Rollup merge of #119554 - matthewjasper:remove-guard-distinction, r=compiler-errors

Fix scoping for let chains in match guards

If let guards were previously represented as a different type of guard in HIR and THIR. This meant that let chains in match guards were not handled correctly because they were treated exactly like normal guards.

- Remove `hir::Guard` and `thir::Guard`.
- Make the scoping different between normal guards and if let guards also check for let chains.

closes #118593

compiler/rustc_ast_lowering/src/expr.rs

@@ -546,20 +546,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
 
     fn lower_arm(&mut self, arm: &Arm) -> hir::Arm<'hir> {
         let pat = self.lower_pat(&arm.pat);
-        let guard = arm.guard.as_ref().map(|cond| {
+        let guard = arm.guard.as_ref().map(|cond| self.lower_expr(cond));
-            if let ExprKind::Let(pat, scrutinee, span, is_recovered) = &cond.kind {
-                hir::Guard::IfLet(self.arena.alloc(hir::Let {
-                    hir_id: self.next_id(),
-                    span: self.lower_span(*span),
-                    pat: self.lower_pat(pat),
-                    ty: None,
-                    init: self.lower_expr(scrutinee),
-                    is_recovered: *is_recovered,
-                }))
-            } else {
-                hir::Guard::If(self.lower_expr(cond))
-            }
-        });
         let hir_id = self.next_id();
         let span = self.lower_span(arm.span);
         self.lower_attrs(hir_id, &arm.attrs);

compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs

@@ -3590,7 +3590,7 @@ impl<'b, 'v> Visitor<'v> for ConditionVisitor<'b> {
                                 ));
                             } else if let Some(guard) = &arm.guard {
                                 self.errors.push((
-                                    arm.pat.span.to(guard.body().span),
+                                    arm.pat.span.to(guard.span),
                                     format!(
                                         "if this pattern and condition are matched, {} is not \
                                          initialized",

compiler/rustc_hir/src/hir.rs

@@ -1258,7 +1258,7 @@ pub struct Arm<'hir> {
     /// If this pattern and the optional guard matches, then `body` is evaluated.
     pub pat: &'hir Pat<'hir>,
     /// Optional guard clause.
-    pub guard: Option<Guard<'hir>>,
+    pub guard: Option<&'hir Expr<'hir>>,
     /// The expression the arm evaluates to if this arm matches.
     pub body: &'hir Expr<'hir>,
 }
@@ -1280,26 +1280,6 @@ pub struct Let<'hir> {
     pub is_recovered: Option<ErrorGuaranteed>,
 }
 
-#[derive(Debug, Clone, Copy, HashStable_Generic)]
-pub enum Guard<'hir> {
-    If(&'hir Expr<'hir>),
-    IfLet(&'hir Let<'hir>),
-}
-
-impl<'hir> Guard<'hir> {
-    /// Returns the body of the guard
-    ///
-    /// In other words, returns the e in either of the following:
-    ///
-    /// - `if e`
-    /// - `if let x = e`
-    pub fn body(&self) -> &'hir Expr<'hir> {
-        match self {
-            Guard::If(e) | Guard::IfLet(Let { init: e, .. }) => e,
-        }
-    }
-}
-
 #[derive(Debug, Clone, Copy, HashStable_Generic)]
 pub struct ExprField<'hir> {
     #[stable_hasher(ignore)]

compiler/rustc_hir/src/intravisit.rs

@@ -619,13 +619,8 @@ pub fn walk_stmt<'v, V: Visitor<'v>>(visitor: &mut V, statement: &'v Stmt<'v>) {
 pub fn walk_arm<'v, V: Visitor<'v>>(visitor: &mut V, arm: &'v Arm<'v>) {
     visitor.visit_id(arm.hir_id);
     visitor.visit_pat(arm.pat);
-    if let Some(ref g) = arm.guard {
+    if let Some(ref e) = arm.guard {
-        match g {
+        visitor.visit_expr(e);
-            Guard::If(ref e) => visitor.visit_expr(e),
-            Guard::IfLet(ref l) => {
-                visitor.visit_let_expr(l);
-            }
-        }
     }
     visitor.visit_expr(arm.body);
 }

compiler/rustc_hir_analysis/src/check/region.rs

@@ -177,6 +177,14 @@ fn resolve_block<'tcx>(visitor: &mut RegionResolutionVisitor<'tcx>, blk: &'tcx h
 }
 
 fn resolve_arm<'tcx>(visitor: &mut RegionResolutionVisitor<'tcx>, arm: &'tcx hir::Arm<'tcx>) {
+    fn has_let_expr(expr: &Expr<'_>) -> bool {
+        match &expr.kind {
+            hir::ExprKind::Binary(_, lhs, rhs) => has_let_expr(lhs) || has_let_expr(rhs),
+            hir::ExprKind::Let(..) => true,
+            _ => false,
+        }
+    }
+
     let prev_cx = visitor.cx;
 
     visitor.terminating_scopes.insert(arm.hir_id.local_id);
@@ -184,7 +192,9 @@ fn resolve_arm<'tcx>(visitor: &mut RegionResolutionVisitor<'tcx>, arm: &'tcx hir
     visitor.enter_node_scope_with_dtor(arm.hir_id.local_id);
     visitor.cx.var_parent = visitor.cx.parent;
 
-    if let Some(hir::Guard::If(expr)) = arm.guard {
+    if let Some(expr) = arm.guard
+        && !has_let_expr(expr)
+    {
         visitor.terminating_scopes.insert(expr.hir_id.local_id);
     }
 

compiler/rustc_hir_pretty/src/lib.rs

@@ -1874,18 +1874,10 @@ impl<'a> State<'a> {
         self.print_pat(arm.pat);
         self.space();
         if let Some(ref g) = arm.guard {
-            match *g {
-                hir::Guard::If(e) => {
             self.word_space("if");
-                    self.print_expr(e);
+            self.print_expr(g);
             self.space();
         }
-                hir::Guard::IfLet(&hir::Let { pat, ty, init, .. }) => {
-                    self.word_nbsp("if");
-                    self.print_let(pat, ty, init);
-                }
-            }
-        }
         self.word_space("=>");
 
         match arm.body.kind {

compiler/rustc_hir_typeck/src/_match.rs

@@ -78,17 +78,10 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         let mut other_arms = vec![]; // Used only for diagnostics.
         let mut prior_arm = None;
         for arm in arms {
-            if let Some(g) = &arm.guard {
+            if let Some(e) = &arm.guard {
                 self.diverges.set(Diverges::Maybe);
-                match g {
-                    hir::Guard::If(e) => {
                 self.check_expr_has_type_or_error(e, tcx.types.bool, |_| {});
             }
-                    hir::Guard::IfLet(l) => {
-                        self.check_expr_let(l);
-                    }
-                };
-            }
 
             self.diverges.set(Diverges::Maybe);
 

compiler/rustc_hir_typeck/src/expr_use_visitor.rs

@@ -669,12 +669,8 @@ impl<'a, 'tcx> ExprUseVisitor<'a, 'tcx> {
         );
         self.walk_pat(discr_place, arm.pat, arm.guard.is_some());
 
-        match arm.guard {
+        if let Some(ref e) = arm.guard {
-            Some(hir::Guard::If(e)) => self.consume_expr(e),
+            self.consume_expr(e)
-            Some(hir::Guard::IfLet(l)) => {
-                self.walk_local(l.init, l.pat, None, |t| t.borrow_expr(l.init, ty::ImmBorrow))
-            }
-            None => {}
         }
 
         self.consume_expr(arm.body);

compiler/rustc_middle/src/thir.rs

@@ -519,20 +519,13 @@ pub struct FruInfo<'tcx> {
 #[derive(Clone, Debug, HashStable)]
 pub struct Arm<'tcx> {
     pub pattern: Box<Pat<'tcx>>,
-    pub guard: Option<Guard<'tcx>>,
+    pub guard: Option<ExprId>,
     pub body: ExprId,
     pub lint_level: LintLevel,
     pub scope: region::Scope,
     pub span: Span,
 }
 
-/// A `match` guard.
-#[derive(Clone, Debug, HashStable)]
-pub enum Guard<'tcx> {
-    If(ExprId),
-    IfLet(Box<Pat<'tcx>>, ExprId),
-}
-
 #[derive(Copy, Clone, Debug, HashStable)]
 pub enum LogicalOp {
     /// The `&&` operator.

compiler/rustc_middle/src/thir/visit.rs

@@ -1,5 +1,5 @@
 use super::{
-    AdtExpr, Arm, Block, ClosureExpr, Expr, ExprKind, Guard, InlineAsmExpr, InlineAsmOperand, Pat,
+    AdtExpr, Arm, Block, ClosureExpr, Expr, ExprKind, InlineAsmExpr, InlineAsmOperand, Pat,
     PatKind, Stmt, StmtKind, Thir,
 };
 
@@ -213,13 +213,8 @@ pub fn walk_arm<'thir, 'tcx: 'thir, V: Visitor<'thir, 'tcx>>(
     visitor: &mut V,
     arm: &'thir Arm<'tcx>,
 ) {
-    match arm.guard {
+    if let Some(expr) = arm.guard {
-        Some(Guard::If(expr)) => visitor.visit_expr(&visitor.thir()[expr]),
+        visitor.visit_expr(&visitor.thir()[expr])
-        Some(Guard::IfLet(ref pat, expr)) => {
-            visitor.visit_pat(pat);
-            visitor.visit_expr(&visitor.thir()[expr]);
-        }
-        None => {}
     }
     visitor.visit_pat(&arm.pattern);
     visitor.visit_expr(&visitor.thir()[arm.body]);

compiler/rustc_mir_build/src/build/expr/into.rs

@@ -82,7 +82,8 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                                         cond,
                                         Some(condition_scope),
                                         condition_scope,
-                                        source_info
+                                        source_info,
+                                        true,
                                     ));
 
                                     this.expr_into_dest(destination, then_blk, then)
@@ -173,6 +174,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                             Some(condition_scope),
                             condition_scope,
                             source_info,
+                            true,
                         )
                     });
                 let (short_circuit, continuation, constant) = match op {

compiler/rustc_mir_build/src/build/matches/mod.rs

@@ -33,6 +33,12 @@ use std::borrow::Borrow;
 use std::mem;
 
 impl<'a, 'tcx> Builder<'a, 'tcx> {
+    /// Lowers a condition in a way that ensures that variables bound in any let
+    /// expressions are definitely initialized in the if body.
+    ///
+    /// If `declare_bindings` is false then variables created in `let`
+    /// expressions will not be declared. This is for if let guards on arms with
+    /// an or pattern, where the guard is lowered multiple times.
     pub(crate) fn then_else_break(
         &mut self,
         mut block: BasicBlock,
@@ -40,6 +46,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
         temp_scope_override: Option<region::Scope>,
         break_scope: region::Scope,
         variable_source_info: SourceInfo,
+        declare_bindings: bool,
     ) -> BlockAnd<()> {
         let this = self;
         let expr = &this.thir[expr_id];
@@ -53,6 +60,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                     temp_scope_override,
                     break_scope,
                     variable_source_info,
+                    declare_bindings,
                 ));
 
                 let rhs_then_block = unpack!(this.then_else_break(
@@ -61,6 +69,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                     temp_scope_override,
                     break_scope,
                     variable_source_info,
+                    declare_bindings,
                 ));
 
                 rhs_then_block.unit()
@@ -75,6 +84,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                             temp_scope_override,
                             local_scope,
                             variable_source_info,
+                            true,
                         )
                     });
                 let rhs_success_block = unpack!(this.then_else_break(
@@ -83,6 +93,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                     temp_scope_override,
                     break_scope,
                     variable_source_info,
+                    true,
                 ));
                 this.cfg.goto(lhs_success_block, variable_source_info, rhs_success_block);
                 rhs_success_block.unit()
@@ -102,6 +113,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                             temp_scope_override,
                             local_scope,
                             variable_source_info,
+                            true,
                         )
                     });
                 this.break_for_else(success_block, break_scope, variable_source_info);
@@ -116,6 +128,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                         temp_scope_override,
                         break_scope,
                         variable_source_info,
+                        declare_bindings,
                     )
                 })
             }
@@ -125,6 +138,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                 temp_scope_override,
                 break_scope,
                 variable_source_info,
+                declare_bindings,
             ),
             ExprKind::Let { expr, ref pat } => this.lower_let_expr(
                 block,
@@ -133,7 +147,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                 break_scope,
                 Some(variable_source_info.scope),
                 variable_source_info.span,
-                true,
+                declare_bindings,
             ),
             _ => {
                 let temp_scope = temp_scope_override.unwrap_or_else(|| this.local_scope());
@@ -417,7 +431,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                         None,
                         arm.span,
                         &arm.pattern,
-                        arm.guard.as_ref(),
+                        arm.guard,
                         opt_scrutinee_place,
                     );
 
@@ -709,7 +723,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
         mut visibility_scope: Option<SourceScope>,
         scope_span: Span,
         pattern: &Pat<'tcx>,
-        guard: Option<&Guard<'tcx>>,
+        guard: Option<ExprId>,
         opt_match_place: Option<(Option<&Place<'tcx>>, Span)>,
     ) -> Option<SourceScope> {
         self.visit_primary_bindings(
@@ -737,11 +751,38 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                 );
             },
         );
-        if let Some(Guard::IfLet(guard_pat, _)) = guard {
+        if let Some(guard_expr) = guard {
+            self.declare_guard_bindings(guard_expr, scope_span, visibility_scope);
+        }
+        visibility_scope
+    }
+
+    /// Declare bindings in a guard. This has to be done when declaring bindings
+    /// for an arm to ensure that or patterns only have one version of each
+    /// variable.
+    pub(crate) fn declare_guard_bindings(
+        &mut self,
+        guard_expr: ExprId,
+        scope_span: Span,
+        visibility_scope: Option<SourceScope>,
+    ) {
+        match self.thir.exprs[guard_expr].kind {
+            ExprKind::Let { expr: _, pat: ref guard_pat } => {
                 // FIXME: pass a proper `opt_match_place`
                 self.declare_bindings(visibility_scope, scope_span, guard_pat, None, None);
             }
-        visibility_scope
+            ExprKind::Scope { value, .. } => {
+                self.declare_guard_bindings(value, scope_span, visibility_scope);
+            }
+            ExprKind::Use { source } => {
+                self.declare_guard_bindings(source, scope_span, visibility_scope);
+            }
+            ExprKind::LogicalOp { op: LogicalOp::And, lhs, rhs } => {
+                self.declare_guard_bindings(lhs, scope_span, visibility_scope);
+                self.declare_guard_bindings(rhs, scope_span, visibility_scope);
+            }
+            _ => {}
+        }
     }
 
     pub(crate) fn storage_live_binding(
@@ -2009,7 +2050,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
         //    * So we eagerly create the reference for the arm and then take a
         //      reference to that.
         if let Some((arm, match_scope)) = arm_match_scope
-            && let Some(guard) = &arm.guard
+            && let Some(guard) = arm.guard
         {
             let tcx = self.tcx;
             let bindings = parent_bindings
@@ -2034,21 +2075,16 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
             let mut guard_span = rustc_span::DUMMY_SP;
 
             let (post_guard_block, otherwise_post_guard_block) =
-                self.in_if_then_scope(match_scope, guard_span, |this| match *guard {
+                self.in_if_then_scope(match_scope, guard_span, |this| {
-                    Guard::If(e) => {
+                    guard_span = this.thir[guard].span;
-                        guard_span = this.thir[e].span;
                     this.then_else_break(
                         block,
-                            e,
+                        guard,
                         None,
                         match_scope,
                         this.source_info(arm.span),
+                        false,
                     )
-                    }
-                    Guard::IfLet(ref pat, s) => {
-                        guard_span = this.thir[s].span;
-                        this.lower_let_expr(block, s, pat, match_scope, None, arm.span, false)
-                    }
                 });
 
             let source_info = self.source_info(guard_span);

compiler/rustc_mir_build/src/thir/cx/expr.rs

@@ -855,13 +855,8 @@ impl<'tcx> Cx<'tcx> {
 
     fn convert_arm(&mut self, arm: &'tcx hir::Arm<'tcx>) -> ArmId {
         let arm = Arm {
-            pattern: self.pattern_from_hir(arm.pat),
+            pattern: self.pattern_from_hir(&arm.pat),
-            guard: arm.guard.as_ref().map(|g| match g {
+            guard: arm.guard.as_ref().map(|g| self.mirror_expr(g)),
-                hir::Guard::If(e) => Guard::If(self.mirror_expr(e)),
-                hir::Guard::IfLet(l) => {
-                    Guard::IfLet(self.pattern_from_hir(l.pat), self.mirror_expr(l.init))
-                }
-            }),
             body: self.mirror_expr(arm.body),
             lint_level: LintLevel::Explicit(arm.hir_id),
             scope: region::Scope { id: arm.hir_id.local_id, data: region::ScopeData::Node },

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

@@ -100,21 +100,11 @@ impl<'p, 'tcx> Visitor<'p, 'tcx> for MatchVisitor<'p, 'tcx> {
     #[instrument(level = "trace", skip(self))]
     fn visit_arm(&mut self, arm: &'p Arm<'tcx>) {
         self.with_lint_level(arm.lint_level, |this| {
-            match arm.guard {
+            if let Some(expr) = 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, Some(expr), pat.span);
-                        this.visit_pat(pat);
-                        this.visit_expr(&this.thir[expr]);
-                    });
-                }
-                None => {}
-            }
             this.visit_pat(&arm.pattern);
             this.visit_expr(&self.thir[arm.body]);
         });

compiler/rustc_mir_build/src/thir/print.rs

@@ -593,9 +593,9 @@ impl<'a, 'tcx> ThirPrinter<'a, 'tcx> {
         print_indented!(self, "pattern: ", depth_lvl + 1);
         self.print_pat(pattern, depth_lvl + 2);
 
-        if let Some(guard) = guard {
+        if let Some(guard) = *guard {
             print_indented!(self, "guard: ", depth_lvl + 1);
-            self.print_guard(guard, depth_lvl + 2);
+            self.print_expr(guard, depth_lvl + 2);
         } else {
             print_indented!(self, "guard: None", depth_lvl + 1);
         }
@@ -764,27 +764,6 @@ impl<'a, 'tcx> ThirPrinter<'a, 'tcx> {
         print_indented!(self, "}", depth_lvl);
     }
 
-    fn print_guard(&mut self, guard: &Guard<'tcx>, depth_lvl: usize) {
-        print_indented!(self, "Guard {", depth_lvl);
-
-        match guard {
-            Guard::If(expr_id) => {
-                print_indented!(self, "If (", depth_lvl + 1);
-                self.print_expr(*expr_id, depth_lvl + 2);
-                print_indented!(self, ")", depth_lvl + 1);
-            }
-            Guard::IfLet(pat, expr_id) => {
-                print_indented!(self, "IfLet (", depth_lvl + 1);
-                self.print_pat(pat, depth_lvl + 2);
-                print_indented!(self, ",", depth_lvl + 1);
-                self.print_expr(*expr_id, depth_lvl + 2);
-                print_indented!(self, ")", depth_lvl + 1);
-            }
-        }
-
-        print_indented!(self, "}", depth_lvl);
-    }
-
     fn print_closure_expr(&mut self, expr: &ClosureExpr<'tcx>, depth_lvl: usize) {
         let ClosureExpr { closure_id, args, upvars, movability, fake_reads } = expr;
 

compiler/rustc_passes/src/liveness.rs

@@ -351,10 +351,7 @@ impl<'tcx> Visitor<'tcx> for IrMaps<'tcx> {
     }
 
     fn visit_arm(&mut self, arm: &'tcx hir::Arm<'tcx>) {
-        self.add_from_pat(arm.pat);
+        self.add_from_pat(&arm.pat);
-        if let Some(hir::Guard::IfLet(let_expr)) = arm.guard {
-            self.add_from_pat(let_expr.pat);
-        }
         intravisit::walk_arm(self, arm);
     }
 
@@ -921,14 +918,11 @@ impl<'a, 'tcx> Liveness<'a, 'tcx> {
                 for arm in arms {
                     let body_succ = self.propagate_through_expr(arm.body, succ);
 
-                    let guard_succ = arm.guard.as_ref().map_or(body_succ, |g| match g {
+                    let guard_succ = arm
-                        hir::Guard::If(e) => self.propagate_through_expr(e, body_succ),
+                        .guard
-                        hir::Guard::IfLet(let_expr) => {
+                        .as_ref()
-                            let let_bind = self.define_bindings_in_pat(let_expr.pat, body_succ);
+                        .map_or(body_succ, |g| self.propagate_through_expr(g, body_succ));
-                            self.propagate_through_expr(let_expr.init, let_bind)
+                    let arm_succ = self.define_bindings_in_pat(&arm.pat, guard_succ);
-                        }
-                    });
-                    let arm_succ = self.define_bindings_in_pat(arm.pat, guard_succ);
                     self.merge_from_succ(ln, arm_succ);
                 }
                 self.propagate_through_expr(e, ln)
@@ -1328,9 +1322,6 @@ impl<'a, 'tcx> Visitor<'tcx> for Liveness<'a, 'tcx> {
 
     fn visit_arm(&mut self, arm: &'tcx hir::Arm<'tcx>) {
         self.check_unused_vars_in_pat(arm.pat, None, None, |_, _, _, _| {});
-        if let Some(hir::Guard::IfLet(let_expr)) = arm.guard {
-            self.check_unused_vars_in_pat(let_expr.pat, None, None, |_, _, _, _| {});
-        }
         intravisit::walk_arm(self, arm);
     }
 }

src/tools/clippy/clippy_lints/src/entry.rs

@@ -8,7 +8,7 @@ use core::fmt::{self, Write};
 use rustc_errors::Applicability;
 use rustc_hir::hir_id::HirIdSet;
 use rustc_hir::intravisit::{walk_expr, Visitor};
-use rustc_hir::{Block, Expr, ExprKind, Guard, HirId, Let, Pat, Stmt, StmtKind, UnOp};
+use rustc_hir::{Block, Expr, ExprKind, HirId, Pat, Stmt, StmtKind, UnOp};
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_session::declare_lint_pass;
 use rustc_span::{Span, SyntaxContext, DUMMY_SP};
@@ -465,7 +465,7 @@ impl<'tcx> Visitor<'tcx> for InsertSearcher<'_, 'tcx> {
                     let mut is_map_used = self.is_map_used;
                     for arm in arms {
                         self.visit_pat(arm.pat);
-                        if let Some(Guard::If(guard) | Guard::IfLet(&Let { init: guard, .. })) = arm.guard {
+                        if let Some(guard) = arm.guard {
                             self.visit_non_tail_expr(guard);
                         }
                         is_map_used |= self.visit_cond_arm(arm.body);

src/tools/clippy/clippy_lints/src/manual_clamp.rs

@@ -11,7 +11,7 @@ use clippy_utils::{
 use itertools::Itertools;
 use rustc_errors::{Applicability, Diagnostic};
 use rustc_hir::def::Res;
-use rustc_hir::{Arm, BinOpKind, Block, Expr, ExprKind, Guard, HirId, PatKind, PathSegment, PrimTy, QPath, StmtKind};
+use rustc_hir::{Arm, BinOpKind, Block, Expr, ExprKind, HirId, PatKind, PathSegment, PrimTy, QPath, StmtKind};
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_middle::ty::Ty;
 use rustc_session::impl_lint_pass;
@@ -394,7 +394,7 @@ fn is_match_pattern<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'tcx>) -> Opt
         // Find possible min/max branches
         let minmax_values = |a: &'tcx Arm<'tcx>| {
             if let PatKind::Binding(_, var_hir_id, _, None) = &a.pat.kind
-                && let Some(Guard::If(e)) = a.guard
+                && let Some(e) = a.guard
             {
                 Some((e, var_hir_id, a.body))
             } else {

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

@@ -7,7 +7,7 @@ use clippy_utils::{
 };
 use rustc_errors::MultiSpan;
 use rustc_hir::LangItem::OptionNone;
-use rustc_hir::{Arm, Expr, Guard, HirId, Let, Pat, PatKind};
+use rustc_hir::{Arm, Expr, HirId, Pat, PatKind};
 use rustc_lint::LateContext;
 use rustc_span::Span;
 
@@ -16,7 +16,7 @@ use super::COLLAPSIBLE_MATCH;
 pub(super) fn check_match<'tcx>(cx: &LateContext<'tcx>, arms: &'tcx [Arm<'_>]) {
     if let Some(els_arm) = arms.iter().rfind(|arm| arm_is_wild_like(cx, arm)) {
         for arm in arms {
-            check_arm(cx, true, arm.pat, arm.body, arm.guard.as_ref(), Some(els_arm.body));
+            check_arm(cx, true, arm.pat, arm.body, arm.guard, Some(els_arm.body));
         }
     }
 }
@@ -35,7 +35,7 @@ fn check_arm<'tcx>(
     outer_is_match: bool,
     outer_pat: &'tcx Pat<'tcx>,
     outer_then_body: &'tcx Expr<'tcx>,
-    outer_guard: Option<&'tcx Guard<'tcx>>,
+    outer_guard: Option<&'tcx Expr<'tcx>>,
     outer_else_body: Option<&'tcx Expr<'tcx>>,
 ) {
     let inner_expr = peel_blocks_with_stmt(outer_then_body);
@@ -71,7 +71,7 @@ fn check_arm<'tcx>(
         // the binding must not be used in the if guard
         && outer_guard.map_or(
             true,
-            |(Guard::If(e) | Guard::IfLet(Let { init: e, .. }))| !is_local_used(cx, *e, binding_id)
+            |e| !is_local_used(cx, e, binding_id)
         )
         // ...or anywhere in the inner expression
         && match inner {

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

@@ -4,7 +4,7 @@ use clippy_utils::source::snippet_with_applicability;
 use clippy_utils::{is_lint_allowed, is_wild, span_contains_comment};
 use rustc_ast::{Attribute, LitKind};
 use rustc_errors::Applicability;
-use rustc_hir::{Arm, BorrowKind, Expr, ExprKind, Guard, Pat, PatKind, QPath};
+use rustc_hir::{Arm, BorrowKind, Expr, ExprKind, Pat, PatKind, QPath};
 use rustc_lint::{LateContext, LintContext};
 use rustc_middle::ty;
 use rustc_span::source_map::Spanned;
@@ -41,14 +41,8 @@ pub(super) fn check_match<'tcx>(
     find_matches_sugg(
         cx,
         scrutinee,
-        arms.iter().map(|arm| {
+        arms.iter()
-            (
+            .map(|arm| (cx.tcx.hir().attrs(arm.hir_id), Some(arm.pat), arm.body, arm.guard)),
-                cx.tcx.hir().attrs(arm.hir_id),
-                Some(arm.pat),
-                arm.body,
-                arm.guard.as_ref(),
-            )
-        }),
         e,
         false,
     )
@@ -67,14 +61,7 @@ where
     I: Clone
         + DoubleEndedIterator
         + ExactSizeIterator
-        + Iterator<
+        + Iterator<Item = (&'a [Attribute], Option<&'a Pat<'b>>, &'a Expr<'b>, Option<&'a Expr<'b>>)>,
-            Item = (
-                &'a [Attribute],
-                Option<&'a Pat<'b>>,
-                &'a Expr<'b>,
-                Option<&'a Guard<'b>>,
-            ),
-        >,
 {
     if !span_contains_comment(cx.sess().source_map(), expr.span)
         && iter.len() >= 2
@@ -115,7 +102,7 @@ where
                 })
                 .join(" | ")
         };
-        let pat_and_guard = if let Some(Guard::If(g)) = first_guard {
+        let pat_and_guard = if let Some(g) = first_guard {
             format!(
                 "{pat} if {}",
                 snippet_with_applicability(cx, g.span, "..", &mut applicability)

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

@@ -8,7 +8,7 @@ use clippy_utils::{
 };
 use rustc_errors::Applicability;
 use rustc_hir::LangItem::OptionNone;
-use rustc_hir::{Arm, BindingAnnotation, ByRef, Expr, ExprKind, Guard, ItemKind, Node, Pat, PatKind, Path, QPath};
+use rustc_hir::{Arm, BindingAnnotation, ByRef, Expr, ExprKind, ItemKind, Node, Pat, PatKind, Path, QPath};
 use rustc_lint::LateContext;
 use rustc_span::sym;
 
@@ -66,18 +66,9 @@ fn check_all_arms(cx: &LateContext<'_>, match_expr: &Expr<'_>, arms: &[Arm<'_>])
         let arm_expr = peel_blocks_with_stmt(arm.body);
 
         if let Some(guard_expr) = &arm.guard {
-            match guard_expr {
+            if guard_expr.can_have_side_effects() {
-                // gives up if `pat if expr` can have side effects
-                Guard::If(if_cond) => {
-                    if if_cond.can_have_side_effects() {
                 return false;
             }
-                },
-                // gives up `pat if let ...` arm
-                Guard::IfLet(_) => {
-                    return false;
-                },
-            };
         }
 
         if let PatKind::Wild = arm.pat.kind {

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

@@ -5,7 +5,7 @@ use clippy_utils::visitors::{for_each_expr, is_local_used};
 use rustc_ast::{BorrowKind, LitKind};
 use rustc_errors::Applicability;
 use rustc_hir::def::{DefKind, Res};
-use rustc_hir::{Arm, BinOpKind, Expr, ExprKind, Guard, MatchSource, Node, Pat, PatKind};
+use rustc_hir::{Arm, BinOpKind, Expr, ExprKind, MatchSource, Node, Pat, PatKind};
 use rustc_lint::LateContext;
 use rustc_span::symbol::Ident;
 use rustc_span::{Span, Symbol};
@@ -21,8 +21,7 @@ pub(super) fn check<'tcx>(cx: &LateContext<'tcx>, arms: &'tcx [Arm<'tcx>]) {
         };
 
         // `Some(x) if matches!(x, y)`
-        if let Guard::If(if_expr) = guard
+        if let ExprKind::Match(
-            && let ExprKind::Match(
             scrutinee,
             [
                 arm,
@@ -34,7 +33,7 @@ pub(super) fn check<'tcx>(cx: &LateContext<'tcx>, arms: &'tcx [Arm<'tcx>]) {
                 },
             ],
             MatchSource::Normal,
-            ) = if_expr.kind
+        ) = guard.kind
             && let Some(binding) = get_pat_binding(cx, scrutinee, outer_arm)
         {
             let pat_span = match (arm.pat.kind, binding.byref_ident) {
@@ -45,14 +44,14 @@ pub(super) fn check<'tcx>(cx: &LateContext<'tcx>, arms: &'tcx [Arm<'tcx>]) {
             emit_redundant_guards(
                 cx,
                 outer_arm,
-                if_expr.span,
+                guard.span,
                 snippet(cx, pat_span, "<binding>"),
                 &binding,
                 arm.guard,
             );
         }
         // `Some(x) if let Some(2) = x`
-        else if let Guard::IfLet(let_expr) = guard
+        else if let ExprKind::Let(let_expr) = guard.kind
             && let Some(binding) = get_pat_binding(cx, let_expr.init, outer_arm)
         {
             let pat_span = match (let_expr.pat.kind, binding.byref_ident) {
@@ -71,8 +70,7 @@ pub(super) fn check<'tcx>(cx: &LateContext<'tcx>, arms: &'tcx [Arm<'tcx>]) {
         }
         // `Some(x) if x == Some(2)`
         // `Some(x) if Some(2) == x`
-        else if let Guard::If(if_expr) = guard
+        else if let ExprKind::Binary(bin_op, local, pat) = guard.kind
-            && let ExprKind::Binary(bin_op, local, pat) = if_expr.kind
             && matches!(bin_op.node, BinOpKind::Eq)
             // Ensure they have the same type. If they don't, we'd need deref coercion which isn't
             // possible (currently) in a pattern. In some cases, you can use something like
@@ -96,16 +94,15 @@ pub(super) fn check<'tcx>(cx: &LateContext<'tcx>, arms: &'tcx [Arm<'tcx>]) {
             emit_redundant_guards(
                 cx,
                 outer_arm,
-                if_expr.span,
+                guard.span,
                 snippet(cx, pat_span, "<binding>"),
                 &binding,
                 None,
             );
-        } else if let Guard::If(if_expr) = guard
+        } else if let ExprKind::MethodCall(path, recv, args, ..) = guard.kind
-            && let ExprKind::MethodCall(path, recv, args, ..) = if_expr.kind
             && let Some(binding) = get_pat_binding(cx, recv, outer_arm)
         {
-            check_method_calls(cx, outer_arm, path.ident.name, recv, args, if_expr, &binding);
+            check_method_calls(cx, outer_arm, path.ident.name, recv, args, guard, &binding);
         }
     }
 }
@@ -216,7 +213,7 @@ fn emit_redundant_guards<'tcx>(
     guard_span: Span,
     binding_replacement: Cow<'static, str>,
     pat_binding: &PatBindingInfo,
-    inner_guard: Option<Guard<'_>>,
+    inner_guard: Option<&Expr<'_>>,
 ) {
     span_lint_and_then(
         cx,
@@ -242,12 +239,7 @@ fn emit_redundant_guards<'tcx>(
                     (
                         guard_span.source_callsite().with_lo(outer_arm.pat.span.hi()),
                         inner_guard.map_or_else(String::new, |guard| {
-                            let (prefix, span) = match guard {
+                            format!(" if {}", snippet(cx, guard.span, "<guard>"))
-                                Guard::If(e) => ("if", e.span),
-                                Guard::IfLet(l) => ("if let", l.span),
-                            };
-
-                            format!(" {prefix} {}", snippet(cx, span, "<guard>"))
                         }),
                     ),
                 ],

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

@@ -9,7 +9,7 @@ use rustc_ast::ast::LitKind;
 use rustc_errors::Applicability;
 use rustc_hir::def::{DefKind, Res};
 use rustc_hir::LangItem::{self, OptionNone, OptionSome, PollPending, PollReady, ResultErr, ResultOk};
-use rustc_hir::{Arm, Expr, ExprKind, Guard, Node, Pat, PatKind, QPath, UnOp};
+use rustc_hir::{Arm, Expr, ExprKind, Node, Pat, PatKind, QPath, UnOp};
 use rustc_lint::LateContext;
 use rustc_middle::ty::{self, GenericArgKind, Ty};
 use rustc_span::{sym, Span, Symbol};
@@ -277,8 +277,6 @@ pub(super) fn check_match<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>, op
             let mut sugg = format!("{}.{good_method}", snippet(cx, result_expr.span, "_"));
 
             if let Some(guard) = maybe_guard {
-                let Guard::If(guard) = *guard else { return }; // `...is_none() && let ...` is a syntax error
-
                 // wow, the HIR for match guards in `PAT if let PAT = expr && expr => ...` is annoying!
                 // `guard` here is `Guard::If` with the let expression somewhere deep in the tree of exprs,
                 // counter to the intuition that it should be `Guard::IfLet`, so we need another check
@@ -319,7 +317,7 @@ fn found_good_method<'tcx>(
     cx: &LateContext<'_>,
     arms: &'tcx [Arm<'tcx>],
     node: (&PatKind<'_>, &PatKind<'_>),
-) -> Option<(&'static str, Option<&'tcx Guard<'tcx>>)> {
+) -> Option<(&'static str, Option<&'tcx Expr<'tcx>>)> {
     match node {
         (
             PatKind::TupleStruct(ref path_left, patterns_left, _),
@@ -409,7 +407,7 @@ fn get_good_method<'tcx>(
     cx: &LateContext<'_>,
     arms: &'tcx [Arm<'tcx>],
     path_left: &QPath<'_>,
-) -> Option<(&'static str, Option<&'tcx Guard<'tcx>>)> {
+) -> Option<(&'static str, Option<&'tcx Expr<'tcx>>)> {
     if let Some(name) = get_ident(path_left) {
         let (expected_item_left, should_be_left, should_be_right) = match name.as_str() {
             "Ok" => (Item::Lang(ResultOk), "is_ok()", "is_err()"),
@@ -478,7 +476,7 @@ fn find_good_method_for_match<'a, 'tcx>(
     expected_item_right: Item,
     should_be_left: &'a str,
     should_be_right: &'a str,
-) -> Option<(&'a str, Option<&'tcx Guard<'tcx>>)> {
+) -> Option<(&'a str, Option<&'tcx Expr<'tcx>>)> {
     let first_pat = arms[0].pat;
     let second_pat = arms[1].pat;
 
@@ -496,8 +494,8 @@ fn find_good_method_for_match<'a, 'tcx>(
 
     match body_node_pair {
         (ExprKind::Lit(lit_left), ExprKind::Lit(lit_right)) => match (&lit_left.node, &lit_right.node) {
-            (LitKind::Bool(true), LitKind::Bool(false)) => Some((should_be_left, arms[0].guard.as_ref())),
+            (LitKind::Bool(true), LitKind::Bool(false)) => Some((should_be_left, arms[0].guard)),
-            (LitKind::Bool(false), LitKind::Bool(true)) => Some((should_be_right, arms[1].guard.as_ref())),
+            (LitKind::Bool(false), LitKind::Bool(true)) => Some((should_be_right, arms[1].guard)),
             _ => None,
         },
         _ => None,
@@ -511,7 +509,7 @@ fn find_good_method_for_matches_macro<'a, 'tcx>(
     expected_item_left: Item,
     should_be_left: &'a str,
     should_be_right: &'a str,
-) -> Option<(&'a str, Option<&'tcx Guard<'tcx>>)> {
+) -> Option<(&'a str, Option<&'tcx Expr<'tcx>>)> {
     let first_pat = arms[0].pat;
 
     let body_node_pair = if is_pat_variant(cx, first_pat, path_left, expected_item_left) {
@@ -522,8 +520,8 @@ fn find_good_method_for_matches_macro<'a, 'tcx>(
 
     match body_node_pair {
         (ExprKind::Lit(lit_left), ExprKind::Lit(lit_right)) => match (&lit_left.node, &lit_right.node) {
-            (LitKind::Bool(true), LitKind::Bool(false)) => Some((should_be_left, arms[0].guard.as_ref())),
+            (LitKind::Bool(true), LitKind::Bool(false)) => Some((should_be_left, arms[0].guard)),
-            (LitKind::Bool(false), LitKind::Bool(true)) => Some((should_be_right, arms[1].guard.as_ref())),
+            (LitKind::Bool(false), LitKind::Bool(true)) => Some((should_be_right, arms[1].guard)),
             _ => None,
         },
         _ => None,

src/tools/clippy/clippy_lints/src/mixed_read_write_in_expression.rs

@@ -1,7 +1,7 @@
 use clippy_utils::diagnostics::{span_lint, span_lint_and_note};
 use clippy_utils::{get_parent_expr, path_to_local, path_to_local_id};
 use rustc_hir::intravisit::{walk_expr, Visitor};
-use rustc_hir::{BinOpKind, Block, Expr, ExprKind, Guard, HirId, Local, Node, Stmt, StmtKind};
+use rustc_hir::{BinOpKind, Block, Expr, ExprKind, HirId, Local, Node, Stmt, StmtKind};
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_middle::ty;
 use rustc_session::declare_lint_pass;
@@ -119,7 +119,7 @@ impl<'a, 'tcx> DivergenceVisitor<'a, 'tcx> {
             ExprKind::Match(e, arms, _) => {
                 self.visit_expr(e);
                 for arm in arms {
-                    if let Some(Guard::If(if_expr)) = arm.guard {
+                    if let Some(if_expr) = arm.guard {
                         self.visit_expr(if_expr);
                     }
                     // make sure top level arm expressions aren't linted

src/tools/clippy/clippy_lints/src/utils/author.rs

@@ -318,17 +318,11 @@ impl<'a, 'tcx> PrintVisitor<'a, 'tcx> {
         self.pat(field!(arm.pat));
         match arm.value.guard {
             None => chain!(self, "{arm}.guard.is_none()"),
-            Some(hir::Guard::If(expr)) => {
+            Some(expr) => {
                 bind!(self, expr);
-                chain!(self, "let Some(Guard::If({expr})) = {arm}.guard");
+                chain!(self, "let Some({expr}) = {arm}.guard");
                 self.expr(expr);
             },
-            Some(hir::Guard::IfLet(let_expr)) => {
-                bind!(self, let_expr);
-                chain!(self, "let Some(Guard::IfLet({let_expr}) = {arm}.guard");
-                self.pat(field!(let_expr.pat));
-                self.expr(field!(let_expr.init));
-            },
         }
         self.expr(field!(arm.body));
     }

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

@@ -8,7 +8,7 @@ use rustc_hir::def::Res;
 use rustc_hir::MatchSource::TryDesugar;
 use rustc_hir::{
     ArrayLen, BinOpKind, BindingAnnotation, Block, BodyId, Closure, Expr, ExprField, ExprKind, FnRetTy, GenericArg,
-    GenericArgs, Guard, HirId, HirIdMap, InlineAsmOperand, Let, Lifetime, LifetimeName, Pat, PatField, PatKind, Path,
+    GenericArgs, HirId, HirIdMap, InlineAsmOperand, Let, Lifetime, LifetimeName, Pat, PatField, PatKind, Path,
     PathSegment, PrimTy, QPath, Stmt, StmtKind, Ty, TyKind, TypeBinding,
 };
 use rustc_lexer::{tokenize, TokenKind};
@@ -320,7 +320,7 @@ impl HirEqInterExpr<'_, '_, '_> {
                     && self.eq_expr(le, re)
                     && over(la, ra, |l, r| {
                         self.eq_pat(l.pat, r.pat)
-                            && both(&l.guard, &r.guard, |l, r| self.eq_guard(l, r))
+                            && both(&l.guard, &r.guard, |l, r| self.eq_expr(l, r))
                             && self.eq_expr(l.body, r.body)
                     })
             },
@@ -410,16 +410,6 @@ impl HirEqInterExpr<'_, '_, '_> {
         left.ident.name == right.ident.name && self.eq_expr(left.expr, right.expr)
     }
 
-    fn eq_guard(&mut self, left: &Guard<'_>, right: &Guard<'_>) -> bool {
-        match (left, right) {
-            (Guard::If(l), Guard::If(r)) => self.eq_expr(l, r),
-            (Guard::IfLet(l), Guard::IfLet(r)) => {
-                self.eq_pat(l.pat, r.pat) && both(&l.ty, &r.ty, |l, r| self.eq_ty(l, r)) && self.eq_expr(l.init, r.init)
-            },
-            _ => false,
-        }
-    }
-
     fn eq_generic_arg(&mut self, left: &GenericArg<'_>, right: &GenericArg<'_>) -> bool {
         match (left, right) {
             (GenericArg::Const(l), GenericArg::Const(r)) => self.eq_body(l.value.body, r.value.body),
@@ -876,7 +866,7 @@ impl<'a, 'tcx> SpanlessHash<'a, 'tcx> {
                 for arm in arms {
                     self.hash_pat(arm.pat);
                     if let Some(ref e) = arm.guard {
-                        self.hash_guard(e);
+                        self.hash_expr(e);
                     }
                     self.hash_expr(arm.body);
                 }
@@ -1056,14 +1046,6 @@ impl<'a, 'tcx> SpanlessHash<'a, 'tcx> {
         }
     }
 
-    pub fn hash_guard(&mut self, g: &Guard<'_>) {
-        match g {
-            Guard::If(expr) | Guard::IfLet(Let { init: expr, .. }) => {
-                self.hash_expr(expr);
-            },
-        }
-    }
-
     pub fn hash_lifetime(&mut self, lifetime: &Lifetime) {
         lifetime.ident.name.hash(&mut self.s);
         std::mem::discriminant(&lifetime.res).hash(&mut self.s);

src/tools/clippy/clippy_utils/src/lib.rs

@@ -3164,7 +3164,7 @@ pub fn is_never_expr<'tcx>(cx: &LateContext<'tcx>, e: &'tcx Expr<'_>) -> Option<
                             self.is_never = false;
                             if let Some(guard) = arm.guard {
                                 let in_final_expr = mem::replace(&mut self.in_final_expr, false);
-                                self.visit_expr(guard.body());
+                                self.visit_expr(guard);
                                 self.in_final_expr = in_final_expr;
                                 // The compiler doesn't consider diverging guards as causing the arm to diverge.
                                 self.is_never = false;
@@ -3223,7 +3223,7 @@ pub fn is_never_expr<'tcx>(cx: &LateContext<'tcx>, e: &'tcx Expr<'_>) -> Option<
         fn visit_arm(&mut self, arm: &Arm<'tcx>) {
             if let Some(guard) = arm.guard {
                 let in_final_expr = mem::replace(&mut self.in_final_expr, false);
-                self.visit_expr(guard.body());
+                self.visit_expr(guard);
                 self.in_final_expr = in_final_expr;
             }
             self.visit_expr(arm.body);

tests/ui/closures/2229_closure_analysis/issue-88118-2.stderr

@@ -1,8 +1,8 @@
 warning: irrefutable `if let` guard pattern
-  --> $DIR/issue-88118-2.rs:10:29
+  --> $DIR/issue-88118-2.rs:10:25
    |
 LL |             Registry if let _ = registry.try_find_description() => { }
-   |                             ^
+   |                         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: this pattern will always match, so the guard is useless
    = help: consider removing the guard and adding a `let` inside the match arm

tests/ui/lint/lint-match-arms-2.stderr

@@ -11,10 +11,10 @@ LL |         #[deny(bindings_with_variant_name)]
    |                ^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: irrefutable `if let` guard pattern
-  --> $DIR/lint-match-arms-2.rs:18:18
+  --> $DIR/lint-match-arms-2.rs:18:14
    |
 LL |         a if let b = a => {}
-   |                  ^
+   |              ^^^^^^^^^
    |
    = note: this pattern will always match, so the guard is useless
    = help: consider removing the guard and adding a `let` inside the match arm

tests/ui/pattern/usefulness/deny-irrefutable-let-patterns.stderr

@@ -22,10 +22,10 @@ LL |     while let _ = 5 {
    = help: consider instead using a `loop { ... }` with a `let` inside it
 
 error: irrefutable `if let` guard pattern
-  --> $DIR/deny-irrefutable-let-patterns.rs:13:18
+  --> $DIR/deny-irrefutable-let-patterns.rs:13:14
    |
 LL |         _ if let _ = 2 => {}
-   |                  ^
+   |              ^^^^^^^^^
    |
    = note: this pattern will always match, so the guard is useless
    = help: consider removing the guard and adding a `let` inside the match arm

tests/ui/rfcs/rfc-2294-if-let-guard/drop-scope.rs

@@ -0,0 +1,72 @@
+// Ensure that temporaries in if-let guards live for the arm
+// regression test for #118593
+
+// check-pass
+
+#![feature(if_let_guard)]
+#![feature(let_chains)]
+
+fn get_temp() -> Option<String> {
+    None
+}
+
+fn let_guard(num: u8) {
+    match num {
+        1 | 2 if let Some(ref a) = get_temp() => {
+            let _b = a;
+        }
+        _ => {}
+    }
+    match num {
+        3 | 4 if let Some(ref mut c) = get_temp() => {
+            let _d = c;
+        }
+        _ => {}
+    }
+}
+
+fn let_let_chain_guard(num: u8) {
+    match num {
+        5 | 6
+            if let Some(ref a) = get_temp()
+                && let Some(ref b) = get_temp() =>
+        {
+            let _x = a;
+            let _y = b;
+        }
+        _ => {}
+    }
+    match num {
+        7 | 8
+            if let Some(ref mut c) = get_temp()
+                && let Some(ref mut d) = get_temp() =>
+        {
+            let _w = c;
+            let _z = d;
+        }
+        _ => {}
+    }
+}
+
+fn let_cond_chain_guard(num: u8) {
+    match num {
+        9 | 10
+            if let Some(ref a) = get_temp()
+                && true =>
+        {
+            let _x = a;
+        }
+        _ => {}
+    }
+    match num {
+        11 | 12
+            if let Some(ref mut b) = get_temp()
+                && true =>
+        {
+            let _w = b;
+        }
+        _ => {}
+    }
+}
+
+fn main() {}

tests/ui/rfcs/rfc-2294-if-let-guard/scope.rs

@@ -0,0 +1,30 @@
+// Tests for #88015 when using if let chains in match guards
+
+//run-pass
+
+#![feature(if_let_guard)]
+#![feature(let_chains)]
+#![allow(irrefutable_let_patterns)]
+
+fn lhs_let(opt: Option<bool>) {
+    match opt {
+        None | Some(false) | Some(true) if let x = 42 && true => assert_eq!(x, 42),
+        _ => panic!()
+    }
+}
+
+fn rhs_let(opt: Option<bool>) {
+    match opt {
+        None | Some(false) | Some(true) if true && let x = 41 => assert_eq!(x, 41),
+        _ => panic!()
+    }
+}
+
+fn main() {
+    lhs_let(None);
+    lhs_let(Some(false));
+    lhs_let(Some(true));
+    rhs_let(None);
+    rhs_let(Some(false));
+    rhs_let(Some(true));
+}

tests/ui/rfcs/rfc-2294-if-let-guard/warns.stderr

@@ -1,8 +1,8 @@
 error: irrefutable `if let` guard pattern
-  --> $DIR/warns.rs:6:24
+  --> $DIR/warns.rs:6:20
    |
 LL |         Some(x) if let () = x => {}
-   |                        ^^
+   |                    ^^^^^^^^^^
    |
    = note: this pattern will always match, so the guard is useless
    = help: consider removing the guard and adding a `let` inside the match arm

tests/ui/stats/hir-stats.stderr

@@ -128,8 +128,8 @@ hir-stats Param                     64 ( 0.7%)             2            32
 hir-stats Body                      72 ( 0.8%)             3            24
 hir-stats InlineAsm                 72 ( 0.8%)             1            72
 hir-stats ImplItemRef               72 ( 0.8%)             2            36
+hir-stats Arm                       80 ( 0.9%)             2            40
 hir-stats FieldDef                  96 ( 1.1%)             2            48
-hir-stats Arm                       96 ( 1.1%)             2            48
 hir-stats Stmt                      96 ( 1.1%)             3            32
 hir-stats - Local                     32 ( 0.4%)             1
 hir-stats - Semi                      32 ( 0.4%)             1
@@ -151,11 +151,11 @@ hir-stats - Wild                      72 ( 0.8%)             1
 hir-stats - Struct                    72 ( 0.8%)             1
 hir-stats - Binding                  216 ( 2.4%)             3
 hir-stats GenericParam             400 ( 4.4%)             5            80
-hir-stats Generics                 560 ( 6.1%)            10            56
+hir-stats Generics                 560 ( 6.2%)            10            56
 hir-stats Ty                       720 ( 7.9%)            15            48
 hir-stats - Ptr                       48 ( 0.5%)             1
 hir-stats - Ref                       48 ( 0.5%)             1
-hir-stats - Path                     624 ( 6.8%)            13
+hir-stats - Path                     624 ( 6.9%)            13
 hir-stats Expr                     768 ( 8.4%)            12            64
 hir-stats - Path                      64 ( 0.7%)             1
 hir-stats - Struct                    64 ( 0.7%)             1
@@ -174,5 +174,5 @@ hir-stats - Use                      352 ( 3.9%)             4
 hir-stats Path                   1_240 (13.6%)            31            40
 hir-stats PathSegment            1_920 (21.1%)            40            48
 hir-stats ----------------------------------------------------------------
-hir-stats Total                  9_112
+hir-stats Total                  9_096
 hir-stats