Extend disallowed_fields lint on variant fields

clippy_lints/src/disallowed_fields.rs

@@ -106,28 +106,55 @@ fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
     }
 
     fn check_pat(&mut self, cx: &LateContext<'tcx>, pat: &'tcx Pat<'_>) {
-        if let PatKind::Struct(struct_path, pat_fields, _) = pat.kind
-            && let Res::Def(DefKind::Struct, struct_def_id) = cx.typeck_results().qpath_res(&struct_path, pat.hir_id)
-        {
-            let adt_def = cx.tcx.adt_def(struct_def_id);
-            for field in pat_fields {
-                if let Some(def_id) = adt_def.all_fields().find_map(|adt_field| {
-                    if field.ident.name == adt_field.name {
-                        Some(adt_field.did)
-                    } else {
-                        None
+        let PatKind::Struct(struct_path, pat_fields, _) = pat.kind else {
+            return;
+        };
+        match cx.typeck_results().qpath_res(&struct_path, pat.hir_id) {
+            Res::Def(DefKind::Struct, struct_def_id) => {
+                let adt_def = cx.tcx.adt_def(struct_def_id);
+                for field in pat_fields {
+                    if let Some(def_id) = adt_def.all_fields().find_map(|adt_field| {
+                        if field.ident.name == adt_field.name {
+                            Some(adt_field.did)
+                        } else {
+                            None
+                        }
+                    }) && let Some(&(path, disallowed_path)) = self.disallowed.get(&def_id)
+                    {
+                        span_lint_and_then(
+                            cx,
+                            DISALLOWED_FIELDS,
+                            field.span,
+                            format!("use of a disallowed field `{path}`"),
+                            disallowed_path.diag_amendment(field.span),
+                        );
                     }
-                }) && let Some(&(path, disallowed_path)) = self.disallowed.get(&def_id)
-                {
-                    span_lint_and_then(
-                        cx,
-                        DISALLOWED_FIELDS,
-                        field.span,
-                        format!("use of a disallowed field `{path}`"),
-                        disallowed_path.diag_amendment(field.span),
-                    );
                 }
-            }
+            },
+            Res::Def(DefKind::Variant, variant_def_id) => {
+                let enum_def_id = cx.tcx.parent(variant_def_id);
+                let variant = cx.tcx.adt_def(enum_def_id).variant_with_id(variant_def_id);
+
+                for field in pat_fields {
+                    if let Some(def_id) = variant.fields.iter().find_map(|adt_field| {
+                        if field.ident.name == adt_field.name {
+                            Some(adt_field.did)
+                        } else {
+                            None
+                        }
+                    }) && let Some(&(path, disallowed_path)) = self.disallowed.get(&def_id)
+                    {
+                        span_lint_and_then(
+                            cx,
+                            DISALLOWED_FIELDS,
+                            field.span,
+                            format!("use of a disallowed field `{path}`"),
+                            disallowed_path.diag_amendment(field.span),
+                        );
+                    }
+                }
+            },
+            _ => {},
         }
     }
 }

clippy_utils/src/paths.rs

@@ -288,6 +288,20 @@ fn local_item_child_by_name(tcx: TyCtxt<'_>, local_id: LocalDefId, ns: PathNS, n
             &root_mod
         },
         Node::Item(item) => &item.kind,
+        Node::Variant(variant) if ns == PathNS::Field => {
+            return if let rustc_hir::VariantData::Struct { fields, .. } = variant.data
+                && let Some(field_def_id) = fields.iter().find_map(|field| {
+                    if field.ident.name == name {
+                        Some(field.def_id.to_def_id())
+                    } else {
+                        None
+                    }
+                }) {
+                Some(field_def_id)
+            } else {
+                None
+            };
+        },
         _ => return None,
     };
 
@@ -330,6 +344,15 @@ fn local_item_child_by_name(tcx: TyCtxt<'_>, local_id: LocalDefId, ns: PathNS, n
                 }
             })
         },
+        ItemKind::Enum(_, _, rustc_hir::EnumDef { variants }) if ns == PathNS::Type => {
+            variants.iter().find_map(|variant| {
+                if variant.ident.name == name {
+                    Some(variant.def_id.to_def_id())
+                } else {
+                    None
+                }
+            })
+        },
         _ => None,
     }
 }

tests/ui-toml/toml_disallowed_fields/clippy.toml

@@ -9,4 +9,6 @@ disallowed-fields = [
     "conf_disallowed_fields::X::y",
     # re-exports
     "conf_disallowed_fields::Y::y",
+    # field of a variant
+    "conf_disallowed_fields::Z::B::x",
 ]

tests/ui-toml/toml_disallowed_fields/conf_disallowed_fields.rs

@@ -7,6 +7,11 @@ struct X {
     y: u32,
 }
 
+enum Z {
+    A { x: u32 },
+    B { x: u32 },
+}
+
 use crate::X as Y;
 
 fn b(X { y }: X) {}
@@ -36,4 +41,10 @@ fn main() {
     match x {
         RangeTo { end } => {}, //~ disallowed_fields
     }
+
+    let x = Z::B { x: 0 };
+    match x {
+        Z::A { x } => {},
+        Z::B { x } => {}, //~ disallowed_fields
+    }
 }

tests/ui-toml/toml_disallowed_fields/conf_disallowed_fields.stderr

@@ -1,5 +1,5 @@
 error: use of a disallowed field `conf_disallowed_fields::Y::y`
-  --> tests/ui-toml/toml_disallowed_fields/conf_disallowed_fields.rs:12:10
+  --> tests/ui-toml/toml_disallowed_fields/conf_disallowed_fields.rs:17:10
    |
 LL | fn b(X { y }: X) {}
    |          ^
@@ -8,25 +8,25 @@ LL | fn b(X { y }: X) {}
    = help: to override `-D warnings` add `#[allow(clippy::disallowed_fields)]`
 
 error: use of a disallowed field `conf_disallowed_fields::Y::y`
-  --> tests/ui-toml/toml_disallowed_fields/conf_disallowed_fields.rs:17:15
+  --> tests/ui-toml/toml_disallowed_fields/conf_disallowed_fields.rs:22:15
    |
 LL |     let _ = x.y;
    |               ^
 
 error: use of a disallowed field `conf_disallowed_fields::Y::y`
-  --> tests/ui-toml/toml_disallowed_fields/conf_disallowed_fields.rs:21:15
+  --> tests/ui-toml/toml_disallowed_fields/conf_disallowed_fields.rs:26:15
    |
 LL |     let _ = x.y;
    |               ^
 
 error: use of a disallowed field `std::ops::Range::start`
-  --> tests/ui-toml/toml_disallowed_fields/conf_disallowed_fields.rs:25:15
+  --> tests/ui-toml/toml_disallowed_fields/conf_disallowed_fields.rs:30:15
    |
 LL |     let _ = x.start;
    |               ^^^^^
 
 error: use of a disallowed field `std::ops::Range::end`
-  --> tests/ui-toml/toml_disallowed_fields/conf_disallowed_fields.rs:27:15
+  --> tests/ui-toml/toml_disallowed_fields/conf_disallowed_fields.rs:32:15
    |
 LL |     let _ = x.end;
    |               ^^^
@@ -34,22 +34,28 @@ LL |     let _ = x.end;
    = note: no end allowed
 
 error: use of a disallowed field `std::ops::Range::start`
-  --> tests/ui-toml/toml_disallowed_fields/conf_disallowed_fields.rs:29:17
+  --> tests/ui-toml/toml_disallowed_fields/conf_disallowed_fields.rs:34:17
    |
 LL |     let Range { start, .. } = x;
    |                 ^^^^^
 
 error: use of a disallowed field `std::ops::RangeTo::end`
-  --> tests/ui-toml/toml_disallowed_fields/conf_disallowed_fields.rs:33:15
+  --> tests/ui-toml/toml_disallowed_fields/conf_disallowed_fields.rs:38:15
    |
 LL |     let _ = x.end;
    |               ^^^
 
 error: use of a disallowed field `std::ops::RangeTo::end`
-  --> tests/ui-toml/toml_disallowed_fields/conf_disallowed_fields.rs:37:19
+  --> tests/ui-toml/toml_disallowed_fields/conf_disallowed_fields.rs:42:19
    |
 LL |         RangeTo { end } => {},
    |                   ^^^
 
-error: aborting due to 8 previous errors
+error: use of a disallowed field `conf_disallowed_fields::Z::B::x`
+  --> tests/ui-toml/toml_disallowed_fields/conf_disallowed_fields.rs:48:16
+   |
+LL |         Z::B { x } => {},
+   |                ^
+
+error: aborting due to 9 previous errors