builder.LibExeObjStep.addIncludeDir() not working in custom build.zig?

[ccll]

I'd like to call GTK functions from my zig program, here is the relevant code:

// build.zig
const cell = b.addExecutable("cell", ...);
cell.setBuildMode(mode);
cell.addIncludeDir("/usr/include/gtk-3.0");

// my module
const builtin = @import("builtin");
const Os = builtin.Os;
const c = switch (builtin.os) {
    Os.linux, Os.macosx => @cImport({
        @cInclude("stdio.h");
        @cInclude("stdlib.h");
        @cInclude("gtk/gtk.h");
    }),
    else => {},
}

But the compiler complaints about not finding the header file:

/home/cailei/proj/cell/infra/win.zig:6:28: error: C import failed
    Os.linux, Os.macosx => @cImport({
                           ^
/tmp/KyXYT4.h:3:10: note: 'gtk/gtk.h' file not found
#include <gtk/gtk.h>
         ^

And the file is apparently there:

$ ll /usr/include/gtk-3.0/gtk/gtk.h                                                   
-rw-r--r-- 1 root root 9663 10月 31 04:07 /usr/include/gtk-3.0/gtk/gtk.h  

[andrewrk]

I just tried this out, and when I do zig build --verbose I get:

zig build-exe /home/andy/tmp/testzig/main.zig --cache-dir /home/andy/tmp/testzig/zig-cache --output /home/andy/tmp/testzig/zig-cache/cell --name cell -isystem /usr/include/gtk-3.0 

which looks like it's passing the correct -isystem argument. Do you get this output?

[bnoordhuis]

Does it work when you add everything that pkg-config --cflags-only-I gtk+-3.0 prints?

[ccll]

@andrewrk Oops! My bad!
I just found out the compile error comes from a "TestStep" I've added in build.zig, which runs before compiling the main executable target.

const cell_test = b.addTest(...);
b.default_step.dependOn(&cell_test.step);

After commented out the test step, the executable target itself compiles fine.

I keep all test cases in the same file as the actual code for clarity and ease of code organization,
for now I could check builtin.is_test and ignore the @Cinclude("gtk/gtk.h") in test mode, as my tests does not use the header file.
In the long term maybe there should be an addIncludeDir() implemented for TestStep?

[andrewrk]

Ah yeah that's a good point. This is a pretty straightforward userland change to std/build.zig if anyone wants to take a crack at it. Otherwise I'll try to fix it soon!