Auto merge of rust-lang#8305 - camsteffen:util-cleanup, r=flip1995

Factor out several utils, add `path_def_id`

changelog: none

This is generally an effort to reduce the total number of utils. `path_def_id` is added which I believe is more "cross-cutting" and also complements `path_to_local`. Best reviewed one commit at a time.

Added:
* `path_def_id`
* `path_res`

Removed:
 * `is_qpath_def_path`
 * `match_any_diagnostic_items`
 * `expr_path_res`
 * `single_segment_path`
 * `differing_macro_contexts`
 * `is_ty_param_lang_item`
 * `is_ty_param_diagnostic_item`
 * `get_qpath_generics`

Renamed:
* `path_to_res` to `def_path_res`
* `get_qpath_generic_tys` to `qpath_generic_tys`

CC `@Jarcho` since this relates to some of your work and you may have input.

clippy_lints/src/blocks_in_if_conditions.rs

@@ -1,8 +1,8 @@
 use clippy_utils::diagnostics::{span_lint, span_lint_and_sugg};
+use clippy_utils::get_parent_expr;
 use clippy_utils::higher;
 use clippy_utils::source::snippet_block_with_applicability;
 use clippy_utils::ty::implements_trait;
-use clippy_utils::{differing_macro_contexts, get_parent_expr};
 use if_chain::if_chain;
 use rustc_errors::Applicability;
 use rustc_hir::intravisit::{walk_expr, Visitor};
@@ -97,7 +97,7 @@ impl<'tcx> LateLintPass<'tcx> for BlocksInIfConditions {
                         if let Some(ex) = &block.expr {
                             // don't dig into the expression here, just suggest that they remove
                             // the block
-                            if expr.span.from_expansion() || differing_macro_contexts(expr.span, ex.span) {
+                            if expr.span.from_expansion() || ex.span.from_expansion() {
                                 return;
                             }
                             let mut applicability = Applicability::MachineApplicable;
@@ -122,7 +122,7 @@ impl<'tcx> LateLintPass<'tcx> for BlocksInIfConditions {
                         }
                     } else {
                         let span = block.expr.as_ref().map_or_else(|| block.stmts[0].span, |e| e.span);
-                        if span.from_expansion() || differing_macro_contexts(expr.span, span) {
+                        if span.from_expansion() || expr.span.from_expansion() {
                             return;
                         }
                         // move block higher

clippy_lints/src/disallowed_methods.rs

@@ -77,7 +77,7 @@ impl<'tcx> LateLintPass<'tcx> for DisallowedMethods {
     fn check_crate(&mut self, cx: &LateContext<'_>) {
         for (index, conf) in self.conf_disallowed.iter().enumerate() {
             let segs: Vec<_> = conf.path().split("::").collect();
-            if let Res::Def(_, id) = clippy_utils::path_to_res(cx, &segs) {
+            if let Res::Def(_, id) = clippy_utils::def_path_res(cx, &segs) {
                 self.disallowed.insert(id, index);
             }
         }

clippy_lints/src/disallowed_types.rs

@@ -96,7 +96,7 @@ impl<'tcx> LateLintPass<'tcx> for DisallowedTypes {
                 ),
             };
             let segs: Vec<_> = path.split("::").collect();
-            match clippy_utils::path_to_res(cx, &segs) {
+            match clippy_utils::def_path_res(cx, &segs) {
                 Res::Def(_, id) => {
                     self.def_ids.insert(id, reason);
                 },

clippy_lints/src/formatting.rs

@@ -1,5 +1,4 @@
 use clippy_utils::diagnostics::{span_lint_and_help, span_lint_and_note};
-use clippy_utils::differing_macro_contexts;
 use clippy_utils::source::snippet_opt;
 use if_chain::if_chain;
 use rustc_ast::ast::{BinOpKind, Block, Expr, ExprKind, StmtKind, UnOp};
@@ -135,7 +134,7 @@ impl EarlyLintPass for Formatting {
 /// Implementation of the `SUSPICIOUS_ASSIGNMENT_FORMATTING` lint.
 fn check_assign(cx: &EarlyContext<'_>, expr: &Expr) {
     if let ExprKind::Assign(ref lhs, ref rhs, _) = expr.kind {
-        if !differing_macro_contexts(lhs.span, rhs.span) && !lhs.span.from_expansion() {
+        if !lhs.span.from_expansion() && !rhs.span.from_expansion() {
             let eq_span = lhs.span.between(rhs.span);
             if let ExprKind::Unary(op, ref sub_rhs) = rhs.kind {
                 if let Some(eq_snippet) = snippet_opt(cx, eq_span) {
@@ -165,7 +164,7 @@ fn check_assign(cx: &EarlyContext<'_>, expr: &Expr) {
 fn check_unop(cx: &EarlyContext<'_>, expr: &Expr) {
     if_chain! {
         if let ExprKind::Binary(ref binop, ref lhs, ref rhs) = expr.kind;
-        if !differing_macro_contexts(lhs.span, rhs.span) && !lhs.span.from_expansion();
+        if !lhs.span.from_expansion() && !rhs.span.from_expansion();
         // span between BinOp LHS and RHS
         let binop_span = lhs.span.between(rhs.span);
         // if RHS is an UnOp
@@ -206,8 +205,8 @@ fn check_else(cx: &EarlyContext<'_>, expr: &Expr) {
     if_chain! {
         if let ExprKind::If(_, then, Some(else_)) = &expr.kind;
         if is_block(else_) || is_if(else_);
-        if !differing_macro_contexts(then.span, else_.span);
-        if !then.span.from_expansion() && !in_external_macro(cx.sess(), expr.span);
+        if !then.span.from_expansion() && !else_.span.from_expansion();
+        if !in_external_macro(cx.sess(), expr.span);
 
         // workaround for rust-lang/rust#43081
         if expr.span.lo().0 != 0 && expr.span.hi().0 != 0;
@@ -268,7 +267,7 @@ fn check_array(cx: &EarlyContext<'_>, expr: &Expr) {
         for element in array {
             if_chain! {
                 if let ExprKind::Binary(ref op, ref lhs, _) = element.kind;
-                if has_unary_equivalent(op.node) && !differing_macro_contexts(lhs.span, op.span);
+                if has_unary_equivalent(op.node) && lhs.span.ctxt() == op.span.ctxt();
                 let space_span = lhs.span.between(op.span);
                 if let Some(space_snippet) = snippet_opt(cx, space_span);
                 let lint_span = lhs.span.with_lo(lhs.span.hi());
@@ -291,8 +290,7 @@ fn check_array(cx: &EarlyContext<'_>, expr: &Expr) {
 
 fn check_missing_else(cx: &EarlyContext<'_>, first: &Expr, second: &Expr) {
     if_chain! {
-        if !differing_macro_contexts(first.span, second.span);
-        if !first.span.from_expansion();
+        if !first.span.from_expansion() && !second.span.from_expansion();
         if let ExprKind::If(cond_expr, ..) = &first.kind;
         if is_block(second) || is_if(second);
 

clippy_lints/src/implicit_hasher.rs

@@ -17,7 +17,6 @@ use rustc_typeck::hir_ty_to_ty;
 use if_chain::if_chain;
 
 use clippy_utils::diagnostics::{multispan_sugg, span_lint_and_then};
-use clippy_utils::differing_macro_contexts;
 use clippy_utils::source::{snippet, snippet_opt};
 use clippy_utils::ty::is_type_diagnostic_item;
 
@@ -123,7 +122,7 @@ impl<'tcx> LateLintPass<'tcx> for ImplicitHasher {
                 vis.visit_ty(impl_.self_ty);
 
                 for target in &vis.found {
-                    if differing_macro_contexts(item.span, target.span()) {
+                    if item.span.ctxt() != target.span().ctxt() {
                         return;
                     }
 

clippy_lints/src/infinite_iter.rs

@@ -1,6 +1,6 @@
 use clippy_utils::diagnostics::span_lint;
 use clippy_utils::ty::{implements_trait, is_type_diagnostic_item};
-use clippy_utils::{get_trait_def_id, higher, is_qpath_def_path, paths};
+use clippy_utils::{get_trait_def_id, higher, match_def_path, path_def_id, paths};
 use rustc_hir::{BorrowKind, Expr, ExprKind};
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_session::{declare_lint_pass, declare_tool_lint};
@@ -167,13 +167,9 @@ fn is_infinite(cx: &LateContext<'_>, expr: &Expr<'_>) -> Finiteness {
         },
         ExprKind::Block(block, _) => block.expr.as_ref().map_or(Finite, |e| is_infinite(cx, e)),
         ExprKind::Box(e) | ExprKind::AddrOf(BorrowKind::Ref, _, e) => is_infinite(cx, e),
-        ExprKind::Call(path, _) => {
-            if let ExprKind::Path(ref qpath) = path.kind {
-                is_qpath_def_path(cx, qpath, path.hir_id, &paths::ITER_REPEAT).into()
-            } else {
-                Finite
-            }
-        },
+        ExprKind::Call(path, _) => path_def_id(cx, path)
+            .map_or(false, |id| match_def_path(cx, id, &paths::ITER_REPEAT))
+            .into(),
         ExprKind::Struct(..) => higher::Range::hir(expr).map_or(false, |r| r.end.is_none()).into(),
         _ => Finite,
     }

clippy_lints/src/loops/single_element_loop.rs

@@ -1,10 +1,9 @@
 use super::SINGLE_ELEMENT_LOOP;
 use clippy_utils::diagnostics::span_lint_and_sugg;
-use clippy_utils::single_segment_path;
-use clippy_utils::source::{indent_of, snippet};
+use clippy_utils::source::{indent_of, snippet_with_applicability};
 use if_chain::if_chain;
 use rustc_errors::Applicability;
-use rustc_hir::{BorrowKind, Expr, ExprKind, Pat, PatKind};
+use rustc_hir::{BorrowKind, Expr, ExprKind, Pat};
 use rustc_lint::LateContext;
 
 pub(super) fn check<'tcx>(
@@ -16,33 +15,30 @@ pub(super) fn check<'tcx>(
 ) {
     let arg_expr = match arg.kind {
         ExprKind::AddrOf(BorrowKind::Ref, _, ref_arg) => ref_arg,
-        ExprKind::MethodCall(method, args, _) if args.len() == 1 && method.ident.name == rustc_span::sym::iter => {
-            &args[0]
-        },
+        ExprKind::MethodCall(method, [arg], _) if method.ident.name == rustc_span::sym::iter => arg,
         _ => return,
     };
     if_chain! {
-        if let PatKind::Binding(.., target, _) = pat.kind;
         if let ExprKind::Array([arg_expression]) = arg_expr.kind;
-        if let ExprKind::Path(ref list_item) = arg_expression.kind;
-        if let Some(list_item_name) = single_segment_path(list_item).map(|ps| ps.ident.name);
         if let ExprKind::Block(block, _) = body.kind;
         if !block.stmts.is_empty();
-
         then {
-            let mut block_str = snippet(cx, block.span, "..").into_owned();
+            let mut applicability = Applicability::MachineApplicable;
+            let pat_snip = snippet_with_applicability(cx, pat.span, "..", &mut applicability);
+            let arg_snip = snippet_with_applicability(cx, arg_expression.span, "..", &mut applicability);
+            let mut block_str = snippet_with_applicability(cx, block.span, "..", &mut applicability).into_owned();
             block_str.remove(0);
             block_str.pop();
-
+            let indent = " ".repeat(indent_of(cx, block.stmts[0].span).unwrap_or(0));
 
             span_lint_and_sugg(
                 cx,
                 SINGLE_ELEMENT_LOOP,
                 expr.span,
                 "for loop over a single element",
                 "try",
-                format!("{{\n{}let {} = &{};{}}}", " ".repeat(indent_of(cx, block.stmts[0].span).unwrap_or(0)), target.name, list_item_name, block_str),
-                Applicability::MachineApplicable
+                format!("{{\n{}let {} = &{};{}}}", indent, pat_snip, arg_snip, block_str),
+                applicability,
             )
         }
     }

clippy_lints/src/matches.rs

@@ -1860,22 +1860,22 @@ where
 mod redundant_pattern_match {
     use super::REDUNDANT_PATTERN_MATCHING;
     use clippy_utils::diagnostics::span_lint_and_then;
-    use clippy_utils::higher;
     use clippy_utils::source::snippet;
     use clippy_utils::sugg::Sugg;
     use clippy_utils::ty::{implements_trait, is_type_diagnostic_item, is_type_lang_item, match_type};
-    use clippy_utils::{is_lang_ctor, is_qpath_def_path, is_trait_method, paths};
+    use clippy_utils::{higher, match_def_path};
+    use clippy_utils::{is_lang_ctor, is_trait_method, paths};
     use if_chain::if_chain;
     use rustc_ast::ast::LitKind;
     use rustc_data_structures::fx::FxHashSet;
     use rustc_errors::Applicability;
-    use rustc_hir::LangItem::{OptionNone, OptionSome, PollPending, PollReady, ResultErr, ResultOk};
+    use rustc_hir::LangItem::{OptionNone, PollPending};
     use rustc_hir::{
         intravisit::{walk_expr, Visitor},
         Arm, Block, Expr, ExprKind, LangItem, MatchSource, Node, Pat, PatKind, QPath, UnOp,
     };
     use rustc_lint::LateContext;
-    use rustc_middle::ty::{self, subst::GenericArgKind, Ty};
+    use rustc_middle::ty::{self, subst::GenericArgKind, DefIdTree, Ty};
     use rustc_span::sym;
 
     pub fn check<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
@@ -2051,28 +2051,31 @@ mod redundant_pattern_match {
         has_else: bool,
     ) {
         // also look inside refs
-        let mut kind = &let_pat.kind;
         // if we have &None for example, peel it so we can detect "if let None = x"
-        if let PatKind::Ref(inner, _mutability) = kind {
-            kind = &inner.kind;
-        }
+        let check_pat = match let_pat.kind {
+            PatKind::Ref(inner, _mutability) => inner,
+            _ => let_pat,
+        };
         let op_ty = cx.typeck_results().expr_ty(let_expr);
         // Determine which function should be used, and the type contained by the corresponding
         // variant.
-        let (good_method, inner_ty) = match kind {
-            PatKind::TupleStruct(ref path, [sub_pat], _) => {
+        let (good_method, inner_ty) = match check_pat.kind {
+            PatKind::TupleStruct(ref qpath, [sub_pat], _) => {
                 if let PatKind::Wild = sub_pat.kind {
-                    if is_lang_ctor(cx, path, ResultOk) {
+                    let res = cx.typeck_results().qpath_res(qpath, check_pat.hir_id);
+                    let Some(id) = res.opt_def_id().and_then(|ctor_id| cx.tcx.parent(ctor_id)) else { return };
+                    let lang_items = cx.tcx.lang_items();
+                    if Some(id) == lang_items.result_ok_variant() {
                         ("is_ok()", try_get_generic_ty(op_ty, 0).unwrap_or(op_ty))
-                    } else if is_lang_ctor(cx, path, ResultErr) {
+                    } else if Some(id) == lang_items.result_err_variant() {
                         ("is_err()", try_get_generic_ty(op_ty, 1).unwrap_or(op_ty))
-                    } else if is_lang_ctor(cx, path, OptionSome) {
+                    } else if Some(id) == lang_items.option_some_variant() {
                         ("is_some()", op_ty)
-                    } else if is_lang_ctor(cx, path, PollReady) {
+                    } else if Some(id) == lang_items.poll_ready_variant() {
                         ("is_ready()", op_ty)
-                    } else if is_qpath_def_path(cx, path, sub_pat.hir_id, &paths::IPADDR_V4) {
+                    } else if match_def_path(cx, id, &paths::IPADDR_V4) {
                         ("is_ipv4()", op_ty)
-                    } else if is_qpath_def_path(cx, path, sub_pat.hir_id, &paths::IPADDR_V6) {
+                    } else if match_def_path(cx, id, &paths::IPADDR_V6) {
                         ("is_ipv6()", op_ty)
                     } else {
                         return;
@@ -2272,17 +2275,22 @@ mod redundant_pattern_match {
         should_be_left: &'a str,
         should_be_right: &'a str,
     ) -> Option<&'a str> {
-        let body_node_pair = if is_qpath_def_path(cx, path_left, arms[0].pat.hir_id, expected_left)
-            && is_qpath_def_path(cx, path_right, arms[1].pat.hir_id, expected_right)
-        {
-            (&(*arms[0].body).kind, &(*arms[1].body).kind)
-        } else if is_qpath_def_path(cx, path_right, arms[1].pat.hir_id, expected_left)
-            && is_qpath_def_path(cx, path_left, arms[0].pat.hir_id, expected_right)
-        {
-            (&(*arms[1].body).kind, &(*arms[0].body).kind)
-        } else {
-            return None;
-        };
+        let left_id = cx
+            .typeck_results()
+            .qpath_res(path_left, arms[0].pat.hir_id)
+            .opt_def_id()?;
+        let right_id = cx
+            .typeck_results()
+            .qpath_res(path_right, arms[1].pat.hir_id)
+            .opt_def_id()?;
+        let body_node_pair =
+            if match_def_path(cx, left_id, expected_left) && match_def_path(cx, right_id, expected_right) {
+                (&(*arms[0].body).kind, &(*arms[1].body).kind)
+            } else if match_def_path(cx, right_id, expected_left) && match_def_path(cx, right_id, expected_right) {
+                (&(*arms[1].body).kind, &(*arms[0].body).kind)
+            } else {
+                return None;
+            };
 
         match body_node_pair {
             (ExprKind::Lit(ref lit_left), ExprKind::Lit(ref lit_right)) => match (&lit_left.node, &lit_right.node) {

clippy_lints/src/methods/chars_cmp.rs

@@ -1,13 +1,12 @@
 use clippy_utils::diagnostics::span_lint_and_sugg;
 use clippy_utils::source::snippet_with_applicability;
-use clippy_utils::{method_chain_args, single_segment_path};
+use clippy_utils::{method_chain_args, path_def_id};
 use if_chain::if_chain;
 use rustc_errors::Applicability;
 use rustc_hir as hir;
 use rustc_lint::LateContext;
 use rustc_lint::Lint;
-use rustc_middle::ty;
-use rustc_span::sym;
+use rustc_middle::ty::{self, DefIdTree};
 
 /// Wrapper fn for `CHARS_NEXT_CMP` and `CHARS_LAST_CMP` lints.
 pub(super) fn check(
@@ -19,11 +18,9 @@ pub(super) fn check(
 ) -> bool {
     if_chain! {
         if let Some(args) = method_chain_args(info.chain, chain_methods);
-        if let hir::ExprKind::Call(fun, arg_char) = info.other.kind;
-        if arg_char.len() == 1;
-        if let hir::ExprKind::Path(ref qpath) = fun.kind;
-        if let Some(segment) = single_segment_path(qpath);
-        if segment.ident.name == sym::Some;
+        if let hir::ExprKind::Call(fun, [arg_char]) = info.other.kind;
+        if let Some(id) = path_def_id(cx, fun).and_then(|ctor_id| cx.tcx.parent(ctor_id));
+        if Some(id) == cx.tcx.lang_items().option_some_variant();
         then {
             let mut applicability = Applicability::MachineApplicable;
             let self_ty = cx.typeck_results().expr_ty_adjusted(&args[0][0]).peel_refs();
@@ -42,7 +39,7 @@ pub(super) fn check(
                         if info.eq { "" } else { "!" },
                         snippet_with_applicability(cx, args[0][0].span, "..", &mut applicability),
                         suggest,
-                        snippet_with_applicability(cx, arg_char[0].span, "..", &mut applicability)),
+                        snippet_with_applicability(cx, arg_char.span, "..", &mut applicability)),
                 applicability,
             );
 

clippy_lints/src/methods/manual_saturating_arithmetic.rs

@@ -1,6 +1,6 @@
 use clippy_utils::diagnostics::span_lint_and_sugg;
-use clippy_utils::is_qpath_def_path;
 use clippy_utils::source::snippet_with_applicability;
+use clippy_utils::{match_def_path, path_def_id};
 use if_chain::if_chain;
 use rustc_ast::ast;
 use rustc_errors::Applicability;
@@ -93,12 +93,12 @@ fn is_min_or_max<'tcx>(cx: &LateContext<'tcx>, expr: &hir::Expr<'_>) -> Option<M
     let ty_str = ty.to_string();
 
     // `std::T::MAX` `std::T::MIN` constants
-    if let hir::ExprKind::Path(path) = &expr.kind {
-        if is_qpath_def_path(cx, path, expr.hir_id, &["core", &ty_str, "MAX"][..]) {
+    if let Some(id) = path_def_id(cx, expr) {
+        if match_def_path(cx, id, &["core", &ty_str, "MAX"]) {
             return Some(MinMax::Max);
         }
 
-        if is_qpath_def_path(cx, path, expr.hir_id, &["core", &ty_str, "MIN"][..]) {
+        if match_def_path(cx, id, &["core", &ty_str, "MIN"]) {
             return Some(MinMax::Min);
         }
     }

clippy_lints/src/methods/option_map_or_none.rs

@@ -1,11 +1,12 @@
 use clippy_utils::diagnostics::span_lint_and_sugg;
 use clippy_utils::source::snippet;
 use clippy_utils::ty::is_type_diagnostic_item;
-use clippy_utils::{is_lang_ctor, single_segment_path};
+use clippy_utils::{is_lang_ctor, path_def_id};
 use rustc_errors::Applicability;
 use rustc_hir as hir;
 use rustc_hir::LangItem::{OptionNone, OptionSome};
 use rustc_lint::LateContext;
+use rustc_middle::ty::DefIdTree;
 use rustc_span::symbol::sym;
 
 use super::OPTION_MAP_OR_NONE;
@@ -76,13 +77,11 @@ pub(super) fn check<'tcx>(
         if let hir::ExprKind::Closure(_, _, id, span, _) = map_arg.kind;
             let arg_snippet = snippet(cx, span, "..");
             let body = cx.tcx.hir().body(id);
-                if let Some((func, arg_char)) = reduce_unit_expression(cx, &body.value);
-                if arg_char.len() == 1;
-                if let hir::ExprKind::Path(ref qpath) = func.kind;
-                if let Some(segment) = single_segment_path(qpath);
-                if segment.ident.name == sym::Some;
+                if let Some((func, [arg_char])) = reduce_unit_expression(cx, &body.value);
+                if let Some(id) = path_def_id(cx, func).and_then(|ctor_id| cx.tcx.parent(ctor_id));
+                if Some(id) == cx.tcx.lang_items().option_some_variant();
                 then {
-                    let func_snippet = snippet(cx, arg_char[0].span, "..");
+                    let func_snippet = snippet(cx, arg_char.span, "..");
                     let msg = "called `map_or(None, ..)` on an `Option` value. This can be done more directly by calling \
                        `map(..)` instead";
                     return span_lint_and_sugg(