Fix ICE in match_same_arms (#16685)

The wrong `TypeckResults` was used in the fallback equality function
passed by the `match_same_arms` and `filter_map` lints. Previously,
those fallback functions had no way of using the proper `TypeckResults`.
Those (one per expression being compared) are now passed to the
registered fallback function.

changelog: [`match_same_arms`]: fix internal compiler error

Fixes rust-lang/rust-clippy#16678
Fixes rust-lang/rust-clippy#16686

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### Summary Notes

- [Beta
nomination](https://github.com/rust-lang/rust-clippy/pull/16685#issuecomment-4017155418)
by [samueltardieu](https://github.com/samueltardieu)

*Managed by `@rustbot`—see
[help](https://forge.rust-lang.org/triagebot/note.html) for details*

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src/tools/clippy/clippy_lints/src/matches/match_same_arms.rs

@@ -12,7 +12,7 @@
 use rustc_hir::{Arm, Expr, HirId, HirIdMap, HirIdMapEntry, HirIdSet, Pat, PatExpr, PatExprKind, PatKind, RangeEnd};
 use rustc_lint::builtin::NON_EXHAUSTIVE_OMITTED_PATTERNS;
 use rustc_lint::{LateContext, LintContext};
-use rustc_middle::ty;
+use rustc_middle::ty::{self, TypeckResults};
 use rustc_span::{ByteSymbol, ErrorGuaranteed, Span, Symbol};
 
 use super::MATCH_SAME_ARMS;
@@ -61,7 +61,10 @@ pub(super) fn check<'tcx>(cx: &LateContext<'tcx>, arms: &'tcx [Arm<'_>]) {
 
         let check_eq_with_pat = |expr_a: &Expr<'_>, expr_b: &Expr<'_>| {
             let mut local_map: HirIdMap<HirId> = HirIdMap::default();
-            let eq_fallback = |a: &Expr<'_>, b: &Expr<'_>| {
+            let eq_fallback = |a_typeck_results: &TypeckResults<'tcx>,
+                               a: &Expr<'_>,
+                               b_typeck_results: &TypeckResults<'tcx>,
+                               b: &Expr<'_>| {
                 if let Some(a_id) = a.res_local_id()
                     && let Some(b_id) = b.res_local_id()
                     && let entry = match local_map.entry(a_id) {
@@ -71,7 +74,7 @@ pub(super) fn check<'tcx>(cx: &LateContext<'tcx>, arms: &'tcx [Arm<'_>]) {
                     }
                     // the names technically don't have to match; this makes the lint more conservative
                     && cx.tcx.hir_name(a_id) == cx.tcx.hir_name(b_id)
-                    && cx.typeck_results().expr_ty(a) == cx.typeck_results().expr_ty(b)
+                    && a_typeck_results.expr_ty(a) == b_typeck_results.expr_ty(b)
                     && pat_contains_local(lhs.pat, a_id)
                     && pat_contains_local(rhs.pat, b_id)
                 {

src/tools/clippy/clippy_lints/src/methods/filter_map.rs

@@ -9,6 +9,7 @@
 use rustc_hir::def::Res;
 use rustc_hir::{Closure, Expr, ExprKind, PatKind, PathSegment, QPath, UnOp};
 use rustc_lint::LateContext;
+use rustc_middle::ty::TypeckResults;
 use rustc_middle::ty::adjustment::Adjust;
 use rustc_span::Span;
 use rustc_span::symbol::{Ident, Symbol};
@@ -136,7 +137,9 @@ pub fn check_map_call(
                     // .map(|y| y[.acceptable_method()].unwrap())
                     && let simple_equal = (receiver.res_local_id() == Some(filter_param_id)
                         && map_arg_peeled.res_local_id() == Some(map_param_id))
-                    && let eq_fallback = (|a: &Expr<'_>, b: &Expr<'_>| {
+                    && let eq_fallback =
+                    (|a_typeck_results: &TypeckResults<'tcx>, a: &Expr<'_>,
+                     b_typeck_results: &TypeckResults<'tcx>, b: &Expr<'_>| {
                         // in `filter(|x| ..)`, replace `*x` with `x`
                         let a_path = if !is_filter_param_ref
                             && let ExprKind::Unary(UnOp::Deref, expr_path) = a.kind
@@ -144,7 +147,7 @@ pub fn check_map_call(
                         // let the filter closure arg and the map closure arg be equal
                         a_path.res_local_id() == Some(filter_param_id)
                             && b.res_local_id() == Some(map_param_id)
-                            && cx.typeck_results().expr_ty_adjusted(a) == cx.typeck_results().expr_ty_adjusted(b)
+                            && a_typeck_results.expr_ty_adjusted(a) == b_typeck_results.expr_ty_adjusted(b)
                     })
                     && (simple_equal
                         || SpanlessEq::new(cx).expr_fallback(eq_fallback).eq_expr(receiver, map_arg_peeled))

src/tools/clippy/clippy_utils/src/hir_utils.rs

@@ -26,7 +26,8 @@
 
 /// Callback that is called when two expressions are not equal in the sense of `SpanlessEq`, but
 /// other conditions would make them equal.
-type SpanlessEqCallback<'a> = dyn FnMut(&Expr<'_>, &Expr<'_>) -> bool + 'a;
+type SpanlessEqCallback<'a, 'tcx> =
+    dyn FnMut(&TypeckResults<'tcx>, &Expr<'_>, &TypeckResults<'tcx>, &Expr<'_>) -> bool + 'a;
 
 /// Determines how paths are hashed and compared for equality.
 #[derive(Copy, Clone, Debug, Default)]
@@ -59,7 +60,7 @@ pub struct SpanlessEq<'a, 'tcx> {
     cx: &'a LateContext<'tcx>,
     maybe_typeck_results: Option<(&'tcx TypeckResults<'tcx>, &'tcx TypeckResults<'tcx>)>,
     allow_side_effects: bool,
-    expr_fallback: Option<Box<SpanlessEqCallback<'a>>>,
+    expr_fallback: Option<Box<SpanlessEqCallback<'a, 'tcx>>>,
     path_check: PathCheck,
 }
 
@@ -94,7 +95,10 @@ pub fn paths_by_resolution(self) -> Self {
     }
 
     #[must_use]
-    pub fn expr_fallback(self, expr_fallback: impl FnMut(&Expr<'_>, &Expr<'_>) -> bool + 'a) -> Self {
+    pub fn expr_fallback(
+        self,
+        expr_fallback: impl FnMut(&TypeckResults<'tcx>, &Expr<'_>, &TypeckResults<'tcx>, &Expr<'_>) -> bool + 'a,
+    ) -> Self {
         Self {
             expr_fallback: Some(Box::new(expr_fallback)),
             ..self
@@ -639,7 +643,15 @@ pub fn eq_expr(&mut self, left: &Expr<'_>, right: &Expr<'_>) -> bool {
             ) => false,
         };
         (is_eq && (!self.should_ignore(left) || !self.should_ignore(right)))
-            || self.inner.expr_fallback.as_mut().is_some_and(|f| f(left, right))
+            || self
+                .inner
+                .maybe_typeck_results
+                .is_some_and(|(left_typeck_results, right_typeck_results)| {
+                    self.inner
+                        .expr_fallback
+                        .as_mut()
+                        .is_some_and(|f| f(left_typeck_results, left, right_typeck_results, right))
+                })
     }
 
     fn eq_exprs(&mut self, left: &[Expr<'_>], right: &[Expr<'_>]) -> bool {

src/tools/clippy/tests/ui/match_same_arms.fixed

@@ -140,3 +140,19 @@ fn main() {
         _ => false,
     };
 }
+
+fn issue16678() {
+    // ICE in Rust 1.94.0
+    match true {
+        true => {
+            fn wrapper(_arg: ()) {
+                _arg;
+            }
+        },
+        false => {
+            fn wrapper(_arg: ()) {
+                _arg;
+            }
+        },
+    }
+}

src/tools/clippy/tests/ui/match_same_arms.rs

@@ -149,3 +149,19 @@ fn main() {
         _ => false,
     };
 }
+
+fn issue16678() {
+    // ICE in Rust 1.94.0
+    match true {
+        true => {
+            fn wrapper(_arg: ()) {
+                _arg;
+            }
+        },
+        false => {
+            fn wrapper(_arg: ()) {
+                _arg;
+            }
+        },
+    }
+}