Gate collapsible_if let_chains lints on edition 2024 and MSRV

Author: Alexendoo

clippy_lints/src/collapsible_if.rs

@@ -1,11 +1,11 @@
 use clippy_config::Conf;
 use clippy_utils::diagnostics::{span_lint_and_sugg, span_lint_and_then};
+use clippy_utils::msrvs::{self, Msrv};
 use clippy_utils::source::{IntoSpan as _, SpanRangeExt, snippet, snippet_block, snippet_block_with_applicability};
 use rustc_ast::BinOpKind;
 use rustc_errors::Applicability;
 use rustc_hir::{Block, Expr, ExprKind, StmtKind};
 use rustc_lint::{LateContext, LateLintPass};
-use rustc_middle::ty::TyCtxt;
 use rustc_session::impl_lint_pass;
 use rustc_span::Span;
 
@@ -78,14 +78,14 @@ declare_clippy_lint! {
 }
 
 pub struct CollapsibleIf {
-    let_chains_enabled: bool,
+    msrv: Msrv,
     lint_commented_code: bool,
 }
 
 impl CollapsibleIf {
-    pub fn new(tcx: TyCtxt<'_>, conf: &'static Conf) -> Self {
+    pub fn new(conf: &'static Conf) -> Self {
         Self {
-            let_chains_enabled: tcx.features().let_chains(),
+            msrv: conf.msrv,
             lint_commented_code: conf.lint_commented_code,
         }
     }
@@ -127,7 +127,7 @@ impl CollapsibleIf {
         if let Some(inner) = expr_block(then)
             && cx.tcx.hir_attrs(inner.hir_id).is_empty()
             && let ExprKind::If(check_inner, _, None) = &inner.kind
-            && self.eligible_condition(check_inner)
+            && self.eligible_condition(cx, check_inner)
             && let ctxt = expr.span.ctxt()
             && inner.span.ctxt() == ctxt
             && (self.lint_commented_code || !block_starts_with_comment(cx, then))
@@ -163,8 +163,9 @@ impl CollapsibleIf {
         }
     }
 
-    pub fn eligible_condition(&self, cond: &Expr<'_>) -> bool {
-        self.let_chains_enabled || !matches!(cond.kind, ExprKind::Let(..))
+    fn eligible_condition(&self, cx: &LateContext<'_>, cond: &Expr<'_>) -> bool {
+        !matches!(cond.kind, ExprKind::Let(..))
+            || (cx.tcx.sess.edition().at_least_rust_2024() && self.msrv.meets(cx, msrvs::LET_CHAINS))
     }
 }
 
@@ -180,7 +181,7 @@ impl LateLintPass<'_> for CollapsibleIf {
             {
                 Self::check_collapsible_else_if(cx, then.span, else_);
             } else if else_.is_none()
-                && self.eligible_condition(cond)
+                && self.eligible_condition(cx, cond)
                 && let ExprKind::Block(then, None) = then.kind
             {
                 self.check_collapsible_if_if(cx, expr, cond, then);

clippy_lints/src/lib.rs

@@ -731,7 +731,7 @@ pub fn register_lints(store: &mut rustc_lint::LintStore, conf: &'static Conf) {
     store.register_early_pass(|| Box::new(unused_unit::UnusedUnit));
     store.register_late_pass(|_| Box::new(unused_unit::UnusedUnit));
     store.register_late_pass(|_| Box::new(returns::Return));
-    store.register_late_pass(move |tcx| Box::new(collapsible_if::CollapsibleIf::new(tcx, conf)));
+    store.register_late_pass(move |_| Box::new(collapsible_if::CollapsibleIf::new(conf)));
     store.register_late_pass(|_| Box::new(items_after_statements::ItemsAfterStatements));
     store.register_early_pass(|| Box::new(precedence::Precedence));
     store.register_late_pass(|_| Box::new(needless_parens_on_range_literals::NeedlessParensOnRangeLiterals));

clippy_utils/src/msrvs.rs

@@ -22,6 +22,7 @@ macro_rules! msrv_aliases {
 
 // names may refer to stabilized feature flags or library items
 msrv_aliases! {
+    1,88,0 { LET_CHAINS }
     1,87,0 { OS_STR_DISPLAY, INT_MIDPOINT }
     1,85,0 { UINT_FLOAT_MIDPOINT }
     1,84,0 { CONST_OPTION_AS_SLICE, MANUAL_DANGLING_PTR }

tests/ui-toml/collapsible_if/collapsible_if_let_chains.fixed

@@ -1,4 +1,3 @@
-#![feature(let_chains)]
 #![warn(clippy::collapsible_if)]
 
 fn main() {

tests/ui-toml/collapsible_if/collapsible_if_let_chains.rs

@@ -1,4 +1,3 @@
-#![feature(let_chains)]
 #![warn(clippy::collapsible_if)]
 
 fn main() {

tests/ui-toml/collapsible_if/collapsible_if_let_chains.stderr

@@ -1,5 +1,5 @@
 error: this `if` statement can be collapsed
-  --> tests/ui-toml/collapsible_if/collapsible_if_let_chains.rs:5:5
+  --> tests/ui-toml/collapsible_if/collapsible_if_let_chains.rs:4:5
    |
 LL | /     if let Some(a) = Some(3) {
 LL | |         // with comment
@@ -21,7 +21,7 @@ LL ~         }
    |
 
 error: this `if` statement can be collapsed
-  --> tests/ui-toml/collapsible_if/collapsible_if_let_chains.rs:13:5
+  --> tests/ui-toml/collapsible_if/collapsible_if_let_chains.rs:12:5
    |
 LL | /     if let Some(a) = Some(3) {
 LL | |         // with comment
@@ -41,7 +41,7 @@ LL ~         }
    |
 
 error: this `if` statement can be collapsed
-  --> tests/ui-toml/collapsible_if/collapsible_if_let_chains.rs:21:5
+  --> tests/ui-toml/collapsible_if/collapsible_if_let_chains.rs:20:5
    |
 LL | /     if Some(3) == Some(4).map(|x| x - 1) {
 LL | |         // with comment

tests/ui/auxiliary/proc_macro_attr.rs

@@ -51,45 +51,44 @@ pub fn rename_my_lifetimes(_args: TokenStream, input: TokenStream) -> TokenStrea
 
     fn mut_receiver_of(sig: &mut Signature) -> Option<&mut FnArg> {
         let arg = sig.inputs.first_mut()?;
-        if let FnArg::Typed(PatType { pat, .. }) = arg {
-            if let Pat::Ident(PatIdent { ident, .. }) = &**pat {
-                if ident == "self" {
-                    return Some(arg);
-                }
-            }
+        if let FnArg::Typed(PatType { pat, .. }) = arg
+            && let Pat::Ident(PatIdent { ident, .. }) = &**pat
+            && ident == "self"
+        {
+            Some(arg)
+        } else {
+            None
         }
-        None
     }
 
     let mut elided = 0;
     let mut item = parse_macro_input!(input as ItemImpl);
 
     // Look for methods having arbitrary self type taken by &mut ref
     for inner in &mut item.items {
-        if let ImplItem::Fn(method) = inner {
-            if let Some(FnArg::Typed(pat_type)) = mut_receiver_of(&mut method.sig) {
-                if let box Type::Reference(reference) = &mut pat_type.ty {
-                    // Target only unnamed lifetimes
-                    let name = match &reference.lifetime {
-                        Some(lt) if lt.ident == "_" => make_name(elided),
-                        None => make_name(elided),
-                        _ => continue,
-                    };
-                    elided += 1;
-
-                    // HACK: Syn uses `Span` from the proc_macro2 crate, and does not seem to reexport it.
-                    // In order to avoid adding the dependency, get a default span from a nonexistent token.
-                    // A default span is needed to mark the code as coming from expansion.
-                    let span = Star::default().span();
-
-                    // Replace old lifetime with the named one
-                    let lifetime = Lifetime::new(&name, span);
-                    reference.lifetime = Some(parse_quote!(#lifetime));
-
-                    // Add lifetime to the generics of the method
-                    method.sig.generics.params.push(parse_quote!(#lifetime));
-                }
-            }
+        if let ImplItem::Fn(method) = inner
+            && let Some(FnArg::Typed(pat_type)) = mut_receiver_of(&mut method.sig)
+            && let box Type::Reference(reference) = &mut pat_type.ty
+        {
+            // Target only unnamed lifetimes
+            let name = match &reference.lifetime {
+                Some(lt) if lt.ident == "_" => make_name(elided),
+                None => make_name(elided),
+                _ => continue,
+            };
+            elided += 1;
+
+            // HACK: Syn uses `Span` from the proc_macro2 crate, and does not seem to reexport it.
+            // In order to avoid adding the dependency, get a default span from a nonexistent token.
+            // A default span is needed to mark the code as coming from expansion.
+            let span = Star::default().span();
+
+            // Replace old lifetime with the named one
+            let lifetime = Lifetime::new(&name, span);
+            reference.lifetime = Some(parse_quote!(#lifetime));
+
+            // Add lifetime to the generics of the method
+            method.sig.generics.params.push(parse_quote!(#lifetime));
         }
     }
 
@@ -129,15 +128,15 @@ pub fn fake_desugar_await(_args: TokenStream, input: TokenStream) -> TokenStream
     let mut async_fn = parse_macro_input!(input as syn::ItemFn);
 
     for stmt in &mut async_fn.block.stmts {
-        if let syn::Stmt::Expr(syn::Expr::Match(syn::ExprMatch { expr: scrutinee, .. }), _) = stmt {
-            if let syn::Expr::Await(syn::ExprAwait { base, await_token, .. }) = scrutinee.as_mut() {
-                let blc = quote_spanned!( await_token.span => {
-                    #[allow(clippy::let_and_return)]
-                    let __pinned = #base;
-                    __pinned
-                });
-                *scrutinee = parse_quote!(#blc);
-            }
+        if let syn::Stmt::Expr(syn::Expr::Match(syn::ExprMatch { expr: scrutinee, .. }), _) = stmt
+            && let syn::Expr::Await(syn::ExprAwait { base, await_token, .. }) = scrutinee.as_mut()
+        {
+            let blc = quote_spanned!( await_token.span => {
+                #[allow(clippy::let_and_return)]
+                let __pinned = #base;
+                __pinned
+            });
+            *scrutinee = parse_quote!(#blc);
         }
     }
 

tests/ui/auxiliary/proc_macros.rs

@@ -1,4 +1,3 @@
-#![feature(let_chains)]
 #![feature(proc_macro_span)]
 #![allow(clippy::needless_if, dead_code)]
 

tests/ui/collapsible_if.fixed

@@ -101,27 +101,8 @@ fn main() {
         }
     }
 
-    // Test behavior wrt. `let_chains`.
-    // None of the cases below should be collapsed.
     fn truth() -> bool { true }
 
-    // Prefix:
-    if let 0 = 1 {
-        if truth() {}
-    }
-
-    // Suffix:
-    if truth() {
-        if let 0 = 1 {}
-    }
-
-    // Midfix:
-    if truth() {
-        if let 0 = 1 {
-            if truth() {}
-        }
-    }
-
     // Fix #5962
     if matches!(true, true)
         && matches!(true, true) {}

tests/ui/collapsible_if.rs

@@ -108,27 +108,8 @@ fn main() {
         }
     }
 
-    // Test behavior wrt. `let_chains`.
-    // None of the cases below should be collapsed.
     fn truth() -> bool { true }
 
-    // Prefix:
-    if let 0 = 1 {
-        if truth() {}
-    }
-
-    // Suffix:
-    if truth() {
-        if let 0 = 1 {}
-    }
-
-    // Midfix:
-    if truth() {
-        if let 0 = 1 {
-            if truth() {}
-        }
-    }
-
     // Fix #5962
     if matches!(true, true) {
         if matches!(true, true) {}