Improve translate-c macro @compileErrors for pragma operators

[kj4tmp]

Zig Version

0.14.0-dev.66+1fdf13a14

Steps to Reproduce and Observed Behavior

possibly related to #4754

create c file with:

#ifndef PACKED
#define PACKED_BEGIN __pragma(pack(push, 1))
#define PACKED
#define PACKED_END __pragma(pack(pop))
#endif

Observed behavior:

zig translate-c src/test-translate.c

outputs:

pub const PACKED_BEGIN = @compileError("unable to translate macro: undefined identifier `__pragma`");
// src/test-translate.c:2:9
pub const PACKED = "";
pub const PACKED_END = @compileError("unable to translate macro: undefined identifier `__pragma`");
// src/test-translate.c:4:9

Context: I am attempting to use zig to wrap and use https://github.com/OpenEtherCATsociety/SOEM
which uses this macro a lot to create packed structs like:

PACKED_BEGIN
typedef struct PACKED
{
   uint16    comm;
   uint16    addr;
   uint16    d2;
} ec_eepromt;
PACKED_END

Expected Behavior

I would have expected zig to handle this macro and create packed structs.
Someone more knowledgeable should define what should be expected with C packed structs (Zig packed structs are not the same as C packed structs)

[Vexu]

Those pragma macros are untranslatable to Zig since Zig doesn't have pragmas or other annotations like that and the rest of the issue is duplicate of #4754

[Srekel]

Those pragma macros are untranslatable to Zig since Zig doesn't have pragmas or other annotations like that and the rest of the issue is duplicate of #4754

Sorry if I'm being dumb but just to be clear, is the intent not to support them (thinking primarily of pragma pack here) in Zig, and use compile errors if it spots them in a C header?

[Vexu]

I meant that the pragma operator cannot be translated in a way where you'd be able to use PACKED_BEGIN in Zig code but if you have a C file that uses it then translate-c should notice it and add the proper alignments to the struct fields.

And this issue can be closed when PACKED_BEGIN has an error that explains the situation better than undefined identifier '__pragma'.