RNA: Fix compile error when assigning to a typed enum in C++ #109136

Julian Eisel · 2023-06-19T19:51:06+02:00

Julian Eisel commented

2023-06-19 19:51:06 +02:00

When a RNA file was compiled in C++, building would fail when defining a
RNA enum property that assigns to a enum value with a defined (i.e.
non-integer) type.

For example, #104831 contains the following in a non-DNA header:

typedef struct AssetShelfType {
  /*...*/
    AssetShelfTypeFlag flag;
  /*...*/
} AssetShelfType;

And a RNA definition like this:

prop = RNA_def_property(srna, "bl_options", PROP_ENUM, PROP_NONE);
RNA_def_property_enum_sdna(prop, NULL, "type->flag");
/*...*/

There's no custom setter callback defined so it would be generated by
makesrna. It would be generated as data->type->flag = value; whereby
value is of type int, which doesn't compile in C++ without cast to the
enum type.

When a RNA file was compiled in C++, building would fail when defining a RNA enum property that assigns to a enum value with a defined (i.e. non-integer) type. ---- For example, #104831 contains the following in a non-DNA header: ```C typedef struct AssetShelfType { /*...*/ AssetShelfTypeFlag flag; /*...*/ } AssetShelfType; ``` And a RNA definition like this: ```C prop = RNA_def_property(srna, "bl_options", PROP_ENUM, PROP_NONE); RNA_def_property_enum_sdna(prop, NULL, "type->flag"); /*...*/ ``` There's no custom setter callback defined so it would be generated by `makesrna`. It would be generated as `data->type->flag = value;` whereby `value` is of type `int`, which doesn't compile in C++ without cast to the enum type.

Julian Eisel added the

Module

Core

label 2023-06-19 19:51:06 +02:00

Julian Eisel added 1 commit 2023-06-19 19:51:20 +02:00

buildbot/vexp-code-patch-coordinator Build done. Details

14599f0258 RNA: Fix compile error when assigning to a typed enum in C++

When a RNA file was compiled in C++, building would fail when defining a
RNA enum property that assigns to a enum value with a defined (i.e.
non-integer) type.

----

For example, #104831 contains the following in a non-DNA header:
```
typedef struct AssetShelfType {
  /*...*/
    AssetShelfTypeFlag flag;
  /*...*/
} AssetShelfType;
```

And a RNA definition like this:
```
prop = RNA_def_property(srna, "bl_options", PROP_ENUM, PROP_NONE);
RNA_def_property_enum_sdna(prop, NULL, "type->flag");
/*...*/
```

There's no custom setter callback defined so it would be generated by
`makesrna`. It would be generated as `data->type->flag = value;` whereby
`value` is of type `int`, which doesn't work in C++. The integer value
needs to be cast to the enum type.

Julian Eisel commented

2023-06-19 19:53:20 +02:00

@blender-bot build

Julian Eisel requested review from Jacques Lucke 2023-06-19 19:55:18 +02:00

Jacques Lucke commented

2023-06-19 19:58:42 +02:00

Afaik we don't allow using enums directly in DNA structs, because their size is not consistent between compilers.

[EDIT] Ah wait, misread, one moment.

Afaik we don't allow using enums directly in DNA structs, because their size is not consistent between compilers. [EDIT] Ah wait, misread, one moment.

Jacques Lucke commented

2023-06-19 20:07:30 +02:00

Assuming typeof compiles with all compilers we support, this is fine. Currently, I'd be surprised if that this extension is supported by every compiler, but we'll see.

If this issue is in C++ only, it maybe better to have a separate code path for C++ that uses decltype.

Assuming `typeof` compiles with all compilers we support, this is fine. Currently, I'd be surprised if that this extension is supported by every compiler, but we'll see. If this issue is in C++ only, it maybe better to have a separate code path for C++ that uses `decltype`.

Jacques Lucke approved these changes 2023-06-19 20:08:37 +02:00

Julian Eisel commented

2023-06-19 20:14:23 +02:00

Meeh, MSVC fails of course. Always thought typeof() is C standard like sizeof(). Back to ifdef'ed decltype() then.

Meeh, MSVC fails of course. Always thought `typeof()` is C standard like `sizeof()`. Back to `ifdef`'ed `decltype()` then.

Julian Eisel changed title from ~~RNA: Fix compile error when assigning to a typed enum in C++~~ to WIP: RNA: Fix compile error when assigning to a typed enum in C++

2023-06-19 20:16:08 +02:00

Julian Eisel added 1 commit 2023-06-19 21:01:21 +02:00

buildbot/vexp-code-patch-coordinator Build done. Details

5be805f9f0 Use `decltype()` instead of `typeof()`

Julian Eisel changed title from ~~WIP: RNA: Fix compile error when assigning to a typed enum in C++~~ to RNA: Fix compile error when assigning to a typed enum in C++

2023-06-19 21:01:54 +02:00

Julian Eisel commented

2023-06-19 21:05:03 +02:00

Using decltype convolutes code a bit, which is annoying. Generated output looks like this for example:

RNA_EXTERN_C void Panel_bl_space_type_set(PointerRNA *ptr, int value)
{
    Panel *data = (Panel *)(ptr->data);
#ifdef __cplusplus
    data->type->space_type = (std::remove_reference_t<decltype(data->type->space_type)>)value;
#else
    data->type->space_type = value;
#endif
}

I guess using -fpermissive is not an option, and I don't see another flag addressing this build error.

Using decltype convolutes code a bit, which is annoying. Generated output looks like this for example: ```Cpp RNA_EXTERN_C void Panel_bl_space_type_set(PointerRNA *ptr, int value) { Panel *data = (Panel *)(ptr->data); #ifdef __cplusplus data->type->space_type = (std::remove_reference_t<decltype(data->type->space_type)>)value; #else data->type->space_type = value; #endif } ``` I guess using `-fpermissive` is not an option, and I don't see another flag addressing this build error.

Julian Eisel requested review from Jacques Lucke 2023-06-19 21:05:09 +02:00

Jacques Lucke approved these changes 2023-06-19 21:06:43 +02:00

Jacques Lucke left a comment

Could also use std::decay_t but this is fine as well.

Could also use `std::decay_t` but this is fine as well.

Julian Eisel commented

2023-06-19 21:08:59 +02:00

Could also use std::decay_t but this is fine as well.

std::remove_reference_t makes the intent explicit, so I prefer that.

Thanks!

> Could also use `std::decay_t` but this is fine as well. `std::remove_reference_t` makes the intent explicit, so I prefer that. Thanks!

Julian Eisel commented

2023-06-19 21:09:45 +02:00

@blender-bot build

Julian Eisel merged commit fa59084025 into main

2023-06-20 11:30:32 +02:00

Julian Eisel referenced this issue from a commit

2023-06-20 11:30:32 +02:00

RNA: Fix compile error when assigning to a typed enum in C++

Julian Eisel deleted branch temp-makesrna-setter-cast

2023-06-20 11:30:33 +02:00

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RNA: Fix compile error when assigning to a typed enum in C++ #109136