fix(cargo-anvil): shorten Windows coverage paths

.anvil.lock

@@ -1,7 +1,7 @@
 version = 1
 tool = "anvil"
 tool_version = "0.8.0"
-catalog_checksum = "sha256:25beddc77b7a0f7c6d7569bd7d252f63770603600e5f3a2701eb0c5adf8ca44f"
+catalog_checksum = "sha256:b878cd5259480f652389bae4c82c73bf8a776386113600d8c76e6f2b8353fd47"
 
 [[file]]
 path = ".anvil/container/Dockerfile.dockerignore"
@@ -125,7 +125,7 @@ checksum = "sha256:7aa0560dc9088b33e80cd55aee0a25090cbd3d3610652afd3734d0ca52ee7
 
 [[file]]
 path = "justfiles/anvil/checks/llvm-cov.just"
-checksum = "sha256:a6c45a290030fc56ab39ce92d7f89b7169485edc58d931381bf7957eec1622bd"
+checksum = "sha256:36986c41d7eb1a1d3c9da2243b5e3b176b4d353be0a3d2c6fe296f7c2fa67a6c"
 
 [[file]]
 path = "justfiles/anvil/checks/loom.just"

crates/cargo-anvil/docs/design/checks.md

@@ -205,7 +205,7 @@ matrix overhead.
 
 | Check        | Invocation                                                                  | Source |
 |--------------|-----------------------------------------------------------------------------|--------|
-| `llvm-cov`   | Runs tests for every affected package under both feature configurations. Packages with a positive coverage threshold run through self-contained `cargo +<catalog-nightly> llvm-cov nextest --no-report` invocations and produce per-config lcov/cobertura reports. Packages declaring `min-lines-percent = 0` still run through plain `cargo nextest`; the opt-out disables measurement and gating, never tests. Per-config reports avoid Windows command-line overflow and are reconciled downstream by cargo-coverage-gate, Codecov, and ADO. Codecov is display-only; the local coverage gate is authoritative. | oxidizer, oxidizer-github; gate via [`cargo-coverage-gate`](../../../cargo-coverage-gate) |
+| `llvm-cov`   | Runs tests for every affected package under both feature configurations. Packages with a positive coverage threshold run through self-contained `cargo +<catalog-nightly> llvm-cov nextest --no-report` invocations and produce per-config lcov/cobertura reports. Packages declaring `min-lines-percent = 0` still run through plain `cargo nextest`; the opt-out disables measurement and gating, never tests. Per-config reports reduce each `llvm-cov` object list, and Windows uses the compact private build directory `target/c` to shorten every object path under the CreateProcess command-line limit. Reports are reconciled downstream by cargo-coverage-gate, Codecov, and ADO. Codecov is display-only; the local coverage gate is authoritative. | oxidizer, oxidizer-github; gate via [`cargo-coverage-gate`](../../../cargo-coverage-gate) |
 | `doc-test`   | Two cargo-test runs over the same affected set: `cargo test --doc --workspace --all-features --locked` and `cargo test --doc --workspace --locked` (default features). Running both catches doctests that only compile under one feature configuration (oxidizer-github runs both). nextest does not run doctests, so this stays a separate cargo-test invocation. | oxidizer, oxidizer-github |
 | `examples`   | `cargo build --workspace --examples --all-features --locked` -- verifies that example targets compile. Local `--run` executes selected examples after compilation with a bounded timeout; cloud workflows never pass it. Packages exclude interactive, credentialed, or otherwise unsuitable examples from an unfiltered run with `[package.metadata.anvil.examples] no-run = ["name"]`. An explicit `--example <name>` overrides the default exclusion. | oxidizer, oxidizer-github |
 

crates/cargo-anvil/templates/justfiles/anvil/checks/llvm-cov.just

@@ -93,6 +93,13 @@ anvil-llvm-cov: anvil-llvm-cov-validate-prereqs anvil-impact
         Write-Host 'anvil-llvm-cov: all affected packages opted out of coverage; tests completed'
         exit 0
     }
+    # cargo-llvm-cov passes every instrumented object to llvm-cov on one
+    # command line. Keep its private Windows build directory compact so the
+    # repeated object paths leave enough room under CreateProcess's 32,767
+    # character limit. Preserve an explicit caller override.
+    if ($IsWindows -and -not $env:CARGO_LLVM_COV_TARGET_DIR) {
+        $env:CARGO_LLVM_COV_TARGET_DIR = 'target/c'
+    }
     # The *report* output directory (target/coverage/) is something we
     # choose and must exist before --output-path runs.
     [System.IO.Directory]::CreateDirectory('target/coverage') | Out-Null
@@ -104,11 +111,12 @@ anvil-llvm-cov: anvil-llvm-cov-validate-prereqs anvil-impact
     #
     # Crucially this does NOT merge both configs' objects into one report.
     # A single `llvm-cov report` over the union shells one `--object=` per
-    # test binary and, on a large workspace, overflows the Windows
+    # test binary and, on a large workspace, can overflow the Windows
     # CreateProcess command-line limit (os error 206, "filename or extension
-    # is too long"). Each per-config report references only ~half the
-    # objects and stays under the limit. The two configs are reconciled
-    # *downstream* instead of via a merged report:
+    # is too long"). Per-config reports reduce the object count, while the
+    # compact Windows target directory above shortens every remaining object
+    # path. The two configs are reconciled *downstream* instead of via a
+    # merged report:
     #   * cargo-coverage-gate merges the two lcov files at the line level
     #     (per-line counts summed) -- this is the gate;
     #   * Codecov ingests both lcov files (it coalesces uploads);

crates/cargo-anvil/tests/recipe_contracts.rs

@@ -71,6 +71,12 @@ fn bolero_uses_its_supported_release_profile_option() {
     );
 }
 
+#[test]
+fn llvm_cov_shortens_its_private_windows_target_directory() {
+    assert!(LLVM_COV.contains("if ($IsWindows -and -not $env:CARGO_LLVM_COV_TARGET_DIR)"));
+    assert!(LLVM_COV.contains("$env:CARGO_LLVM_COV_TARGET_DIR = 'target/c'"));
+}
+
 #[test]
 fn developer_options_are_explicit_and_cloud_defaults_stay_non_interactive() {
     assert!(BUILD.contains("[arg(\"package\", long"));
@@ -109,6 +115,9 @@ if ($env:FAKE_CARGO_TOOLCHAIN_LOG) {
 if ($env:FAKE_CARGO_AUTO_INSTALL_LOG) {
     Add-Content -LiteralPath $env:FAKE_CARGO_AUTO_INSTALL_LOG -Value $env:RUSTUP_AUTO_INSTALL
 }
+if ($env:FAKE_CARGO_LLVM_COV_TARGET_DIR_LOG) {
+    Add-Content -LiteralPath $env:FAKE_CARGO_LLVM_COV_TARGET_DIR_LOG -Value $env:CARGO_LLVM_COV_TARGET_DIR
+}
 if ($args -contains 'each') {
     exit [int]$env:FAKE_EACH_EXIT
 }
@@ -1562,6 +1571,54 @@ fn all_coverage_opted_out_packages_run_both_test_configurations() {
     assert_failed(&failed, "plain nextest failure for an opted-out package");
 }
 
+#[cfg(windows)]
+#[test]
+fn windows_coverage_uses_the_compact_target_directory() {
+    if !tools_available() {
+        return;
+    }
+    let tmp = fixture(
+        &[("llvm-cov.just", LLVM_COV), ("impact.just", IMPACT)],
+        &[
+            "anvil-component-nightly-llvm-tools-validate-prereqs",
+            "anvil-tool-cargo-llvm-cov-validate-prereqs",
+            "anvil-tool-cargo-nextest-validate-prereqs",
+            "anvil-tool-cargo-coverage-gate-validate-prereqs",
+            "anvil-component-nightly-llvm-tools-install",
+            "anvil-tool-cargo-llvm-cov-install installer",
+            "anvil-tool-cargo-nextest-install installer",
+            "anvil-tool-cargo-coverage-gate-install installer",
+            "anvil-impact",
+        ],
+    );
+    let target_dir_log = tmp.path().join("target-dir.log");
+    seed_include(tmp.path(), "affected", "--package fixture@0.1.0 --package measured@0.1.0");
+    let output = run_just(
+        tmp.path(),
+        &["anvil-llvm-cov"],
+        &[
+            ("FAKE_SECOND_PACKAGE_NAME", OsStr::new("measured")),
+            ("FAKE_CARGO_LLVM_COV_TARGET_DIR_LOG", target_dir_log.as_os_str()),
+        ],
+    );
+    assert!(
+        output.status.success(),
+        "Windows coverage path should succeed:\n{}",
+        String::from_utf8_lossy(&output.stderr)
+    );
+    let configured_dirs: Vec<_> = fs::read_to_string(target_dir_log)
+        .unwrap()
+        .lines()
+        .filter(|line| !line.is_empty())
+        .map(str::to_owned)
+        .collect();
+    assert!(!configured_dirs.is_empty());
+    assert!(
+        configured_dirs.iter().all(|dir| dir == "target/c"),
+        "unexpected coverage target directories: {configured_dirs:?}"
+    );
+}
+
 #[cfg(windows)]
 #[test]
 fn windows_arm64_fallback_accepts_empty_nextest_sets_in_both_configurations() {

justfiles/anvil/checks/llvm-cov.just

@@ -93,6 +93,13 @@ anvil-llvm-cov: anvil-llvm-cov-validate-prereqs anvil-impact
         Write-Host 'anvil-llvm-cov: all affected packages opted out of coverage; tests completed'
         exit 0
     }
+    # cargo-llvm-cov passes every instrumented object to llvm-cov on one
+    # command line. Keep its private Windows build directory compact so the
+    # repeated object paths leave enough room under CreateProcess's 32,767
+    # character limit. Preserve an explicit caller override.
+    if ($IsWindows -and -not $env:CARGO_LLVM_COV_TARGET_DIR) {
+        $env:CARGO_LLVM_COV_TARGET_DIR = 'target/c'
+    }
     # The *report* output directory (target/coverage/) is something we
     # choose and must exist before --output-path runs.
     [System.IO.Directory]::CreateDirectory('target/coverage') | Out-Null
@@ -104,11 +111,12 @@ anvil-llvm-cov: anvil-llvm-cov-validate-prereqs anvil-impact
     #
     # Crucially this does NOT merge both configs' objects into one report.
     # A single `llvm-cov report` over the union shells one `--object=` per
-    # test binary and, on a large workspace, overflows the Windows
+    # test binary and, on a large workspace, can overflow the Windows
     # CreateProcess command-line limit (os error 206, "filename or extension
-    # is too long"). Each per-config report references only ~half the
-    # objects and stays under the limit. The two configs are reconciled
-    # *downstream* instead of via a merged report:
+    # is too long"). Per-config reports reduce the object count, while the
+    # compact Windows target directory above shortens every remaining object
+    # path. The two configs are reconciled *downstream* instead of via a
+    # merged report:
     #   * cargo-coverage-gate merges the two lcov files at the line level
     #     (per-line counts summed) -- this is the gate;
     #   * Codecov ingests both lcov files (it coalesces uploads);