Gazelle: don't treat -framework options as paths (#756) Fixes #646
| Bazel 0.5.2 | Bazel HEAD |
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The rules are in the alpha stage of development. They support:
They currently do not support (in order of importance):
Note: The latest version of these rules (0.5.4) require Bazel ≥ 0.5.2 to work.
The master branch is only guaranteed to work with the latest version of Bazel.
Decide on the name of your package, eg. github.com/joe/project. It's important to choose a name that will match where others will download your code. This will be a prefix for import paths within your project.
Create a file at the top of your repository named WORKSPACE, and add the following code, verbatim. This will let Bazel fetch necessary dependencies from this repository and a few others. You can add more external dependencies to this file later (see go_repository below).
git_repository( name = "io_bazel_rules_go", remote = "https://github.com/bazelbuild/rules_go.git", tag = "0.5.4", ) load("@io_bazel_rules_go//go:def.bzl", "go_rules_dependencies", "go_register_toolchains") go_rules_dependencies() go_register_toolchains()
Add a BUILD file to the top of your project. Declare the name of your workspace using go_prefix. This is used by Bazel to translate between build targets and import paths. Also add the gazelle rule.
load("@io_bazel_rules_go//go:def.bzl", "go_prefix", "gazelle") go_prefix("github.com/joe/project") gazelle(name = "gazelle")
If your project can be built with go build, you can generate your BUILD files using Gazelle. If not, or if you just want to understand the things gazelle is going to generate for you, read on.
For a library github.com/joe/project/lib, create lib/BUILD, containing a single library with the special name “go_default_library.” Using this name tells Bazel to set up the files so it can be imported in .go files as (in this example) github.com/joe/project/lib. See the FAQ below for more information on this name.
load("@io_bazel_rules_go//go:def.bzl", "go_library") go_library( name = "go_default_library", srcs = ["file.go"] )
Inside your project, you can use this library by declaring a dependency on the full Bazel name (including :go_default_library), and in the .go files, import it as shown above.
go_binary( ... deps = ["//lib:go_default_library"] )
To declare a test,
go_test( name = "mytest", srcs = ["file_test.go"], library = ":go_default_library" )
For instructions on how to depend on external libraries, see Vendoring.md.
If your project can be built with go build, you can generate and update your BUILD files automatically using Gazelle, a tool included in this repository. See the Gazelle README for more information.
The gazelle rule in your root BUILD file gives you the ability to build and run gazelle on your project using Bazel. This is the preferred way to run Gazelle.
bazel run //:gazelle
By default, Gazelle assumes external dependencies are present in your WORKSPACE file, following a certain naming convention. For example, it expects the repository for github.com/jane/utils to be named @com_github_jane_utils. If you prefer to use vendoring, add external=vendored to the gazelle rule. See Vendoring.md.
You can build binaries in static linking mode using
bazel build --output_groups=static //:my_binary
You can depend on static binaries (e.g., for packaging) using filegroup:
go_binary( name = "foo", srcs = ["foo.go"], ) filegroup( name = "foo_static", srcs = [":foo"], output_group = "static", )
You can run tests with the race detector enabled using
bazel test --features=race //...
You can build binaries with the race detector enabled using
bazel build --output_groups=race //...
The difference is necessary because the rules for binaries can produce both race and non-race versions, but tools used during the build should always be built in the non-race configuration. --output_groups is needed to select the configuration of the final binary only. For tests, only one executable can be tested, and --features is needed to select the race configuration.
go tool?Yes, this setup was deliberately chosen to be compatible with the go tool. Make sure your workspace appears under
$GOPATH/src/github.com/joe/project/
eg.
mkdir -p $GOPATH/src/github.com/joe/ ln -s my/bazel/workspace $GOPATH/src/github.com/joe/project
and it should work.
go_default_library name?This is used to keep import paths consistent in libraries that can be built with go build.
In order to compile and link correctly, the Go rules need to be able to translate between Bazel labels and Go import paths. Let's say your project name is github.com/joe/project, and you have a library in the foo/bar directory named bar. The Bazel label for this would be //foo/bar:bar. The Go import path for this would be github.com/joe/project/foo/bar/bar.
This is not what go build expects; it expects github.com/joe/project/foo/bar/bar to refer to a library built from .go files in the directory foo/bar/bar.
In order to avoid this conflict, you can name your library go_default_library. The full Bazel label for this library would be //foo/bar:go_default_library. The import path would be github.com/joe/project/foo/bar.
BUILD files generated with Gazelle, including those in external projects imported with go_repository, will have libraries named go_default_library automatically.
go_rules_dependenciesgo_rules_dependencies()
Adds Go-related external dependencies to the WORKSPACE, including the Go toolchain and standard library. All the other workspace rules and build rules assume that this rule is placed in the WORKSPACE. When nested workspaces arrive this will be redundant.
go_register_toolchainsgo_register_toolchains(go_version)
Installs the Go toolchains. If go_version is specified, it sets the SDK version to use (for example, "1.8.2"). By default, the latest SDK will be used.
go_repositorygo_repository(name, importpath, commit, tag, vcs, remote, urls, strip_prefix, type, sha256, build_file_name, build_file_generation, build_tags)
Fetches a remote repository of a Go project, and generates BUILD.bazel files if they are not already present. In vcs mode, it recognizes importpath redirection.
importpath must always be specified. This is used as the root import path for libraries in the repository.
If the repository should be fetched using a VCS, either commit or tag must be specified. remote and vcs may be specified if they can't be inferred from importpath using the normal go logic.
If the repository should be fetched using source archives, urls and sha256 must be specified. strip_prefix and type may be specified to control how the archives are unpacked.
build_file_name, build_file_generation, and build_tags may be used to control how BUILD.bazel files are generated. By default, Gazelle will generate BUILD.bazel files if they are not already present.
The rule below fetches a repository with Git. Import path redirection is used to automatically determine the true location of the repository.
load("@io_bazel_rules_go//go:def.bzl", "go_repository") go_repository( name = "org_golang_x_tools", importpath = "golang.org/x/tools", commit = "663269851cdddc898f963782f74ea574bcd5c814", )
The rule below fetches a repository archive with HTTP. GitHub provides HTTP archives for all repositories. It's generally faster to fetch these than to checkout a repository with Git, but the strip_prefix part can break if the repository is renamed.
load("@io_bazel_rules_go//go:def.bzl", "go_repository") go_repository( name = "org_golang_x_tools", importpath = "golang.org/x/tools", urls = ["https://codeload.github.com/golang/tools/zip/663269851cdddc898f963782f74ea574bcd5c814"], strip_prefix = "tools-663269851cdddc898f963782f74ea574bcd5c814", type = "zip", )
new_go_repositorynew_go_repository is deprecated. Please use go_repository instead, which has the same functionality.
go_prefixgo_prefix(prefix)
go_prefix declares the common prefix of the import path which is shared by all Go libraries in the repository. A go_prefix rule must be declared in the top-level BUILD file for any repository containing Go rules. This is used by the Bazel rules during compilation to map import paths to dependencies. See the FAQ for more information.
go_librarygo_library(name, srcs, deps, data, library, gc_goopts)
go_library builds a Go library from a set of source files that are all part of the same package. This library cannot contain cgo code (see cgo_library).
cgo_librarycgo_library(name, srcs, copts, clinkopts, cdeps, deps, data, gc_goopts)
cgo_library builds a Go library from a set of cgo source files that are part of the same package. This library cannot contain pure Go code (see the note below).
srcs cannot contain pure-Go files, which do not have import "C". So you need to define another go_library when you build a go package with both cgo-enabled and pure-Go sources.
cgo_library( name = "cgo_enabled", srcs = ["cgo-enabled.go", "foo.cc", "bar.S", "baz.a"], ) go_library( name = "go_default_library", srcs = ["pure-go.go"], library = ":cgo_enabled", )
go_binarygo_binary(name, srcs, deps, data, library, linkstamp, x_defs, gc_goopts, gc_linkopts)
go_binary builds an executable from a set of source files, which must all be in the main package. You can run the with bazel run, or you can run it directly.
go_testgo_test(name, srcs, deps, data, library, gc_goopts, gc_linkopts, rundir)
go_test builds a set of tests that can be run with bazel test. This can contain sources for internal tests or external tests, but not both (see example below).
To run all tests in the workspace, and print output on failure (the equivalent of “go test ./...” from go_prefix in a GOPATH tree), run
bazel test --test_output=errors //...
You can run specific tests by passing the --test_filter=pattern argument to Bazel. You can pass arguments to tests by passing --test_arg=arg arguments to Bazel.
To write an internal test, reference the library being tested with the library attribute instead of the deps attribute. This will compile the test sources into the same package as the library sources.
go_library( name = "go_default_library", srcs = ["lib.go"], ) go_test( name = "go_default_test", srcs = ["lib_test.go"], library = ":go_default_library", )
To write an external test, reference the library being tested with the deps attribute.
go_library( name = "go_default_library", srcs = ["lib.go"], ) go_test( name = "go_default_xtest", srcs = ["lib_x_test.go"], deps = [":go_default_library"], )
go_proto_librarygo_proto_library(name, srcs, deps, has_services)
go_embed_datago_embed_data(name, src, srcs, out, package, var, flatten, string)
The foo_data rule below will generate a file named foo_data.go, which can be included in a library. Gazelle will find and add these files automatically.
load("@io_bazel_rules_go//go:def.bzl", "go_embed_data", "go_library") go_embed_data( name = "foo_data", src = "foo.txt", out = "foo_data.go", package = "foo", string = True, var = "Data", ) go_library( name = "go_default_library", srcs = ["foo_data.go"], )
The generated file will look like this:
// Generated by go_embed_data for //:foo_data. DO NOT EDIT. package foo var Data = "Contents of foo.txt"