Aliasing not working as expected when using FetchContent

[mathiasplans]

Hey!

I have this in my CMake files:

include(FetchContent)
FetchContent_Declare(
  printf_library
  GIT_REPOSITORY https://github.com/eyalroz/printf.git
  GIT_TAG        dd63281
)

set(BUILD_SHARED_LIBS OFF)
set(SUPPORT_EXPONENTIAL_SPECIFIERS OFF)
set(SUPPORT_MSVC_STYLE_INTEGER_SPECIFIERS OFF)
set(SUPPORT_LONG_LONG OFF)
set(USE_DOUBLE_INTERNALLY OFF)
set(SUPPORT_WRITEBACK_SPECIFIER OFF)
set(CHECK_FOR_NUL_IN_FORMAT_SPECIFIER ON)
set(ALIAS_STANDARD_FUNCTION_NAMES "SOFT")

FetchContent_MakeAvailable(printf_library)

Now when I include "printf/printf.h" in my code, the aliases are not working as expected. I have set the ALIAS_STANDARD_FUNCTION_NAMES to "SOFT", so I expected the aliasing to work in my code.

The problem is that "printf/printf.h" has this code:

#ifdef PRINTF_INCLUDE_CONFIG_H
#include "printf_config.h"
#endif

This works well when compiling the source file "printf/printf.c", since the CMakeLists.txt has the following line:

target_compile_definitions(printf PRIVATE PRINTF_INCLUDE_CONFIG_H)

However, this define does not carry over to my main project. That means that the "printf_config.h" will not be taken into account when I include "printf/printf.h". I think this is bad, since the library uses a different header internally compared to the header we can include in our projects. I tried solving it by defining PRINTF_INCLUDE_CONFIG_H in the main project, but then I get this error:

[build] In file included from C:/Users/mathi/Documents/kw/boomboard/cmake/stm32cubemx/../../Core/Inc/printer.h:2,
[build]                  from C:/Users/mathi/Documents/kw/boomboard/Core/Src/perf.cpp:4:
[build] C:/Users/mathi/Documents/kw/boomboard/build/Debug/_deps/printf_library-src/src/printf/printf.h:43:10: fatal error: printf_config.h: No such file or directory
[build]    43 | #include "printf_config.h"
[build]       |          ^~~~~~~~~~~~~~~~~
[build] compilation terminated.

What fixed it for me was defining PRINTF_ALIAS_STANDARD_FUNCTION_NAMES_SOFT.

I think "printf_config.h" should be able to be included by the users. Or if the manual definition is the intended way the documentation should be made more clear.

[eyalroz]

1. Are you using the last release, or the development branch?
2. Since the aliasing definitions are used in printf.h, I believe we need to make the that target_compile_definitions() public rather than private.

[eyalroz]

Please try checking out and using the branch "printf-config-for-the-masses".

[mathiasplans]

I tried it out. I have to add the include path myself:

target_include_directories(${CMAKE_PROJECT_NAME} PRIVATE
   ...
   build/Debug/_deps/printf_library-build/include
)

I think the include directory should also then be public.

[eyalroz]

I tried it out. I have to add the include path myself:

Oh, right, you tried it with FetchContent rather than an installaion. Hmm.

[eyalroz]

What do you think about alias-outside-config? So, not forcing printf_config.h on everybody (I'm mulling over making its exposure a CMake option), but rather propagating the aliasing setting.

[mathiasplans]

There is a bug, you define ALIAS_STANDARD_FUNCTION_NAMES_${ALIAS_STANDARD_FUNCTION_NAMES} but it should be PRINTF_ALIAS_STANDARD_FUNCTION_NAMES_${ALIAS_STANDARD_FUNCTION_NAMES} since printf.h has:

#if PRINTF_ALIAS_STANDARD_FUNCTION_NAMES_SOFT
# define printf     printf_
# define sprintf    sprintf_
# define vsprintf   vsprintf_
# define snprintf   snprintf_
# define vsnprintf  vsnprintf_
# define vprintf    vprintf_
#endif

With that change, it works.

[eyalroz]

So, I think that's what we'll go with, for now.