[-fpermissive]

[wmjenkinson]

How can I resolve this error:

ok_png.cpp:125:59: error: invalid conversion from 'void*' to 'uint8_t*' {aka 'unsigned char*'} [-fpermissive]
125 | #define ok_alloc(decoder, size) (decoder)->allocator.alloc((decoder)->allocator_user_data, (size))

#define ok_alloc(decoder, size) (decoder)->allocator.alloc((decoder)->allocator_user_data, (size))

[rsta2]

#define ok_alloc(decoder, size) (decoder)->allocator.alloc(reinterpret_cast<uint8_t *>((decoder)->allocator_user_data), (size))

[wmjenkinson]

Hello rsta2, I tried that but I get a new error message, as follows:

ok_png.cpp: In function 'bool ok_png_read_data(ok_png_decoder*, uint32_t)':
ok_png.cpp:125:98: error: request for member 'allocator_user_data' in '(uint8_t)decoder', which is of non-class type 'uint8_t' {aka 'unsigned char'}
125 | #define ok_alloc(decoder, size) (decoder)->allocator.alloc(reinterpret_cast<uint8_t *>(decoder)->allocator_user_data, (size))

Just to let you know I'm porting a png decoder example from github.

[rsta2]

This is not the exact modification, that I wrote. The extra parentheses around ((decoder)->allocator_user_data) are missing.

[wmjenkinson]

#define ok_alloc(decoder, size) (decoder)->allocator.alloc(reinterpret_cast<uint8_t *>((decoder)->allocator_user_data), (size))

ok_png.cpp: In function 'bool ok_png_read_data(ok_png_decoder*, uint32_t)':
ok_png.cpp:125:59: error: invalid conversion from 'void*' to 'uint8_t*' {aka 'unsigned char*'} [-fpermissive]
125 | #define ok_alloc(decoder, size) (decoder)->allocator.alloc(reinterpret_cast<uint8_t *>((decoder)->allocator_user_data), (size))

[rsta2]

I guess it's this project?

#define ok_alloc(decoder, size) reinterpret_cast<uint8_t*>((decoder)->allocator.alloc((decoder)->allocator_user_data, (size)))

This solves this problem, but you will get more errors. You have to cast the result of every ok_alloc() occurrence to the expected result type, if it is not uint8_t*. C is not that permissive and can assign a void* to any pointer variable, but C++ is.

[wmjenkinson]

Thank you rsta2. Do you have paypal and I'll send you the price of a few pints?

[rsta2]

You are welcome. Thank you for your offer, but this is not necessary. I'm glad, that you are using Circle.