build(proto): use prebuilt protoc toolchain instead of compiling from source#165
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… source Registers toolchains_protoc and enables proto toolchain resolution so the proto rules resolve a downloaded protoc binary instead of building @protobuf//:protoc (and its abseil/upb C++ deps) from source on every cold build. Why the noise existed (and why it's gone): the proto rules compiled protoc + abseil from source using the host's Clang, which is newer than the pinned abseil and flagged a deprecated builtin ~800x as build-action stderr; with a prebuilt protoc binary no C++ is compiled, so those warnings are never produced. Cold `make test` (after `bazel clean`): | Metric | Before | After | |-------------------------------------|---------|-------| | make test output | 30,868 | 69 | | abseil deprecation warnings | 802 | 0 | | protobuf/abseil `[for tool]` compiles | ~250+ | 0 | | `external/` lines | 9,741 | 1 | | tests passing | 35 | 35 | | cold wall time | ~84s | ~11s | Changes: - MODULE.bazel: add toolchains_protoc (listed first to win toolchain resolution over the transitive protobuf module) and register its toolchain - .bazelrc: --incompatible_enable_proto_toolchain_resolution No generated *.pb.go changes; rules_go needs no BUILD changes. Validated with bazel clean + make test (35/35 pass), bazel build //..., bazel mod tidy, gazelle. Co-authored-by: Cursor <cursoragent@cursor.com>
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Summary
Updates bazel such that the proto rules resolve a downloaded protoc binary instead of building
@protobuf//:protoc(and itsabseil/upbC++ deps) from source on every cold build.Before this code change, 30k lines of noise was being dumped to terminal on
make test, because the proto rules were compiling protoc and abseil from source which caused issues depending on hostclangversion (mine was newer than that was required which led to hundreds of deprecation warnings).After this code change, we no longer build protoc and abseil from source and no longer see deprecation warnings. It's also faster since we don't need to build protoc from scratch.
Cold
make test(afterbazel clean):[for tool]compilesexternal/linesTest Plan
✅
make test && make fmt && make lint✅
bazel clean && make testproduces clean output without compile warningsIssues
Stack