incompatible_use_specific_tool_files: Use appropriate artifacts from cc_toolchain as inputs to C++ actions.

[scentini]

cc_toolchain has attributes corresponding to various toolchain components like ar_files, compiler_files, and as_files. Previously, Bazel used broad file groups like all_files as inputs for several classes of actions and ignored the more specific toolchain attributes. --incompatible_use_specific_tool_files brings these attributes into use.

Namely, under this flag:

• C and C++ compilation actions use compiler_files rather than all_files.
• Static library-generating actions use ar_files rather than linker_files.
• Non-processed assembler actions use as_files rather than all_files. Preprocessed assembly actions use compiler_files because preprocessing is usually done by the C compiler.

Relevant issues: #6927, #6928.

Migration

For every cc_toolchain rule, ensure

• compiler_files contains the compiler binary and standard library header files if necessary
• as_files includes the assembler (e.g., gas)
• ar_files includes the static archive tool (e.g., ar)

Expected timeline

Disabled by default in 0.27.
Enabled in the September 2019 release.

[scentini]

@benjaminp Can you please update this issue with migration details?

[benjaminp]

(I lack permissions to edit the actual issue, but here we go.)

cc_toolchain has attributes corresponding to various toolchain components like ar_files, compiler_files, and as_files. Previously, Bazel used broad file groups like all_files as inputs for several classes of actions and ignored the more specific toolchain attributes. --incompatible_use_specific_tool_files brings these attributes into use.

Namely, under this flag:

• C and C++ compilation actions use compiler_files rather than all_files.
• Static library-generating actions use ar_files rather than linker_files.
• Non-processed assembler actions use as_files rather than all_files. Preprocessed assembly actions use compiler_files because preprocessing is usually done by the C compiler.

Migration

For every cc_toolchain rule, ensure

• compiler_files contains the compiler binary and standard library header files if necessary
• as_files includes the assembler (e.g., gas)
• ar_files includes the static archive tool (e.g., ar)

Expected timeline

Disabled by default in 0.27.
Enabled in the September 2019 release.

[kkiningh]

With this flag enabled I get the following error on OSX 10.14.2 when I try to compile a cc_library.

src/main/tools/process-wrapper-legacy.cc:58: "execvp(external/local_config_cc/wrapped_ar, ...)": No such file or directory

Simple example here.