fix(diag): Give diagnostics the same display path behavior as rustc

src/cargo/diagnostics/mod.rs

@@ -68,7 +68,7 @@ pub mod passes;
 pub mod rules;
 
 pub use lint::{Lint, LintGroup, LintLevel, LintLevelProduct, LintLevelSource};
-pub use report::{AsIndex, get_key_value, get_key_value_span, rel_cwd_manifest_path};
+pub use report::{AsIndex, cwd_rel_path, get_key_value, get_key_value_span, workspace_rel_path};
 pub use rules::{LINT_GROUPS, LINTS};
 
 pub struct GlobalDiagnosticStats {

src/cargo/diagnostics/passes.rs

@@ -39,8 +39,13 @@ pub enum ParsePassRule<'r> {
     },
 }
 
-type FnDiagnosticManifest =
-    fn(ManifestFor<'_>, &Path, &mut ScopedDiagnosticStats<'_>, &GlobalContext) -> CargoResult<()>;
+type FnDiagnosticManifest = fn(
+    &Workspace<'_>,
+    ManifestFor<'_>,
+    &Path,
+    &mut ScopedDiagnosticStats<'_>,
+    &GlobalContext,
+) -> CargoResult<()>;
 
 type FnDiagnosticWorkspace = fn(
     &Workspace<'_>,
@@ -59,6 +64,7 @@ type FnDiagnosticPackage = fn(
 ) -> CargoResult<()>;
 
 type FnLintManifest = fn(
+    &Workspace<'_>,
     manifest: ManifestFor<'_>,
     manifest_path: &Path,
     LintLevelProduct,
@@ -127,14 +133,21 @@ fn emit_parse_pkg_diagnostics(
         match rule {
             ParsePassRule::DiagnosticManifest { rule } => {
                 let manifest = pkg.into();
-                rule(manifest, &path, &mut pkg_stats, workspace.gctx())?;
+                rule(workspace, manifest, &path, &mut pkg_stats, workspace.gctx())?;
             }
             ParsePassRule::LintManifest { rule, lint } => {
                 if workspace.gctx().cli_unstable().cargo_lints {
                     let manifest: ManifestFor<'_> = pkg.into();
                     let level = manifest.lint_level(&cargo_lints, lint);
                     if level.level != LintLevel::Allow {
-                        rule(manifest, &path, level, &mut pkg_stats, workspace.gctx())?;
+                        rule(
+                            workspace,
+                            manifest,
+                            &path,
+                            level,
+                            &mut pkg_stats,
+                            workspace.gctx(),
+                        )?;
                     }
                 }
             }
@@ -203,6 +216,7 @@ fn emit_parse_ws_diagnostics(
             ParsePassRule::DiagnosticManifest { rule } => {
                 let manifest = (workspace, workspace.root_maybe()).into();
                 rule(
+                    workspace,
                     manifest,
                     workspace.root_manifest(),
                     &mut pkg_stats,
@@ -215,6 +229,7 @@ fn emit_parse_ws_diagnostics(
                     let level = manifest.lint_level(&cargo_lints, lint);
                     if level.level != LintLevel::Allow {
                         rule(
+                            workspace,
                             manifest,
                             workspace.root_manifest(),
                             level,

src/cargo/diagnostics/report.rs

@@ -2,13 +2,36 @@ use std::borrow::Cow;
 use std::ops::Range;
 use std::path::Path;
 
+use cargo_util::paths::normalize_path;
 use pathdiff::diff_paths;
 
 use crate::GlobalContext;
+use crate::core::Workspace;
 
-/// Gets the relative path to a manifest from the current working directory, or
-/// the absolute path of the manifest if a relative path cannot be constructed
-pub fn rel_cwd_manifest_path(path: &Path, gctx: &GlobalContext) -> String {
+/// Display path, generally relative to the workspace
+///
+/// Mirrors [`crate::util::path_args`]
+pub fn workspace_rel_path(ws: &Workspace<'_>, path: &Path) -> String {
+    // Determine which path we make this relative to: usually it's the workspace root,
+    // but this can be overwritten with a `-Z` flag.
+    let root = match &ws.gctx().cli_unstable().root_dir {
+        None => ws.root().to_owned(),
+        Some(root_dir) => normalize_path(&ws.gctx().cwd().join(root_dir)),
+    };
+    if let Ok(path) = path.strip_prefix(&root) {
+        path
+    } else {
+        path
+    }
+    .display()
+    .to_string()
+}
+
+/// Display path, generally relative to cwd
+///
+/// Prefer [`workspace_rel_path`].
+/// This is for when there is no workspace available.
+pub fn cwd_rel_path(path: &Path, gctx: &GlobalContext) -> String {
     diff_paths(path, gctx.cwd())
         .unwrap_or_else(|| path.to_path_buf())
         .display()

src/cargo/diagnostics/rules/blanket_hint_mostly_unused.rs

@@ -18,7 +18,7 @@ use crate::diagnostics::Lint;
 use crate::diagnostics::LintLevelProduct;
 use crate::diagnostics::ScopedDiagnosticStats;
 use crate::diagnostics::get_key_value_span;
-use crate::diagnostics::rel_cwd_manifest_path;
+use crate::diagnostics::workspace_rel_path;
 
 pub static LINT: &Lint = &Lint {
     name: "blanket_hint_mostly_unused",
@@ -57,7 +57,7 @@ hint-mostly-unused = true
 
 #[instrument(skip_all)]
 pub(crate) fn lint_workspace(
-    _ws: &Workspace<'_>,
+    ws: &Workspace<'_>,
     maybe_pkg: &MaybePackage,
     path: &Path,
     level: LintLevelProduct,
@@ -70,7 +70,7 @@ pub(crate) fn lint_workspace(
     } = level;
 
     let level = lint_level.to_diagnostic_level();
-    let manifest_path = rel_cwd_manifest_path(path, gctx);
+    let manifest_path = workspace_rel_path(ws, path);
     let mut paths = Vec::new();
 
     if let Some(profiles) = maybe_pkg.profiles() {

src/cargo/diagnostics/rules/deferred_parse_diagnostics.rs

@@ -5,12 +5,14 @@ use tracing::instrument;
 use crate::CargoResult;
 use crate::GlobalContext;
 use crate::core::MaybePackage;
+use crate::core::Workspace;
 use crate::diagnostics::ManifestFor;
 use crate::diagnostics::ScopedDiagnosticStats;
-use crate::diagnostics::rel_cwd_manifest_path;
+use crate::diagnostics::workspace_rel_path;
 
 #[instrument(skip_all)]
 pub(crate) fn diagnose_manifest(
+    ws: &Workspace<'_>,
     manifest: ManifestFor<'_>,
     manifest_path: &Path,
     pkg_stats: &mut ScopedDiagnosticStats<'_>,
@@ -31,7 +33,7 @@ pub(crate) fn diagnose_manifest(
         }
     };
 
-    let manifest_path = rel_cwd_manifest_path(manifest_path, gctx);
+    let manifest_path = workspace_rel_path(ws, manifest_path);
     for warning in warnings {
         let msg = format!("{manifest_path}: {}", warning.message);
         if warning.is_critical {

src/cargo/diagnostics/rules/im_a_teapot.rs

@@ -17,7 +17,7 @@ use crate::diagnostics::Lint;
 use crate::diagnostics::LintLevelProduct;
 use crate::diagnostics::ScopedDiagnosticStats;
 use crate::diagnostics::get_key_value_span;
-use crate::diagnostics::rel_cwd_manifest_path;
+use crate::diagnostics::workspace_rel_path;
 
 /// This lint is only to be used for testing purposes
 pub static LINT: &Lint = &Lint {
@@ -31,7 +31,7 @@ pub static LINT: &Lint = &Lint {
 
 #[instrument(skip_all)]
 pub(crate) fn lint_package(
-    _ws: &Workspace<'_>,
+    ws: &Workspace<'_>,
     pkg: &Package,
     path: &Path,
     level: LintLevelProduct,
@@ -50,7 +50,7 @@ pub(crate) fn lint_package(
         .is_some_and(|p| p.im_a_teapot.is_some())
     {
         let level = lint_level.to_diagnostic_level();
-        let manifest_path = rel_cwd_manifest_path(path, gctx);
+        let manifest_path = workspace_rel_path(ws, path);
         let emitted_source = LINT.emitted_source(lint_level, source);
 
         let mut desc = Group::with_title(level.primary_title(LINT.desc));

src/cargo/diagnostics/rules/implicit_minimum_version_req.rs

@@ -25,7 +25,7 @@ use crate::diagnostics::LintLevelProduct;
 use crate::diagnostics::LintLevelSource;
 use crate::diagnostics::ScopedDiagnosticStats;
 use crate::diagnostics::get_key_value;
-use crate::diagnostics::rel_cwd_manifest_path;
+use crate::diagnostics::workspace_rel_path;
 use crate::util::OptVersionReq;
 
 pub static LINT: &Lint = &Lint {
@@ -86,7 +86,7 @@ serde = "1.0.219"
 
 #[instrument(skip_all)]
 pub(crate) fn lint_package(
-    _ws: &Workspace<'_>,
+    ws: &Workspace<'_>,
     pkg: &Package,
     manifest_path: &Path,
     level: LintLevelProduct,
@@ -98,7 +98,7 @@ pub(crate) fn lint_package(
         source,
     } = level;
 
-    let manifest_path = rel_cwd_manifest_path(manifest_path, gctx);
+    let manifest_path = workspace_rel_path(ws, manifest_path);
 
     let manifest = pkg.manifest();
 
@@ -147,7 +147,7 @@ pub(crate) fn lint_package(
 
 #[instrument(skip_all)]
 pub(crate) fn lint_workspace(
-    _ws: &Workspace<'_>,
+    ws: &Workspace<'_>,
     maybe_pkg: &MaybePackage,
     manifest_path: &Path,
     level: LintLevelProduct,
@@ -159,7 +159,7 @@ pub(crate) fn lint_workspace(
         source,
     } = level;
 
-    let manifest_path = rel_cwd_manifest_path(manifest_path, gctx);
+    let manifest_path = workspace_rel_path(ws, manifest_path);
 
     let document = maybe_pkg.document();
     let contents = maybe_pkg.contents();

src/cargo/diagnostics/rules/missing_lints_features.rs

@@ -12,13 +12,15 @@ use crate::CargoResult;
 use crate::GlobalContext;
 use crate::core::Feature;
 use crate::core::MaybePackage;
+use crate::core::Workspace;
 use crate::diagnostics::ManifestFor;
 use crate::diagnostics::ScopedDiagnosticStats;
 use crate::diagnostics::get_key_value_span;
-use crate::diagnostics::rel_cwd_manifest_path;
+use crate::diagnostics::workspace_rel_path;
 
 #[instrument(skip_all)]
 pub(crate) fn diagnose_manifest(
+    ws: &Workspace<'_>,
     manifest: ManifestFor<'_>,
     manifest_path: &Path,
     pkg_stats: &mut ScopedDiagnosticStats<'_>,
@@ -51,23 +53,24 @@ pub(crate) fn diagnose_manifest(
         .and_then(|lints| lints.get("cargo"));
 
     if let Some(cargo_lints) = ws_lints {
-        diagnose_manifest_inner(&manifest, manifest_path, cargo_lints, pkg_stats, gctx)?;
+        diagnose_manifest_inner(ws, &manifest, manifest_path, cargo_lints, pkg_stats, gctx)?;
     }
     if let Some(cargo_lints) = pkg_lints {
-        diagnose_manifest_inner(&manifest, manifest_path, cargo_lints, pkg_stats, gctx)?;
+        diagnose_manifest_inner(ws, &manifest, manifest_path, cargo_lints, pkg_stats, gctx)?;
     }
 
     Ok(())
 }
 
 fn diagnose_manifest_inner(
+    ws: &Workspace<'_>,
     manifest: &ManifestFor<'_>,
     manifest_path: &Path,
     cargo_lints: &manifest::TomlToolLints,
     pkg_stats: &mut ScopedDiagnosticStats<'_>,
     gctx: &GlobalContext,
 ) -> CargoResult<()> {
-    let manifest_path = rel_cwd_manifest_path(manifest_path, gctx);
+    let manifest_path = workspace_rel_path(ws, manifest_path);
     for lint_name in cargo_lints.keys().map(|name| name) {
         let Some((name, default_level, feature_gate)) = find_lint_or_group(lint_name) else {
             continue;

src/cargo/diagnostics/rules/missing_lints_inheritance.rs

@@ -15,7 +15,7 @@ use crate::core::Workspace;
 use crate::diagnostics::Lint;
 use crate::diagnostics::LintLevelProduct;
 use crate::diagnostics::ScopedDiagnosticStats;
-use crate::diagnostics::rel_cwd_manifest_path;
+use crate::diagnostics::workspace_rel_path;
 
 pub static LINT: &Lint = &Lint {
     name: "missing_lints_inheritance",
@@ -87,7 +87,7 @@ pub(crate) fn lint_package(
     let contents = manifest.contents();
     let level = lint_level.to_diagnostic_level();
     let emitted_source = LINT.emitted_source(lint_level, source);
-    let manifest_path = rel_cwd_manifest_path(manifest_path, gctx);
+    let manifest_path = workspace_rel_path(ws, manifest_path);
 
     let mut primary = Group::with_title(level.primary_title(LINT.desc));
     primary = primary.element(Origin::path(&manifest_path));

src/cargo/diagnostics/rules/non_kebab_case_bins.rs

@@ -20,7 +20,7 @@ use crate::diagnostics::LintLevelProduct;
 use crate::diagnostics::LintLevelSource;
 use crate::diagnostics::ScopedDiagnosticStats;
 use crate::diagnostics::get_key_value_span;
-use crate::diagnostics::rel_cwd_manifest_path;
+use crate::diagnostics::workspace_rel_path;
 
 pub static LINT: &Lint = &Lint {
     name: "non_kebab_case_bins",
@@ -77,7 +77,7 @@ pub(crate) fn lint_package(
         source,
     } = level;
 
-    let manifest_path = rel_cwd_manifest_path(manifest_path, gctx);
+    let manifest_path = workspace_rel_path(ws, manifest_path);
 
     lint_package_inner(ws, pkg, &manifest_path, lint_level, source, pkg_stats, gctx)
 }

src/cargo/diagnostics/rules/non_kebab_case_features.rs

@@ -19,7 +19,7 @@ use crate::diagnostics::LintLevelProduct;
 use crate::diagnostics::LintLevelSource;
 use crate::diagnostics::ScopedDiagnosticStats;
 use crate::diagnostics::get_key_value_span;
-use crate::diagnostics::rel_cwd_manifest_path;
+use crate::diagnostics::workspace_rel_path;
 
 pub static LINT: &Lint = &Lint {
     name: "non_kebab_case_features",
@@ -60,7 +60,7 @@ foo-bar = []
 
 #[instrument(skip_all)]
 pub(crate) fn lint_package(
-    _ws: &Workspace<'_>,
+    ws: &Workspace<'_>,
     pkg: &Package,
     manifest_path: &Path,
     level: LintLevelProduct,
@@ -72,7 +72,7 @@ pub(crate) fn lint_package(
         source,
     } = level;
 
-    let manifest_path = rel_cwd_manifest_path(manifest_path, gctx);
+    let manifest_path = workspace_rel_path(ws, manifest_path);
 
     lint_package_inner(pkg, &manifest_path, lint_level, source, pkg_stats, gctx)
 }

src/cargo/diagnostics/rules/non_kebab_case_packages.rs

@@ -19,7 +19,7 @@ use crate::diagnostics::LintLevelProduct;
 use crate::diagnostics::LintLevelSource;
 use crate::diagnostics::ScopedDiagnosticStats;
 use crate::diagnostics::get_key_value_span;
-use crate::diagnostics::rel_cwd_manifest_path;
+use crate::diagnostics::workspace_rel_path;
 
 pub static LINT: &Lint = &Lint {
     name: "non_kebab_case_packages",
@@ -60,7 +60,7 @@ name = "foo-bar"
 
 #[instrument(skip_all)]
 pub(crate) fn lint_package(
-    _ws: &Workspace<'_>,
+    ws: &Workspace<'_>,
     pkg: &Package,
     manifest_path: &Path,
     level: LintLevelProduct,
@@ -72,7 +72,7 @@ pub(crate) fn lint_package(
         source,
     } = level;
 
-    let manifest_path = rel_cwd_manifest_path(manifest_path, gctx);
+    let manifest_path = workspace_rel_path(ws, manifest_path);
 
     lint_package_inner(pkg, &manifest_path, lint_level, source, pkg_stats, gctx)
 }

src/cargo/diagnostics/rules/non_snake_case_features.rs

@@ -19,7 +19,7 @@ use crate::diagnostics::LintLevelProduct;
 use crate::diagnostics::LintLevelSource;
 use crate::diagnostics::ScopedDiagnosticStats;
 use crate::diagnostics::get_key_value_span;
-use crate::diagnostics::rel_cwd_manifest_path;
+use crate::diagnostics::workspace_rel_path;
 
 pub static LINT: &Lint = &Lint {
     name: "non_snake_case_features",
@@ -60,7 +60,7 @@ foo_bar = []
 
 #[instrument(skip_all)]
 pub(crate) fn lint_package(
-    _ws: &Workspace<'_>,
+    ws: &Workspace<'_>,
     pkg: &Package,
     manifest_path: &Path,
     level: LintLevelProduct,
@@ -72,7 +72,7 @@ pub(crate) fn lint_package(
         source,
     } = level;
 
-    let manifest_path = rel_cwd_manifest_path(manifest_path, gctx);
+    let manifest_path = workspace_rel_path(ws, manifest_path);
 
     lint_package_inner(pkg, &manifest_path, lint_level, source, pkg_stats, gctx)
 }