Introduce shorten_virtual_includes cc toolchain feature #26528
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I can confirm with Bazel built at this change and bazelbuild/rules_cc#438, I can build protobuf 31.1 with |
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src/main/starlark/builtins_bzl/common/cc/compile/cc_compilation_helper.bzl
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| virtual_include_dir = paths.join(paths.join(package_source_root(label.workspace_name, label.package, is_sibling_repository_layout), _VIRTUAL_INCLUDES_DIR), label.name) | ||
| source_package_path = package_source_root(label.workspace_name, label.package, is_sibling_repository_layout) | ||
| if shorten_virtual_includes: | ||
| virtual_include_dir = paths.join(_VIRTUAL_INCLUDES_DIR, "%x" % hash(paths.join(source_package_path, label.name))) |
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The Starlark hash is not particularly collision resistant, even on non-adversarial inputs. What would happen if this collides?
This could be an argument for introducing a better hash function to Starkark.
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Yeah, we had the same discussion when reviewing the previous PR internally. We should probably upgrade it, but in another change.
…n_helper.bzl Co-authored-by: Fabian Meumertzheim <[email protected]>
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Copybara Import from #438 BEGIN_PUBLIC Support shorten_virtual_includes (#438) Context: bazelbuild/bazel#26528, protocolbuffers/protobuf#20085 Enable `shorten_virtual_includes` for MSVC toolchains to shorten virtual include paths to mitigate long path issue on windows. Closes #438 END_PUBLIC COPYBARA_INTEGRATE_REVIEW=#438 from meteorcloudy:shorten_virtual_includes 5ab4b94 PiperOrigin-RevId: 781977791 Change-Id: Ia683103cb9da2eed8cca165ccf1243f3ee1357da
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Fixes bazelbuild#18683 Related: protocolbuffers/protobuf#20085 This change is a rework of bazelbuild#26005 to enable short virtual includes based on a cc feature, therefore we can limit the change to only MSVC compiler on Windows. RELNOTES: If a cc toolchain feature named `shorten_virtual_includes` is enabled, virtual include header files are linked under `bin/_virtual_includes/<hash of target path>` instead of `bin/<target package path>/_virtual_includes/<target name>`. This shortens the virtual include paths which is critical for mitigating long path issue with MSVC on Windows. Closes bazelbuild#26528. PiperOrigin-RevId: 781975309 Change-Id: Ia573a5f25707ad2462aa3a4459fc66db1779df36
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In the future, please consider documenting features like this here. |
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Ah, thanks for catching this, will fix it now! |
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@armandomontanez Doc added at 6ce0384 |
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Fixes #18683 Related: protocolbuffers/protobuf#20085 This change is a rework of #26005 to enable short virtual includes based on a cc feature, therefore we can limit the change to only MSVC compiler on Windows. RELNOTES: If a cc toolchain feature named `shorten_virtual_includes` is enabled, virtual include header files are linked under `bin/_virtual_includes/<hash of target path>` instead of `bin/<target package path>/_virtual_includes/<target name>`. This shortens the virtual include paths which is critical for mitigating long path issue with MSVC on Windows. Closes #26528. PiperOrigin-RevId: 781975309 Change-Id: Ia573a5f25707ad2462aa3a4459fc66db1779df36 --------- Co-authored-by: Googler <[email protected]>
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Fixes #18683
Related: protocolbuffers/protobuf#20085
This change is a rework of #26005 to enable short virtual includes based on a cc feature, therefore we can limit the change to only MSVC compiler on Windows.
RELNOTES: If a cc toolchain feature named
shorten_virtual_includesis enabled, virtual include header files are linked underbin/_virtual_includes/<hash of target path>instead ofbin/<target package path>/_virtual_includes/<target name>. This shortens the virtual include paths which is critical for mitigating long path issue with MSVC on Windows.