Auto merge of #6807 - anall:feature/use_new_diagnostics, r=Manishearth

migrate paths to newly-added diagnostic items

This gets rid of the following paths:
  * OS_STRING
  * TO_OWNED
  * TO_STRING

Removes some usages of:
 * PATH_BUF

Per #5393

also removes unneeded `is_ty_param_path` from `clippy_lints::types` and relocates `is_ty_param_lang_item` and `is_ty_param_diagnostic_item` to `clippy_utils`.

changelog: none

8 files changed, 64 insertions, 67 deletions

diff --git a/clippy_lints/src/misc.rs b/clippy_lints/src/misc.rs
index 12f91d7bf63..b9be1f7e60c 100644
--- a/clippy_lints/src/misc.rs
+++ b/clippy_lints/src/misc.rs
@@ -12,12 +12,13 @@ use rustc_middle::ty::{self, Ty};
 use rustc_session::{declare_lint_pass, declare_tool_lint};
 use rustc_span::hygiene::DesugaringKind;
 use rustc_span::source_map::{ExpnKind, Span};
+use rustc_span::symbol::sym;
 
 use crate::consts::{constant, Constant};
 use crate::utils::sugg::Sugg;
 use crate::utils::{
-    get_item_name, get_parent_expr, higher, implements_trait, in_constant, is_integer_const, iter_input_pats,
-    last_path_segment, match_qpath, match_trait_method, paths, snippet, snippet_opt, span_lint, span_lint_and_sugg,
+    get_item_name, get_parent_expr, higher, implements_trait, in_constant, is_diagnostic_assoc_item, is_integer_const,
+    iter_input_pats, last_path_segment, match_qpath, snippet, snippet_opt, span_lint, span_lint_and_sugg,
     span_lint_and_then, span_lint_hir_and_then, unsext, SpanlessEq,
 };
 
@@ -554,11 +555,16 @@ fn check_to_owned(cx: &LateContext<'_>, expr: &Expr<'_>, other: &Expr<'_>, left:
 
     let (arg_ty, snip) = match expr.kind {
         ExprKind::MethodCall(.., ref args, _) if args.len() == 1 => {
-            if match_trait_method(cx, expr, &paths::TO_STRING) || match_trait_method(cx, expr, &paths::TO_OWNED) {
-                (cx.typeck_results().expr_ty(&args[0]), snippet(cx, args[0].span, ".."))
-            } else {
-                return;
-            }
+            if_chain!(
+                if let Some(expr_def_id) = cx.typeck_results().type_dependent_def_id(expr.hir_id);
+                if is_diagnostic_assoc_item(cx, expr_def_id, sym::ToString)
+                    || is_diagnostic_assoc_item(cx, expr_def_id, sym::ToOwned);
+                then {
+                    (cx.typeck_results().expr_ty(&args[0]), snippet(cx, args[0].span, ".."))
+                } else {
+                    return;
+                }
+            )
         },
         ExprKind::Call(ref path, ref v) if v.len() == 1 => {
             if let ExprKind::Path(ref path) = path.kind {
diff --git a/clippy_lints/src/path_buf_push_overwrite.rs b/clippy_lints/src/path_buf_push_overwrite.rs
index 6eeb031d383..4a7b0ad07aa 100644
--- a/clippy_lints/src/path_buf_push_overwrite.rs
+++ b/clippy_lints/src/path_buf_push_overwrite.rs
@@ -1,10 +1,11 @@
-use crate::utils::{match_type, paths, span_lint_and_sugg};
+use crate::utils::{is_type_diagnostic_item, span_lint_and_sugg};
 use if_chain::if_chain;
 use rustc_ast::ast::LitKind;
 use rustc_errors::Applicability;
 use rustc_hir::{Expr, ExprKind};
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_session::{declare_lint_pass, declare_tool_lint};
+use rustc_span::symbol::sym;
 use std::path::{Component, Path};
 
 declare_clippy_lint! {
@@ -46,7 +47,7 @@ impl<'tcx> LateLintPass<'tcx> for PathBufPushOverwrite {
             if let ExprKind::MethodCall(ref path, _, ref args, _) = expr.kind;
             if path.ident.name == sym!(push);
             if args.len() == 2;
-            if match_type(cx, cx.typeck_results().expr_ty(&args[0]).peel_refs(), &paths::PATH_BUF);
+            if is_type_diagnostic_item(cx, cx.typeck_results().expr_ty(&args[0]).peel_refs(), sym::PathBuf);
             if let Some(get_index_arg) = args.get(1);
             if let ExprKind::Lit(ref lit) = get_index_arg.kind;
             if let LitKind::Str(ref path_lit, _) = lit.node;
diff --git a/clippy_lints/src/ptr.rs b/clippy_lints/src/ptr.rs
index 5474fdf30bf..6ea2d8b06d8 100644
--- a/clippy_lints/src/ptr.rs
+++ b/clippy_lints/src/ptr.rs
@@ -233,7 +233,7 @@ fn check_fn(cx: &LateContext<'_>, decl: &FnDecl<'_>, fn_id: HirId, opt_body_id:
                         },
                     );
                 }
-            } else if match_type(cx, ty, &paths::PATH_BUF) {
+            } else if is_type_diagnostic_item(cx, ty, sym::PathBuf) {
                 if let Some(spans) = get_spans(cx, opt_body_id, idx, &[("clone", ".to_path_buf()"), ("as_path", "")]) {
                     span_lint_and_then(
                         cx,
diff --git a/clippy_lints/src/redundant_clone.rs b/clippy_lints/src/redundant_clone.rs
index d74ba10ac50..99263bf8b5c 100644
--- a/clippy_lints/src/redundant_clone.rs
+++ b/clippy_lints/src/redundant_clone.rs
@@ -1,6 +1,6 @@
 use crate::utils::{
-    fn_has_unsatisfiable_preds, has_drop, is_copy, is_type_diagnostic_item, match_def_path, match_type, paths,
-    snippet_opt, span_lint_hir, span_lint_hir_and_then, walk_ptrs_ty_depth,
+    fn_has_unsatisfiable_preds, has_drop, is_copy, is_type_diagnostic_item, match_def_path, paths, snippet_opt,
+    span_lint_hir, span_lint_hir_and_then, walk_ptrs_ty_depth,
 };
 use if_chain::if_chain;
 use rustc_data_structures::{fx::FxHashMap, transitive_relation::TransitiveRelation};
@@ -166,8 +166,8 @@ impl<'tcx> LateLintPass<'tcx> for RedundantClone {
                         is_call_with_ref_arg(cx, mir, &pred_terminator.kind);
                     if res == cloned;
                     if cx.tcx.is_diagnostic_item(sym::deref_method, pred_fn_def_id);
-                    if match_type(cx, pred_arg_ty, &paths::PATH_BUF)
-                        || match_type(cx, pred_arg_ty, &paths::OS_STRING);
+                    if is_type_diagnostic_item(cx, pred_arg_ty, sym::PathBuf)
+                        || is_type_diagnostic_item(cx, pred_arg_ty, sym::OsString);
                     then {
                         (pred_arg, res)
                     } else {
diff --git a/clippy_lints/src/to_string_in_display.rs b/clippy_lints/src/to_string_in_display.rs
index fdd105e6246..84ec2aa18ab 100644
--- a/clippy_lints/src/to_string_in_display.rs
+++ b/clippy_lints/src/to_string_in_display.rs
@@ -1,8 +1,9 @@
-use crate::utils::{match_def_path, match_trait_method, path_to_local_id, paths, span_lint};
+use crate::utils::{is_diagnostic_assoc_item, match_def_path, path_to_local_id, paths, span_lint};
 use if_chain::if_chain;
 use rustc_hir::{Expr, ExprKind, HirId, Impl, ImplItem, ImplItemKind, Item, ItemKind};
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_session::{declare_tool_lint, impl_lint_pass};
+use rustc_span::symbol::sym;
 
 declare_clippy_lint! {
     /// **What it does:** Checks for uses of `to_string()` in `Display` traits.
@@ -92,7 +93,8 @@ impl LateLintPass<'_> for ToStringInDisplay {
             if let Some(self_hir_id) = self.self_hir_id;
             if let ExprKind::MethodCall(ref path, _, args, _) = expr.kind;
             if path.ident.name == sym!(to_string);
-            if match_trait_method(cx, expr, &paths::TO_STRING);
+            if let Some(expr_def_id) = cx.typeck_results().type_dependent_def_id(expr.hir_id);
+            if is_diagnostic_assoc_item(cx, expr_def_id, sym::ToString);
             if path_to_local_id(&args[0], self_hir_id);
             then {
                 span_lint(
diff --git a/clippy_lints/src/types.rs b/clippy_lints/src/types.rs
index c420be26fc6..ce201b956d8 100644
--- a/clippy_lints/src/types.rs
+++ b/clippy_lints/src/types.rs
@@ -23,7 +23,7 @@ use rustc_semver::RustcVersion;
 use rustc_session::{declare_lint_pass, declare_tool_lint, impl_lint_pass};
 use rustc_span::hygiene::{ExpnKind, MacroKind};
 use rustc_span::source_map::Span;
-use rustc_span::symbol::{sym, Symbol};
+use rustc_span::symbol::sym;
 use rustc_target::abi::LayoutOf;
 use rustc_target::spec::abi::Abi;
 use rustc_typeck::hir_ty_to_ty;
@@ -33,10 +33,10 @@ use crate::utils::paths;
 use crate::utils::sugg::Sugg;
 use crate::utils::{
     clip, comparisons, differing_macro_contexts, get_qpath_generic_tys, higher, in_constant, indent_of, int_bits,
-    is_hir_ty_cfg_dependant, is_type_diagnostic_item, last_path_segment, match_def_path, match_path, meets_msrv,
-    method_chain_args, multispan_sugg, numeric_literal::NumericLiteral, reindent_multiline, sext, snippet, snippet_opt,
-    snippet_with_applicability, snippet_with_macro_callsite, span_lint, span_lint_and_help, span_lint_and_sugg,
-    span_lint_and_then, unsext,
+    is_hir_ty_cfg_dependant, is_ty_param_diagnostic_item, is_ty_param_lang_item, is_type_diagnostic_item,
+    last_path_segment, match_def_path, match_path, meets_msrv, method_chain_args, multispan_sugg,
+    numeric_literal::NumericLiteral, reindent_multiline, sext, snippet, snippet_opt, snippet_with_applicability,
+    snippet_with_macro_callsite, span_lint, span_lint_and_help, span_lint_and_sugg, span_lint_and_then, unsext,
 };
 
 declare_clippy_lint! {
@@ -287,51 +287,12 @@ impl<'tcx> LateLintPass<'tcx> for Types {
     }
 }
 
-/// Checks if the first type parameter is a lang item.
-fn is_ty_param_lang_item(cx: &LateContext<'_>, qpath: &QPath<'tcx>, item: LangItem) -> Option<&'tcx hir::Ty<'tcx>> {
-    let ty = get_qpath_generic_tys(qpath).next()?;
-
-    if let TyKind::Path(qpath) = &ty.kind {
-        cx.qpath_res(qpath, ty.hir_id)
-            .opt_def_id()
-            .and_then(|id| (cx.tcx.lang_items().require(item) == Ok(id)).then(|| ty))
-    } else {
-        None
-    }
-}
-
-/// Checks if the first type parameter is a diagnostic item.
-fn is_ty_param_diagnostic_item(cx: &LateContext<'_>, qpath: &QPath<'tcx>, item: Symbol) -> Option<&'tcx hir::Ty<'tcx>> {
-    let ty = get_qpath_generic_tys(qpath).next()?;
-
-    if let TyKind::Path(qpath) = &ty.kind {
-        cx.qpath_res(qpath, ty.hir_id)
-            .opt_def_id()
-            .and_then(|id| cx.tcx.is_diagnostic_item(item, id).then(|| ty))
-    } else {
-        None
-    }
-}
-
-/// Checks if the first type parameter is a given item.
-fn is_ty_param_path(cx: &LateContext<'_>, qpath: &QPath<'tcx>, path: &[&str]) -> Option<&'tcx hir::Ty<'tcx>> {
-    let ty = get_qpath_generic_tys(qpath).next()?;
-
-    if let TyKind::Path(qpath) = &ty.kind {
-        cx.qpath_res(qpath, ty.hir_id)
-            .opt_def_id()
-            .and_then(|id| match_def_path(cx, id, path).then(|| ty))
-    } else {
-        None
-    }
-}
-
 fn match_buffer_type(cx: &LateContext<'_>, qpath: &QPath<'_>) -> Option<&'static str> {
     if is_ty_param_diagnostic_item(cx, qpath, sym::string_type).is_some() {
         Some("str")
-    } else if is_ty_param_path(cx, qpath, &paths::OS_STRING).is_some() {
+    } else if is_ty_param_diagnostic_item(cx, qpath, sym::OsString).is_some() {
         Some("std::ffi::OsStr")
-    } else if is_ty_param_path(cx, qpath, &paths::PATH_BUF).is_some() {
+    } else if is_ty_param_diagnostic_item(cx, qpath, sym::PathBuf).is_some() {
         Some("std::path::Path")
     } else {
         None
diff --git a/clippy_utils/src/lib.rs b/clippy_utils/src/lib.rs
index 6582ad71707..3845667802d 100644
--- a/clippy_utils/src/lib.rs
+++ b/clippy_utils/src/lib.rs
@@ -64,8 +64,8 @@ use rustc_hir::intravisit::{self, NestedVisitorMap, Visitor};
 use rustc_hir::Node;
 use rustc_hir::{
     def, Arm, Block, Body, Constness, Crate, Expr, ExprKind, FnDecl, GenericArgs, HirId, Impl, ImplItem, ImplItemKind,
-    Item, ItemKind, MatchSource, Param, Pat, PatKind, Path, PathSegment, QPath, TraitItem, TraitItemKind, TraitRef,
-    TyKind, Unsafety,
+    Item, ItemKind, LangItem, MatchSource, Param, Pat, PatKind, Path, PathSegment, QPath, TraitItem, TraitItemKind,
+    TraitRef, TyKind, Unsafety,
 };
 use rustc_infer::infer::TyCtxtInferExt;
 use rustc_lint::{LateContext, Level, Lint, LintContext};
@@ -232,6 +232,36 @@ pub fn is_type_lang_item(cx: &LateContext<'_>, ty: Ty<'_>, lang_item: hir::LangI
     }
 }
 
+/// Checks if the first type parameter is a lang item.
+pub fn is_ty_param_lang_item(cx: &LateContext<'_>, qpath: &QPath<'tcx>, item: LangItem) -> Option<&'tcx hir::Ty<'tcx>> {
+    let ty = get_qpath_generic_tys(qpath).next()?;
+
+    if let TyKind::Path(qpath) = &ty.kind {
+        cx.qpath_res(qpath, ty.hir_id)
+            .opt_def_id()
+            .and_then(|id| (cx.tcx.lang_items().require(item) == Ok(id)).then(|| ty))
+    } else {
+        None
+    }
+}
+
+/// Checks if the first type parameter is a diagnostic item.
+pub fn is_ty_param_diagnostic_item(
+    cx: &LateContext<'_>,
+    qpath: &QPath<'tcx>,
+    item: Symbol,
+) -> Option<&'tcx hir::Ty<'tcx>> {
+    let ty = get_qpath_generic_tys(qpath).next()?;
+
+    if let TyKind::Path(qpath) = &ty.kind {
+        cx.qpath_res(qpath, ty.hir_id)
+            .opt_def_id()
+            .and_then(|id| cx.tcx.is_diagnostic_item(item, id).then(|| ty))
+    } else {
+        None
+    }
+}
+
 /// Checks if the method call given in `expr` belongs to the given trait.
 pub fn match_trait_method(cx: &LateContext<'_>, expr: &Expr<'_>, path: &[&str]) -> bool {
     let def_id = cx.typeck_results().type_dependent_def_id(expr.hir_id).unwrap();
diff --git a/clippy_utils/src/paths.rs b/clippy_utils/src/paths.rs
index 14c38459dde..3e79646da3f 100644
--- a/clippy_utils/src/paths.rs
+++ b/clippy_utils/src/paths.rs
@@ -84,7 +84,6 @@ pub const OPTION: [&str; 3] = ["core", "option", "Option"];
 pub const OPTION_NONE: [&str; 4] = ["core", "option", "Option", "None"];
 pub const OPTION_SOME: [&str; 4] = ["core", "option", "Option", "Some"];
 pub const ORD: [&str; 3] = ["core", "cmp", "Ord"];
-pub const OS_STRING: [&str; 4] = ["std", "ffi", "os_str", "OsString"];
 pub const OS_STRING_AS_OS_STR: [&str; 5] = ["std", "ffi", "os_str", "OsString", "as_os_str"];
 pub const OS_STR_TO_OS_STRING: [&str; 5] = ["std", "ffi", "os_str", "OsStr", "to_os_string"];
 pub(super) const PANICKING_PANIC: [&str; 3] = ["core", "panicking", "panic"];
@@ -155,9 +154,7 @@ pub const SYMBOL_TO_IDENT_STRING: [&str; 4] = ["rustc_span", "symbol", "Symbol",
 pub const SYM_MODULE: [&str; 3] = ["rustc_span", "symbol", "sym"];
 #[cfg(feature = "internal-lints")]
 pub const SYNTAX_CONTEXT: [&str; 3] = ["rustc_span", "hygiene", "SyntaxContext"];
-pub const TO_OWNED: [&str; 3] = ["alloc", "borrow", "ToOwned"];
 pub const TO_OWNED_METHOD: [&str; 4] = ["alloc", "borrow", "ToOwned", "to_owned"];
-pub const TO_STRING: [&str; 3] = ["alloc", "string", "ToString"];
 pub const TO_STRING_METHOD: [&str; 4] = ["alloc", "string", "ToString", "to_string"];
 pub const TRANSMUTE: [&str; 4] = ["core", "intrinsics", "", "transmute"];
 pub const TRY_FROM: [&str; 4] = ["core", "convert", "TryFrom", "try_from"];