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;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2016 Petter <petter@mykolab.ch>
;;; Copyright © 2017 Leo Famulari <leo@famulari.name>
;;;
;;; This file is part of GNU Guix.
;;;
;;; GNU Guix is free software; you can redistribute it and/or modify it
;;; under the terms of the GNU General Public License as published by
;;; the Free Software Foundation; either version 3 of the License, or (at
;;; your option) any later version.
;;;
;;; GNU Guix is distributed in the hope that it will be useful, but
;;; WITHOUT ANY WARRANTY; without even the implied warranty of
;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
;;; GNU General Public License for more details.
;;;
;;; You should have received a copy of the GNU General Public License
;;; along with GNU Guix. If not, see <http://www.gnu.org/licenses/>.
(define-module (guix build go-build-system)
#:use-module ((guix build gnu-build-system) #:prefix gnu:)
#:use-module (guix build utils)
#:use-module (ice-9 match)
#:use-module (srfi srfi-1)
#:export (%standard-phases
go-build))
;; Commentary:
;;
;; Build procedures for Go packages. This is the builder-side code.
;;
;; Software written in Go is either a 'package' (i.e. library) or 'command'
;; (i.e. executable). Both types can be built with either the `go build` or `go
;; install` commands. However, `go build` discards the result of the build
;; process for Go libraries, so we use `go install`, which preserves the
;; results. [0]
;; Go software is developed and built within a particular filesystem hierarchy
;; structure called a 'workspace' [1]. This workspace is found by Go
;; via the GOPATH environment variable. Typically, all Go source code
;; and compiled objects are kept in a single workspace, but it is
;; possible for GOPATH to contain a list of directories, and that is
;; what we do in this go-build-system. [2]
;;
;; Go software, whether a package or a command, is uniquely named using
;; an 'import path'. The import path is based on the URL of the
;; software's source. Since most source code is provided over the
;; internet, the import path is typically a combination of the remote
;; URL and the source repository's filesystem structure. For example,
;; the Go port of the common `du` command is hosted on github.com, at
;; <https://github.com/calmh/du>. Thus, the import path is
;; <github.com/calmh/du>. [3]
;;
;; It may be possible to programatically guess a package's import path
;; based on the source URL, but we don't try that in this revision of
;; the go-build-system.
;;
;; Modules of modular Go libraries are named uniquely with their
;; filesystem paths. For example, the supplemental but "standardized"
;; libraries developed by the Go upstream developers are available at
;; <https://golang.org/x/{net,text,crypto, et cetera}>. The Go IPv4
;; library's import path is <golang.org/x/net/ipv4>. The source of
;; such modular libraries must be unpacked at the top-level of the
;; filesystem structure of the library. So the IPv4 library should be
;; unpacked to <golang.org/x/net>. This is handled in the
;; go-build-system with the optional #:unpack-path key.
;;
;; In general, Go software is built using a standardized build mechanism
;; that does not require any build scripts like Makefiles. This means
;; that all modules of modular libraries cannot be built with a single
;; command. Each module must be built individually. This complicates
;; certain cases, and these issues are currently resolved by creating a
;; filesystem union of the required modules of such libraries. I think
;; this could be improved in future revisions of the go-build-system.
;;
;; [0] `go build`:
;; https://golang.org/cmd/go/#hdr-Compile_packages_and_dependencies
;; `go install`:
;; https://golang.org/cmd/go/#hdr-Compile_and_install_packages_and_dependencies
;; [1] Go workspace example, from <https://golang.org/doc/code.html#Workspaces>:
;; bin/
;; hello # command executable
;; outyet # command executable
;; pkg/
;; linux_amd64/
;; github.com/golang/example/
;; stringutil.a # package object
;; src/
;; github.com/golang/example/
;; .git/ # Git repository metadata
;; hello/
;; hello.go # command source
;; outyet/
;; main.go # command source
;; main_test.go # test source
;; stringutil/
;; reverse.go # package source
;; reverse_test.go # test source
;; golang.org/x/image/
;; .git/ # Git repository metadata
;; bmp/
;; reader.go # package source
;; writer.go # package source
;; ... (many more repositories and packages omitted) ...
;;
;; [2] https://golang.org/doc/code.html#GOPATH
;; [3] https://golang.org/doc/code.html#ImportPaths
;;
;; Code:
(define* (unpack #:key source import-path unpack-path #:allow-other-keys)
"Unpack SOURCE in the UNPACK-PATH, or the IMPORT-PATH is the UNPACK-PATH is
unset. When SOURCE is a directory, copy it instead of unpacking."
(if (string-null? import-path)
((display "WARNING: The Go import path is unset.\n")))
(if (string-null? unpack-path)
(set! unpack-path import-path))
(mkdir "src")
(let ((dest (string-append "src/" unpack-path)))
(mkdir-p dest)
(if (file-is-directory? source)
(begin
(copy-recursively source dest #:keep-mtime? #t)
#t)
(if (string-suffix? ".zip" source)
(zero? (system* "unzip" "-d" dest source))
(zero? (system* "tar" "-C" dest "-xvf" source))))))
(define* (install-source #:key install-source? outputs #:allow-other-keys)
"Install the source code to the output directory."
(let* ((out (assoc-ref outputs "out"))
(source "src")
(dest (string-append out "/" source)))
(if install-source?
(copy-recursively source dest #:keep-mtime? #t)
#t)))
(define (go-package? name)
(string-prefix? "go-" name))
(define (go-inputs inputs)
"Return the alist of INPUTS that are Go software."
;; XXX This should not check the file name of the store item. Instead we
;; should pass, from the host side, the list of inputs that are packages using
;; the go-build-system.
(alist-delete "go" ; Exclude the Go compiler
(alist-delete "source" ; Exclude the source code of the package being built
(filter (match-lambda
((label . directory)
(go-package? ((compose package-name->name+version
strip-store-file-name)
directory)))
(_ #f))
inputs))))
(define* (setup-environment #:key inputs outputs #:allow-other-keys)
"Export the variables GOPATH and GOBIN, which are based on INPUTS and OUTPUTS,
respectively."
(let ((out (assoc-ref outputs "out")))
;; GOPATH is where Go looks for the source code of the build's dependencies.
(set-path-environment-variable "GOPATH"
;; XXX Matching "." hints that we could do
;; something simpler here...
(list ".")
(match (go-inputs inputs)
(((_ . dir) ...)
dir)))
;; Add the source code of the package being built to GOPATH.
(if (getenv "GOPATH")
(setenv "GOPATH" (string-append (getcwd) ":" (getenv "GOPATH")))
(setenv "GOPATH" (getcwd)))
;; Where to install compiled executable files ('commands' in Go parlance').
(setenv "GOBIN" out)
#t))
(define* (build #:key import-path #:allow-other-keys)
"Build the package named by IMPORT-PATH."
(or
(zero? (system* "go" "install"
"-v" ; print the name of packages as they are compiled
"-x" ; print each command as it is invoked
;; Respectively, strip the symbol table and debug
;; information, and the DWARF symbol table.
"-ldflags=-s -w"
import-path))
(begin
(display (string-append "Building '" import-path "' failed.\n"
"Here are the results of `go env`:\n"))
(system* "go" "env")
#f)))
(define* (check #:key tests? import-path #:allow-other-keys)
"Run the tests for the package named by IMPORT-PATH."
(if tests?
(zero? (system* "go" "test" import-path))))
(define* (install #:key outputs #:allow-other-keys)
"Install the compiled libraries. `go install` installs these files to
$GOPATH/pkg, so we have to copy them into the output direcotry manually.
Compiled executable files should have already been installed to the store based
on $GOBIN in the build phase."
(when (file-exists? "pkg")
(copy-recursively "pkg" (string-append (assoc-ref outputs "out") "/pkg")))
#t)
(define %standard-phases
(modify-phases gnu:%standard-phases
(delete 'configure)
(delete 'patch-generated-file-shebangs)
(replace 'unpack unpack)
(add-after 'unpack 'install-source install-source)
(add-before 'build 'setup-environment setup-environment)
(replace 'build build)
(replace 'check check)
(replace 'install install)))
(define* (go-build #:key inputs (phases %standard-phases)
#:allow-other-keys #:rest args)
"Build the given Go package, applying all of PHASES in order."
(apply gnu:gnu-build #:inputs inputs #:phases phases args))
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