Update upstream source from tag 'upstream/1.52.1+dfsg1'

[rustc.git] / src / tools / clippy / clippy_lints / src / types / redundant_allocation.rs

diff --git a/src/tools/clippy/clippy_lints/src/types/redundant_allocation.rs b/src/tools/clippy/clippy_lints/src/types/redundant_allocation.rs
new file mode 100644 (file)
index 0000000..5da6db1
--- /dev/null
+++ b/src/tools/clippy/clippy_lints/src/types/redundant_allocation.rs
@@ -0,0 +1,84 @@
+use rustc_errors::Applicability;
+use rustc_hir::{self as hir, def_id::DefId, LangItem, QPath, TyKind};
+use rustc_lint::LateContext;
+use rustc_span::symbol::sym;
+
+use crate::utils::{
+    get_qpath_generic_tys, is_ty_param_diagnostic_item, is_ty_param_lang_item, snippet_with_applicability,
+    span_lint_and_sugg,
+};
+
+use super::{utils, REDUNDANT_ALLOCATION};
+
+pub(super) fn check(cx: &LateContext<'_>, hir_ty: &hir::Ty<'_>, qpath: &QPath<'_>, def_id: DefId) -> bool {
+    if Some(def_id) == cx.tcx.lang_items().owned_box() {
+        if let Some(span) = utils::match_borrows_parameter(cx, qpath) {
+            let mut applicability = Applicability::MachineApplicable;
+            span_lint_and_sugg(
+                cx,
+                REDUNDANT_ALLOCATION,
+                hir_ty.span,
+                "usage of `Box<&T>`",
+                "try",
+                snippet_with_applicability(cx, span, "..", &mut applicability).to_string(),
+                applicability,
+            );
+            return true;
+        }
+    }
+
+    if cx.tcx.is_diagnostic_item(sym::Rc, def_id) {
+        if let Some(ty) = is_ty_param_diagnostic_item(cx, qpath, sym::Rc) {
+            let mut applicability = Applicability::MachineApplicable;
+            span_lint_and_sugg(
+                cx,
+                REDUNDANT_ALLOCATION,
+                hir_ty.span,
+                "usage of `Rc<Rc<T>>`",
+                "try",
+                snippet_with_applicability(cx, ty.span, "..", &mut applicability).to_string(),
+                applicability,
+            );
+            true
+        } else if let Some(ty) = is_ty_param_lang_item(cx, qpath, LangItem::OwnedBox) {
+            let qpath = match &ty.kind {
+                TyKind::Path(qpath) => qpath,
+                _ => return false,
+            };
+            let inner_span = match get_qpath_generic_tys(qpath).next() {
+                Some(ty) => ty.span,
+                None => return false,
+            };
+            let mut applicability = Applicability::MachineApplicable;
+            span_lint_and_sugg(
+                cx,
+                REDUNDANT_ALLOCATION,
+                hir_ty.span,
+                "usage of `Rc<Box<T>>`",
+                "try",
+                format!(
+                    "Rc<{}>",
+                    snippet_with_applicability(cx, inner_span, "..", &mut applicability)
+                ),
+                applicability,
+            );
+            true
+        } else {
+            utils::match_borrows_parameter(cx, qpath).map_or(false, |span| {
+                let mut applicability = Applicability::MachineApplicable;
+                span_lint_and_sugg(
+                    cx,
+                    REDUNDANT_ALLOCATION,
+                    hir_ty.span,
+                    "usage of `Rc<&T>`",
+                    "try",
+                    snippet_with_applicability(cx, span, "..", &mut applicability).to_string(),
+                    applicability,
+                );
+                true
+            })
+        }
+    } else {
+        false
+    }
+}