`unnecessary_lazy_eval` show suggestions on multiline lint

[rust.git] / clippy_lints / src / methods / unnecessary_lazy_eval.rs

diff --git a/clippy_lints/src/methods/unnecessary_lazy_eval.rs b/clippy_lints/src/methods/unnecessary_lazy_eval.rs
index cde89983a2656aff2d0a50eb646b690699a79c6b..0dd41a4dacfc5eed68f50c423e545c7a84c4bde1 100644 (file)
--- a/clippy_lints/src/methods/unnecessary_lazy_eval.rs
+++ b/clippy_lints/src/methods/unnecessary_lazy_eval.rs
@@ -1,5 +1,7 @@
-use crate::utils::{eager_or_lazy, usage};
-use crate::utils::{is_type_diagnostic_item, snippet, span_lint_and_sugg};
+use clippy_utils::diagnostics::span_lint_and_then;
+use clippy_utils::source::snippet;
+use clippy_utils::ty::is_type_diagnostic_item;
+use clippy_utils::{eager_or_lazy, usage};
 use rustc_errors::Applicability;
 use rustc_hir as hir;
 use rustc_lint::LateContext;
@@ -9,17 +11,18 @@
 
 /// lint use of `<fn>_else(simple closure)` for `Option`s and `Result`s that can be
 /// replaced with `<fn>(return value of simple closure)`
-pub(super) fn lint<'tcx>(
+pub(super) fn check<'tcx>(
     cx: &LateContext<'tcx>,
     expr: &'tcx hir::Expr<'_>,
-    args: &'tcx [hir::Expr<'_>],
+    recv: &'tcx hir::Expr<'_>,
+    arg: &'tcx hir::Expr<'_>,
     simplify_using: &str,
 ) {
-    let is_option = is_type_diagnostic_item(cx, cx.typeck_results().expr_ty(&args[0]), sym::option_type);
-    let is_result = is_type_diagnostic_item(cx, cx.typeck_results().expr_ty(&args[0]), sym::result_type);
+    let is_option = is_type_diagnostic_item(cx, cx.typeck_results().expr_ty(recv), sym::Option);
+    let is_result = is_type_diagnostic_item(cx, cx.typeck_results().expr_ty(recv), sym::Result);
 
     if is_option || is_result {
-        if let hir::ExprKind::Closure(_, _, eid, _, _) = args[1].kind {
+        if let hir::ExprKind::Closure(_, _, eid, _, _) = arg.kind {
             let body = cx.tcx.hir().body(eid);
             let body_expr = &body.value;
 
@@ -27,27 +30,34 @@ pub(super) fn lint<'tcx>(
                 return;
             }
 
-            if eager_or_lazy::is_eagerness_candidate(cx, body_expr) {
+            if eager_or_lazy::switch_to_eager_eval(cx, body_expr) {
                 let msg = if is_option {
                     "unnecessary closure used to substitute value for `Option::None`"
                 } else {
                     "unnecessary closure used to substitute value for `Result::Err`"
                 };
+                let applicability = if body
+                    .params
+                    .iter()
+                    // bindings are checked to be unused above
+                    .all(|param| matches!(param.pat.kind, hir::PatKind::Binding(..) | hir::PatKind::Wild))
+                {
+                    Applicability::MachineApplicable
+                } else {
+                    // replacing the lambda may break type inference
+                    Applicability::MaybeIncorrect
+                };
 
-                span_lint_and_sugg(
-                    cx,
-                    UNNECESSARY_LAZY_EVALUATIONS,
-                    expr.span,
-                    msg,
-                    &format!("Use `{}` instead", simplify_using),
-                    format!(
-                        "{0}.{1}({2})",
-                        snippet(cx, args[0].span, ".."),
-                        simplify_using,
-                        snippet(cx, body_expr.span, ".."),
-                    ),
-                    Applicability::MachineApplicable,
-                );
+                if let hir::ExprKind::MethodCall(_, _, span) = expr.kind {
+                    span_lint_and_then(cx, UNNECESSARY_LAZY_EVALUATIONS, expr.span, msg, |diag| {
+                        diag.span_suggestion(
+                            span,
+                            &format!("use `{}(..)` instead", simplify_using),
+                            format!("{}({})", simplify_using, snippet(cx, body_expr.span, "..")),
+                            applicability,
+                        );
+                    });
+                }
             }
         }
     }