Auto merge of #13801 - Muscraft:add-lint-reason, r=epage

Add where lint was set

`rustc` and `clippy` both show why the lint was emitted and where the level was set the first time it was emitted for a package. We already showed why the list was being emitted but did not show where the lint level was set. This PR adds where the lint was set at.

src/cargo/core/workspace.rs

@@ -1180,6 +1180,21 @@ impl<'gctx> Workspace<'gctx> {
     }
 
     pub fn emit_lints(&self, pkg: &Package, path: &Path) -> CargoResult<()> {
+        let ws_lints = self
+            .root_maybe()
+            .workspace_config()
+            .inheritable()
+            .and_then(|i| i.lints().ok())
+            .unwrap_or_default();
+
+        let ws_cargo_lints = ws_lints
+            .get("cargo")
+            .cloned()
+            .unwrap_or_default()
+            .into_iter()
+            .map(|(k, v)| (k.replace('-', "_"), v))
+            .collect();
+
         let mut error_count = 0;
         let toml_lints = pkg
             .manifest()
@@ -1197,9 +1212,30 @@ impl<'gctx> Workspace<'gctx> {
             .map(|(name, lint)| (name.replace('-', "_"), lint))
             .collect();
 
-        check_im_a_teapot(pkg, &path, &normalized_lints, &mut error_count, self.gctx)?;
-        check_implicit_features(pkg, &path, &normalized_lints, &mut error_count, self.gctx)?;
-        unused_dependencies(pkg, &path, &normalized_lints, &mut error_count, self.gctx)?;
+        check_im_a_teapot(
+            pkg,
+            &path,
+            &normalized_lints,
+            &ws_cargo_lints,
+            &mut error_count,
+            self.gctx,
+        )?;
+        check_implicit_features(
+            pkg,
+            &path,
+            &normalized_lints,
+            &ws_cargo_lints,
+            &mut error_count,
+            self.gctx,
+        )?;
+        unused_dependencies(
+            pkg,
+            &path,
+            &normalized_lints,
+            &ws_cargo_lints,
+            &mut error_count,
+            self.gctx,
+        )?;
         if error_count > 0 {
             Err(crate::util::errors::AlreadyPrintedError::new(anyhow!(
                 "encountered {error_count} errors(s) while running lints"

src/cargo/util/lints.rs

@@ -85,40 +85,41 @@ pub struct Lint {
 }
 
 impl Lint {
-    pub fn level(&self, lints: &TomlToolLints, edition: Edition) -> LintLevel {
-        let edition_level = self
-            .edition_lint_opts
-            .filter(|(e, _)| edition >= *e)
-            .map(|(_, l)| l);
-
-        if self.default_level == LintLevel::Forbid || edition_level == Some(LintLevel::Forbid) {
-            return LintLevel::Forbid;
-        }
-
-        let level = self
-            .groups
+    pub fn level(
+        &self,
+        pkg_lints: &TomlToolLints,
+        ws_lints: &TomlToolLints,
+        edition: Edition,
+    ) -> (LintLevel, LintLevelReason) {
+        self.groups
             .iter()
-            .map(|g| g.name)
-            .chain(std::iter::once(self.name))
-            .filter_map(|n| lints.get(n).map(|l| (n, l)))
-            .max_by_key(|(n, l)| {
+            .map(|g| {
                 (
-                    l.level() == TomlLintLevel::Forbid,
-                    l.priority(),
-                    std::cmp::Reverse(*n),
+                    g.name,
+                    level_priority(
+                        g.name,
+                        g.default_level,
+                        g.edition_lint_opts,
+                        pkg_lints,
+                        ws_lints,
+                        edition,
+                    ),
                 )
-            });
-
-        match level {
-            Some((_, toml_lint)) => toml_lint.level().into(),
-            None => {
-                if let Some(level) = edition_level {
-                    level
-                } else {
-                    self.default_level
-                }
-            }
-        }
+            })
+            .chain(std::iter::once((
+                self.name,
+                level_priority(
+                    self.name,
+                    self.default_level,
+                    self.edition_lint_opts,
+                    pkg_lints,
+                    ws_lints,
+                    edition,
+                ),
+            )))
+            .max_by_key(|(n, (l, _, p))| (l == &LintLevel::Forbid, *p, std::cmp::Reverse(*n)))
+            .map(|(_, (l, r, _))| (l, r))
+            .unwrap()
     }
 }
 
@@ -163,6 +164,64 @@ impl From<TomlLintLevel> for LintLevel {
     }
 }
 
+#[derive(Copy, Clone, Debug)]
+pub enum LintLevelReason {
+    Default,
+    Edition(Edition),
+    Package,
+    Workspace,
+}
+
+impl Display for LintLevelReason {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            LintLevelReason::Default => write!(f, "by default"),
+            LintLevelReason::Edition(edition) => write!(f, "in edition {}", edition),
+            LintLevelReason::Package => write!(f, "in `[lints]`"),
+            LintLevelReason::Workspace => write!(f, "in `[workspace.lints]`"),
+        }
+    }
+}
+
+fn level_priority(
+    name: &str,
+    default_level: LintLevel,
+    edition_lint_opts: Option<(Edition, LintLevel)>,
+    pkg_lints: &TomlToolLints,
+    ws_lints: &TomlToolLints,
+    edition: Edition,
+) -> (LintLevel, LintLevelReason, i8) {
+    let (unspecified_level, reason) = if let Some(level) = edition_lint_opts
+        .filter(|(e, _)| edition >= *e)
+        .map(|(_, l)| l)
+    {
+        (level, LintLevelReason::Edition(edition))
+    } else {
+        (default_level, LintLevelReason::Default)
+    };
+
+    // Don't allow the group to be overridden if the level is `Forbid`
+    if unspecified_level == LintLevel::Forbid {
+        return (unspecified_level, reason, 0);
+    }
+
+    if let Some(defined_level) = pkg_lints.get(name) {
+        (
+            defined_level.level().into(),
+            LintLevelReason::Package,
+            defined_level.priority(),
+        )
+    } else if let Some(defined_level) = ws_lints.get(name) {
+        (
+            defined_level.level().into(),
+            LintLevelReason::Workspace,
+            defined_level.priority(),
+        )
+    } else {
+        (unspecified_level, reason, 0)
+    }
+}
+
 const IM_A_TEAPOT: Lint = Lint {
     name: "im_a_teapot",
     desc: "`im_a_teapot` is specified",
@@ -174,12 +233,13 @@ const IM_A_TEAPOT: Lint = Lint {
 pub fn check_im_a_teapot(
     pkg: &Package,
     path: &Path,
-    lints: &TomlToolLints,
+    pkg_lints: &TomlToolLints,
+    ws_lints: &TomlToolLints,
     error_count: &mut usize,
     gctx: &GlobalContext,
 ) -> CargoResult<()> {
     let manifest = pkg.manifest();
-    let lint_level = IM_A_TEAPOT.level(lints, manifest.edition());
+    let (lint_level, reason) = IM_A_TEAPOT.level(pkg_lints, ws_lints, manifest.edition());
     if lint_level == LintLevel::Allow {
         return Ok(());
     }
@@ -194,7 +254,10 @@ pub fn check_im_a_teapot(
         }
         let level = lint_level.to_diagnostic_level();
         let manifest_path = rel_cwd_manifest_path(path, gctx);
-        let emitted_reason = format!("`cargo::{}` is set to `{lint_level}`", IM_A_TEAPOT.name);
+        let emitted_reason = format!(
+            "`cargo::{}` is set to `{lint_level}` {reason}",
+            IM_A_TEAPOT.name
+        );
 
         let key_span = get_span(manifest.document(), &["package", "im-a-teapot"], false).unwrap();
         let value_span = get_span(manifest.document(), &["package", "im-a-teapot"], true).unwrap();
@@ -242,7 +305,8 @@ const IMPLICIT_FEATURES: Lint = Lint {
 pub fn check_implicit_features(
     pkg: &Package,
     path: &Path,
-    lints: &TomlToolLints,
+    pkg_lints: &TomlToolLints,
+    ws_lints: &TomlToolLints,
     error_count: &mut usize,
     gctx: &GlobalContext,
 ) -> CargoResult<()> {
@@ -253,7 +317,7 @@ pub fn check_implicit_features(
         return Ok(());
     }
 
-    let lint_level = IMPLICIT_FEATURES.level(lints, edition);
+    let (lint_level, reason) = IMPLICIT_FEATURES.level(pkg_lints, ws_lints, edition);
     if lint_level == LintLevel::Allow {
         return Ok(());
     }
@@ -298,7 +362,7 @@ pub fn check_implicit_features(
         );
         if emitted_source.is_none() {
             emitted_source = Some(format!(
-                "`cargo::{}` is set to `{lint_level}`",
+                "`cargo::{}` is set to `{lint_level}` {reason}",
                 IMPLICIT_FEATURES.name
             ));
             message = message.footer(Level::Note.title(emitted_source.as_ref().unwrap()));
@@ -325,7 +389,8 @@ const UNUSED_OPTIONAL_DEPENDENCY: Lint = Lint {
 pub fn unused_dependencies(
     pkg: &Package,
     path: &Path,
-    lints: &TomlToolLints,
+    pkg_lints: &TomlToolLints,
+    ws_lints: &TomlToolLints,
     error_count: &mut usize,
     gctx: &GlobalContext,
 ) -> CargoResult<()> {
@@ -335,7 +400,7 @@ pub fn unused_dependencies(
         return Ok(());
     }
 
-    let lint_level = UNUSED_OPTIONAL_DEPENDENCY.level(lints, edition);
+    let (lint_level, reason) = UNUSED_OPTIONAL_DEPENDENCY.level(pkg_lints, ws_lints, edition);
     if lint_level == LintLevel::Allow {
         return Ok(());
     }
@@ -401,7 +466,7 @@ pub fn unused_dependencies(
                     );
                     if emitted_source.is_none() {
                         emitted_source = Some(format!(
-                            "`cargo::{}` is set to `{lint_level}`",
+                            "`cargo::{}` is set to `{lint_level}` {reason}",
                             UNUSED_OPTIONAL_DEPENDENCY.name
                         ));
                         message =

src/cargo/util/toml/mod.rs

@@ -411,15 +411,7 @@ fn resolve_toml(
         }
         resolved_toml.target = (!resolved_target.is_empty()).then_some(resolved_target);
 
-        let resolved_lints = original_toml
-            .lints
-            .clone()
-            .map(|value| lints_inherit_with(value, || inherit()?.lints()))
-            .transpose()?;
-        resolved_toml.lints = resolved_lints.map(|lints| manifest::InheritableLints {
-            workspace: false,
-            lints,
-        });
+        resolved_toml.lints = original_toml.lints.clone();
 
         let resolved_badges = original_toml
             .badges
@@ -803,7 +795,7 @@ impl InheritableFields {
     }
 
     /// Gets the field `workspace.lint`.
-    fn lints(&self) -> CargoResult<manifest::TomlLints> {
+    pub fn lints(&self) -> CargoResult<manifest::TomlLints> {
         let Some(val) = &self.lints else {
             bail!("`workspace.lints` was not defined");
         };
@@ -1276,18 +1268,18 @@ fn to_real_manifest(
         }
     }
 
-    verify_lints(
-        resolved_toml.resolved_lints().expect("previously resolved"),
-        gctx,
-        warnings,
-    )?;
-    let default = manifest::TomlLints::default();
-    let rustflags = lints_to_rustflags(
-        resolved_toml
-            .resolved_lints()
-            .expect("previously resolved")
-            .unwrap_or(&default),
-    );
+    let resolved_lints = resolved_toml
+        .lints
+        .clone()
+        .map(|value| {
+            lints_inherit_with(value, || {
+                load_inheritable_fields(gctx, manifest_file, &workspace_config)?.lints()
+            })
+        })
+        .transpose()?;
+
+    verify_lints(resolved_lints.as_ref(), gctx, warnings)?;
+    let rustflags = lints_to_rustflags(&resolved_lints.unwrap_or_default());
 
     let metadata = ManifestMetadata {
         description: resolved_package