fix: manual_instant_elapsed wrongly unmangled macros

Author: profetia

clippy_lints/src/time_subtraction.rs

@@ -96,11 +96,8 @@ impl LateLintPass<'_> for UncheckedTimeSubtraction {
 
         if lhs_ty.is_diag_item(cx, sym::Instant) {
             // Instant::now() - instant
-            if is_instant_now_call(cx, lhs)
-                && rhs_ty.is_diag_item(cx, sym::Instant)
-                && let Some(sugg) = Sugg::hir_opt(cx, rhs)
-            {
-                print_manual_instant_elapsed_sugg(cx, expr, sugg);
+            if is_instant_now_call(cx, lhs) && rhs_ty.is_diag_item(cx, sym::Instant) {
+                print_manual_instant_elapsed_sugg(cx, expr, rhs);
             }
             // instant - duration
             else if rhs_ty.is_diag_item(cx, sym::Duration)
@@ -150,15 +147,17 @@ fn is_time_type(cx: &LateContext<'_>, ty: Ty<'_>) -> bool {
     ty.is_diag_item(cx, sym::Duration) || ty.is_diag_item(cx, sym::Instant)
 }
 
-fn print_manual_instant_elapsed_sugg(cx: &LateContext<'_>, expr: &Expr<'_>, sugg: Sugg<'_>) {
+fn print_manual_instant_elapsed_sugg(cx: &LateContext<'_>, expr: &Expr<'_>, rhs: &Expr<'_>) {
+    let mut applicability = Applicability::MachineApplicable;
+    let sugg = Sugg::hir_with_context(cx, rhs, expr.span.ctxt(), "<instant>", &mut applicability);
     span_lint_and_sugg(
         cx,
         MANUAL_INSTANT_ELAPSED,
         expr.span,
         "manual implementation of `Instant::elapsed`",
         "try",
         format!("{}.elapsed()", sugg.maybe_paren()),
-        Applicability::MachineApplicable,
+        applicability,
     );
 }
 

tests/ui/manual_instant_elapsed.fixed

@@ -28,3 +28,19 @@ fn main() {
     //
     //~^^ manual_instant_elapsed
 }
+
+fn issue16236() {
+    use std::ops::Sub as _;
+    macro_rules! deref {
+        ($e:expr) => {
+            *$e
+        };
+    }
+
+    let start = &Instant::now();
+    let _ = deref!(start).elapsed();
+    //~^ manual_instant_elapsed
+
+    deref!(start).elapsed();
+    //~^ manual_instant_elapsed
+}

tests/ui/manual_instant_elapsed.rs

@@ -28,3 +28,19 @@ fn main() {
     //
     //~^^ manual_instant_elapsed
 }
+
+fn issue16236() {
+    use std::ops::Sub as _;
+    macro_rules! deref {
+        ($e:expr) => {
+            *$e
+        };
+    }
+
+    let start = &Instant::now();
+    let _ = Instant::now().sub(deref!(start));
+    //~^ manual_instant_elapsed
+
+    Instant::now() - deref!(start);
+    //~^ manual_instant_elapsed
+}

tests/ui/manual_instant_elapsed.stderr

@@ -13,5 +13,17 @@ error: manual implementation of `Instant::elapsed`
 LL |     Instant::now() - *ref_to_instant; // to ensure parens are added correctly
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `(*ref_to_instant).elapsed()`
 
-error: aborting due to 2 previous errors
+error: manual implementation of `Instant::elapsed`
+  --> tests/ui/manual_instant_elapsed.rs:41:13
+   |
+LL |     let _ = Instant::now().sub(deref!(start));
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `deref!(start).elapsed()`
+
+error: manual implementation of `Instant::elapsed`
+  --> tests/ui/manual_instant_elapsed.rs:44:5
+   |
+LL |     Instant::now() - deref!(start);
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `deref!(start).elapsed()`
+
+error: aborting due to 4 previous errors