *.h files:

Example
SPDLOG_INLINE void prevent_child_fd(FILE *f) { #ifdef _WIN32 #do what is needed for _WIN32 #elif __CYGWIN__ #do what is needed for cygwin #else ... #endif }

Unfortunately I'm not experienced enough to know how to fix this line for Cygwin:
file: os-inl.h line: 139
auto fd = fileno(f);

It is an undeclared identifier in my environment.

[frankkopp]

There are a few things I noticed.

Some files do not exist in the current master branch, Such as spdlog/details/os-inl.h.
Do you know which commit in master the source file refers to?

I was refering to the 1.x branch.

And most of the differences in pach.diff.txt show that the include path has been changed to a relative path.
It may be affected by the order of header paths specified to the compiler.
If there is a header file with the same name, it is possible that an unintended file is included.

I changed the include paths so that it would compile in my environment. The former paths did not work for me (files not found). I just changed these to relative paths to see if it compiles at all.

Be carefull - I'm having two different issues here:

1. can't complile spdlog (1.x branch) itself due to cygwin not knowing fileno()
2. when coping all header files from the 1.x branch to my project the header includes do not work. (it worked with the "master" branch header files.

Thanks
Frank

[gabime]

when coping all header files from the 1.x branch to my project the header includes do not work. (it worked with the "master" branch header files.

Did you set the include search flag to point to the copied folder?

[tt4g]

So I think the issue is not CMAKE or CYGWIN but it is in the *.h files.
I guess the solution would be to support CYGWIN in the *.h files:

In my opinion, there is no problem with the header file because fileno was not found in the difference of pach.diff.txt.

[tt4g]

Also copying headers to other project only works for "master" branch. 1.x branch does not work:
#includes are not working. I found a workaround by changing the #inclide paths.

Here the diff for my changes so my project compiles with the spdlog headers:

Is patch.diff.txt the difference between 1.x branch and 1.x branch after changing #include paths?
If so, please ignore my opinion below.

In my opinion, there is no problem with the header file because fileno was not found in the difference of pach.diff.txt.

I thought it was the difference between master branch and v1.x branch (both changed #include paths).

[gabime]

Fixed and verified. The solution is to add in CMakeLists.txt

if(CMAKE_SYSTEM_NAME MATCHES "CYGWIN")
	set(CMAKE_CXX_EXTENSIONS  ON)
endif()

As for using the header-only by copy - works fine in latets commit. Please make sure you set correctly the search path flag to the parent of the "spdlog" folder

[frankkopp]

Wow - super fast! Thanks. Will test tomorrow and provide feedback.

[frankkopp]

Confirmed that I can now compile spdlog and also include it in my project.