implemented lint unnecessary_min

CHANGELOG.md

@@ -5668,6 +5668,7 @@ Released 2018-09-13
 [`unnecessary_lazy_evaluations`]: https://rust-lang.github.io/rust-clippy/master/index.html#unnecessary_lazy_evaluations
 [`unnecessary_literal_unwrap`]: https://rust-lang.github.io/rust-clippy/master/index.html#unnecessary_literal_unwrap
 [`unnecessary_map_on_constructor`]: https://rust-lang.github.io/rust-clippy/master/index.html#unnecessary_map_on_constructor
+[`unnecessary_min`]: https://rust-lang.github.io/rust-clippy/master/index.html#unnecessary_min
 [`unnecessary_mut_passed`]: https://rust-lang.github.io/rust-clippy/master/index.html#unnecessary_mut_passed
 [`unnecessary_operation`]: https://rust-lang.github.io/rust-clippy/master/index.html#unnecessary_operation
 [`unnecessary_owned_empty_strings`]: https://rust-lang.github.io/rust-clippy/master/index.html#unnecessary_owned_empty_strings

clippy_config/src/conf.rs

@@ -645,8 +645,7 @@ impl Conf {
                 }
             },
             Err(error) => {
-                sess.dcx()
-                    .err(format!("error finding Clippy's configuration file: {error}"));
+                sess.dcx().err(format!("error finding Clippy's configuration file: {error}"));
             },
         }
 

clippy_config/src/msrvs.rs

@@ -107,8 +107,7 @@ impl Msrv {
 
         if let Some(msrv_attr) = msrv_attrs.next() {
             if let Some(duplicate) = msrv_attrs.last() {
-                sess.dcx()
-                    .struct_span_err(duplicate.span, "`clippy::msrv` is defined multiple times")
+                sess.dcx().struct_span_err(duplicate.span, "`clippy::msrv` is defined multiple times")
                     .span_note(msrv_attr.span, "first definition found here")
                     .emit();
             }
@@ -118,8 +117,7 @@ impl Msrv {
                     return Some(version);
                 }
 
-                sess.dcx()
-                    .span_err(msrv_attr.span, format!("`{msrv}` is not a valid Rust version"));
+                sess.dcx().span_err(msrv_attr.span, format!("`{msrv}` is not a valid Rust version"));
             } else {
                 sess.dcx().span_err(msrv_attr.span, "bad clippy attribute");
             }

clippy_lints/src/async_yields_async.rs

@@ -2,7 +2,10 @@ use clippy_utils::diagnostics::span_lint_hir_and_then;
 use clippy_utils::source::snippet;
 use clippy_utils::ty::implements_trait;
 use rustc_errors::Applicability;
-use rustc_hir::{Closure, ClosureKind, CoroutineDesugaring, CoroutineKind, CoroutineSource, Expr, ExprKind, QPath};
+use rustc_hir::{
+    Closure, ClosureKind, CoroutineDesugaring, CoroutineKind, CoroutineSource, Expr, ExprKind, QPath,
+};
+
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_session::declare_lint_pass;
 

clippy_lints/src/declared_lints.rs

@@ -447,6 +447,7 @@ pub(crate) static LINTS: &[&crate::LintInfo] = &[
     crate::methods::UNNECESSARY_JOIN_INFO,
     crate::methods::UNNECESSARY_LAZY_EVALUATIONS_INFO,
     crate::methods::UNNECESSARY_LITERAL_UNWRAP_INFO,
+    crate::methods::UNNECESSARY_MIN_INFO,
     crate::methods::UNNECESSARY_SORT_BY_INFO,
     crate::methods::UNNECESSARY_TO_OWNED_INFO,
     crate::methods::UNWRAP_OR_DEFAULT_INFO,

clippy_lints/src/len_zero.rs

@@ -8,8 +8,8 @@ use rustc_hir::def::Res;
 use rustc_hir::def_id::{DefId, DefIdSet};
 use rustc_hir::{
     AssocItemKind, BinOpKind, Expr, ExprKind, FnRetTy, GenericArg, GenericBound, ImplItem, ImplItemKind,
-    ImplicitSelfKind, Item, ItemKind, Mutability, Node, OpaqueTyOrigin, PatKind, PathSegment, PrimTy, QPath,
-    TraitItemRef, TyKind, TypeBindingKind,
+    ImplicitSelfKind, Item, ItemKind, Mutability, Node, PatKind, PathSegment, PrimTy, QPath, TraitItemRef,
+    TyKind, TypeBindingKind, OpaqueTyOrigin,
 };
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_middle::ty::{self, AssocKind, FnSig, Ty};

clippy_lints/src/manual_async_fn.rs

@@ -3,9 +3,9 @@ use clippy_utils::source::{position_before_rarrow, snippet_block, snippet_opt};
 use rustc_errors::Applicability;
 use rustc_hir::intravisit::FnKind;
 use rustc_hir::{
-    Block, Body, Closure, ClosureKind, CoroutineDesugaring, CoroutineKind, CoroutineSource, Expr, ExprKind, FnDecl,
-    FnRetTy, GenericArg, GenericBound, ImplItem, Item, ItemKind, LifetimeName, Node, Term, TraitRef, Ty, TyKind,
-    TypeBindingKind,
+    Block, Body, Closure, CoroutineDesugaring, CoroutineKind, CoroutineSource, Expr, ExprKind, FnDecl, FnRetTy,
+    GenericArg, GenericBound, ImplItem, Item, ItemKind, LifetimeName, Node, Term, TraitRef, Ty, TyKind,
+    TypeBindingKind, ClosureKind,
 };
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_session::declare_lint_pass;
@@ -171,14 +171,23 @@ fn captures_all_lifetimes(inputs: &[Ty<'_>], output_lifetimes: &[LifetimeName])
             .iter()
             .all(|in_lt| output_lifetimes.iter().any(|out_lt| in_lt == out_lt))
 }
-
-fn desugared_async_block<'tcx>(cx: &LateContext<'tcx>, block: &'tcx Block<'tcx>) -> Option<&'tcx Body<'tcx>> {
+fn desugared_async_block<'tcx>(
+    cx: &LateContext<'tcx>,
+    block: &'tcx Block<'tcx>,
+) -> Option<&'tcx Body<'tcx>> {
     if let Some(Expr {
-        kind: ExprKind::Closure(&Closure { kind, body, .. }),
+        kind:
+            ExprKind::Closure(&Closure {
+                kind:
+                    ClosureKind::Coroutine(CoroutineKind::Desugared(
+                        CoroutineDesugaring::Async,
+                        CoroutineSource::Block,
+                    )),
+                body,
+                ..
+            }),
         ..
     }) = block.expr
-        && let ClosureKind::Coroutine(CoroutineKind::Desugared(CoroutineDesugaring::Async, CoroutineSource::Block)) =
-            kind
     {
         return Some(cx.tcx.hir().body(body));
     }

clippy_lints/src/methods/mod.rs

@@ -110,6 +110,7 @@ mod unnecessary_iter_cloned;
 mod unnecessary_join;
 mod unnecessary_lazy_eval;
 mod unnecessary_literal_unwrap;
+mod unnecessary_min;
 mod unnecessary_sort_by;
 mod unnecessary_to_owned;
 mod unwrap_expect_used;
@@ -3754,6 +3755,27 @@ declare_clippy_lint! {
     "using `Option.map_or(Err(_), Ok)`, which is more succinctly expressed as `Option.ok_or(_)`"
 }
 
+declare_clippy_lint! {
+    /// ### What it does
+    /// Checks for unnecessary calls to `min()`
+    ///
+    /// ### Why is this bad?
+    ///
+    /// In these cases it is not necessary to call `min()`
+    /// ### Example
+    /// ```no_run
+    /// let _ = 0.min(7_u32);
+    /// ```
+    /// Use instead:
+    /// ```no_run
+    /// let _ = 7;
+    /// ```
+    #[clippy::version = "1.76.0"]
+    pub UNNECESSARY_MIN,
+    complexity,
+    "using 'min()' when there is no need for it"
+}
+
 declare_clippy_lint! {
     /// ### What it does
     /// Checks for iterators of `Result`s using `.filter(Result::is_ok).map(Result::unwrap)` that may
@@ -3980,6 +4002,7 @@ impl_lint_pass!(Methods => [
     UNNECESSARY_FALLIBLE_CONVERSIONS,
     JOIN_ABSOLUTE_PATHS,
     OPTION_MAP_OR_ERR_OK,
+    UNNECESSARY_MIN,
     RESULT_FILTER_MAP,
     ITER_FILTER_IS_SOME,
     ITER_FILTER_IS_OK,
@@ -4264,6 +4287,7 @@ impl Methods {
                     Some(("bytes", recv2, [], _, _)) => bytes_count_to_len::check(cx, expr, recv, recv2),
                     _ => {},
                 },
+                ("min", [arg]) => unnecessary_min::check(cx, expr, recv, arg),
                 ("drain", ..) => {
                     if let Node::Stmt(Stmt { hir_id: _, kind, .. }) = cx.tcx.hir().get_parent(expr.hir_id)
                         && matches!(kind, StmtKind::Semi(_))

clippy_lints/src/methods/unnecessary_min.rs

@@ -0,0 +1,111 @@
+use std::cmp::Ordering;
+
+use super::UNNECESSARY_MIN;
+use clippy_utils::diagnostics::span_lint_and_sugg;
+
+use clippy_utils::consts::{constant, Constant};
+use clippy_utils::source::snippet;
+use clippy_utils::{clip, int_bits, unsext};
+use hir::Expr;
+
+use rustc_errors::Applicability;
+use rustc_hir as hir;
+use rustc_lint::LateContext;
+
+use rustc_middle::ty;
+use rustc_span::Span;
+
+pub fn check<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>, recv: &'tcx Expr<'_>, arg: &'tcx Expr<'_>) {
+    if both_are_constant(cx, expr, recv, arg) {
+        return;
+    }
+    one_extrema(cx, expr, recv, arg);
+}
+fn lint(cx: &LateContext<'_>, expr: &Expr<'_>, sugg: Span, other: Span) {
+    let msg = format!(
+        "`{}` is never greater than `{}` and has therefore no effect",
+        snippet(cx, sugg, "Not yet implemented"),
+        snippet(cx, other, "Not yet implemented")
+    );
+    span_lint_and_sugg(
+        cx,
+        UNNECESSARY_MIN,
+        expr.span,
+        &msg,
+        "try",
+        snippet(cx, sugg, "Not yet implemented").to_string(),
+        Applicability::MachineApplicable,
+    );
+}
+
+fn try_to_eval<'tcx>(
+    cx: &LateContext<'tcx>,
+    recv: &'tcx Expr<'_>,
+    arg: &'tcx Expr<'_>,
+) -> (Option<Constant<'tcx>>, Option<Constant<'tcx>>) {
+    (
+        (constant(cx, cx.typeck_results(), recv)),
+        (constant(cx, cx.typeck_results(), arg)),
+    )
+}
+#[derive(Debug)]
+enum Extrema {
+    Minimum,
+    Maximum,
+}
+fn detect_extrema<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) -> Option<Extrema> {
+    let ty = cx.typeck_results().expr_ty(expr);
+
+    let cv = constant(cx, cx.typeck_results(), expr)?;
+
+    match (ty.kind(), cv) {
+        (&ty::Uint(_), Constant::Int(0)) => Some(Extrema::Minimum),
+        (&ty::Int(ity), Constant::Int(i)) if i == unsext(cx.tcx, i128::MIN >> (128 - int_bits(cx.tcx, ity)), ity) => {
+            Some(Extrema::Minimum)
+        },
+
+        (&ty::Int(ity), Constant::Int(i)) if i == unsext(cx.tcx, i128::MAX >> (128 - int_bits(cx.tcx, ity)), ity) => {
+            Some(Extrema::Maximum)
+        },
+        (&ty::Uint(uty), Constant::Int(i)) if i == clip(cx.tcx, u128::MAX, uty) => Some(Extrema::Maximum),
+
+        _ => None,
+    }
+}
+fn both_are_constant<'tcx>(
+    cx: &LateContext<'tcx>,
+    expr: &'tcx Expr<'_>,
+    recv: &'tcx Expr<'_>,
+    arg: &'tcx Expr<'_>,
+) -> bool {
+    let ty = cx.typeck_results().expr_ty(recv);
+    if let (Some(left), Some(right)) = try_to_eval(cx, recv, arg)
+        && let Some(ord) = Constant::partial_cmp(cx.tcx, ty, &left, &right)
+    {
+        let (sugg, other) = match ord {
+            Ordering::Less => (recv.span, arg.span),
+            Ordering::Equal | Ordering::Greater => (arg.span, recv.span),
+        };
+
+        lint(cx, expr, sugg, other);
+        return true;
+    }
+    false
+}
+fn one_extrema<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>, recv: &'tcx Expr<'_>, arg: &'tcx Expr<'_>) -> bool {
+    if let Some(extrema) = detect_extrema(cx, recv) {
+        match extrema {
+            Extrema::Minimum => lint(cx, expr, recv.span, arg.span),
+            Extrema::Maximum => lint(cx, expr, arg.span, recv.span),
+        }
+        return true;
+    } else if let Some(extrema) = detect_extrema(cx, arg) {
+        match extrema {
+            Extrema::Minimum => lint(cx, expr, arg.span, recv.span),
+            Extrema::Maximum => lint(cx, expr, recv.span, arg.span),
+        }
+        return true;
+    }
+
+    false
+}

clippy_lints/src/redundant_async_block.rs

@@ -6,9 +6,7 @@ use clippy_utils::source::{snippet, walk_span_to_context};
 use clippy_utils::ty::implements_trait;
 use clippy_utils::visitors::for_each_expr;
 use rustc_errors::Applicability;
-use rustc_hir::{
-    Closure, ClosureKind, CoroutineDesugaring, CoroutineKind, CoroutineSource, Expr, ExprKind, MatchSource,
-};
+use rustc_hir::{Closure, ClosureKind, CoroutineKind, CoroutineSource, CoroutineDesugaring, Expr, ExprKind, MatchSource};
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_middle::lint::in_external_macro;
 use rustc_middle::ty::UpvarCapture;
@@ -77,13 +75,7 @@ impl<'tcx> LateLintPass<'tcx> for RedundantAsyncBlock {
 fn desugar_async_block<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) -> Option<&'tcx Expr<'tcx>> {
     if let ExprKind::Closure(Closure { body, def_id, kind, .. }) = expr.kind
         && let body = cx.tcx.hir().body(*body)
-        && matches!(
-            kind,
-            ClosureKind::Coroutine(CoroutineKind::Desugared(
-                CoroutineDesugaring::Async,
-                CoroutineSource::Block
-            ))
-        )
+        && matches!(kind, ClosureKind::Coroutine(CoroutineKind::Desugared(CoroutineDesugaring::Async, CoroutineSource::Block)))
     {
         cx.typeck_results()
             .closure_min_captures

clippy_lints/src/redundant_closure_call.rs

@@ -5,7 +5,7 @@ use clippy_utils::sugg::Sugg;
 use rustc_errors::Applicability;
 use rustc_hir as hir;
 use rustc_hir::intravisit::{Visitor as HirVisitor, Visitor};
-use rustc_hir::{intravisit as hir_visit, ClosureKind, CoroutineDesugaring, CoroutineKind, CoroutineSource, Node};
+use rustc_hir::{intravisit as hir_visit, CoroutineKind, CoroutineSource, CoroutineDesugaring, Node, ClosureKind};
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_middle::hir::nested_filter;
 use rustc_middle::lint::in_external_macro;
@@ -66,8 +66,7 @@ impl<'tcx> Visitor<'tcx> for ReturnVisitor {
 fn is_async_closure(body: &hir::Body<'_>) -> bool {
     if let hir::ExprKind::Closure(innermost_closure_generated_by_desugar) = body.value.kind
         // checks whether it is `async || whatever_expression`
-        && let ClosureKind::Coroutine(CoroutineKind::Desugared(CoroutineDesugaring::Async, CoroutineSource::Closure))
-            = innermost_closure_generated_by_desugar.kind
+        && let ClosureKind::Coroutine(CoroutineKind::Desugared(CoroutineDesugaring::Async, CoroutineSource::Closure)) = innermost_closure_generated_by_desugar.kind
     {
         true
     } else {

clippy_utils/src/attrs.rs

@@ -76,14 +76,12 @@ pub fn get_attr<'a>(
                 })
                 .map_or_else(
                     || {
-                        sess.dcx()
-                            .span_err(attr_segments[1].ident.span, "usage of unknown attribute");
+                        sess.dcx().span_err(attr_segments[1].ident.span, "usage of unknown attribute");
                         false
                     },
                     |deprecation_status| {
-                        let mut diag = sess
-                            .dcx()
-                            .struct_span_err(attr_segments[1].ident.span, "usage of deprecated attribute");
+                        let mut diag =
+                            sess.dcx().struct_span_err(attr_segments[1].ident.span, "usage of deprecated attribute");
                         match *deprecation_status {
                             DeprecationStatus::Deprecated => {
                                 diag.emit();
@@ -134,8 +132,7 @@ pub fn get_unique_attr<'a>(
     let mut unique_attr: Option<&ast::Attribute> = None;
     for attr in get_attr(sess, attrs, name) {
         if let Some(duplicate) = unique_attr {
-            sess.dcx()
-                .struct_span_err(attr.span, format!("`{name}` is defined multiple times"))
+            sess.dcx().struct_span_err(attr.span, format!("`{name}` is defined multiple times"))
                 .span_note(duplicate.span, "first definition found here")
                 .emit();
         } else {

tests/ui/cast.rs

@@ -8,7 +8,12 @@
     clippy::cast_sign_loss,
     clippy::cast_possible_wrap
 )]
-#![allow(clippy::cast_abs_to_unsigned, clippy::no_effect, clippy::unnecessary_operation)]
+#![allow(
+    clippy::cast_abs_to_unsigned,
+    clippy::no_effect,
+    clippy::unnecessary_operation,
+    clippy::unnecessary_min
+)]
 
 fn main() {
     // Test clippy::cast_precision_loss