Build.zig do step if certain directory changes?

Help
1

Im trying to migrate my project to the new build system. Is there a way to say “rerun this step if a directory and its content changes”?
This is my code rn, java-sources.zig just walks the first arg dir and writes the abs path of it into the second arg.

const java_sources = b.addRunArtifact(b.addExecutable(.{
    .name = "java-sources",
    .root_module = b.createModule(.{
        .root_source_file = b.path("src/build-tools/java-sources.zig"),
        .target = target,
        .optimize = .debug,
    }),
}));

java_sources.addDirectoryArg2(b.path("src/runtime-java/"), .{});
const java_sources_file = java_sources.addOutputFileArg2("java-sources.txt", .{});

const javac = b.addSystemCommand(&.{
    "javac",
    "-cp",
    "asset/jar-libs/*",
    "-d"
});
javac.step.dependOn(&java_sources.step);
const class_dir = javac.addOutputDirectoryArg2("class", .{});
javac.addPrefixedFileArg("@", java_sources_file);

const jar = b.addSystemCommand(&.{ // jar cvf myapp.jar -C bin .
    "jar",
    "cvf"
});
jar.step.dependOn(&javac.step);
const jar_file = jar.addOutputFileArg("runtime.jar");
jar.addArg("-C");
jar.addDirectoryArg(class_dir);
jar.addArg(".");

b.getInstallStep().dependOn(&jar.step);
b.getInstallStep().dependOn(&b.addInstallBinFile(jar_file, "runtime.jar").step);
b.getInstallStep().dependOn(&b.addInstallBinFile(java_sources_file, "java-source.txt").step);

i thought it was enough to just reference the dir with b.path but its not apparently

2

I found this:

std.Build.dependOnDirectoryMetadata - indicates that the build.zig logic depends on a particular directory’s last modification date.

from here: 0.17.0 Release Notes ⚡ The Zig Programming Language

I myself had to sift through build system code to get my apk producer working inside termux and it was a great success. And I think it’s really worth just browsing definitions with the help of lsp.

Pretty sure dependOnDirectoryMetadata will work for you

3

Configure cache poisoning should solve it for you. Specifically, either std.Build.dependOnDirectoryMetadata or std.Build.dependOnDirectoryContents. The difference is described in their documentation. Beware: they are not recursive.

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