Rollup merge of #142787 - samueltardieu:diag-items-for-clippy, r=Manishearth,Urgau

Add diagnostic items for Clippy

Clippy still uses some paths to access items from the standard library. Adding the missing diagnostic items allows removing the last remaining paths.

Closes rust-lang/rust-clippy#5393

7 files changed, 16 insertions, 24 deletions

diff --git a/clippy_lints/src/casts/manual_dangling_ptr.rs b/clippy_lints/src/casts/manual_dangling_ptr.rs
index 61dfc0fc042..d9e88d6a401 100644
--- a/clippy_lints/src/casts/manual_dangling_ptr.rs
+++ b/clippy_lints/src/casts/manual_dangling_ptr.rs
@@ -1,6 +1,6 @@
 use clippy_utils::diagnostics::span_lint_and_sugg;
 use clippy_utils::source::SpanRangeExt;
-use clippy_utils::{expr_or_init, path_def_id, paths, std_or_core};
+use clippy_utils::{expr_or_init, is_path_diagnostic_item, std_or_core, sym};
 use rustc_ast::LitKind;
 use rustc_errors::Applicability;
 use rustc_hir::{Expr, ExprKind, GenericArg, Mutability, QPath, Ty, TyKind};
@@ -53,8 +53,7 @@ fn is_expr_const_aligned(cx: &LateContext<'_>, expr: &Expr<'_>, to: &Ty<'_>) ->
 
 fn is_align_of_call(cx: &LateContext<'_>, fun: &Expr<'_>, to: &Ty<'_>) -> bool {
     if let ExprKind::Path(QPath::Resolved(_, path)) = fun.kind
-        && let Some(fun_id) = path_def_id(cx, fun)
-        && paths::ALIGN_OF.matches(cx, fun_id)
+        && is_path_diagnostic_item(cx, fun, sym::mem_align_of)
         && let Some(args) = path.segments.last().and_then(|seg| seg.args)
         && let [GenericArg::Type(generic_ty)] = args.args
     {
diff --git a/clippy_lints/src/manual_option_as_slice.rs b/clippy_lints/src/manual_option_as_slice.rs
index b55c11f2d5b..922db174e3d 100644
--- a/clippy_lints/src/manual_option_as_slice.rs
+++ b/clippy_lints/src/manual_option_as_slice.rs
@@ -1,7 +1,7 @@
 use clippy_config::Conf;
 use clippy_utils::diagnostics::{span_lint, span_lint_and_sugg};
 use clippy_utils::msrvs::Msrv;
-use clippy_utils::{is_none_arm, msrvs, paths, peel_hir_expr_refs, sym};
+use clippy_utils::{is_none_arm, msrvs, peel_hir_expr_refs, sym};
 use rustc_errors::Applicability;
 use rustc_hir::def::{DefKind, Res};
 use rustc_hir::{Arm, Expr, ExprKind, LangItem, Pat, PatKind, QPath, is_range_literal};
@@ -220,5 +220,5 @@ fn is_empty_slice(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
 }
 
 fn is_slice_from_ref(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
-    paths::SLICE_FROM_REF.matches_path(cx, expr)
+    clippy_utils::is_path_diagnostic_item(cx, expr, sym::slice_from_ref)
 }
diff --git a/clippy_lints/src/methods/io_other_error.rs b/clippy_lints/src/methods/io_other_error.rs
index ec4b9c7ae2e..9276261606e 100644
--- a/clippy_lints/src/methods/io_other_error.rs
+++ b/clippy_lints/src/methods/io_other_error.rs
@@ -1,6 +1,6 @@
 use clippy_utils::diagnostics::span_lint_and_then;
 use clippy_utils::msrvs::{self, Msrv};
-use clippy_utils::{expr_or_init, paths};
+use clippy_utils::{expr_or_init, is_path_diagnostic_item, sym};
 use rustc_errors::Applicability;
 use rustc_hir::{Expr, ExprKind, QPath};
 use rustc_lint::LateContext;
@@ -10,8 +10,11 @@ pub(super) fn check(cx: &LateContext<'_>, expr: &Expr<'_>, path: &Expr<'_>, args
         && !expr.span.from_expansion()
         && !error_kind.span.from_expansion()
         && let ExprKind::Path(QPath::TypeRelative(_, new_segment)) = path.kind
-        && paths::IO_ERROR_NEW.matches_path(cx, path)
-        && paths::IO_ERRORKIND_OTHER_CTOR.matches_path(cx, expr_or_init(cx, error_kind))
+        && is_path_diagnostic_item(cx, path, sym::io_error_new)
+        && let ExprKind::Path(QPath::Resolved(_, init_path)) = &expr_or_init(cx, error_kind).kind
+        && let [.., error_kind_ty, error_kind_variant] = init_path.segments
+        && cx.tcx.is_diagnostic_item(sym::io_errorkind, error_kind_ty.res.def_id())
+        && error_kind_variant.ident.name == sym::Other
         && msrv.meets(cx, msrvs::IO_ERROR_OTHER)
     {
         span_lint_and_then(
diff --git a/clippy_lints/src/single_range_in_vec_init.rs b/clippy_lints/src/single_range_in_vec_init.rs
index 54d09ff9ee4..dda2f8cc1d0 100644
--- a/clippy_lints/src/single_range_in_vec_init.rs
+++ b/clippy_lints/src/single_range_in_vec_init.rs
@@ -3,7 +3,7 @@ use clippy_utils::higher::VecArgs;
 use clippy_utils::macros::root_macro_call_first_node;
 use clippy_utils::source::SpanRangeExt;
 use clippy_utils::ty::implements_trait;
-use clippy_utils::{is_no_std_crate, paths};
+use clippy_utils::{is_no_std_crate, sym};
 use rustc_ast::{LitIntType, LitKind, UintTy};
 use rustc_errors::Applicability;
 use rustc_hir::{Expr, ExprKind, LangItem, QPath, StructTailExpr};
@@ -100,7 +100,7 @@ impl LateLintPass<'_> for SingleRangeInVecInit {
             && let Some(start_snippet) = start.span.get_source_text(cx)
             && let Some(end_snippet) = end.span.get_source_text(cx)
         {
-            let should_emit_every_value = if let Some(step_def_id) = paths::ITER_STEP.only(cx)
+            let should_emit_every_value = if let Some(step_def_id) = cx.tcx.get_diagnostic_item(sym::range_step)
                 && implements_trait(cx, ty, step_def_id, &[])
             {
                 true
diff --git a/clippy_lints/src/to_digit_is_some.rs b/clippy_lints/src/to_digit_is_some.rs
index 7d7d74f27b3..3e847543e1c 100644
--- a/clippy_lints/src/to_digit_is_some.rs
+++ b/clippy_lints/src/to_digit_is_some.rs
@@ -2,7 +2,7 @@ use clippy_config::Conf;
 use clippy_utils::diagnostics::span_lint_and_sugg;
 use clippy_utils::msrvs::{self, Msrv};
 use clippy_utils::source::snippet_with_applicability;
-use clippy_utils::{is_in_const_context, paths, sym};
+use clippy_utils::{is_in_const_context, is_path_diagnostic_item, sym};
 use rustc_errors::Applicability;
 use rustc_hir as hir;
 use rustc_lint::{LateContext, LateLintPass};
@@ -62,7 +62,7 @@ impl<'tcx> LateLintPass<'tcx> for ToDigitIsSome {
                     }
                 },
                 hir::ExprKind::Call(to_digits_call, [char_arg, radix_arg]) => {
-                    if paths::CHAR_TO_DIGIT.matches_path(cx, to_digits_call) {
+                    if is_path_diagnostic_item(cx, to_digits_call, sym::char_to_digit) {
                         Some((false, char_arg, radix_arg))
                     } else {
                         None
diff --git a/clippy_lints/src/useless_concat.rs b/clippy_lints/src/useless_concat.rs
index 1ed1fbb3b9c..96845adb04a 100644
--- a/clippy_lints/src/useless_concat.rs
+++ b/clippy_lints/src/useless_concat.rs
@@ -1,8 +1,7 @@
 use clippy_utils::diagnostics::span_lint_and_sugg;
 use clippy_utils::macros::macro_backtrace;
-use clippy_utils::paths::CONCAT;
 use clippy_utils::source::snippet_opt;
-use clippy_utils::tokenize_with_text;
+use clippy_utils::{sym, tokenize_with_text};
 use rustc_ast::LitKind;
 use rustc_errors::Applicability;
 use rustc_hir::{Expr, ExprKind};
@@ -43,7 +42,7 @@ impl LateLintPass<'_> for UselessConcat {
             // Get the direct parent of the expression.
             && let Some(macro_call) = macro_backtrace(expr.span).next()
             // Check if the `concat` macro from the `core` library.
-            && CONCAT.matches(cx, macro_call.def_id)
+            && cx.tcx.is_diagnostic_item(sym::macro_concat, macro_call.def_id)
             // We get the original code to parse it.
             && let Some(original_code) = snippet_opt(cx, macro_call.span)
             // This check allows us to ensure that the code snippet:
diff --git a/clippy_utils/src/paths.rs b/clippy_utils/src/paths.rs
index f37a609497e..8bbcb220210 100644
--- a/clippy_utils/src/paths.rs
+++ b/clippy_utils/src/paths.rs
@@ -126,15 +126,6 @@ path_macros! {
     macro_path: PathNS::Macro,
 }
 
-// Paths in `core`/`alloc`/`std`. This should be avoided and cleaned up by adding diagnostic items.
-pub static ALIGN_OF: PathLookup = value_path!(core::mem::align_of);
-pub static CHAR_TO_DIGIT: PathLookup = value_path!(char::to_digit);
-pub static CONCAT: PathLookup = macro_path!(core::concat);
-pub static IO_ERROR_NEW: PathLookup = value_path!(std::io::Error::new);
-pub static IO_ERRORKIND_OTHER_CTOR: PathLookup = value_path!(std::io::ErrorKind::Other);
-pub static ITER_STEP: PathLookup = type_path!(core::iter::Step);
-pub static SLICE_FROM_REF: PathLookup = value_path!(core::slice::from_ref);
-
 // Paths in external crates
 pub static FUTURES_IO_ASYNCREADEXT: PathLookup = type_path!(futures_util::AsyncReadExt);
 pub static FUTURES_IO_ASYNCWRITEEXT: PathLookup = type_path!(futures_util::AsyncWriteExt);