CGLM_USE_ANONYMOUS_STRUCT: expected an expression

[EranStockdale]

Hello there!

I'm trying to use cglm. It was working fine until I set my C++ standard (yes yes I know cglm is for C) to C++20, I'm getting errors such as this:

src/client/main.cpp:191:101: error: 'vec3s' {aka 'union vec3s'} has no member named 'x'
  191 |                         ImGui::Text("Camera Movement Direction %f, %f, %f", cameraMovementDirection.x, cameraMovementDirection.y, cameraMovementDirection.z);

Now, I dug into cglm/struct.h and found

#if CGLM_USE_ANONYMOUS_STRUCT

blocking the property definitions. Okay, that's fine, add -DCGLM_USE_ANONYMOUS_STRUCT to the compiler flags. Nope. Here:

Anyhow, how can I fix this? I have a feeling the ifs should be ifdefs. I'm happy to submit a PR if this is the case.

Thanks,
Eran

[recp]

Hi @EranStockdale,

Thanks for the feedbacks,

https://github.com/recp/cglm/blob/master/include/cglm/types-struct.h#L20-L54

Must also check C++ compiler / version too I guess, it must enable anonymous structs by default if no CGLM_NO_ANONYMOUS_STRUCT is defined and if it is supported by compiler

how can I fix this? I have a feeling the ifs should be ifdefs. I'm happy to submit a PR if this is the case.

Sure, thanks, I'll wait a PR then :)

ifdef may be better but it must not break something on the projects that use cglm (probably not), also as I mentioned above we may need to check C++ compiler and versions to bring this to Cpp

FWIW, -DCGLM_USE_ANONYMOUS_STRUCT should have been --> -DCGLM_USE_ANONYMOUS_STRUCT=1 since it expects value rather than just a definition

[EranStockdale]

@recp

ifdef may be better but it must not break something on the projects that use cglm (probably not), also as I mentioned above we may need to check C++ compiler and versions to bring this to Cpp

Ah yeah that's true. Realistically I should probably just use normal glm, but I'm aiming for my project to be as C-style as possible (but things like imgui are tripping me up),. I'll submit a PR for the ifdefs when I get home if you like, but I'm actually relatively new to C/C++ so I'm not sure I can help much in regards to the compiler version checking.

FWIW, -DCGLM_USE_ANONYMOUS_STRUCT should have been --> -DCGLM_USE_ANONYMOUS_STRUCT=1 since it expects value rather than just a definition

Ahhh right, good point! It does still pass the if check, though, so that wasn't the cause of the issue ;)

[recp]

@EranStockdale no prob, may I ask about your environment, for instance compiler (including version, visual studio version if it is vs), OS... to fix this asap

[EranStockdale]

@EranStockdale no prob, may I ask about your environment, for instance compiler (including version, visual studio version if it is vs), OS... to fix this asap

Yeah. I'm on Windows 11, MinGW GCC/G++ v13.2.0

[recp]

thanks for sharing that, there may not be an issue according to:

/*
 * Anonymous structs are available since C11, but we'd like to be compatible
 * with C99 and C89 too. So let's figure out if we should be using them or not.
 * It's simply a convenience feature, you can e.g. build the library with
 * anonymous structs and your application without them and they'll still be
 * compatible, cglm doesn't use the anonymous structs internally.
 */
#ifndef CGLM_USE_ANONYMOUS_STRUCT
   /* If the user doesn't explicitly specify if they want anonymous structs or
    * not, then we'll try to intuit an appropriate choice. */
#  if defined(CGLM_NO_ANONYMOUS_STRUCT)
     /* The user has defined CGLM_NO_ANONYMOUS_STRUCT. This used to be the
      * only #define governing the use of anonymous structs, so for backward
      * compatibility, we still honor that choice and disable them. */
#    define CGLM_USE_ANONYMOUS_STRUCT 0
     /* Disable anonymous structs if strict ANSI mode is enabled for C89 or C99 */
#  elif defined(__STRICT_ANSI__) && \
        (!defined(__STDC_VERSION__) || (__STDC_VERSION__ < 201112L))
     /* __STRICT_ANSI__ is defined and we're in C89
      * or C99 mode (C11 or later not detected) */
#    define CGLM_USE_ANONYMOUS_STRUCT 0
#  elif (defined(__STDC_VERSION__) && __STDC_VERSION__ >= 201112L) || \
        (defined(__cplusplus)      && __cplusplus >= 201103L)
     /* We're compiling for C11 or this is the MSVC compiler. In either
      * case, anonymous structs are available, so use them. */
#    define CGLM_USE_ANONYMOUS_STRUCT 1
#  elif defined(__GNUC__) && (__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 6))
     /* GCC 4.6 and onwards support anonymous structs as an extension */
#    define CGLM_USE_ANONYMOUS_STRUCT 1
#  elif defined(__clang__) && __clang_major__ >= 3
     /* Clang 3.0 and onwards support anonymous structs as an extension */
#    define CGLM_USE_ANONYMOUS_STRUCT 1
#  elif defined(_MSC_VER) && (_MSC_VER >= 1900) /*  Visual Studio 2015 */
     /* We can support anonymous structs
      * since Visual Studio 2015 or 2017 (1910) maybe? */
#    define CGLM_USE_ANONYMOUS_STRUCT 1
#  else
     /* Otherwise, we're presumably building for C99 or C89 and can't rely
      * on anonymous structs being available. Turn them off. */
#    define CGLM_USE_ANONYMOUS_STRUCT 0
#  endif
#endif

this contains what happens actually:

we support anonymous structs if compiler supports it

• C11+
• gnu89, gnu99, ++
• cplusplus >= 201103
• Visual Studio 2015+ for msvc

if compiler is set to c89, c99 then it will be disabled especially due to __STRICT_ANSI__.

For instance ( vscode c_cpp_perties.json )

anonymous structs feature is disabled and STRICT_ANSI is enabled:

"cStandard": "c99",
"cppStandard": "c++11",

anonymous structs feature is enabled and SUPPORTED:

"cStandard": "gnu99",
"cppStandard": "gnu++11",

so it must work properly on MinGW, but if there is bug it must be fixed asap.

[EranStockdale]

@recp sorry, stuff happened so I couldn't work on this. I've set the thingies to the following

"cStandard": "gnu99",
"cppStandard": "gnu++11",

And it's still not working. Any advice on where to proceed from here?