copy assignment not allowed in union

RE: copy assignment not allowed in union

Nguyen Hoan Hoang — Tue, 30 Jan 2018 18:09:50 GMT

C++ cannot skip definitions in between. All definitions above the one that causes the error has to be filled in order. You can however skip all bellow. For example :

static const app_usbd_config_t usbd_config = {
    .ev_state_proc = usbd_user_ev_handler
};

Will cause the error but :

static const app_usbd_config_t usbd_config = {
    .ev_isr_handler = NULL,
    .ev_state_proc = usbd_user_ev_handler
};

will not.

for union stuff :

typedef struct a {
	int z;
	union {
		int b;
		struct {
			uint8_t c;
			uint16_t d;
		} f;
	};
} A;

A x = {
	.z = 0,
	{ .f = {.c = 1, .d = 2} }
};

A y = {
	.z = 0,
	{ .b = 3 }
};

RE: copy assignment not allowed in union

nvp — Tue, 30 Jan 2018 17:25:27 GMT

I will eventually be using some custom C++ code to communicate with some peripheral devices, but in the context of this question, the problem can be demonstrated without introducing any additional code to the usbd_hid_generic peripheral example. Some of the code in the original app_usbd_class_base.h is incompatible with the C++ standards as enforced by the arm-none-eabi-g++ compiler.

In order to work around the problem, I implemented option 2 from my original post. I reverted main back to a C program and I wrote a new wrapper.h and wrapper.cpp to interface the C++ classes in the libraries that I was using. These wrapper functions took Class::f(x,y,z) and made a C-style function class_f(void* instance, x, y, z) that could bridge the gap. Using extern "C" here provides C-style hooks. Since all calls to the usbd are exclusively in main.c, compiled by gcc, this avoids the problem.

RE: copy assignment not allowed in union

MartinBL — Mon, 29 Jan 2018 08:58:08 GMT

@nvp Are the errors just located in app_usbd_class_base.h? Or did you add some custom code?

RE: copy assignment not allowed in union

nvp — Fri, 26 Jan 2018 22:37:47 GMT

The USB interface uses a struct, not a class. The header files themselves include extern "C" declarations as well, but I added a few additional blocks in main.cpp; no difference.

RE: copy assignment not allowed in union

MartinBL — Fri, 26 Jan 2018 11:26:22 GMT

Can you try to put extern "C" { } around the USB class instance initialization?

RE: copy assignment not allowed in union

nvp — Thu, 25 Jan 2018 17:20:20 GMT

I was using version 6.3.1. I tried with version 7.2.1 with the same result.

RE: copy assignment not allowed in union

Nguyen Hoan Hoang — Thu, 25 Jan 2018 17:00:12 GMT

which compiler version are you using ? have you tried with v6 or v7 ?

RE: copy assignment not allowed in union

nvp — Thu, 25 Jan 2018 16:14:30 GMT

Same error: [...]/app_usbd_class_baseh.:674:5: sorry, unimplemented: non-trivial designated initializers not supported

RE: copy assignment not allowed in union

Nguyen Hoan Hoang — Wed, 24 Jan 2018 23:53:08 GMT

set it to -std=gnu++11 or more recent one.