Merge remote-tracking branch 'upstream/master' into rustup

8 files changed, 114 insertions, 23 deletions

diff --git a/clippy_lints/src/methods/ip_constant.rs b/clippy_lints/src/methods/ip_constant.rs
new file mode 100644
index 00000000000..83803fba6a1
--- /dev/null
+++ b/clippy_lints/src/methods/ip_constant.rs
@@ -0,0 +1,52 @@
+use clippy_utils::consts::{ConstEvalCtxt, Constant};
+use clippy_utils::diagnostics::span_lint_and_then;
+use rustc_errors::Applicability;
+use rustc_hir::{Expr, ExprKind, QPath, Ty, TyKind};
+use rustc_lint::LateContext;
+use rustc_span::sym;
+use smallvec::SmallVec;
+
+use super::IP_CONSTANT;
+
+pub(super) fn check(cx: &LateContext<'_>, expr: &Expr<'_>, func: &Expr<'_>, args: &[Expr<'_>]) {
+    if let ExprKind::Path(QPath::TypeRelative(
+        Ty {
+            kind: TyKind::Path(QPath::Resolved(_, func_path)),
+            ..
+        },
+        p,
+    )) = func.kind
+        && p.ident.name == sym::new
+        && let Some(func_def_id) = func_path.res.opt_def_id()
+        && matches!(
+            cx.tcx.get_diagnostic_name(func_def_id),
+            Some(sym::Ipv4Addr | sym::Ipv6Addr)
+        )
+        && let Some(args) = args
+            .iter()
+            .map(|arg| {
+                if let Some(Constant::Int(constant @ (0 | 1 | 127 | 255))) = ConstEvalCtxt::new(cx).eval(arg) {
+                    u8::try_from(constant).ok()
+                } else {
+                    None
+                }
+            })
+            .collect::<Option<SmallVec<[u8; 8]>>>()
+    {
+        let constant_name = match args.as_slice() {
+            [0, 0, 0, 0] | [0, 0, 0, 0, 0, 0, 0, 0] => "UNSPECIFIED",
+            [127, 0, 0, 1] | [0, 0, 0, 0, 0, 0, 0, 1] => "LOCALHOST",
+            [255, 255, 255, 255] => "BROADCAST",
+            _ => return,
+        };
+
+        span_lint_and_then(cx, IP_CONSTANT, expr.span, "hand-coded well-known IP address", |diag| {
+            diag.span_suggestion_verbose(
+                expr.span.with_lo(p.ident.span.lo()),
+                "use",
+                constant_name,
+                Applicability::MachineApplicable,
+            );
+        });
+    }
+}
diff --git a/clippy_lints/src/methods/iter_kv_map.rs b/clippy_lints/src/methods/iter_kv_map.rs
index c88462129af..cbb1b450e60 100644
--- a/clippy_lints/src/methods/iter_kv_map.rs
+++ b/clippy_lints/src/methods/iter_kv_map.rs
@@ -46,7 +46,7 @@ pub(super) fn check<'tcx>(
 
         if let ExprKind::Path(rustc_hir::QPath::Resolved(_, path)) = body_expr.kind
             && let [local_ident] = path.segments
-            && local_ident.ident.as_str() == bound_ident.as_str()
+            && local_ident.ident.name == bound_ident.name
         {
             span_lint_and_sugg(
                 cx,
diff --git a/clippy_lints/src/methods/manual_saturating_arithmetic.rs b/clippy_lints/src/methods/manual_saturating_arithmetic.rs
index e2df8ce1513..c785b23bc9c 100644
--- a/clippy_lints/src/methods/manual_saturating_arithmetic.rs
+++ b/clippy_lints/src/methods/manual_saturating_arithmetic.rs
@@ -72,9 +72,9 @@ fn is_min_or_max(cx: &LateContext<'_>, expr: &hir::Expr<'_>) -> Option<MinMax> {
     if let hir::ExprKind::Call(func, []) = &expr.kind
         && let hir::ExprKind::Path(hir::QPath::TypeRelative(_, segment)) = &func.kind
     {
-        match segment.ident.as_str() {
-            "max_value" => return Some(MinMax::Max),
-            "min_value" => return Some(MinMax::Min),
+        match segment.ident.name {
+            sym::max_value => return Some(MinMax::Max),
+            sym::min_value => return Some(MinMax::Min),
             _ => {},
         }
     }
diff --git a/clippy_lints/src/methods/mod.rs b/clippy_lints/src/methods/mod.rs
index bc159206985..347960e0003 100644
--- a/clippy_lints/src/methods/mod.rs
+++ b/clippy_lints/src/methods/mod.rs
@@ -37,6 +37,7 @@ mod inefficient_to_string;
 mod inspect_for_each;
 mod into_iter_on_ref;
 mod io_other_error;
+mod ip_constant;
 mod is_digit_ascii_radix;
 mod is_empty;
 mod iter_cloned_collect;
@@ -4528,6 +4529,42 @@ declare_clippy_lint! {
     "detect swap with a temporary value"
 }
 
+declare_clippy_lint! {
+    /// ### What it does
+    /// Checks for IP addresses that could be replaced with predefined constants such as
+    /// `Ipv4Addr::new(127, 0, 0, 1)` instead of using the appropriate constants.
+    ///
+    /// ### Why is this bad?
+    /// Using specific IP addresses like `127.0.0.1` or `::1` is less clear and less maintainable than using the
+    /// predefined constants `Ipv4Addr::LOCALHOST` or `Ipv6Addr::LOCALHOST`. These constants improve code
+    /// readability, make the intent explicit, and are less error-prone.
+    ///
+    /// ### Example
+    /// ```no_run
+    /// use std::net::{Ipv4Addr, Ipv6Addr};
+    ///
+    /// // IPv4 loopback
+    /// let addr_v4 = Ipv4Addr::new(127, 0, 0, 1);
+    ///
+    /// // IPv6 loopback
+    /// let addr_v6 = Ipv6Addr::new(0, 0, 0, 0, 0, 0, 0, 1);
+    /// ```
+    /// Use instead:
+    /// ```no_run
+    /// use std::net::{Ipv4Addr, Ipv6Addr};
+    ///
+    /// // IPv4 loopback
+    /// let addr_v4 = Ipv4Addr::LOCALHOST;
+    ///
+    /// // IPv6 loopback
+    /// let addr_v6 = Ipv6Addr::LOCALHOST;
+    /// ```
+    #[clippy::version = "1.89.0"]
+    pub IP_CONSTANT,
+    pedantic,
+    "hardcoded localhost IP address"
+}
+
 #[expect(clippy::struct_excessive_bools)]
 pub struct Methods {
     avoid_breaking_exported_api: bool,
@@ -4706,6 +4743,7 @@ impl_lint_pass!(Methods => [
     MANUAL_CONTAINS,
     IO_OTHER_ERROR,
     SWAP_WITH_TEMPORARY,
+    IP_CONSTANT,
 ]);
 
 /// Extracts a method call name, args, and `Span` of the method name.
@@ -4738,6 +4776,7 @@ impl<'tcx> LateLintPass<'tcx> for Methods {
                 useless_nonzero_new_unchecked::check(cx, expr, func, args, self.msrv);
                 io_other_error::check(cx, expr, func, args, self.msrv);
                 swap_with_temporary::check(cx, expr, func, args);
+                ip_constant::check(cx, expr, func, args);
             },
             ExprKind::MethodCall(method_call, receiver, args, _) => {
                 let method_span = method_call.ident.span;
diff --git a/clippy_lints/src/methods/needless_collect.rs b/clippy_lints/src/methods/needless_collect.rs
index 2b75d6a8248..0075bf166cc 100644
--- a/clippy_lints/src/methods/needless_collect.rs
+++ b/clippy_lints/src/methods/needless_collect.rs
@@ -44,11 +44,10 @@ pub(super) fn check<'tcx>(
 
             if let ExprKind::MethodCall(name, _, args @ ([] | [_]), _) = parent.kind {
                 let mut app = Applicability::MachineApplicable;
-                let name = name.ident.as_str();
                 let collect_ty = cx.typeck_results().expr_ty(collect_expr);
 
-                let sugg: String = match name {
-                    "len" => {
+                let sugg: String = match name.ident.name {
+                    sym::len => {
                         if let Some(adt) = collect_ty.ty_adt_def()
                             && matches!(
                                 cx.tcx.get_diagnostic_name(adt.did()),
@@ -60,13 +59,13 @@ pub(super) fn check<'tcx>(
                             return;
                         }
                     },
-                    "is_empty"
+                    sym::is_empty
                         if is_is_empty_sig(cx, parent.hir_id)
                             && iterates_same_ty(cx, cx.typeck_results().expr_ty(iter_expr), collect_ty) =>
                     {
                         "next().is_none()".into()
                     },
-                    "contains" => {
+                    sym::contains => {
                         if is_contains_sig(cx, parent.hir_id, iter_expr)
                             && let Some(arg) = args.first()
                         {
diff --git a/clippy_lints/src/methods/open_options.rs b/clippy_lints/src/methods/open_options.rs
index bce314e64f0..fd368024177 100644
--- a/clippy_lints/src/methods/open_options.rs
+++ b/clippy_lints/src/methods/open_options.rs
@@ -1,14 +1,14 @@
 use rustc_data_structures::fx::FxHashMap;
 
 use clippy_utils::diagnostics::{span_lint, span_lint_and_then};
-use clippy_utils::paths;
 use clippy_utils::ty::is_type_diagnostic_item;
+use clippy_utils::{paths, sym};
 use rustc_ast::ast::LitKind;
 use rustc_hir::{Expr, ExprKind};
 use rustc_lint::LateContext;
 use rustc_middle::ty::Ty;
+use rustc_span::Span;
 use rustc_span::source_map::Spanned;
-use rustc_span::{Span, sym};
 
 use super::{NONSENSICAL_OPEN_OPTIONS, SUSPICIOUS_OPEN_OPTIONS};
 
@@ -87,23 +87,23 @@ fn get_open_options(
                 _ => Argument::Unknown,
             };
 
-            match path.ident.as_str() {
-                "create" => {
+            match path.ident.name {
+                sym::create => {
                     options.push((OpenOption::Create, argument_option, span));
                 },
-                "create_new" => {
+                sym::create_new => {
                     options.push((OpenOption::CreateNew, argument_option, span));
                 },
-                "append" => {
+                sym::append => {
                     options.push((OpenOption::Append, argument_option, span));
                 },
-                "truncate" => {
+                sym::truncate => {
                     options.push((OpenOption::Truncate, argument_option, span));
                 },
-                "read" => {
+                sym::read => {
                     options.push((OpenOption::Read, argument_option, span));
                 },
-                "write" => {
+                sym::write => {
                     options.push((OpenOption::Write, argument_option, span));
                 },
                 _ => {
diff --git a/clippy_lints/src/methods/str_splitn.rs b/clippy_lints/src/methods/str_splitn.rs
index 6935ae1f391..6f78d6c6128 100644
--- a/clippy_lints/src/methods/str_splitn.rs
+++ b/clippy_lints/src/methods/str_splitn.rs
@@ -285,9 +285,9 @@ fn parse_iter_usage<'tcx>(
             let did = cx.typeck_results().type_dependent_def_id(e.hir_id)?;
             let iter_id = cx.tcx.get_diagnostic_item(sym::Iterator)?;
 
-            match (name.ident.as_str(), args) {
-                ("next", []) if cx.tcx.trait_of_item(did) == Some(iter_id) => (IterUsageKind::Nth(0), e.span),
-                ("next_tuple", []) => {
+            match (name.ident.name, args) {
+                (sym::next, []) if cx.tcx.trait_of_item(did) == Some(iter_id) => (IterUsageKind::Nth(0), e.span),
+                (sym::next_tuple, []) => {
                     return if paths::ITERTOOLS_NEXT_TUPLE.matches(cx, did)
                         && let ty::Adt(adt_def, subs) = cx.typeck_results().expr_ty(e).kind()
                         && cx.tcx.is_diagnostic_item(sym::Option, adt_def.did())
@@ -303,7 +303,7 @@ fn parse_iter_usage<'tcx>(
                         None
                     };
                 },
-                ("nth" | "skip", [idx_expr]) if cx.tcx.trait_of_item(did) == Some(iter_id) => {
+                (sym::nth | sym::skip, [idx_expr]) if cx.tcx.trait_of_item(did) == Some(iter_id) => {
                     if let Some(Constant::Int(idx)) = ConstEvalCtxt::new(cx).eval(idx_expr) {
                         let span = if name.ident.as_str() == "nth" {
                             e.span
diff --git a/clippy_lints/src/methods/unnecessary_sort_by.rs b/clippy_lints/src/methods/unnecessary_sort_by.rs
index dbff08bc51c..edd4ecd2b4a 100644
--- a/clippy_lints/src/methods/unnecessary_sort_by.rs
+++ b/clippy_lints/src/methods/unnecessary_sort_by.rs
@@ -5,7 +5,8 @@ use clippy_utils::{is_trait_method, std_or_core};
 use rustc_errors::Applicability;
 use rustc_hir::{Closure, Expr, ExprKind, Mutability, Param, Pat, PatKind, Path, PathSegment, QPath};
 use rustc_lint::LateContext;
-use rustc_middle::ty::{self, GenericArgKind};
+use rustc_middle::ty;
+use rustc_middle::ty::GenericArgKind;
 use rustc_span::sym;
 use rustc_span::symbol::Ident;
 use std::iter;