Skip to content

Latest commit

 

History

History
142 lines (89 loc) · 6.3 KB

expand_make_vars.md

File metadata and controls

142 lines (89 loc) · 6.3 KB
Raw

Public API for expanding variables

expand_template

expand_template(name, data, is_executable, out, substitutions, template)

Template expansion

This performs a simple search over the template file for the keys in substitutions, and replaces them with the corresponding values.

Values may also use location templates as documented in expand_locations as well as configuration variables such as $(BINDIR), $(TARGET_CPU), and $(COMPILATION_MODE) as documented in expand_variables.

ATTRIBUTES

Name Description Type Mandatory Default
name A unique name for this target. Name required
data List of targets for additional lookup information. List of labels optional []
is_executable Whether to mark the output file as executable. Boolean optional False
out Where to write the expanded file. Label required
substitutions Mapping of strings to substitutions. Dictionary: String -> String required
template The template file to expand. Label required

expand_locations

expand_locations(ctx, input, targets)

Expand location templates.

Expands all $(execpath ...), $(rootpath ...) and deprecated $(location ...) templates in the given string by replacing with the expanded path. Expansion only works for labels that point to direct dependencies of this rule or that are explicitly listed in the optional argument targets.

See https://docs.bazel.build/versions/main/be/make-variables.html#predefined_label_variables.

Use $(rootpath) and $(rootpaths) to expand labels to the runfiles path that a built binary can use to find its dependencies. This path is of the format:

  • ./file
  • path/to/file
  • ../external_repo/path/to/file

Use $(execpath) and $(execpaths) to expand labels to the execroot (where Bazel runs build actions). This is of the format:

  • ./file
  • path/to/file
  • external/external_repo/path/to/file
  • <bin_dir>/path/to/file
  • <bin_dir>/external/external_repo/path/to/file

The deprecated $(location) and $(locations) expansions returns either the execpath or rootpath depending on the context.

PARAMETERS

Name Description Default Value
ctx context none
input String to be expanded none
targets List of targets for additional lookup information. []

RETURNS

The expanded path or the original path

expand_variables

expand_variables(ctx, s, outs, output_dir, attribute_name)

Expand make variables and substitute like genrule does.

This function is the same as ctx.expand_make_variables with the additional genrule-like substitutions of:

  • $@: The output file if it is a single file. Else triggers a build error.

  • $(@D): The output directory.

    If there is only one file name in outs, this expands to the directory containing that file.

    If there is only one directory in outs, this expands to the single output directory.

    If there are multiple files, this instead expands to the package's root directory in the bin tree, even if all generated files belong to the same subdirectory!

  • $(RULEDIR): The output directory of the rule, that is, the directory corresponding to the name of the package containing the rule under the bin tree.

  • $(BUILD_FILE_PATH)": ctx.build_file_path

  • $(VERSION_FILE)": ctx.version_file.path

  • $(INFO_FILE)": ctx.info_file.path

  • $(TARGET)": "@%s//%s:%s" % (ctx.label.workspace_name, ctx.label.package, ctx.label.name)

  • $(WORKSPACE)": ctx.workspace_name

See https://docs.bazel.build/versions/main/be/general.html#genrule.cmd and https://docs.bazel.build/versions/main/be/make-variables.html#predefined_genrule_variables for more information of how these special variables are expanded.

PARAMETERS

Name Description Default Value
ctx starlark rule context none
s expression to expand none
outs declared outputs of the rule, for expanding references to outputs []
output_dir whether the rule is expected to output a directory (TreeArtifact) Deprecated. For backward compatability with @aspect_bazel_lib 1.x. Pass output tree artifacts to outs instead. False
attribute_name name of the attribute containing the expression. Used for error reporting. "args"

RETURNS

s with the variables expanded