Auto merge of #10175 - koka831:fix/10171, r=giraffate

Use original variable name in the suggestion Fix #10171 --- changelog: Sugg: [`manual_let_else`]: Now suggest the correct variable name [#10175](#10175)
rust-lang · May 18, 2023 · 7e18451 · 7e18451
2 parents c490974 + 07c8c50
commit 7e18451
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Showing 4 changed files with 100 additions and 62 deletions.
diff --git a/clippy_lints/src/manual_let_else.rs b/clippy_lints/src/manual_let_else.rs
@@ -38,7 +38,6 @@ declare_clippy_lint! {
     /// Could be written:
     ///
     /// ```rust
-    /// # #![feature(let_else)]
     /// # fn main () {
     /// # let w = Some(0);
     /// let Some(v) = w else { return };
@@ -69,29 +68,23 @@ impl_lint_pass!(ManualLetElse => [MANUAL_LET_ELSE]);
 
 impl<'tcx> LateLintPass<'tcx> for ManualLetElse {
     fn check_stmt(&mut self, cx: &LateContext<'_>, stmt: &'tcx Stmt<'tcx>) {
-        let if_let_or_match = if_chain! {
-            if self.msrv.meets(msrvs::LET_ELSE);
-            if !in_external_macro(cx.sess(), stmt.span);
-            if let StmtKind::Local(local) = stmt.kind;
-            if let Some(init) = local.init;
-            if local.els.is_none();
-            if local.ty.is_none();
-            if init.span.ctxt() == stmt.span.ctxt();
-            if let Some(if_let_or_match) = IfLetOrMatch::parse(cx, init);
-            then {
-                if_let_or_match
-            } else {
-                return;
-            }
-        };
+        if !self.msrv.meets(msrvs::LET_ELSE) || in_external_macro(cx.sess(), stmt.span) {
+            return;
+        }
 
+        if let StmtKind::Local(local) = stmt.kind &&
+            let Some(init) = local.init &&
+            local.els.is_none() &&
+            local.ty.is_none() &&
+            init.span.ctxt() == stmt.span.ctxt() &&
+            let Some(if_let_or_match) = IfLetOrMatch::parse(cx, init) {
         match if_let_or_match {
             IfLetOrMatch::IfLet(if_let_expr, let_pat, if_then, if_else) => if_chain! {
                 if expr_is_simple_identity(let_pat, if_then);
                 if let Some(if_else) = if_else;
                 if expr_diverges(cx, if_else);
                 then {
-                    emit_manual_let_else(cx, stmt.span, if_let_expr, let_pat, if_else);
+                    emit_manual_let_else(cx, stmt.span, if_let_expr, local.pat, let_pat, if_else);
                 }
             },
             IfLetOrMatch::Match(match_expr, arms, source) => {
@@ -128,15 +121,23 @@ impl<'tcx> LateLintPass<'tcx> for ManualLetElse {
                     return;
                 }
 
-                emit_manual_let_else(cx, stmt.span, match_expr, pat_arm.pat, diverging_arm.body);
+                emit_manual_let_else(cx, stmt.span, match_expr, local.pat, pat_arm.pat, diverging_arm.body);
             },
         }
+        };
     }
 
     extract_msrv_attr!(LateContext);
 }
 
-fn emit_manual_let_else(cx: &LateContext<'_>, span: Span, expr: &Expr<'_>, pat: &Pat<'_>, else_body: &Expr<'_>) {
+fn emit_manual_let_else(
+    cx: &LateContext<'_>,
+    span: Span,
+    expr: &Expr<'_>,
+    local: &Pat<'_>,
+    pat: &Pat<'_>,
+    else_body: &Expr<'_>,
+) {
     span_lint_and_then(
         cx,
         MANUAL_LET_ELSE,
@@ -145,12 +146,11 @@ fn emit_manual_let_else(cx: &LateContext<'_>, span: Span, expr: &Expr<'_>, pat:
         |diag| {
             // This is far from perfect, for example there needs to be:
             // * mut additions for the bindings
-            // * renamings of the bindings
+            // * renamings of the bindings for `PatKind::Or`
             // * unused binding collision detection with existing ones
             // * putting patterns with at the top level | inside ()
             // for this to be machine applicable.
             let mut app = Applicability::HasPlaceholders;
-            let (sn_pat, _) = snippet_with_context(cx, pat.span, span.ctxt(), "", &mut app);
             let (sn_expr, _) = snippet_with_context(cx, expr.span, span.ctxt(), "", &mut app);
             let (sn_else, _) = snippet_with_context(cx, else_body.span, span.ctxt(), "", &mut app);
 
@@ -159,10 +159,21 @@ fn emit_manual_let_else(cx: &LateContext<'_>, span: Span, expr: &Expr<'_>, pat:
             } else {
                 format!("{{ {sn_else} }}")
             };
-            let sn_bl = if matches!(pat.kind, PatKind::Or(..)) {
-                format!("({sn_pat})")
-            } else {
-                sn_pat.into_owned()
+            let sn_bl = match pat.kind {
+                PatKind::Or(..) => {
+                    let (sn_pat, _) = snippet_with_context(cx, pat.span, span.ctxt(), "", &mut app);
+                    format!("({sn_pat})")
+                },
+                // Replace the variable name iff `TupleStruct` has one argument like `Variant(v)`.
+                PatKind::TupleStruct(ref w, args, ..) if args.len() == 1 => {
+                    let sn_wrapper = cx.sess().source_map().span_to_snippet(w.span()).unwrap_or_default();
+                    let (sn_inner, _) = snippet_with_context(cx, local.span, span.ctxt(), "", &mut app);
+                    format!("{sn_wrapper}({sn_inner})")
+                },
+                _ => {
+                    let (sn_pat, _) = snippet_with_context(cx, pat.span, span.ctxt(), "", &mut app);
+                    sn_pat.into_owned()
+                },
             };
             let sugg = format!("let {sn_bl} = {sn_expr} else {else_bl};");
             diag.span_suggestion(span, "consider writing", sugg, app);

diff --git a/tests/ui/manual_let_else.rs b/tests/ui/manual_let_else.rs
@@ -8,6 +8,12 @@
 )]
 #![warn(clippy::manual_let_else)]
 
+enum Variant {
+    A(usize, usize),
+    B(usize),
+    C,
+}
+
 fn g() -> Option<()> {
     None
 }
@@ -135,6 +141,15 @@ fn fire() {
         };
     }
     create_binding_if_some!(w, g());
+
+    fn e() -> Variant {
+        Variant::A(0, 0)
+    }
+
+    // Should not be renamed
+    let v = if let Variant::A(a, 0) = e() { a } else { return };
+    // Should be renamed
+    let v = if let Variant::B(b) = e() { b } else { return };
 }
 
 fn not_fire() {

diff --git a/tests/ui/manual_let_else.stderr b/tests/ui/manual_let_else.stderr
@@ -1,13 +1,13 @@
 error: this could be rewritten as `let...else`
-  --> $DIR/manual_let_else.rs:18:5
+  --> $DIR/manual_let_else.rs:24:5
    |
 LL |     let v = if let Some(v_some) = g() { v_some } else { return };
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider writing: `let Some(v_some) = g() else { return };`
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider writing: `let Some(v) = g() else { return };`
    |
    = note: `-D clippy::manual-let-else` implied by `-D warnings`
 
 error: this could be rewritten as `let...else`
-  --> $DIR/manual_let_else.rs:19:5
+  --> $DIR/manual_let_else.rs:25:5
    |
 LL | /     let v = if let Some(v_some) = g() {
 LL | |         v_some
@@ -18,13 +18,13 @@ LL | |     };
    |
 help: consider writing
    |
-LL ~     let Some(v_some) = g() else {
+LL ~     let Some(v) = g() else {
 LL +         return;
 LL +     };
    |
 
 error: this could be rewritten as `let...else`
-  --> $DIR/manual_let_else.rs:25:5
+  --> $DIR/manual_let_else.rs:31:5
    |
 LL | /     let v = if let Some(v) = g() {
 LL | |         // Blocks around the identity should have no impact
@@ -45,25 +45,25 @@ LL +     };
    |
 
 error: this could be rewritten as `let...else`
-  --> $DIR/manual_let_else.rs:38:9
+  --> $DIR/manual_let_else.rs:44:9
    |
 LL |         let v = if let Some(v_some) = g() { v_some } else { continue };
-   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider writing: `let Some(v_some) = g() else { continue };`
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider writing: `let Some(v) = g() else { continue };`
 
 error: this could be rewritten as `let...else`
-  --> $DIR/manual_let_else.rs:39:9
+  --> $DIR/manual_let_else.rs:45:9
    |
 LL |         let v = if let Some(v_some) = g() { v_some } else { break };
-   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider writing: `let Some(v_some) = g() else { break };`
+   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider writing: `let Some(v) = g() else { break };`
 
 error: this could be rewritten as `let...else`
-  --> $DIR/manual_let_else.rs:43:5
+  --> $DIR/manual_let_else.rs:49:5
    |
 LL |     let v = if let Some(v_some) = g() { v_some } else { panic!() };
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider writing: `let Some(v_some) = g() else { panic!() };`
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider writing: `let Some(v) = g() else { panic!() };`
 
 error: this could be rewritten as `let...else`
-  --> $DIR/manual_let_else.rs:46:5
+  --> $DIR/manual_let_else.rs:52:5
    |
 LL | /     let v = if let Some(v_some) = g() {
 LL | |         v_some
@@ -74,13 +74,13 @@ LL | |     };
    |
 help: consider writing
    |
-LL ~     let Some(v_some) = g() else {
+LL ~     let Some(v) = g() else {
 LL +         std::process::abort()
 LL +     };
    |
 
 error: this could be rewritten as `let...else`
-  --> $DIR/manual_let_else.rs:53:5
+  --> $DIR/manual_let_else.rs:59:5
    |
 LL | /     let v = if let Some(v_some) = g() {
 LL | |         v_some
@@ -91,13 +91,13 @@ LL | |     };
    |
 help: consider writing
    |
-LL ~     let Some(v_some) = g() else {
+LL ~     let Some(v) = g() else {
 LL +         if true { return } else { panic!() }
 LL +     };
    |
 
 error: this could be rewritten as `let...else`
-  --> $DIR/manual_let_else.rs:60:5
+  --> $DIR/manual_let_else.rs:66:5
    |
 LL | /     let v = if let Some(v_some) = g() {
 LL | |         v_some
@@ -109,14 +109,14 @@ LL | |     };
    |
 help: consider writing
    |
-LL ~     let Some(v_some) = g() else {
+LL ~     let Some(v) = g() else {
 LL +         if true {}
 LL +         panic!();
 LL +     };
    |
 
 error: this could be rewritten as `let...else`
-  --> $DIR/manual_let_else.rs:70:5
+  --> $DIR/manual_let_else.rs:76:5
    |
 LL | /     let v = if let Some(v_some) = g() {
 LL | |         v_some
@@ -129,7 +129,7 @@ LL | |     };
    |
 help: consider writing
    |
-LL ~     let Some(v_some) = g() else {
+LL ~     let Some(v) = g() else {
 LL +         match () {
 LL +             _ if panic!() => {},
 LL +             _ => panic!(),
@@ -138,13 +138,13 @@ LL +     };
    |
 
 error: this could be rewritten as `let...else`
-  --> $DIR/manual_let_else.rs:80:5
+  --> $DIR/manual_let_else.rs:86:5
    |
 LL |     let v = if let Some(v_some) = g() { v_some } else { if panic!() {} };
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider writing: `let Some(v_some) = g() else { if panic!() {} };`
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider writing: `let Some(v) = g() else { if panic!() {} };`
 
 error: this could be rewritten as `let...else`
-  --> $DIR/manual_let_else.rs:83:5
+  --> $DIR/manual_let_else.rs:89:5
    |
 LL | /     let v = if let Some(v_some) = g() {
 LL | |         v_some
@@ -157,15 +157,15 @@ LL | |     };
    |
 help: consider writing
    |
-LL ~     let Some(v_some) = g() else {
+LL ~     let Some(v) = g() else {
 LL +         match panic!() {
 LL +             _ => {},
 LL +         }
 LL +     };
    |
 
 error: this could be rewritten as `let...else`
-  --> $DIR/manual_let_else.rs:92:5
+  --> $DIR/manual_let_else.rs:98:5
    |
 LL | /     let v = if let Some(v_some) = g() {
 LL | |         v_some
@@ -178,15 +178,15 @@ LL | |     };
    |
 help: consider writing
    |
-LL ~     let Some(v_some) = g() else { if true {
+LL ~     let Some(v) = g() else { if true {
 LL +         return;
 LL +     } else {
 LL +         panic!("diverge");
 LL +     } };
    |
 
 error: this could be rewritten as `let...else`
-  --> $DIR/manual_let_else.rs:101:5
+  --> $DIR/manual_let_else.rs:107:5
    |
 LL | /     let v = if let Some(v_some) = g() {
 LL | |         v_some
@@ -199,7 +199,7 @@ LL | |     };
    |
 help: consider writing
    |
-LL ~     let Some(v_some) = g() else {
+LL ~     let Some(v) = g() else {
 LL +         match (g(), g()) {
 LL +             (Some(_), None) => return,
 LL +             (None, Some(_)) => {
@@ -215,7 +215,7 @@ LL +     };
    |
 
 error: this could be rewritten as `let...else`
-  --> $DIR/manual_let_else.rs:118:5
+  --> $DIR/manual_let_else.rs:124:5
    |
 LL | /     let (v, w) = if let Some(v_some) = g().map(|v| (v, 42)) {
 LL | |         v_some
@@ -226,13 +226,13 @@ LL | |     };
    |
 help: consider writing
    |
-LL ~     let Some(v_some) = g().map(|v| (v, 42)) else {
+LL ~     let Some((v, w)) = g().map(|v| (v, 42)) else {
 LL +         return;
 LL +     };
    |
 
 error: this could be rewritten as `let...else`
-  --> $DIR/manual_let_else.rs:125:5
+  --> $DIR/manual_let_else.rs:131:5
    |
 LL | /     let v = if let (Some(v_some), w_some) = (g(), 0) {
 LL | |         (w_some, v_some)
@@ -249,24 +249,36 @@ LL +     };
    |
 
 error: this could be rewritten as `let...else`
-  --> $DIR/manual_let_else.rs:134:13
+  --> $DIR/manual_let_else.rs:140:13
    |
 LL |             let $n = if let Some(v) = $e { v } else { return };
-   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider writing: `let Some(v) = g() else { return };`
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider writing: `let Some($n) = g() else { return };`
 ...
 LL |     create_binding_if_some!(w, g());
    |     ------------------------------- in this macro invocation
    |
    = note: this error originates in the macro `create_binding_if_some` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: this could be rewritten as `let...else`
-  --> $DIR/manual_let_else.rs:247:5
+  --> $DIR/manual_let_else.rs:150:5
+   |
+LL |     let v = if let Variant::A(a, 0) = e() { a } else { return };
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider writing: `let Variant::A(a, 0) = e() else { return };`
+
+error: this could be rewritten as `let...else`
+  --> $DIR/manual_let_else.rs:152:5
+   |
+LL |     let v = if let Variant::B(b) = e() { b } else { return };
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider writing: `let Variant::B(v) = e() else { return };`
+
+error: this could be rewritten as `let...else`
+  --> $DIR/manual_let_else.rs:262:5
    |
 LL | /     let _ = match ff {
 LL | |         Some(value) => value,
 LL | |         _ => macro_call!(),
 LL | |     };
-   | |______^ help: consider writing: `let Some(value) = ff else { macro_call!() };`
+   | |______^ help: consider writing: `let Some(_) = ff else { macro_call!() };`
 
-error: aborting due to 18 previous errors
+error: aborting due to 20 previous errors