Auto merge of rust-lang#7016 - camsteffen:bind-map-paths, r=Manishearth

Remove paths from bind_instead_of_map

changelog: none

Author: bors

clippy_lints/src/methods/bind_instead_of_map.rs

@@ -1,80 +1,66 @@
 use super::{contains_return, BIND_INSTEAD_OF_MAP};
 use clippy_utils::diagnostics::{multispan_sugg_with_applicability, span_lint_and_sugg, span_lint_and_then};
 use clippy_utils::source::{snippet, snippet_with_macro_callsite};
-use clippy_utils::ty::match_type;
-use clippy_utils::{in_macro, match_qpath, method_calls, paths, remove_blocks, visitors::find_all_ret_expressions};
+use clippy_utils::{in_macro, remove_blocks, visitors::find_all_ret_expressions};
 use if_chain::if_chain;
 use rustc_errors::Applicability;
 use rustc_hir as hir;
+use rustc_hir::def::{CtorKind, CtorOf, DefKind, Res};
+use rustc_hir::{LangItem, QPath};
 use rustc_lint::LateContext;
+use rustc_middle::ty::DefIdTree;
 use rustc_span::Span;
 
 pub(crate) struct OptionAndThenSome;
 
 impl BindInsteadOfMap for OptionAndThenSome {
-    const TYPE_NAME: &'static str = "Option";
-    const TYPE_QPATH: &'static [&'static str] = &paths::OPTION;
-
+    const VARIANT_LANG_ITEM: LangItem = LangItem::OptionSome;
     const BAD_METHOD_NAME: &'static str = "and_then";
-    const BAD_VARIANT_NAME: &'static str = "Some";
-    const BAD_VARIANT_QPATH: &'static [&'static str] = &paths::OPTION_SOME;
-
     const GOOD_METHOD_NAME: &'static str = "map";
 }
 
 pub(crate) struct ResultAndThenOk;
 
 impl BindInsteadOfMap for ResultAndThenOk {
-    const TYPE_NAME: &'static str = "Result";
-    const TYPE_QPATH: &'static [&'static str] = &paths::RESULT;
-
+    const VARIANT_LANG_ITEM: LangItem = LangItem::ResultOk;
     const BAD_METHOD_NAME: &'static str = "and_then";
-    const BAD_VARIANT_NAME: &'static str = "Ok";
-    const BAD_VARIANT_QPATH: &'static [&'static str] = &paths::RESULT_OK;
-
     const GOOD_METHOD_NAME: &'static str = "map";
 }
 
 pub(crate) struct ResultOrElseErrInfo;
 
 impl BindInsteadOfMap for ResultOrElseErrInfo {
-    const TYPE_NAME: &'static str = "Result";
-    const TYPE_QPATH: &'static [&'static str] = &paths::RESULT;
-
+    const VARIANT_LANG_ITEM: LangItem = LangItem::ResultErr;
     const BAD_METHOD_NAME: &'static str = "or_else";
-    const BAD_VARIANT_NAME: &'static str = "Err";
-    const BAD_VARIANT_QPATH: &'static [&'static str] = &paths::RESULT_ERR;
-
     const GOOD_METHOD_NAME: &'static str = "map_err";
 }
 
 pub(crate) trait BindInsteadOfMap {
-    const TYPE_NAME: &'static str;
-    const TYPE_QPATH: &'static [&'static str];
-
+    const VARIANT_LANG_ITEM: LangItem;
     const BAD_METHOD_NAME: &'static str;
-    const BAD_VARIANT_NAME: &'static str;
-    const BAD_VARIANT_QPATH: &'static [&'static str];
-
     const GOOD_METHOD_NAME: &'static str;
 
-    fn no_op_msg() -> String {
-        format!(
+    fn no_op_msg(cx: &LateContext<'_>) -> Option<String> {
+        let variant_id = cx.tcx.lang_items().require(Self::VARIANT_LANG_ITEM).ok()?;
+        let item_id = cx.tcx.parent(variant_id)?;
+        Some(format!(
             "using `{}.{}({})`, which is a no-op",
-            Self::TYPE_NAME,
+            cx.tcx.item_name(item_id),
             Self::BAD_METHOD_NAME,
-            Self::BAD_VARIANT_NAME
-        )
+            cx.tcx.item_name(variant_id),
+        ))
     }
 
-    fn lint_msg() -> String {
-        format!(
+    fn lint_msg(cx: &LateContext<'_>) -> Option<String> {
+        let variant_id = cx.tcx.lang_items().require(Self::VARIANT_LANG_ITEM).ok()?;
+        let item_id = cx.tcx.parent(variant_id)?;
+        Some(format!(
             "using `{}.{}(|x| {}(y))`, which is more succinctly expressed as `{}(|x| y)`",
-            Self::TYPE_NAME,
+            cx.tcx.item_name(item_id),
             Self::BAD_METHOD_NAME,
-            Self::BAD_VARIANT_NAME,
+            cx.tcx.item_name(variant_id),
             Self::GOOD_METHOD_NAME
-        )
+        ))
     }
 
     fn lint_closure_autofixable(
@@ -85,17 +71,12 @@ pub(crate) trait BindInsteadOfMap {
         closure_args_span: Span,
     ) -> bool {
         if_chain! {
-            if let hir::ExprKind::Call(ref some_expr, ref some_args) = closure_expr.kind;
-            if let hir::ExprKind::Path(ref qpath) = some_expr.kind;
-            if match_qpath(qpath, Self::BAD_VARIANT_QPATH);
-            if some_args.len() == 1;
+            if let hir::ExprKind::Call(ref some_expr, [inner_expr]) = closure_expr.kind;
+            if let hir::ExprKind::Path(QPath::Resolved(_, path)) = some_expr.kind;
+            if Self::is_variant(cx, path.res);
+            if !contains_return(inner_expr);
+            if let Some(msg) = Self::lint_msg(cx);
             then {
-                let inner_expr = &some_args[0];
-
-                if contains_return(inner_expr) {
-                    return false;
-                }
-
                 let some_inner_snip = if inner_expr.span.from_expansion() {
                     snippet_with_macro_callsite(cx, inner_expr.span, "_")
                 } else {
@@ -109,7 +90,7 @@ pub(crate) trait BindInsteadOfMap {
                     cx,
                     BIND_INSTEAD_OF_MAP,
                     expr.span,
-                    Self::lint_msg().as_ref(),
+                    &msg,
                     "try this",
                     note,
                     Applicability::MachineApplicable,
@@ -126,41 +107,46 @@ pub(crate) trait BindInsteadOfMap {
         let can_sugg: bool = find_all_ret_expressions(cx, closure_expr, |ret_expr| {
             if_chain! {
                 if !in_macro(ret_expr.span);
-                if let hir::ExprKind::Call(ref func_path, ref args) = ret_expr.kind;
-                if let hir::ExprKind::Path(ref qpath) = func_path.kind;
-                if match_qpath(qpath, Self::BAD_VARIANT_QPATH);
-                if args.len() == 1;
-                if !contains_return(&args[0]);
+                if let hir::ExprKind::Call(ref func_path, [arg]) = ret_expr.kind;
+                if let hir::ExprKind::Path(QPath::Resolved(_, path)) = func_path.kind;
+                if Self::is_variant(cx, path.res);
+                if !contains_return(arg);
                 then {
-                    suggs.push((ret_expr.span, args[0].span.source_callsite()));
+                    suggs.push((ret_expr.span, arg.span.source_callsite()));
                     true
                 } else {
                     false
                 }
             }
         });
-
-        if can_sugg {
-            span_lint_and_then(cx, BIND_INSTEAD_OF_MAP, expr.span, Self::lint_msg().as_ref(), |diag| {
-                multispan_sugg_with_applicability(
-                    diag,
-                    "try this",
-                    Applicability::MachineApplicable,
-                    std::iter::once((*method_calls(expr, 1).2.get(0).unwrap(), Self::GOOD_METHOD_NAME.into())).chain(
-                        suggs
-                            .into_iter()
-                            .map(|(span1, span2)| (span1, snippet(cx, span2, "_").into())),
-                    ),
-                )
-            });
-        }
-        can_sugg
+        let (span, msg) = if_chain! {
+            if can_sugg;
+            if let hir::ExprKind::MethodCall(_, span, ..) = expr.kind;
+            if let Some(msg) = Self::lint_msg(cx);
+            then { (span, msg) } else { return false; }
+        };
+        span_lint_and_then(cx, BIND_INSTEAD_OF_MAP, expr.span, &msg, |diag| {
+            multispan_sugg_with_applicability(
+                diag,
+                "try this",
+                Applicability::MachineApplicable,
+                std::iter::once((span, Self::GOOD_METHOD_NAME.into())).chain(
+                    suggs
+                        .into_iter()
+                        .map(|(span1, span2)| (span1, snippet(cx, span2, "_").into())),
+                ),
+            )
+        });
+        true
     }
 
     /// Lint use of `_.and_then(|x| Some(y))` for `Option`s
     fn check(cx: &LateContext<'_>, expr: &hir::Expr<'_>, recv: &hir::Expr<'_>, arg: &hir::Expr<'_>) -> bool {
-        if !match_type(cx, cx.typeck_results().expr_ty(recv), Self::TYPE_QPATH) {
-            return false;
+        if_chain! {
+            if let Some(adt) = cx.typeck_results().expr_ty(recv).ty_adt_def();
+            if let Ok(vid) = cx.tcx.lang_items().require(Self::VARIANT_LANG_ITEM);
+            if Some(adt.did) == cx.tcx.parent(vid);
+            then {} else { return false; }
         }
 
         match arg.kind {
@@ -175,19 +161,30 @@ pub(crate) trait BindInsteadOfMap {
                 }
             },
             // `_.and_then(Some)` case, which is no-op.
-            hir::ExprKind::Path(ref qpath) if match_qpath(qpath, Self::BAD_VARIANT_QPATH) => {
-                span_lint_and_sugg(
-                    cx,
-                    BIND_INSTEAD_OF_MAP,
-                    expr.span,
-                    Self::no_op_msg().as_ref(),
-                    "use the expression directly",
-                    snippet(cx, recv.span, "..").into(),
-                    Applicability::MachineApplicable,
-                );
+            hir::ExprKind::Path(QPath::Resolved(_, path)) if Self::is_variant(cx, path.res) => {
+                if let Some(msg) = Self::no_op_msg(cx) {
+                    span_lint_and_sugg(
+                        cx,
+                        BIND_INSTEAD_OF_MAP,
+                        expr.span,
+                        &msg,
+                        "use the expression directly",
+                        snippet(cx, recv.span, "..").into(),
+                        Applicability::MachineApplicable,
+                    );
+                }
                 true
             },
             _ => false,
         }
     }
+
+    fn is_variant(cx: &LateContext<'_>, res: Res) -> bool {
+        if let Res::Def(DefKind::Ctor(CtorOf::Variant, CtorKind::Fn), id) = res {
+            if let Ok(variant_id) = cx.tcx.lang_items().require(Self::VARIANT_LANG_ITEM) {
+                return cx.tcx.parent(id) == Some(variant_id);
+            }
+        }
+        false
+    }
 }