add emit_asm aspect to view rustc assembly output#21
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Introduces a Bazel aspect that compiles Rust targets with `--emit=asm` and demangles the output via `rustfilt`, producing a `.s` file in an `asm_files` output group. The aspect forces `codegen-units=1` so rustc emits a single .s file with a predictable name rather than per-CGU files whose count isn't known at action declaration time. DWARF is stripped (`debuginfo=0`) to reduce noise, and `--sysroot` is derived from the rustc executable path. An `//tools/emit_asm:opt` string flag allows overriding the optimization level independently of the build configuration. `rust_test` targets are handled correctly via `--test` rather than `--crate-type bin`. On the module side, `bazel_skylib` is added as a dev dep for `string_flag`, and an isolated `bindeps` crate extension pulls in `rustfilt` as a host binary built against a nightly `rust_host_tools` toolchain. ``` bazel build //path/to:target \ --aspects=//tools/emit_asm:aspect.bzl%emit_asm_aspect \ --output_groups=asm_files \ --//tools/emit_asm:opt=3 ```
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Introduces a Bazel aspect that compiles Rust targets with
--emit=asmand demangles the output viarustfilt, producing a.sfile in anasm_filesoutput group.The aspect forces
codegen-units=1so rustc emits a single .s file with a predictable name rather than per-CGU files whose count isn't known at action declaration time. DWARF is stripped (debuginfo=0) to reduce noise, and--sysrootis derived from the rustc executable path. An//tools/emit_asm:optstring flag allows overriding the optimization level independently of the build configuration.rust_testtargets are handled correctly via--testrather than--crate-type bin.On the module side,
bazel_skylibis added as a dev dep forstring_flag, and an isolatedbindepscrate extension pulls inrustfiltas a host binary built against a nightlyrust_host_toolstoolchain.