Fix std-instead-of-core FP when not all items come from the new crate

clippy_lints/src/std_instead_of_core.rs

@@ -1,10 +1,10 @@
 use clippy_config::Conf;
-use clippy_utils::diagnostics::span_lint_and_sugg;
+use clippy_utils::diagnostics::{span_lint_and_help, span_lint_and_sugg};
 use clippy_utils::is_from_proc_macro;
 use clippy_utils::msrvs::Msrv;
 use rustc_attr_data_structures::{StabilityLevel, StableSince};
 use rustc_errors::Applicability;
-use rustc_hir::def::Res;
+use rustc_hir::def::{DefKind, Res};
 use rustc_hir::def_id::DefId;
 use rustc_hir::{Block, Body, HirId, Path, PathSegment};
 use rustc_lint::{LateContext, LateLintPass, Lint, LintContext};
@@ -88,94 +88,137 @@ declare_clippy_lint! {
 }
 
 pub struct StdReexports {
-    lint_point: (Span, Option<LintPoint>),
+    lint_points: Option<(Span, Vec<LintPoint>)>,
     msrv: Msrv,
 }
 
 impl StdReexports {
     pub fn new(conf: &'static Conf) -> Self {
         Self {
-            lint_point: Default::default(),
+            lint_points: Option::default(),
             msrv: conf.msrv,
         }
     }
 
-    fn lint_if_finish(&mut self, cx: &LateContext<'_>, (span, item): (Span, Option<LintPoint>)) {
-        if span.source_equal(self.lint_point.0) {
-            return;
+    fn lint_if_finish(&mut self, cx: &LateContext<'_>, krate: Span, lint_point: LintPoint) {
+        match &mut self.lint_points {
+            Some((prev_krate, prev_lints)) if prev_krate.overlaps(krate) => {
+                prev_lints.push(lint_point);
+            },
+            _ => emit_lints(cx, self.lint_points.replace((krate, vec![lint_point]))),
         }
-
-        if !self.lint_point.0.is_dummy() {
-            emit_lints(cx, &self.lint_point);
-        }
-
-        self.lint_point = (span, item);
     }
 }
 
 impl_lint_pass!(StdReexports => [STD_INSTEAD_OF_CORE, STD_INSTEAD_OF_ALLOC, ALLOC_INSTEAD_OF_CORE]);
 
-type LintPoint = (&'static Lint, &'static str, &'static str);
+#[derive(Debug)]
+enum LintPoint {
+    Available(Span, &'static Lint, &'static str, &'static str),
+    Conflict,
+}
 
 impl<'tcx> LateLintPass<'tcx> for StdReexports {
     fn check_path(&mut self, cx: &LateContext<'tcx>, path: &Path<'tcx>, _: HirId) {
-        if let Res::Def(_, def_id) = path.res
+        if let Res::Def(def_kind, def_id) = path.res
             && let Some(first_segment) = get_first_segment(path)
             && is_stable(cx, def_id, self.msrv)
             && !path.span.in_external_macro(cx.sess().source_map())
             && !is_from_proc_macro(cx, &first_segment.ident)
+            && !matches!(def_kind, DefKind::Macro(_))
+            && let Some(last_segment) = path.segments.last()
         {
             let (lint, used_mod, replace_with) = match first_segment.ident.name {
                 sym::std => match cx.tcx.crate_name(def_id.krate) {
                     sym::core => (STD_INSTEAD_OF_CORE, "std", "core"),
                     sym::alloc => (STD_INSTEAD_OF_ALLOC, "std", "alloc"),
                     _ => {
-                        self.lint_if_finish(cx, (first_segment.ident.span, None));
+                        self.lint_if_finish(cx, first_segment.ident.span, LintPoint::Conflict);
                         return;
                     },
                 },
                 sym::alloc => {
                     if cx.tcx.crate_name(def_id.krate) == sym::core {
                         (ALLOC_INSTEAD_OF_CORE, "alloc", "core")
                     } else {
-                        self.lint_if_finish(cx, (first_segment.ident.span, None));
+                        self.lint_if_finish(cx, first_segment.ident.span, LintPoint::Conflict);
                         return;
                     }
                 },
-                _ => return,
+                _ => {
+                    self.lint_if_finish(cx, first_segment.ident.span, LintPoint::Conflict);
+                    return;
+                },
             };
 
-            self.lint_if_finish(cx, (first_segment.ident.span, Some((lint, used_mod, replace_with))));
+            self.lint_if_finish(
+                cx,
+                first_segment.ident.span,
+                LintPoint::Available(last_segment.ident.span, lint, used_mod, replace_with),
+            );
         }
     }
 
     fn check_block_post(&mut self, cx: &LateContext<'tcx>, _: &Block<'tcx>) {
-        self.lint_if_finish(cx, Default::default());
+        emit_lints(cx, self.lint_points.take());
     }
 
     fn check_body_post(&mut self, cx: &LateContext<'tcx>, _: &Body<'tcx>) {
-        self.lint_if_finish(cx, Default::default());
+        emit_lints(cx, self.lint_points.take());
     }
 
     fn check_crate_post(&mut self, cx: &LateContext<'tcx>) {
-        self.lint_if_finish(cx, Default::default());
+        emit_lints(cx, self.lint_points.take());
     }
 }
 
-fn emit_lints(cx: &LateContext<'_>, (span, item): &(Span, Option<LintPoint>)) {
-    let Some((lint, used_mod, replace_with)) = item else {
+fn emit_lints(cx: &LateContext<'_>, lint_points: Option<(Span, Vec<LintPoint>)>) {
+    let Some((krate_span, lint_points)) = lint_points else {
         return;
     };
 
-    span_lint_and_sugg(
-        cx,
-        lint,
-        *span,
-        format!("used import from `{used_mod}` instead of `{replace_with}`"),
-        format!("consider importing the item from `{replace_with}`"),
-        (*replace_with).to_string(),
-        Applicability::MachineApplicable,
-    );
+    let mut lint: Option<(&'static Lint, &'static str, &'static str)> = None;
+    let mut has_conflict = false;
+    for lint_point in &lint_points {
+        match lint_point {
+            LintPoint::Available(_, l, used_mod, replace_with)
+                if lint.is_none_or(|(prev_l, ..)| l.name == prev_l.name) =>
+            {
+                lint = Some((l, used_mod, replace_with));
+            },
+            _ => {
+                has_conflict = true;
+                break;
+            },
+        }
+    }
+
+    if !has_conflict && let Some((lint, used_mod, replace_with)) = lint {
+        span_lint_and_sugg(
+            cx,
+            lint,
+            krate_span,
+            format!("used import from `{used_mod}` instead of `{replace_with}`"),
+            format!("consider importing the item from `{replace_with}`"),
+            (*replace_with).to_string(),
+            Applicability::MachineApplicable,
+        );
+        return;
+    }
+
+    for lint_point in lint_points {
+        let LintPoint::Available(span, lint, used_mod, replace_with) = lint_point else {
+            continue;
+        };
+        span_lint_and_help(
+            cx,
+            lint,
+            span,
+            format!("used import from `{used_mod}` instead of `{replace_with}`"),
+            None,
+            format!("consider importing the item from `{replace_with}`"),
+        );
+    }
 }
 
 /// Returns the first named segment of a [`Path`].

tests/ui/std_instead_of_core.fixed

@@ -8,7 +8,6 @@ extern crate alloc;
 #[macro_use]
 extern crate proc_macro_derive;
 
-#[warn(clippy::std_instead_of_core)]
 fn std_instead_of_core() {
     // Regular import
     use core::hash::Hasher;
@@ -90,9 +89,3 @@ fn msrv_1_76(_: std::net::IpAddr) {}
 #[clippy::msrv = "1.77"]
 fn msrv_1_77(_: core::net::IpAddr) {}
 //~^ std_instead_of_core
-
-#[warn(clippy::std_instead_of_core)]
-#[rustfmt::skip]
-fn issue14982() {
-    use std::{collections::HashMap, hash::Hash};
-}

tests/ui/std_instead_of_core.rs

@@ -8,7 +8,6 @@ extern crate alloc;
 #[macro_use]
 extern crate proc_macro_derive;
 
-#[warn(clippy::std_instead_of_core)]
 fn std_instead_of_core() {
     // Regular import
     use std::hash::Hasher;
@@ -90,9 +89,3 @@ fn msrv_1_76(_: std::net::IpAddr) {}
 #[clippy::msrv = "1.77"]
 fn msrv_1_77(_: std::net::IpAddr) {}
 //~^ std_instead_of_core
-
-#[warn(clippy::std_instead_of_core)]
-#[rustfmt::skip]
-fn issue14982() {
-    use std::{collections::HashMap, hash::Hash};
-}

tests/ui/std_instead_of_core.stderr

@@ -1,5 +1,5 @@
 error: used import from `std` instead of `core`
-  --> tests/ui/std_instead_of_core.rs:14:9
+  --> tests/ui/std_instead_of_core.rs:13:9
    |
 LL |     use std::hash::Hasher;
    |         ^^^ help: consider importing the item from `core`: `core`
@@ -8,61 +8,61 @@ LL |     use std::hash::Hasher;
    = help: to override `-D warnings` add `#[allow(clippy::std_instead_of_core)]`
 
 error: used import from `std` instead of `core`
-  --> tests/ui/std_instead_of_core.rs:17:11
+  --> tests/ui/std_instead_of_core.rs:16:11
    |
 LL |     use ::std::hash::Hash;
    |           ^^^ help: consider importing the item from `core`: `core`
 
 error: used import from `std` instead of `core`
-  --> tests/ui/std_instead_of_core.rs:23:9
+  --> tests/ui/std_instead_of_core.rs:22:9
    |
 LL |     use std::fmt::{Debug, Result};
    |         ^^^ help: consider importing the item from `core`: `core`
 
 error: used import from `std` instead of `core`
-  --> tests/ui/std_instead_of_core.rs:28:9
+  --> tests/ui/std_instead_of_core.rs:27:9
    |
 LL |     use std::{
    |         ^^^ help: consider importing the item from `core`: `core`
 
 error: used import from `std` instead of `core`
-  --> tests/ui/std_instead_of_core.rs:35:15
+  --> tests/ui/std_instead_of_core.rs:34:15
    |
 LL |     let ptr = std::ptr::null::<u32>();
    |               ^^^ help: consider importing the item from `core`: `core`
 
 error: used import from `std` instead of `core`
-  --> tests/ui/std_instead_of_core.rs:37:21
+  --> tests/ui/std_instead_of_core.rs:36:21
    |
 LL |     let ptr_mut = ::std::ptr::null_mut::<usize>();
    |                     ^^^ help: consider importing the item from `core`: `core`
 
 error: used import from `std` instead of `core`
-  --> tests/ui/std_instead_of_core.rs:41:16
+  --> tests/ui/std_instead_of_core.rs:40:16
    |
 LL |     let cell = std::cell::Cell::new(8u32);
    |                ^^^ help: consider importing the item from `core`: `core`
 
 error: used import from `std` instead of `core`
-  --> tests/ui/std_instead_of_core.rs:43:27
+  --> tests/ui/std_instead_of_core.rs:42:27
    |
 LL |     let cell_absolute = ::std::cell::Cell::new(8u32);
    |                           ^^^ help: consider importing the item from `core`: `core`
 
 error: used import from `std` instead of `core`
-  --> tests/ui/std_instead_of_core.rs:48:9
+  --> tests/ui/std_instead_of_core.rs:47:9
    |
 LL |     use std::error::Error;
    |         ^^^ help: consider importing the item from `core`: `core`
 
 error: used import from `std` instead of `core`
-  --> tests/ui/std_instead_of_core.rs:52:9
+  --> tests/ui/std_instead_of_core.rs:51:9
    |
 LL |     use std::iter::Iterator;
    |         ^^^ help: consider importing the item from `core`: `core`
 
 error: used import from `std` instead of `alloc`
-  --> tests/ui/std_instead_of_core.rs:59:9
+  --> tests/ui/std_instead_of_core.rs:58:9
    |
 LL |     use std::vec;
    |         ^^^ help: consider importing the item from `alloc`: `alloc`
@@ -71,13 +71,13 @@ LL |     use std::vec;
    = help: to override `-D warnings` add `#[allow(clippy::std_instead_of_alloc)]`
 
 error: used import from `std` instead of `alloc`
-  --> tests/ui/std_instead_of_core.rs:61:9
+  --> tests/ui/std_instead_of_core.rs:60:9
    |
 LL |     use std::vec::Vec;
    |         ^^^ help: consider importing the item from `alloc`: `alloc`
 
 error: used import from `alloc` instead of `core`
-  --> tests/ui/std_instead_of_core.rs:67:9
+  --> tests/ui/std_instead_of_core.rs:66:9
    |
 LL |     use alloc::slice::from_ref;
    |         ^^^^^ help: consider importing the item from `core`: `core`
@@ -86,13 +86,13 @@ LL |     use alloc::slice::from_ref;
    = help: to override `-D warnings` add `#[allow(clippy::alloc_instead_of_core)]`
 
 error: used import from `std` instead of `core`
-  --> tests/ui/std_instead_of_core.rs:82:9
+  --> tests/ui/std_instead_of_core.rs:81:9
    |
 LL |         std::intrinsics::copy(a, b, 1);
    |         ^^^ help: consider importing the item from `core`: `core`
 
 error: used import from `std` instead of `core`
-  --> tests/ui/std_instead_of_core.rs:91:17
+  --> tests/ui/std_instead_of_core.rs:90:17
    |
 LL | fn msrv_1_77(_: std::net::IpAddr) {}
    |                 ^^^ help: consider importing the item from `core`: `core`

tests/ui/std_instead_of_core_unfixable.rs

@@ -0,0 +1,18 @@
+//@no-rustfix
+
+#![warn(clippy::std_instead_of_core)]
+#![warn(clippy::std_instead_of_alloc)]
+#![allow(unused_imports)]
+
+#[rustfmt::skip]
+fn issue14982() {
+    use std::{collections::HashMap, hash::Hash};
+    //~^ std_instead_of_core
+}
+
+#[rustfmt::skip]
+fn issue15143() {
+    use std::{error::Error, vec::Vec, fs::File};
+    //~^ std_instead_of_core
+    //~| std_instead_of_alloc
+}

tests/ui/std_instead_of_core_unfixable.stderr

@@ -0,0 +1,30 @@
+error: used import from `std` instead of `core`
+  --> tests/ui/std_instead_of_core_unfixable.rs:9:43
+   |
+LL |     use std::{collections::HashMap, hash::Hash};
+   |                                           ^^^^
+   |
+   = help: consider importing the item from `core`
+   = note: `-D clippy::std-instead-of-core` implied by `-D warnings`
+   = help: to override `-D warnings` add `#[allow(clippy::std_instead_of_core)]`
+
+error: used import from `std` instead of `core`
+  --> tests/ui/std_instead_of_core_unfixable.rs:15:22
+   |
+LL |     use std::{error::Error, vec::Vec, fs::File};
+   |                      ^^^^^
+   |
+   = help: consider importing the item from `core`
+
+error: used import from `std` instead of `alloc`
+  --> tests/ui/std_instead_of_core_unfixable.rs:15:34
+   |
+LL |     use std::{error::Error, vec::Vec, fs::File};
+   |                                  ^^^
+   |
+   = help: consider importing the item from `alloc`
+   = note: `-D clippy::std-instead-of-alloc` implied by `-D warnings`
+   = help: to override `-D warnings` add `#[allow(clippy::std_instead_of_alloc)]`
+
+error: aborting due to 3 previous errors
+