X-Git-Url: https://git.lizzy.rs/?a=blobdiff_plain;f=clippy_lints%2Fsrc%2Funused_unit.rs;h=1164ac4938fb6a28edce06017a0c0082869eaa83;hb=e6455ea72ca3a4602f6a6b097cb80647a1f69388;hp=f61fd2ecd735d915964c5b3ce80bfaa6da56e29e;hpb=39aca5ff9f5317fa1a66eb71772219575e05ba0f;p=rust.git

diff --git a/clippy_lints/src/unused_unit.rs b/clippy_lints/src/unused_unit.rs
index f61fd2ecd73..1164ac4938f 100644
--- a/clippy_lints/src/unused_unit.rs
+++ b/clippy_lints/src/unused_unit.rs
@@ -1,29 +1,33 @@
+use clippy_utils::diagnostics::span_lint_and_sugg;
+use clippy_utils::source::{position_before_rarrow, snippet_opt};
 use if_chain::if_chain;
 use rustc_ast::ast;
 use rustc_ast::visit::FnKind;
 use rustc_errors::Applicability;
-use rustc_lint::{EarlyContext, EarlyLintPass, LintContext};
+use rustc_lint::{EarlyContext, EarlyLintPass};
 use rustc_session::{declare_lint_pass, declare_tool_lint};
 use rustc_span::source_map::Span;
 use rustc_span::BytePos;
 
-use crate::utils::{position_before_rarrow, span_lint_and_sugg};
-
 declare_clippy_lint! {
-    /// **What it does:** Checks for unit (`()`) expressions that can be removed.
+    /// ### What it does
+    /// Checks for unit (`()`) expressions that can be removed.
     ///
-    /// **Why is this bad?** Such expressions add no value, but can make the code
+    /// ### Why is this bad?
+    /// Such expressions add no value, but can make the code
     /// less readable. Depending on formatting they can make a `break` or `return`
     /// statement look like a function call.
     ///
-    /// **Known problems:** None.
-    ///
-    /// **Example:**
+    /// ### Example
     /// ```rust
     /// fn return_unit() -> () {
     ///     ()
     /// }
     /// ```
+    /// is equivalent to
+    /// ```rust
+    /// fn return_unit() {}
+    /// ```
     pub UNUSED_UNIT,
     style,
     "needless unit expression"
@@ -45,9 +49,11 @@ fn check_fn(&mut self, cx: &EarlyContext<'_>, kind: FnKind<'_>, span: Span, _: a
 
     fn check_block(&mut self, cx: &EarlyContext<'_>, block: &ast::Block) {
         if_chain! {
-            if let Some(ref stmt) = block.stmts.last();
+            if let Some(stmt) = block.stmts.last();
             if let ast::StmtKind::Expr(ref expr) = stmt.kind;
-            if is_unit_expr(expr) && !stmt.span.from_expansion();
+            if is_unit_expr(expr);
+            let ctxt = block.span.ctxt();
+            if stmt.span.ctxt() == ctxt && expr.span.ctxt() == ctxt;
             then {
                 let sp = expr.span;
                 span_lint_and_sugg(
@@ -119,17 +125,16 @@ fn is_unit_expr(expr: &ast::Expr) -> bool {
 }
 
 fn lint_unneeded_unit_return(cx: &EarlyContext<'_>, ty: &ast::Ty, span: Span) {
-    let (ret_span, appl) = if let Ok(fn_source) = cx.sess().source_map().span_to_snippet(span.with_hi(ty.span.hi())) {
-        position_before_rarrow(fn_source).map_or((ty.span, Applicability::MaybeIncorrect), |rpos| {
-            (
-                #[allow(clippy::cast_possible_truncation)]
-                ty.span.with_lo(BytePos(span.lo().0 + rpos as u32)),
-                Applicability::MachineApplicable,
-            )
-        })
-    } else {
-        (ty.span, Applicability::MaybeIncorrect)
-    };
+    let (ret_span, appl) =
+        snippet_opt(cx, span.with_hi(ty.span.hi())).map_or((ty.span, Applicability::MaybeIncorrect), |fn_source| {
+            position_before_rarrow(&fn_source).map_or((ty.span, Applicability::MaybeIncorrect), |rpos| {
+                (
+                    #[allow(clippy::cast_possible_truncation)]
+                    ty.span.with_lo(BytePos(span.lo().0 + rpos as u32)),
+                    Applicability::MachineApplicable,
+                )
+            })
+        });
     span_lint_and_sugg(
         cx,
         UNUSED_UNIT,