Don't store ty and span in IntRange

We prefer to grab `ty` and `span` from `pcx`. This makes it consistent
with other constructors.

Author: Nadrieril

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

@@ -37,14 +37,12 @@ use std::ops::RangeInclusive;
 ///
 /// `IntRange` is never used to encode an empty range or a "range" that wraps
 /// around the (offset) space: i.e., `range.lo <= range.hi`.
-#[derive(Clone, Debug)]
-pub(super) struct IntRange<'tcx> {
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub(super) struct IntRange {
     range: RangeInclusive<u128>,
-    ty: Ty<'tcx>,
-    span: Span,
 }
 
-impl<'tcx> IntRange<'tcx> {
+impl IntRange {
     #[inline]
     fn is_integral(ty: Ty<'_>) -> bool {
         matches!(ty.kind(), ty::Char | ty::Int(_) | ty::Uint(_) | ty::Bool)
@@ -59,7 +57,7 @@ impl<'tcx> IntRange<'tcx> {
     }
 
     #[inline]
-    fn integral_size_and_signed_bias(tcx: TyCtxt<'tcx>, ty: Ty<'_>) -> Option<(Size, u128)> {
+    fn integral_size_and_signed_bias(tcx: TyCtxt<'_>, ty: Ty<'_>) -> Option<(Size, u128)> {
         match *ty.kind() {
             ty::Bool => Some((Size::from_bytes(1), 0)),
             ty::Char => Some((Size::from_bytes(4), 0)),
@@ -73,12 +71,11 @@ impl<'tcx> IntRange<'tcx> {
     }
 
     #[inline]
-    fn from_const(
+    fn from_const<'tcx>(
         tcx: TyCtxt<'tcx>,
         param_env: ty::ParamEnv<'tcx>,
         value: &Const<'tcx>,
-        span: Span,
-    ) -> Option<IntRange<'tcx>> {
+    ) -> Option<IntRange> {
         if let Some((target_size, bias)) = Self::integral_size_and_signed_bias(tcx, value.ty) {
             let ty = value.ty;
             let val = (|| {
@@ -95,21 +92,20 @@ impl<'tcx> IntRange<'tcx> {
                 value.try_eval_bits(tcx, param_env, ty)
             })()?;
             let val = val ^ bias;
-            Some(IntRange { range: val..=val, ty, span })
+            Some(IntRange { range: val..=val })
         } else {
             None
         }
     }
 
     #[inline]
-    fn from_range(
+    fn from_range<'tcx>(
         tcx: TyCtxt<'tcx>,
         lo: u128,
         hi: u128,
         ty: Ty<'tcx>,
         end: &RangeEnd,
-        span: Span,
-    ) -> Option<IntRange<'tcx>> {
+    ) -> Option<IntRange> {
         if Self::is_integral(ty) {
             // Perform a shift if the underlying types are signed,
             // which makes the interval arithmetic simpler.
@@ -120,14 +116,14 @@ impl<'tcx> IntRange<'tcx> {
                 // This should have been caught earlier by E0030.
                 bug!("malformed range pattern: {}..={}", lo, (hi - offset));
             }
-            Some(IntRange { range: lo..=(hi - offset), ty, span })
+            Some(IntRange { range: lo..=(hi - offset) })
         } else {
             None
         }
     }
 
     // The return value of `signed_bias` should be XORed with an endpoint to encode/decode it.
-    fn signed_bias(tcx: TyCtxt<'tcx>, ty: Ty<'tcx>) -> u128 {
+    fn signed_bias(tcx: TyCtxt<'_>, ty: Ty<'_>) -> u128 {
         match *ty.kind() {
             ty::Int(ity) => {
                 let bits = Integer::from_attr(&tcx, SignedInt(ity)).size().bits() as u128;
@@ -142,12 +138,10 @@ impl<'tcx> IntRange<'tcx> {
     }
 
     fn intersection(&self, other: &Self) -> Option<Self> {
-        let ty = self.ty;
         let (lo, hi) = self.boundaries();
         let (other_lo, other_hi) = other.boundaries();
         if lo <= other_hi && other_lo <= hi {
-            let span = other.span;
-            Some(IntRange { range: max(lo, other_lo)..=min(hi, other_hi), ty, span })
+            Some(IntRange { range: max(lo, other_lo)..=min(hi, other_hi) })
         } else {
             None
         }
@@ -170,24 +164,23 @@ impl<'tcx> IntRange<'tcx> {
         lo == other_hi || hi == other_lo
     }
 
-    fn to_pat(&self, tcx: TyCtxt<'tcx>) -> Pat<'tcx> {
+    fn to_pat<'tcx>(&self, tcx: TyCtxt<'tcx>, ty: Ty<'tcx>) -> Pat<'tcx> {
         let (lo, hi) = self.boundaries();
 
-        let bias = IntRange::signed_bias(tcx, self.ty);
+        let bias = IntRange::signed_bias(tcx, ty);
         let (lo, hi) = (lo ^ bias, hi ^ bias);
 
-        let ty = ty::ParamEnv::empty().and(self.ty);
-        let lo_const = ty::Const::from_bits(tcx, lo, ty);
-        let hi_const = ty::Const::from_bits(tcx, hi, ty);
+        let env = ty::ParamEnv::empty().and(ty);
+        let lo_const = ty::Const::from_bits(tcx, lo, env);
+        let hi_const = ty::Const::from_bits(tcx, hi, env);
 
         let kind = if lo == hi {
             PatKind::Constant { value: lo_const }
         } else {
             PatKind::Range(PatRange { lo: lo_const, hi: hi_const, end: RangeEnd::Included })
         };
 
-        // This is a brand new pattern, so we don't reuse `self.span`.
-        Pat { ty: self.ty, span: DUMMY_SP, kind: Box::new(kind) }
+        Pat { ty, span: DUMMY_SP, kind: Box::new(kind) }
     }
 
     /// For exhaustive integer matching, some constructors are grouped within other constructors
@@ -222,13 +215,11 @@ impl<'tcx> IntRange<'tcx> {
     /// boundaries for each interval range, sort them, then create constructors for each new interval
     /// between every pair of boundary points. (This essentially sums up to performing the intuitive
     /// merging operation depicted above.)
-    fn split<'p>(
+    fn split<'p, 'tcx>(
         &self,
         pcx: PatCtxt<'_, 'p, 'tcx>,
         hir_id: Option<HirId>,
     ) -> SmallVec<[Constructor<'tcx>; 1]> {
-        let ty = pcx.ty;
-
         /// Represents a border between 2 integers. Because the intervals spanning borders
         /// must be able to cover every integer, we need to be able to represent
         /// 2^128 + 1 such borders.
@@ -239,7 +230,7 @@ impl<'tcx> IntRange<'tcx> {
         }
 
         // A function for extracting the borders of an integer interval.
-        fn range_borders(r: IntRange<'_>) -> impl Iterator<Item = Border> {
+        fn range_borders(r: IntRange) -> impl Iterator<Item = Border> {
             let (lo, hi) = r.range.into_inner();
             let from = Border::JustBefore(lo);
             let to = match hi.checked_add(1) {
@@ -257,21 +248,23 @@ impl<'tcx> IntRange<'tcx> {
         // class lies between 2 borders.
         let row_borders = pcx
             .matrix
-            .head_ctors(pcx.cx)
-            .filter_map(|ctor| ctor.as_int_range())
-            .filter_map(|range| {
+            .head_ctors_and_spans(pcx.cx)
+            .filter_map(|(ctor, span)| Some((ctor.as_int_range()?, span)))
+            .filter_map(|(range, span)| {
                 let intersection = self.intersection(&range);
                 let should_lint = self.suspicious_intersection(&range);
                 if let (Some(range), 1, true) = (&intersection, row_len, should_lint) {
                     // FIXME: for now, only check for overlapping ranges on simple range
                     // patterns. Otherwise with the current logic the following is detected
                     // as overlapping:
-                    //   match (10u8, true) {
-                    //    (0 ..= 125, false) => {}
-                    //    (126 ..= 255, false) => {}
-                    //    (0 ..= 255, true) => {}
-                    //  }
-                    overlaps.push(range.clone());
+                    // ```
+                    // match (0u8, true) {
+                    //   (0 ..= 125, false) => {}
+                    //   (125 ..= 255, true) => {}
+                    //   _ => {}
+                    // }
+                    // ```
+                    overlaps.push((range.clone(), span));
                 }
                 intersection
             })
@@ -280,7 +273,7 @@ impl<'tcx> IntRange<'tcx> {
         let mut borders: Vec<_> = row_borders.chain(self_borders).collect();
         borders.sort_unstable();
 
-        self.lint_overlapping_patterns(pcx.cx.tcx, hir_id, ty, overlaps);
+        self.lint_overlapping_patterns(pcx, hir_id, overlaps);
 
         // We're going to iterate through every adjacent pair of borders, making sure that
         // each represents an interval of nonnegative length, and convert each such
@@ -298,33 +291,32 @@ impl<'tcx> IntRange<'tcx> {
                 [Border::JustBefore(n), Border::AfterMax] => Some(n..=u128::MAX),
                 [Border::AfterMax, _] => None,
             })
-            .map(|range| IntRange { range, ty, span: pcx.span })
+            .map(|range| IntRange { range })
             .map(IntRange)
             .collect()
     }
 
     fn lint_overlapping_patterns(
         &self,
-        tcx: TyCtxt<'tcx>,
+        pcx: PatCtxt<'_, '_, '_>,
         hir_id: Option<HirId>,
-        ty: Ty<'tcx>,
-        overlaps: Vec<IntRange<'tcx>>,
+        overlaps: Vec<(IntRange, Span)>,
     ) {
         if let (true, Some(hir_id)) = (!overlaps.is_empty(), hir_id) {
-            tcx.struct_span_lint_hir(
+            pcx.cx.tcx.struct_span_lint_hir(
                 lint::builtin::OVERLAPPING_PATTERNS,
                 hir_id,
-                self.span,
+                pcx.span,
                 |lint| {
                     let mut err = lint.build("multiple patterns covering the same range");
-                    err.span_label(self.span, "overlapping patterns");
-                    for int_range in overlaps {
+                    err.span_label(pcx.span, "overlapping patterns");
+                    for (int_range, span) in overlaps {
                         // Use the real type for user display of the ranges:
                         err.span_label(
-                            int_range.span,
+                            span,
                             &format!(
                                 "this range overlaps on `{}`",
-                                IntRange { range: int_range.range, ty, span: DUMMY_SP }.to_pat(tcx),
+                                int_range.to_pat(pcx.cx.tcx, pcx.ty),
                             ),
                         );
                     }
@@ -347,13 +339,6 @@ impl<'tcx> IntRange<'tcx> {
     }
 }
 
-/// Ignore spans when comparing, they don't carry semantic information as they are only for lints.
-impl<'tcx> std::cmp::PartialEq for IntRange<'tcx> {
-    fn eq(&self, other: &Self) -> bool {
-        self.range == other.range && self.ty == other.ty
-    }
-}
-
 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
 enum SliceKind {
     /// Patterns of length `n` (`[x, y]`).
@@ -547,7 +532,7 @@ pub(super) enum Constructor<'tcx> {
     /// Enum variants.
     Variant(DefId),
     /// Ranges of integer literal values (`2`, `2..=5` or `2..5`).
-    IntRange(IntRange<'tcx>),
+    IntRange(IntRange),
     /// Ranges of floating-point literal values (`2.0..=5.2`).
     FloatRange(&'tcx ty::Const<'tcx>, &'tcx ty::Const<'tcx>, RangeEnd),
     /// String literals. Strings are not quite the same as `&[u8]` so we treat them separately.
@@ -570,7 +555,7 @@ impl<'tcx> Constructor<'tcx> {
         matches!(self, Wildcard)
     }
 
-    fn as_int_range(&self) -> Option<&IntRange<'tcx>> {
+    fn as_int_range(&self) -> Option<&IntRange> {
         match self {
             IntRange(range) => Some(range),
             _ => None,
@@ -605,8 +590,7 @@ impl<'tcx> Constructor<'tcx> {
                 Variant(adt_def.variants[variant_index].def_id)
             }
             PatKind::Constant { value } => {
-                if let Some(int_range) = IntRange::from_const(cx.tcx, cx.param_env, value, pat.span)
-                {
+                if let Some(int_range) = IntRange::from_const(cx.tcx, cx.param_env, value) {
                     IntRange(int_range)
                 } else {
                     match pat.ty.kind() {
@@ -630,7 +614,6 @@ impl<'tcx> Constructor<'tcx> {
                     hi.eval_bits(cx.tcx, cx.param_env, hi.ty),
                     ty,
                     &end,
-                    pat.span,
                 ) {
                     IntRange(int_range)
                 } else {
@@ -815,8 +798,7 @@ fn all_constructors<'p, 'tcx>(pcx: PatCtxt<'_, 'p, 'tcx>) -> Vec<Constructor<'tc
     let make_range = |start, end| {
         IntRange(
             // `unwrap()` is ok because we know the type is an integer.
-            IntRange::from_range(cx.tcx, start, end, pcx.ty, &RangeEnd::Included, pcx.span)
-                .unwrap(),
+            IntRange::from_range(cx.tcx, start, end, pcx.ty, &RangeEnd::Included).unwrap(),
         )
     };
     match pcx.ty.kind() {
@@ -1221,7 +1203,7 @@ impl<'p, 'tcx> Fields<'p, 'tcx> {
             },
             &Str(value) => PatKind::Constant { value },
             &FloatRange(lo, hi, end) => PatKind::Range(PatRange { lo, hi, end }),
-            IntRange(range) => return range.to_pat(pcx.cx.tcx),
+            IntRange(range) => return range.to_pat(pcx.cx.tcx, pcx.ty),
             NonExhaustive => PatKind::Wild,
             Opaque => bug!("we should not try to apply an opaque constructor"),
             Wildcard => bug!(

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

@@ -535,14 +535,22 @@ impl<'p, 'tcx> Matrix<'p, 'tcx> {
         self.patterns.iter().map(|r| r.head())
     }
 
-    /// Iterate over the first constructor of each row
+    /// Iterate over the first constructor of each row.
     pub(super) fn head_ctors<'a>(
         &'a self,
         cx: &'a MatchCheckCtxt<'p, 'tcx>,
-    ) -> impl Iterator<Item = &'a Constructor<'tcx>> + Captures<'a> + Captures<'p> {
+    ) -> impl Iterator<Item = &'a Constructor<'tcx>> + Captures<'p> {
         self.patterns.iter().map(move |r| r.head_ctor(cx))
     }
 
+    /// Iterate over the first constructor and the corresponding span of each row.
+    pub(super) fn head_ctors_and_spans<'a>(
+        &'a self,
+        cx: &'a MatchCheckCtxt<'p, 'tcx>,
+    ) -> impl Iterator<Item = (&'a Constructor<'tcx>, Span)> + Captures<'p> {
+        self.patterns.iter().map(move |r| (r.head_ctor(cx), r.head().span))
+    }
+
     /// This computes `S(constructor, self)`. See top of the file for explanations.
     fn specialize_constructor(
         &self,