Consider lint check attributes on match arms

compiler/rustc_lint/src/late.rs

@@ -240,8 +240,10 @@ impl<'tcx, T: LateLintPass<'tcx>> hir_visit::Visitor<'tcx> for LateContextAndPas
     }
 
     fn visit_arm(&mut self, a: &'tcx hir::Arm<'tcx>) {
-        lint_callback!(self, check_arm, a);
-        hir_visit::walk_arm(self, a);
+        self.with_lint_attrs(a.hir_id, |cx| {
+            lint_callback!(cx, check_arm, a);
+            hir_visit::walk_arm(cx, a);
+        })
     }
 
     fn visit_generic_param(&mut self, p: &'tcx hir::GenericParam<'tcx>) {

compiler/rustc_mir_build/src/thir/pattern/check_match.rs

@@ -90,35 +90,34 @@ impl<'a, 'tcx> Visitor<'a, 'tcx> for MatchVisitor<'a, '_, 'tcx> {
 
     #[instrument(level = "trace", skip(self))]
     fn visit_arm(&mut self, arm: &Arm<'tcx>) {
-        match arm.guard {
-            Some(Guard::If(expr)) => {
-                self.with_let_source(LetSource::IfLetGuard, |this| {
-                    this.visit_expr(&this.thir[expr])
-                });
-            }
-            Some(Guard::IfLet(ref pat, expr)) => {
-                self.with_let_source(LetSource::IfLetGuard, |this| {
-                    this.check_let(pat, expr, LetSource::IfLetGuard, pat.span);
-                    this.visit_pat(pat);
-                    this.visit_expr(&this.thir[expr]);
-                });
+        self.with_lint_level(arm.lint_level, |this| {
+            match arm.guard {
+                Some(Guard::If(expr)) => {
+                    this.with_let_source(LetSource::IfLetGuard, |this| {
+                        this.visit_expr(&this.thir[expr])
+                    });
+                }
+                Some(Guard::IfLet(ref pat, expr)) => {
+                    this.with_let_source(LetSource::IfLetGuard, |this| {
+                        this.check_let(pat, expr, LetSource::IfLetGuard, pat.span);
+                        this.visit_pat(pat);
+                        this.visit_expr(&this.thir[expr]);
+                    });
+                }
+                None => {}
             }
-            None => {}
-        }
-        self.visit_pat(&arm.pattern);
-        self.visit_expr(&self.thir[arm.body]);
+            this.visit_pat(&arm.pattern);
+            this.visit_expr(&self.thir[arm.body]);
+        });
     }
 
     #[instrument(level = "trace", skip(self))]
     fn visit_expr(&mut self, ex: &Expr<'tcx>) {
         match ex.kind {
             ExprKind::Scope { value, lint_level, .. } => {
-                let old_lint_level = self.lint_level;
-                if let LintLevel::Explicit(hir_id) = lint_level {
-                    self.lint_level = hir_id;
-                }
-                self.visit_expr(&self.thir[value]);
-                self.lint_level = old_lint_level;
+                self.with_lint_level(lint_level, |this| {
+                    this.visit_expr(&this.thir[value]);
+                });
                 return;
             }
             ExprKind::If { cond, then, else_opt, if_then_scope: _ } => {
@@ -190,6 +189,17 @@ impl<'p, 'tcx> MatchVisitor<'_, 'p, 'tcx> {
         self.let_source = old_let_source;
     }
 
+    fn with_lint_level(&mut self, new_lint_level: LintLevel, f: impl FnOnce(&mut Self)) {
+        if let LintLevel::Explicit(hir_id) = new_lint_level {
+            let old_lint_level = self.lint_level;
+            self.lint_level = hir_id;
+            f(self);
+            self.lint_level = old_lint_level;
+        } else {
+            f(self);
+        }
+    }
+
     fn check_patterns(&self, pat: &Pat<'tcx>, rf: RefutableFlag) {
         pat.walk_always(|pat| check_borrow_conflicts_in_at_patterns(self, pat));
         check_for_bindings_named_same_as_variants(self, pat, rf);
@@ -236,7 +246,9 @@ impl<'p, 'tcx> MatchVisitor<'_, 'p, 'tcx> {
         for &arm in arms {
             // Check the arm for some things unrelated to exhaustiveness.
             let arm = &self.thir.arms[arm];
-            self.check_patterns(&arm.pattern, Refutable);
+            self.with_lint_level(arm.lint_level, |this| {
+                this.check_patterns(&arm.pattern, Refutable);
+            });
         }
 
         let tarms: Vec<_> = arms

tests/ui/lint/lint-attr-everywhere-early.rs

@@ -134,6 +134,14 @@ fn expressions() {
         }
     }
 
+    match f {
+        #[deny(ellipsis_inclusive_range_patterns)]
+        Match{f1: 0...100} => {}
+        //~^ ERROR range patterns are deprecated
+        //~| WARNING this is accepted in the current edition
+        _ => {}
+    }
+
     // Statement Block
     {
         #![deny(unsafe_code)]

tests/ui/lint/lint-attr-everywhere-early.stderr

@@ -384,103 +384,117 @@ note: the lint level is defined here
 LL |         #[deny(while_true)]
    |                ^^^^^^^^^^
 
+error: `...` range patterns are deprecated
+  --> $DIR/lint-attr-everywhere-early.rs:139:20
+   |
+LL |         Match{f1: 0...100} => {}
+   |                    ^^^ help: use `..=` for an inclusive range
+   |
+   = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
+   = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
+note: the lint level is defined here
+  --> $DIR/lint-attr-everywhere-early.rs:138:16
+   |
+LL |         #[deny(ellipsis_inclusive_range_patterns)]
+   |                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
 error: usage of an `unsafe` block
-  --> $DIR/lint-attr-everywhere-early.rs:140:9
+  --> $DIR/lint-attr-everywhere-early.rs:148:9
    |
 LL |         unsafe {}
    |         ^^^^^^^^^
    |
 note: the lint level is defined here
-  --> $DIR/lint-attr-everywhere-early.rs:139:17
+  --> $DIR/lint-attr-everywhere-early.rs:147:17
    |
 LL |         #![deny(unsafe_code)]
    |                 ^^^^^^^^^^^
 
 error: usage of an `unsafe` block
-  --> $DIR/lint-attr-everywhere-early.rs:144:9
+  --> $DIR/lint-attr-everywhere-early.rs:152:9
    |
 LL |         unsafe {}
    |         ^^^^^^^^^
    |
 note: the lint level is defined here
-  --> $DIR/lint-attr-everywhere-early.rs:143:16
+  --> $DIR/lint-attr-everywhere-early.rs:151:16
    |
 LL |         #[deny(unsafe_code)]
    |                ^^^^^^^^^^^
 
 error: usage of an `unsafe` block
-  --> $DIR/lint-attr-everywhere-early.rs:149:5
+  --> $DIR/lint-attr-everywhere-early.rs:157:5
    |
 LL |     unsafe {};
    |     ^^^^^^^^^
    |
 note: the lint level is defined here
-  --> $DIR/lint-attr-everywhere-early.rs:148:12
+  --> $DIR/lint-attr-everywhere-early.rs:156:12
    |
 LL |     #[deny(unsafe_code)]
    |            ^^^^^^^^^^^
 
 error: usage of an `unsafe` block
-  --> $DIR/lint-attr-everywhere-early.rs:151:27
+  --> $DIR/lint-attr-everywhere-early.rs:159:27
    |
 LL |     [#[deny(unsafe_code)] unsafe {123}];
    |                           ^^^^^^^^^^^^
    |
 note: the lint level is defined here
-  --> $DIR/lint-attr-everywhere-early.rs:151:13
+  --> $DIR/lint-attr-everywhere-early.rs:159:13
    |
 LL |     [#[deny(unsafe_code)] unsafe {123}];
    |             ^^^^^^^^^^^
 
 error: usage of an `unsafe` block
-  --> $DIR/lint-attr-everywhere-early.rs:152:27
+  --> $DIR/lint-attr-everywhere-early.rs:160:27
    |
 LL |     (#[deny(unsafe_code)] unsafe {123},);
    |                           ^^^^^^^^^^^^
    |
 note: the lint level is defined here
-  --> $DIR/lint-attr-everywhere-early.rs:152:13
+  --> $DIR/lint-attr-everywhere-early.rs:160:13
    |
 LL |     (#[deny(unsafe_code)] unsafe {123},);
    |             ^^^^^^^^^^^
 
 error: usage of an `unsafe` block
-  --> $DIR/lint-attr-everywhere-early.rs:154:31
+  --> $DIR/lint-attr-everywhere-early.rs:162:31
    |
 LL |     call(#[deny(unsafe_code)] unsafe {123});
    |                               ^^^^^^^^^^^^
    |
 note: the lint level is defined here
-  --> $DIR/lint-attr-everywhere-early.rs:154:17
+  --> $DIR/lint-attr-everywhere-early.rs:162:17
    |
 LL |     call(#[deny(unsafe_code)] unsafe {123});
    |                 ^^^^^^^^^^^
 
 error: usage of an `unsafe` block
-  --> $DIR/lint-attr-everywhere-early.rs:156:38
+  --> $DIR/lint-attr-everywhere-early.rs:164:38
    |
 LL |     TupleStruct(#[deny(unsafe_code)] unsafe {123});
    |                                      ^^^^^^^^^^^^
    |
 note: the lint level is defined here
-  --> $DIR/lint-attr-everywhere-early.rs:156:24
+  --> $DIR/lint-attr-everywhere-early.rs:164:24
    |
 LL |     TupleStruct(#[deny(unsafe_code)] unsafe {123});
    |                        ^^^^^^^^^^^
 
 error: `...` range patterns are deprecated
-  --> $DIR/lint-attr-everywhere-early.rs:167:18
+  --> $DIR/lint-attr-everywhere-early.rs:175:18
    |
 LL |             f1: 0...100,
    |                  ^^^ help: use `..=` for an inclusive range
    |
    = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
    = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
 note: the lint level is defined here
-  --> $DIR/lint-attr-everywhere-early.rs:166:20
+  --> $DIR/lint-attr-everywhere-early.rs:174:20
    |
 LL |             #[deny(ellipsis_inclusive_range_patterns)]
    |                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-error: aborting due to 36 previous errors
+error: aborting due to 37 previous errors
 

tests/ui/lint/lint-attr-everywhere-late.rs

@@ -162,6 +162,11 @@ fn expressions() {
         }
     }
 
+    match 123 {
+        #[deny(non_snake_case)]
+        ARM_VAR => {} //~ ERROR variable `ARM_VAR` should have a snake case name
+    }
+
     // Statement Block
     {
         #![deny(enum_intrinsics_non_enums)]