Adapted the lint to use the new SpanlessEq

Author: xFrednet

clippy_lints/src/copies.rs

@@ -295,11 +295,21 @@ fn scan_block_for_eq(cx: &LateContext<'tcx>, blocks: &[&Block<'tcx>]) -> (usize,
         let l_stmts = win[0].stmts;
         let r_stmts = win[1].stmts;
 
+        // `SpanlessEq` now keeps track of the locals and is therefore context sensitive clippy#6752.
+        // The comparison therefor needs to be done in a way that builds the correct context.
         let mut evaluator = SpanlessEq::new(cx);
+        let mut evaluator = evaluator.inter_expr();
+
         let current_start_eq = count_eq(&mut l_stmts.iter(), &mut r_stmts.iter(), |l, r| evaluator.eq_stmt(l, r));
-        let current_end_eq = count_eq(&mut l_stmts.iter().rev(), &mut r_stmts.iter().rev(), |l, r| {
-            evaluator.eq_stmt(l, r)
-        });
+
+        let current_end_eq = {
+            // We skip the middle statements which can't be equal
+            let end_comparison_count = l_stmts.len().min(r_stmts.len()) - current_start_eq;
+            let it1 = l_stmts.iter().skip(l_stmts.len() - end_comparison_count);
+            let it2 = r_stmts.iter().skip(r_stmts.len() - end_comparison_count);
+            it1.zip(it2)
+                .fold(0, |acc, (l, r)| if evaluator.eq_stmt(l, r) { acc + 1 } else { 0 })
+        };
         let block_expr_eq = both(&win[0].expr, &win[1].expr, |l, r| evaluator.eq_expr(l, r));
 
         // IF_SAME_THEN_ELSE
@@ -458,8 +468,8 @@ fn emit_shared_code_in_if_blocks_lint(
     // Emit lint
     if suggestions.len() == 1 {
         let (place_str, span, sugg) = suggestions.pop().unwrap();
-        let msg = format!("All if blocks contain the same code at the {}", place_str);
-        let help = format!("Consider moving the {} statements out like this", place_str);
+        let msg = format!("all if blocks contain the same code at the {}", place_str);
+        let help = format!("consider moving the {} statements out like this", place_str);
         span_lint_and_then(cx, SHARED_CODE_IN_IF_BLOCKS, span, msg.as_str(), |diag| {
             diag.span_suggestion(span, help.as_str(), sugg, Applicability::Unspecified);
 
@@ -472,20 +482,20 @@ fn emit_shared_code_in_if_blocks_lint(
             cx,
             SHARED_CODE_IN_IF_BLOCKS,
             start_span,
-            "All if blocks contain the same code at the start and the end. Here at the start:",
+            "all if blocks contain the same code at the start and the end. Here at the start",
             move |diag| {
-                diag.span_note(end_span, "And here at the end:");
+                diag.span_note(end_span, "and here at the end");
 
                 diag.span_suggestion(
                     start_span,
-                    "Consider moving the start statements out like this:",
+                    "consider moving the start statements out like this",
                     start_sugg,
                     Applicability::Unspecified,
                 );
 
                 diag.span_suggestion(
                     end_span,
-                    "And consider moving the end statements out like this:",
+                    "and consider moving the end statements out like this",
                     end_sugg,
                     Applicability::Unspecified,
                 );

clippy_utils/src/hir_utils.rs

@@ -58,13 +58,14 @@ impl<'a, 'tcx> SpanlessEq<'a, 'tcx> {
 
     /// Use this method to wrap comparisons that may involve inter-expression context.
     /// See `self.locals`.
-    fn inter_expr(&mut self) -> HirEqInterExpr<'_, 'a, 'tcx> {
+    pub fn inter_expr(&mut self) -> HirEqInterExpr<'_, 'a, 'tcx> {
         HirEqInterExpr {
             inner: self,
             locals: FxHashMap::default(),
         }
     }
 
+    #[allow(dead_code)]
     pub fn eq_block(&mut self, left: &Block<'_>, right: &Block<'_>) -> bool {
         self.inter_expr().eq_block(left, right)
     }
@@ -82,17 +83,17 @@ impl<'a, 'tcx> SpanlessEq<'a, 'tcx> {
     }
 }
 
-struct HirEqInterExpr<'a, 'b, 'tcx> {
+pub struct HirEqInterExpr<'a, 'b, 'tcx> {
     inner: &'a mut SpanlessEq<'b, 'tcx>,
 
-    // When binding are declared, the binding ID in the left expression is mapped to the one on the
-    // right. For example, when comparing `{ let x = 1; x + 2 }` and `{ let y = 1; y + 2 }`,
-    // these blocks are considered equal since `x` is mapped to `y`.
+    /// When binding are declared, the binding ID in the left expression is mapped to the one on the
+    /// right. For example, when comparing `{ let x = 1; x + 2 }` and `{ let y = 1; y + 2 }`,
+    /// these blocks are considered equal since `x` is mapped to `y`.
     locals: FxHashMap<HirId, HirId>,
 }
 
 impl HirEqInterExpr<'_, '_, '_> {
-    fn eq_stmt(&mut self, left: &Stmt<'_>, right: &Stmt<'_>) -> bool {
+    pub fn eq_stmt(&mut self, left: &Stmt<'_>, right: &Stmt<'_>) -> bool {
         match (&left.kind, &right.kind) {
             (&StmtKind::Local(ref l), &StmtKind::Local(ref r)) => {
                 self.eq_pat(&l.pat, &r.pat)
@@ -159,7 +160,7 @@ impl HirEqInterExpr<'_, '_, '_> {
     }
 
     #[allow(clippy::similar_names)]
-    fn eq_expr(&mut self, left: &Expr<'_>, right: &Expr<'_>) -> bool {
+    pub fn eq_expr(&mut self, left: &Expr<'_>, right: &Expr<'_>) -> bool {
         if !self.inner.allow_side_effects && differing_macro_contexts(left.span, right.span) {
             return false;
         }

tests/ui/if_same_then_else.stderr

@@ -82,31 +82,5 @@ LL | |         42
 LL | |     };
    | |_____^
 
-error: this `if` has identical blocks
-  --> $DIR/if_same_then_else.rs:95:13
-   |
-LL |       if true {
-   |  _____________^
-LL | |         let bar = if true { 42 } else { 43 };
-LL | |
-LL | |         while foo() {
-...  |
-LL | |         bar + 1;
-LL | |     } else {
-   | |_____^
-   |
-note: same as this
-  --> $DIR/if_same_then_else.rs:102:12
-   |
-LL |       } else {
-   |  ____________^
-LL | |         //~ ERROR same body as `if` block
-LL | |         let bar = if true { 42 } else { 43 };
-LL | |
-...  |
-LL | |         bar + 1;
-LL | |     }
-   | |_____^
-
-error: aborting due to 5 previous errors
+error: aborting due to 4 previous errors
 

tests/ui/if_same_then_else2.stderr

@@ -1,19 +1,5 @@
 error: this `if` has identical blocks
-  --> $DIR/if_same_then_else2.rs:21:12
-   |
-LL |       } else {
-   |  ____________^
-LL | |         //~ ERROR same body as `if` block
-LL | |         for _ in &[42] {
-LL | |             let bar: &Option<_> = &Some::<u8>(42);
-...  |
-LL | |         }
-LL | |     }
-   | |_____^
-   |
-   = note: `-D clippy::if-same-then-else` implied by `-D warnings`
-note: same as this
-  --> $DIR/if_same_then_else2.rs:12:13
+  --> $DIR/if_same_then_else2.rs:13:13
    |
 LL |       if true {
    |  _____________^
@@ -33,7 +19,7 @@ LL |       } else {
    |  ____________^
 LL | |         //~ ERROR same body as `if` block
 LL | |         for _ in &[42] {
-LL | |             let foo: &Option<_> = &Some::<u8>(42);
+LL | |             let bar: &Option<_> = &Some::<u8>(42);
 ...  |
 LL | |         }
 LL | |     }
@@ -115,25 +101,5 @@ LL | |         Ok("foo")?;
 LL | |     }
    | |_____^
 
-error: this `if` has identical blocks
-  --> $DIR/if_same_then_else2.rs:122:20
-   |
-LL |       } else if true {
-   |  ____________________^
-LL | |         let foo = "";
-LL | |         return Ok(&foo[0..]);
-LL | |     } else {
-   | |_____^
-   |
-note: same as this
-  --> $DIR/if_same_then_else2.rs:125:12
-   |
-LL |       } else {
-   |  ____________^
-LL | |         let foo = "";
-LL | |         return Ok(&foo[0..]);
-LL | |     }
-   | |_____^
-
-error: aborting due to 6 previous errors
+error: aborting due to 5 previous errors
 

tests/ui/shared_code_in_if_blocks/shared_at_bot.rs

@@ -4,7 +4,6 @@
 // This tests the shared_code_in_if_blocks lint at the end of blocks
 
 fn simple_examples() {
-    // TODO xFrednet 2021-01-06: Test with const literals at the end
     let x = 1;
 
     let _ = if x == 7 {
@@ -45,8 +44,8 @@ fn simple_examples() {
         println!("This is also eq with the else block");
         println!("Same end of block");
     } else {
-        println!("Same end of block");
         println!("This is also eq with the else block");
+        println!("Same end of block");
     }
 
     // Use of outer scope value
@@ -69,21 +68,11 @@ fn simple_examples() {
         );
     }
 
-    // TODO xFrednet 2021-01.13: Fix lint for `if let`
-    let index = Some(8);
-    if let Some(index) = index {
-        println!("The index is: {}", index);
-
-        println!("Same end of block");
-    } else {
-        println!("Same end of block");
-    }
-
     if x == 9 {
         if x == 8 {
             // No parent!!
-            println!("Hello World");
             println!("---");
+            println!("Hello World");
         } else {
             println!("Hello World");
         }