Uniformly handle HIR literals in visitors and lints

Author: oli-obk

compiler/rustc_hir/src/intravisit.rs

@@ -345,6 +345,9 @@ pub trait Visitor<'v>: Sized {
     fn visit_pat_expr(&mut self, expr: &'v PatExpr<'v>) -> Self::Result {
         walk_pat_expr(self, expr)
     }
+    fn visit_lit(&mut self, _hir_id: HirId, _lit: &'v Lit, _negated: bool) -> Self::Result {
+        Self::Result::output()
+    }
     fn visit_anon_const(&mut self, c: &'v AnonConst) -> Self::Result {
         walk_anon_const(self, c)
     }
@@ -754,7 +757,7 @@ pub fn walk_pat_field<'v, V: Visitor<'v>>(visitor: &mut V, field: &'v PatField<'
 pub fn walk_pat_expr<'v, V: Visitor<'v>>(visitor: &mut V, expr: &'v PatExpr<'v>) -> V::Result {
     try_visit!(visitor.visit_id(expr.hir_id));
     match &expr.kind {
-        PatExprKind::Lit { .. } => V::Result::output(),
+        PatExprKind::Lit { lit, negated } => visitor.visit_lit(expr.hir_id, lit, *negated),
         PatExprKind::ConstBlock(c) => visitor.visit_inline_const(c),
         PatExprKind::Path(qpath) => visitor.visit_qpath(qpath, expr.hir_id, expr.span),
     }
@@ -902,7 +905,8 @@ pub fn walk_expr<'v, V: Visitor<'v>>(visitor: &mut V, expression: &'v Expr<'v>)
             try_visit!(visitor.visit_expr(expr));
             visit_opt!(visitor, visit_ty_unambig, ty);
         }
-        ExprKind::Lit(_) | ExprKind::Err(_) => {}
+        ExprKind::Lit(lit) => try_visit!(visitor.visit_lit(expression.hir_id, lit, false)),
+        ExprKind::Err(_) => {}
     }
     V::Result::output()
 }

compiler/rustc_lint/src/late.rs

@@ -152,6 +152,10 @@ impl<'tcx, T: LateLintPass<'tcx>> hir_visit::Visitor<'tcx> for LateContextAndPas
         hir_visit::walk_pat(self, p);
     }
 
+    fn visit_lit(&mut self, hir_id: HirId, lit: &'tcx hir::Lit, negated: bool) {
+        lint_callback!(self, check_lit, hir_id, lit, negated);
+    }
+
     fn visit_expr_field(&mut self, field: &'tcx hir::ExprField<'tcx>) {
         self.with_lint_attrs(field.hir_id, |cx| hir_visit::walk_expr_field(cx, field))
     }

compiler/rustc_lint/src/passes.rs

@@ -23,6 +23,7 @@ macro_rules! late_lint_methods {
             fn check_stmt(a: &'tcx rustc_hir::Stmt<'tcx>);
             fn check_arm(a: &'tcx rustc_hir::Arm<'tcx>);
             fn check_pat(a: &'tcx rustc_hir::Pat<'tcx>);
+            fn check_lit(hir_id: rustc_hir::HirId, a: &'tcx rustc_hir::Lit, negated: bool);
             fn check_expr(a: &'tcx rustc_hir::Expr<'tcx>);
             fn check_expr_post(a: &'tcx rustc_hir::Expr<'tcx>);
             fn check_ty(a: &'tcx rustc_hir::Ty<'tcx, rustc_hir::AmbigArg>);

compiler/rustc_lint/src/types.rs

@@ -5,7 +5,7 @@ use rustc_abi::{BackendRepr, ExternAbi, TagEncoding, VariantIdx, Variants, Wrapp
 use rustc_data_structures::fx::FxHashSet;
 use rustc_errors::DiagMessage;
 use rustc_hir::intravisit::VisitorExt;
-use rustc_hir::{AmbigArg, Expr, ExprKind, LangItem};
+use rustc_hir::{AmbigArg, Expr, ExprKind, HirId, LangItem};
 use rustc_middle::bug;
 use rustc_middle::ty::layout::{LayoutOf, SizeSkeleton};
 use rustc_middle::ty::{
@@ -536,6 +536,16 @@ fn lint_fn_pointer<'tcx>(
 }
 
 impl<'tcx> LateLintPass<'tcx> for TypeLimits {
+    fn check_lit(
+        &mut self,
+        cx: &LateContext<'tcx>,
+        hir_id: HirId,
+        lit: &'tcx hir::Lit,
+        negated: bool,
+    ) {
+        lint_literal(cx, self, hir_id, lit.span, lit, negated)
+    }
+
     fn check_expr(&mut self, cx: &LateContext<'tcx>, e: &'tcx hir::Expr<'tcx>) {
         match e.kind {
             hir::ExprKind::Unary(hir::UnOp::Neg, expr) => {
@@ -557,7 +567,6 @@ impl<'tcx> LateLintPass<'tcx> for TypeLimits {
                     }
                 }
             }
-            hir::ExprKind::Lit(lit) => lint_literal(cx, self, e.hir_id, e.span, lit),
             hir::ExprKind::Call(path, [l, r])
                 if let ExprKind::Path(ref qpath) = path.kind
                     && let Some(def_id) = cx.qpath_res(qpath, path.hir_id).opt_def_id()

compiler/rustc_lint/src/types/literal.rs

@@ -245,11 +245,12 @@ fn lint_int_literal<'tcx>(
     lit: &hir::Lit,
     t: ty::IntTy,
     v: u128,
+    negated: bool,
 ) {
     let int_type = t.normalize(cx.sess().target.pointer_width);
     let (min, max) = int_ty_range(int_type);
     let max = max as u128;
-    let negative = type_limits.negated_expr_id == Some(hir_id);
+    let negative = negated ^ (type_limits.negated_expr_id == Some(hir_id));
 
     // Detect literal value out of range [min, max] inclusive
     // avoiding use of -min to prevent overflow/panic
@@ -359,17 +360,21 @@ pub(crate) fn lint_literal<'tcx>(
     hir_id: HirId,
     span: Span,
     lit: &hir::Lit,
+    negated: bool,
 ) {
     match *cx.typeck_results().node_type(hir_id).kind() {
         ty::Int(t) => {
             match lit.node {
                 ast::LitKind::Int(v, ast::LitIntType::Signed(_) | ast::LitIntType::Unsuffixed) => {
-                    lint_int_literal(cx, type_limits, hir_id, span, lit, t, v.get())
+                    lint_int_literal(cx, type_limits, hir_id, span, lit, t, v.get(), negated)
                 }
                 _ => bug!(),
             };
         }
-        ty::Uint(t) => lint_uint_literal(cx, hir_id, span, lit, t),
+        ty::Uint(t) => {
+            assert!(!negated);
+            lint_uint_literal(cx, hir_id, span, lit, t)
+        }
         ty::Float(t) => {
             let (is_infinite, sym) = match lit.node {
                 ast::LitKind::Float(v, _) => match t {

tests/ui/pattern/overflowing-literals.rs

@@ -3,8 +3,6 @@
 #![feature(pattern_types)]
 #![feature(pattern_type_macro)]
 
-//@ check-pass
-
 use std::pat::pattern_type;
 
 // FIXME(pattern_types): also reject overflowing literals
@@ -14,6 +12,7 @@ type TooSmall = pattern_type!(i8 is -500..);
 fn main() {
     match 5_u8 {
         500 => {}
+        //~^ ERROR literal out of range for `u8`
         _ => {}
     }
 }

tests/ui/pattern/overflowing-literals.stderr

@@ -0,0 +1,11 @@
+error: literal out of range for `u8`
+  --> $DIR/overflowing-literals.rs:14:9
+   |
+LL |         500 => {}
+   |         ^^^
+   |
+   = note: the literal `500` does not fit into the type `u8` whose range is `0..=255`
+   = note: `#[deny(overflowing_literals)]` on by default
+
+error: aborting due to 1 previous error
+