1e3347fb46
Adds `cargo llvm-cov` to the devshell and a coverage workflow that runs only when someone asks for it. Manual dispatch rather than nightly or per-PR, per the discussion on the issue: a coverage run needs its own instrumented build and cannot reuse the normal test artifacts, so it roughly doubles a test job. "Do we have glaring holes" is a question someone asks occasionally, not a gate every PR pays for, and not a number worth spending farm time on every night whether or not anyone reads it. Manual dispatch costs nothing until the answer is wanted. Its own workflow file rather than a job in ci.yml: that file already has a `workflow_dispatch` trigger so `hive-forge ci-rerun` can retrigger without an empty commit, and a trigger there fires EVERY job in the file -- a coverage job added there would run on every pull request. No threshold and no --fail-under-lines. A coverage gate mostly teaches people to write assertion-free tests that execute lines; the report is the deliverable and the number is for a human to read. The devshell needs LLVM_COV / LLVM_PROFDATA set explicitly: cargo llvm-cov expects rustup's `llvm-tools-preview` beside the toolchain and nixpkgs has no such component, so without them it aborts with "failed to find llvm-tools-preview" -- which reads like a missing install rather than a path the shell has to name. Verified by running it: `cargo llvm-cov --package hive-types` produces a real report (3 tests, 85.44% regions). Both the variable names and the package were wrong on the first attempt and only running it said so -- the names take no `_PATH` suffix, and the binaries are in `llvmPackages.llvm`, not `llvmPackages.bintools`, which is the linker wrapper and ships neither.
39 lines
1.5 KiB
Nix
39 lines
1.5 KiB
Nix
# Dev shell: the rust toolchain plus the exact native build inputs
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# the crane derivations use (git, sqlite, pkg-config, cmake — see
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# ../rust.nix), so a plain `cargo build` / `cargo test` in the shell
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# sees the same toolchain shape as CI.
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{ pkgs, rust }:
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{
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default = pkgs.mkShell {
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packages =
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rust.nativeBuildInputs
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++ (with pkgs; [
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cargo
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cargo-llvm-cov
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clippy
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rust-analyzer
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rustc
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rustfmt
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]);
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# `cargo llvm-cov` shells out to `llvm-profdata` and `llvm-cov`,
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# which it expects to find as rustup's `llvm-tools-preview` beside
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# the rustc toolchain. Nixpkgs has no such component, so without
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# these it aborts with "failed to find llvm-tools-preview" — a
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# message that reads like a missing install rather than a path the
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# shell simply has to name.
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#
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# ⚠️ Both the variable names and the package were wrong on the first
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# attempt and only the tool itself said so: it reads `LLVM_COV` /
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# `LLVM_PROFDATA` (no `_PATH` suffix), and the binaries live in
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# `llvmPackages.llvm` — `llvmPackages.bintools` is the linker
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# wrapper and ships neither.
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#
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# Coverage is deliberately NOT part of `nix flake check`: an
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# instrumented build cannot reuse the normal test artifacts, so it
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# roughly doubles a test job. It runs on manual dispatch — see
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# .forgejo/workflows/coverage.yml for why that rather than nightly.
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LLVM_PROFDATA = "${pkgs.llvmPackages.llvm}/bin/llvm-profdata";
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LLVM_COV = "${pkgs.llvmPackages.llvm}/bin/llvm-cov";
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};
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}
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