[go-nuts] How can I workaround Syscall non portable usage -- build packages conditionally based on target OS?

I think you're looking for +build flags.

grep -r "// +build" $GOROOT/src/pkg

That looks like exactly what I want. Thanks.

Also, simply naming files with _<GOARCH> and _<GOOS> in them will also
work, and was the older method of doing system based conditional
compilation before the build tag system was created.

eg:

fi_linux.go => only builds for Linux targets
fi_darwin_386.go => only builds for 32-bit intel Mac OS X targets
fi_windows_amd64.go => only builds for 64-bit Windows targets

Both systems are supported by the go tool, but the newer build tags are
more flexible, and have a larger selection of criteria, such as go version,
cgo availability, app engine compilation, and user proivded tags.

Here are some things to note:

    - These features are provided by the go tool, not the lower-level 6g/8g
    compilers, so if you call the compilers yourself, the logic won't happen.
    - If you explicitly name a file on the command line, neither set of
    rules takes effect
    - The filename rule is checked first, and then if passing, the build
    tags, so you can't override filename rules with contradictory build rules,
    but they can work together.
    - Both sets of rules apply to any file type handled by the go tool, for
    example CGO, SWIG and assembly code files can also use these rules (quite
    important for assembly)
       - File formats that aren't text-based, such as .syso files can't use
       build tag rules, but still can use filename rules.
    - The build tag expressions will only work if correctly positioned in a
    go file, "go vet" will check the most common cases (you can use "go vet
    file.go" to make sure the named file is checked)
    - There is no "test" build tag, so you can't control which files are
    only used for testing via build tag expressions

I ended up going with the file naming convention and it works like a charm.