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Documentation for @bazel_lib@v3.2.0 — View source
Public API for expanding variables

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Function: expand_locations

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.

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Parameters

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ctx
name
required
context
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input
name
required
String to be expanded
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targets
name
default:"[]"
List of targets for additional lookup information.
Returns: The expanded path or the original path
Deprecated: Use vanilla ctx.expand_location(input, targets = targets) instead

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Function: expand_variables

Expand make variables and substitute like genrule does. Bazel pre-defined variables are expanded however only $@, $(@D) and $(RULEDIR) of pre-defined genrule variables are supported. This function is the same as ctx.expand_make_variables with the additional genrule-like substitutions of:
  • $<: The input file if it is a single file. Else triggers a build error.
  • $@: 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): ctx.label
  • $(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.

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Parameters

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ctx
name
required
starlark rule context
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s
name
required
expression to expand
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outs
name
default:"[]"
declared outputs of the rule, for expanding references to outputs
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inputs
name
default:"[]"
declared inputs of the rule, for expanding references to inputs
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attribute_name
name
default:"args"
name of the attribute containing the expression. Used for error reporting.
Returns: s with the variables expanded