Documentation issue in section "Exporting a C Library"

[robertblackwell]

The example given in the Documentation section Exporting C Libraries does not build (at least when I try). The required C headers file (mathtest.h) is not found.

Need to add -femit-h to

zig build-lib mathtest.zig  -femit-h 

and or add the line

lib.emit_h = true

following

const lib = b.addSharedLibrary("mathtest", "mathtest.zig", version(1,0,0));

in the build.zig file.

There is, I think, a similar issue with the example under the heading Mixing Object Files because it fails to build for a similar reason.

[kliberty]

Adding -femit-h with the current master build zig-linux-x86_64-0.6.0+4b48fccad does not actually produce a .h file.

zig/src/Compilation.zig

Line 2708 in d44486b

log.warn("-femit-h is not available in the stage1 backend; no .h file will be produced", .{});

[robertblackwell]

I am using zig 0.6.0+288198e51. It does produce a .h file.
So if I upgrade to to a more recent 0.6.0 my "fix" will not work ?
How do I produce a .h file then and make the example in the docs work?
I finally found this comment

// TODO we would like to #include "mathtest.h" here but this feature has been disabled in
// the stage1 compiler. Users will have to wait until self-hosted is available for
// the "generate .h file" feature.

in zig/test/shared_library/test.c

So at this point zig does not deliver "One of the primary use cases for Zig is exporting a library with the C ABI" without writing the libraries .h file by hand. AND the docs don't tell users that.

[kliberty]

It probably should be mentioned in the docs, however, we're both trying to use daily builds from the master branch. In theory when 0.7.0 is released the self hosting compiler will support -femit-h again, so I think there is an argument to made about allowing the discrepancy to remain.

In the meantime, my solution will probably be to use the version you mentioned.

[hhstore]

• +1.
• https://ziglang.org/learn/overview/#export-functions-variables-and-types-for-c-code-to-depend-on
• any update?

➤ zig version
0.10.0-dev.2617+47c4d4450

errors:

zig build-lib  src/zigmath.zig -femit-h

warning(compilation): -femit-h is not available in the stage1 backend; no .h file will be produced

[hhstore]

@everyone

Refer to my example below, it can be solved.

• https://github.com/better-zig/learn-zig/blob/main/packages/zig-to-c/readme.md

1. First generate the c header file based on zig v0.6.0 + docker.

# cd this-dir/; do:
docker run --platform linux/x86_64 -v $PWD:/app euantorano/zig:0.6.0 build-lib src/mathtest.zig -femit-h

3. Then, compile normally based on the current version (zig v0.10). check build.zig

Chinese Reference:

• C 语言调用 Zig (FFI 完整用例) zigcc/forum#12

[kassane]

It is possible to export to C only using stage2. So if you download version 0.9.1 or higher, add the -fno-stage1 flag and the header will be generated.

Example: https://jedi.sh/zigo

[edyu]

Still doesn't work as of 0.11.0-dev.2969+855493bb8

[edyu]

It is possible to export to C only using stage2. So if you download version 0.9.1 or higher, add the -fno-stage1 flag and the header will be generated.

Example: https://jedi.sh/zigo

site doesn't work

[kassane]

It is possible to export to C only using stage2. So if you download version 0.9.1 or higher, add the -fno-stage1 flag and the header will be generated.

Example: https://jedi.sh/zigo

site doesn't work

Old reference.

Archived website:
https://web.archive.org/https://jedi.sh/zigo