| // Copyright 2011 The Go Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style |
| // license that can be found in the LICENSE file. |
| |
| // Package build gathers information about Go packages. |
| // |
| // # Go Path |
| // |
| // The Go path is a list of directory trees containing Go source code. |
| // It is consulted to resolve imports that cannot be found in the standard |
| // Go tree. The default path is the value of the GOPATH environment |
| // variable, interpreted as a path list appropriate to the operating system |
| // (on Unix, the variable is a colon-separated string; |
| // on Windows, a semicolon-separated string; |
| // on Plan 9, a list). |
| // |
| // Each directory listed in the Go path must have a prescribed structure: |
| // |
| // The src/ directory holds source code. The path below 'src' determines |
| // the import path or executable name. |
| // |
| // The pkg/ directory holds installed package objects. |
| // As in the Go tree, each target operating system and |
| // architecture pair has its own subdirectory of pkg |
| // (pkg/GOOS_GOARCH). |
| // |
| // If DIR is a directory listed in the Go path, a package with |
| // source in DIR/src/foo/bar can be imported as "foo/bar" and |
| // has its compiled form installed to "DIR/pkg/GOOS_GOARCH/foo/bar.a" |
| // (or, for gccgo, "DIR/pkg/gccgo/foo/libbar.a"). |
| // |
| // The bin/ directory holds compiled commands. |
| // Each command is named for its source directory, but only |
| // using the final element, not the entire path. That is, the |
| // command with source in DIR/src/foo/quux is installed into |
| // DIR/bin/quux, not DIR/bin/foo/quux. The foo/ is stripped |
| // so that you can add DIR/bin to your PATH to get at the |
| // installed commands. |
| // |
| // Here's an example directory layout: |
| // |
| // GOPATH=/home/user/gocode |
| // |
| // /home/user/gocode/ |
| // src/ |
| // foo/ |
| // bar/ (go code in package bar) |
| // x.go |
| // quux/ (go code in package main) |
| // y.go |
| // bin/ |
| // quux (installed command) |
| // pkg/ |
| // linux_amd64/ |
| // foo/ |
| // bar.a (installed package object) |
| // |
| // # Build Constraints |
| // |
| // A build constraint, also known as a build tag, is a line comment that begins |
| // |
| // //go:build |
| // |
| // that lists the conditions under which a file should be included in the |
| // package. Build constraints may also be part of a file's name |
| // (for example, source_windows.go will only be included if the target |
| // operating system is windows). |
| // |
| // See 'go help buildconstraint' |
| // (https://golang.org/cmd/go/#hdr-Build_constraints) for details. |
| // |
| // # Binary-Only Packages |
| // |
| // In Go 1.12 and earlier, it was possible to distribute packages in binary |
| // form without including the source code used for compiling the package. |
| // The package was distributed with a source file not excluded by build |
| // constraints and containing a "//go:binary-only-package" comment. Like a |
| // build constraint, this comment appeared at the top of a file, preceded |
| // only by blank lines and other line comments and with a blank line |
| // following the comment, to separate it from the package documentation. |
| // Unlike build constraints, this comment is only recognized in non-test |
| // Go source files. |
| // |
| // The minimal source code for a binary-only package was therefore: |
| // |
| // //go:binary-only-package |
| // |
| // package mypkg |
| // |
| // The source code could include additional Go code. That code was never |
| // compiled but would be processed by tools like godoc and might be useful |
| // as end-user documentation. |
| // |
| // "go build" and other commands no longer support binary-only-packages. |
| // Import and ImportDir will still set the BinaryOnly flag in packages |
| // containing these comments for use in tools and error messages. |
| package build |
