Support tuples

Author: est31

clippy_lints/src/manual_let_else.rs

@@ -8,6 +8,7 @@ use rustc_hir::{Expr, ExprKind, MatchSource, Pat, QPath, Stmt, StmtKind};
 use rustc_lint::{LateContext, LateLintPass, LintContext};
 use rustc_middle::lint::in_external_macro;
 use rustc_semver::RustcVersion;
+use rustc_data_structures::stable_set::FxHashSet;
 use rustc_session::{declare_tool_lint, impl_lint_pass};
 use rustc_span::Span;
 
@@ -206,20 +207,33 @@ fn pat_has_no_bindings(pat: &'_ Pat<'_>) -> bool {
 
 /// Checks if the passed block is a simple identity referring to bindings created by the pattern
 fn expr_is_simple_identity(pat: &'_ Pat<'_>, expr: &'_ Expr<'_>) -> bool {
-    // TODO support patterns with multiple bindings and tuples, like:
+    // We support patterns with multiple bindings and tuples, like:
     //   let ... = if let (Some(foo), bar) = g() { (foo, bar) } else { ... }
-    if_chain! {
-        if let ExprKind::Path(QPath::Resolved(_ty, path)) = &peel_blocks(expr).kind;
-        if let [path_seg] = path.segments;
-        then {
-            let mut pat_bindings = Vec::new();
-            pat.each_binding_or_first(&mut |_ann, _hir_id, _sp, ident| {
-                pat_bindings.push(ident);
-            });
-            if let [binding] = &pat_bindings[..] {
-                return path_seg.ident == *binding;
+    let peeled = peel_blocks(expr);
+    let paths = match peeled.kind {
+        ExprKind::Tup(exprs) | ExprKind::Array(exprs) => exprs,
+        ExprKind::Path(_) => std::slice::from_ref(peeled),
+        _ => return false,
+    };
+    let mut pat_bindings = FxHashSet::default();
+    pat.each_binding_or_first(&mut |_ann, _hir_id, _sp, ident| {
+        pat_bindings.insert(ident);
+    });
+    if pat_bindings.len() < paths.len() {
+        return false;
+    }
+    for path in paths {
+        if_chain! {
+            if let ExprKind::Path(QPath::Resolved(_ty, path)) = path.kind;
+            if let [path_seg] = path.segments;
+            then {
+                if !pat_bindings.remove(&path_seg.ident) {
+                    return false;
+                }
+            } else {
+                return false;
             }
         }
     }
-    false
+    true
 }

tests/ui/manual_let_else.rs

@@ -83,18 +83,20 @@ fn fire() {
         return;
     };
 
+    // Tuples supported for the identity block and pattern
+    let v = if let (Some(v_some), w_some) = (g(), 0) {
+        (w_some, v_some)
+    } else {
+        return;
+    };
+
     // entirely inside macro lints
     macro_rules! create_binding_if_some {
         ($n:ident, $e:expr) => {
-            let $n = if let Some(v) = $e {
-                v
-            } else {
-                return
-            };
+            let $n = if let Some(v) = $e { v } else { return };
         };
     }
     create_binding_if_some!(w, g());
-
 }
 
 fn not_fire() {
@@ -164,11 +166,7 @@ fn not_fire() {
     // Macro boundary inside let
     macro_rules! some_or_return {
         ($e:expr) => {
-            if let Some(v) = $e {
-                v
-            } else {
-                return
-            }
+            if let Some(v) = $e { v } else { return }
         };
     }
     let v = some_or_return!(g());
@@ -180,4 +178,4 @@ fn not_fire() {
         };
     }
     create_binding_if_some!(v, g());
-}
+}

tests/ui/manual_let_else.stderr

@@ -101,19 +101,25 @@ LL | |     };
    | |______^
 
 error: this could be rewritten as `let else`
-  --> $DIR/manual_let_else.rs:89:13
+  --> $DIR/manual_let_else.rs:87:5
    |
-LL | /             let $n = if let Some(v) = $e {
-LL | |                 v
-LL | |             } else {
-LL | |                 return
-LL | |             };
-   | |______________^
+LL | /     let v = if let (Some(v_some), w_some) = (g(), 0) {
+LL | |         (w_some, v_some)
+LL | |     } else {
+LL | |         return;
+LL | |     };
+   | |______^
+
+error: this could be rewritten as `let else`
+  --> $DIR/manual_let_else.rs:96:13
+   |
+LL |             let $n = if let Some(v) = $e { v } else { return };
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 ...
-LL |       create_binding_if_some!(w, g());
-   |       ------------------------------- in this macro invocation
+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: aborting due to 12 previous errors
+error: aborting due to 13 previous errors