Rollup merge of rust-lang#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 rust-lang#118593

Author: matthiaskrgr

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);

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 {

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 {

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| {
-            (
-                cx.tcx.hir().attrs(arm.hir_id),
-                Some(arm.pat),
-                arm.body,
-                arm.guard.as_ref(),
-            )
-        }),
+        arms.iter()
+            .map(|arm| (cx.tcx.hir().attrs(arm.hir_id), Some(arm.pat), arm.body, arm.guard)),
         e,
         false,
     )
@@ -67,14 +61,7 @@ where
     I: Clone
         + DoubleEndedIterator
         + ExactSizeIterator
-        + Iterator<
-            Item = (
-                &'a [Attribute],
-                Option<&'a Pat<'b>>,
-                &'a Expr<'b>,
-                Option<&'a Guard<'b>>,
-            ),
-        >,
+        + Iterator<Item = (&'a [Attribute], Option<&'a Pat<'b>>, &'a Expr<'b>, Option<&'a Expr<'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)

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 {
-                // 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 guard_expr.can_have_side_effects() {
+                return false;
+            }
         }
 
         if let PatKind::Wild = arm.pat.kind {

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};
@@ -21,20 +21,19 @@ 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
-            && let ExprKind::Match(
-                scrutinee,
-                [
-                    arm,
-                    Arm {
-                        pat: Pat {
-                            kind: PatKind::Wild, ..
-                        },
-                        ..
+        if let ExprKind::Match(
+            scrutinee,
+            [
+                arm,
+                Arm {
+                    pat: Pat {
+                        kind: PatKind::Wild, ..
                     },
-                ],
-                MatchSource::Normal,
-            ) = if_expr.kind
+                    ..
+                },
+            ],
+            MatchSource::Normal,
+        ) = 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
-            && let ExprKind::Binary(bin_op, local, pat) = if_expr.kind
+        else if let ExprKind::Binary(bin_op, local, pat) = guard.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
-            && let ExprKind::MethodCall(path, recv, args, ..) = if_expr.kind
+        } else if let ExprKind::MethodCall(path, recv, args, ..) = guard.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 {
-                                Guard::If(e) => ("if", e.span),
-                                Guard::IfLet(l) => ("if let", l.span),
-                            };
-
-                            format!(" {prefix} {}", snippet(cx, span, "<guard>"))
+                            format!(" if {}", snippet(cx, guard.span, "<guard>"))
                         }),
                     ),
                 ],

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(false), LitKind::Bool(true)) => Some((should_be_right, arms[1].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)),
             _ => 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(false), LitKind::Bool(true)) => Some((should_be_right, arms[1].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)),
             _ => None,
         },
         _ => None,

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

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));
     }