Rollup merge of #73870 - sexxi-goose:projection-ty, r=nikomatsakis

[rust.git] / clippy_lints / src / map_unit_fn.rs

diff --git a/clippy_lints/src/map_unit_fn.rs b/clippy_lints/src/map_unit_fn.rs
index a4e1b2c0d3326a1f4058132ecb86af2862281fec..316a71c500512d287b449ee4dfe4ecdde637093f 100644 (file)
--- a/clippy_lints/src/map_unit_fn.rs
+++ b/clippy_lints/src/map_unit_fn.rs
@@ -1,10 +1,9 @@
-use crate::utils::paths;
-use crate::utils::{iter_input_pats, match_type, method_chain_args, snippet, span_lint_and_then};
+use crate::utils::{is_type_diagnostic_item, iter_input_pats, method_chain_args, snippet, span_lint_and_then};
 use if_chain::if_chain;
-use rustc::ty::{self, Ty};
 use rustc_errors::Applicability;
 use rustc_hir as hir;
 use rustc_lint::{LateContext, LateLintPass};
+use rustc_middle::ty::{self, Ty};
 use rustc_session::{declare_lint_pass, declare_tool_lint};
 use rustc_span::source_map::Span;
 
@@ -101,8 +100,8 @@ fn is_unit_type(ty: Ty<'_>) -> bool {
     }
 }
 
-fn is_unit_function(cx: &LateContext<'_, '_>, expr: &hir::Expr<'_>) -> bool {
-    let ty = cx.tables.expr_ty(expr);
+fn is_unit_function(cx: &LateContext<'_>, expr: &hir::Expr<'_>) -> bool {
+    let ty = cx.tables().expr_ty(expr);
 
     if let ty::FnDef(id, _) = ty.kind {
         if let Some(fn_type) = cx.tcx.fn_sig(id).no_bound_vars() {
@@ -112,21 +111,21 @@ fn is_unit_function(cx: &LateContext<'_, '_>, expr: &hir::Expr<'_>) -> bool {
     false
 }
 
-fn is_unit_expression(cx: &LateContext<'_, '_>, expr: &hir::Expr<'_>) -> bool {
-    is_unit_type(cx.tables.expr_ty(expr))
+fn is_unit_expression(cx: &LateContext<'_>, expr: &hir::Expr<'_>) -> bool {
+    is_unit_type(cx.tables().expr_ty(expr))
 }
 
 /// The expression inside a closure may or may not have surrounding braces and
 /// semicolons, which causes problems when generating a suggestion. Given an
 /// expression that evaluates to '()' or '!', recursively remove useless braces
 /// and semi-colons until is suitable for including in the suggestion template
-fn reduce_unit_expression<'a>(cx: &LateContext<'_, '_>, expr: &'a hir::Expr<'_>) -> Option<Span> {
+fn reduce_unit_expression<'a>(cx: &LateContext<'_>, expr: &'a hir::Expr<'_>) -> Option<Span> {
     if !is_unit_expression(cx, expr) {
         return None;
     }
 
     match expr.kind {
-        hir::ExprKind::Call(_, _) | hir::ExprKind::MethodCall(_, _, _) => {
+        hir::ExprKind::Call(_, _) | hir::ExprKind::MethodCall(_, _, _, _) => {
             // Calls can't be reduced any more
             Some(expr.span)
         },
@@ -161,10 +160,10 @@ fn reduce_unit_expression<'a>(cx: &LateContext<'_, '_>, expr: &'a hir::Expr<'_>)
     }
 }
 
-fn unit_closure<'a, 'tcx>(
-    cx: &LateContext<'a, 'tcx>,
-    expr: &'a hir::Expr<'a>,
-) -> Option<(&'tcx hir::Param<'tcx>, &'a hir::Expr<'a>)> {
+fn unit_closure<'tcx>(
+    cx: &LateContext<'tcx>,
+    expr: &hir::Expr<'_>,
+) -> Option<(&'tcx hir::Param<'tcx>, &'tcx hir::Expr<'tcx>)> {
     if let hir::ExprKind::Closure(_, ref decl, inner_expr_id, _, _) = expr.kind {
         let body = cx.tcx.hir().body(inner_expr_id);
         let body_expr = &body.value;
@@ -186,12 +185,12 @@ fn unit_closure<'a, 'tcx>(
 /// `x.field` => `x_field`
 /// `y` => `_y`
 ///
-/// Anything else will return `_`.
-fn let_binding_name(cx: &LateContext<'_, '_>, var_arg: &hir::Expr<'_>) -> String {
+/// Anything else will return `a`.
+fn let_binding_name(cx: &LateContext<'_>, var_arg: &hir::Expr<'_>) -> String {
     match &var_arg.kind {
         hir::ExprKind::Field(_, _) => snippet(cx, var_arg.span, "_").replace(".", "_"),
         hir::ExprKind::Path(_) => format!("_{}", snippet(cx, var_arg.span, "")),
-        _ => "_".to_string(),
+        _ => "a".to_string(),
     }
 }
 
@@ -203,12 +202,12 @@ fn suggestion_msg(function_type: &str, map_type: &str) -> String {
     )
 }
 
-fn lint_map_unit_fn(cx: &LateContext<'_, '_>, stmt: &hir::Stmt<'_>, expr: &hir::Expr<'_>, map_args: &[hir::Expr<'_>]) {
+fn lint_map_unit_fn(cx: &LateContext<'_>, stmt: &hir::Stmt<'_>, expr: &hir::Expr<'_>, map_args: &[hir::Expr<'_>]) {
     let var_arg = &map_args[0];
 
-    let (map_type, variant, lint) = if match_type(cx, cx.tables.expr_ty(var_arg), &paths::OPTION) {
+    let (map_type, variant, lint) = if is_type_diagnostic_item(cx, cx.tables().expr_ty(var_arg), sym!(option_type)) {
         ("Option", "Some", OPTION_MAP_UNIT_FN)
-    } else if match_type(cx, cx.tables.expr_ty(var_arg), &paths::RESULT) {
+    } else if is_type_diagnostic_item(cx, cx.tables().expr_ty(var_arg), sym!(result_type)) {
         ("Result", "Ok", RESULT_MAP_UNIT_FN)
     } else {
         return;
@@ -225,13 +224,13 @@ fn lint_map_unit_fn(cx: &LateContext<'_, '_>, stmt: &hir::Stmt<'_>, expr: &hir::
             binding = let_binding_name(cx, var_arg)
         );
 
-        span_lint_and_then(cx, lint, expr.span, &msg, |db| {
-            db.span_suggestion(stmt.span, "try this", suggestion, Applicability::MachineApplicable);
+        span_lint_and_then(cx, lint, expr.span, &msg, |diag| {
+            diag.span_suggestion(stmt.span, "try this", suggestion, Applicability::MachineApplicable);
         });
     } else if let Some((binding, closure_expr)) = unit_closure(cx, fn_arg) {
         let msg = suggestion_msg("closure", map_type);
 
-        span_lint_and_then(cx, lint, expr.span, &msg, |db| {
+        span_lint_and_then(cx, lint, expr.span, &msg, |diag| {
             if let Some(reduced_expr_span) = reduce_unit_expression(cx, closure_expr) {
                 let suggestion = format!(
                     "if let {0}({1}) = {2} {{ {3} }}",
@@ -240,7 +239,7 @@ fn lint_map_unit_fn(cx: &LateContext<'_, '_>, stmt: &hir::Stmt<'_>, expr: &hir::
                     snippet(cx, var_arg.span, "_"),
                     snippet(cx, reduced_expr_span, "_")
                 );
-                db.span_suggestion(
+                diag.span_suggestion(
                     stmt.span,
                     "try this",
                     suggestion,
@@ -253,14 +252,14 @@ fn lint_map_unit_fn(cx: &LateContext<'_, '_>, stmt: &hir::Stmt<'_>, expr: &hir::
                     snippet(cx, binding.pat.span, "_"),
                     snippet(cx, var_arg.span, "_"),
                 );
-                db.span_suggestion(stmt.span, "try this", suggestion, Applicability::HasPlaceholders);
+                diag.span_suggestion(stmt.span, "try this", suggestion, Applicability::HasPlaceholders);
             }
         });
     }
 }
 
-impl<'a, 'tcx> LateLintPass<'a, 'tcx> for MapUnit {
-    fn check_stmt(&mut self, cx: &LateContext<'_, '_>, stmt: &hir::Stmt<'_>) {
+impl<'tcx> LateLintPass<'tcx> for MapUnit {
+    fn check_stmt(&mut self, cx: &LateContext<'_>, stmt: &hir::Stmt<'_>) {
         if stmt.span.from_expansion() {
             return;
         }