Added expression check for shared_code_in_if_blocks

Author: xFrednet

clippy_lints/src/copies.rs

@@ -180,11 +180,11 @@ fn lint_same_then_else(cx: &LateContext<'_>, blocks: &[&Block<'_>], has_uncondit
         }
     }
 
-    fn lint_duplicate_code(cx: &LateContext<'_>, position: &str, lint_span: Span) {
+    fn lint_duplicate_code(cx: &LateContext<'_>, position: &str, lint_start: Span, lint_end: Span) {
         span_lint_and_help(
             cx,
             SHARED_CODE_IN_IF_BLOCKS,
-            lint_span,
+            lint_start.to(lint_end),
             format!("All if blocks contain the same code at the {}", position).as_str(),
             None,
             "Consider moving the code out of the if statement to prevent code duplication",
@@ -196,9 +196,16 @@ fn lint_same_then_else(cx: &LateContext<'_>, blocks: &[&Block<'_>], has_uncondit
         return;
     }
 
+    let eval_expr = if let Some(expr) = blocks[0].expr {
+        cx.typeck_results().expr_ty(expr).is_unit()
+    } else {
+        false
+    };
+
     // Check if each block has shared code
     let mut start_eq = usize::MAX;
     let mut end_eq = usize::MAX;
+    let mut expr_eq = true;
     for (index, win) in blocks.windows(2).enumerate() {
         let l_stmts = win[0].stmts;
         let r_stmts = win[1].stmts;
@@ -208,12 +215,13 @@ fn lint_same_then_else(cx: &LateContext<'_>, blocks: &[&Block<'_>], has_uncondit
         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_block_expr_eq = both(&win[0].expr, &win[1].expr, |l, r| evaluator.eq_expr(l, r));
+        
+        let block_expr_eq = both(&win[0].expr, &win[1].expr, |l, r| evaluator.eq_expr(l, r));
 
         // IF_SAME_THEN_ELSE
         // We only lint the first two blocks (index == 0). Further blocks will be linted when that if
         // statement is checked
-        if index == 0 && current_block_expr_eq && l_stmts.len() == r_stmts.len() && l_stmts.len() == current_start_eq {
+        if index == 0 && block_expr_eq && l_stmts.len() == r_stmts.len() && l_stmts.len() == current_start_eq {
             span_lint_and_note(
                 cx,
                 IF_SAME_THEN_ELSE,
@@ -228,9 +236,10 @@ fn lint_same_then_else(cx: &LateContext<'_>, blocks: &[&Block<'_>], has_uncondit
 
         start_eq = min(start_eq, current_start_eq);
         end_eq = min(end_eq, current_end_eq);
+        expr_eq = expr_eq && block_expr_eq;
 
         // We can return if the eq count is 0 from both sides or if it has no unconditional else case
-        if !has_unconditional_else || start_eq == 0 && end_eq == 0 {
+        if !has_unconditional_else || (start_eq == 0 && end_eq == 0 && !(eval_expr && expr_eq)) {
             return;
         };
     }
@@ -245,18 +254,22 @@ fn lint_same_then_else(cx: &LateContext<'_>, blocks: &[&Block<'_>], has_uncondit
     if start_eq != 0 {
         let start = first_block.span.shrink_to_lo();
         let end = get_source_span(first_block.stmts[start_eq - 1].span);
-        let lint_span = start.to(end);
 
-        lint_duplicate_code(cx, "start", lint_span);
+        lint_duplicate_code(cx, "start", start, end);
     }
 
-    if end_eq != 0 {
+    let lint_end = first_block.span.shrink_to_hi();
+    if end_eq != 0 && (!eval_expr || expr_eq) {
         let index = first_block.stmts.len() - end_eq;
         let start = get_source_span(first_block.stmts[index].span);
-        let end = first_block.span.shrink_to_hi();
-        let lint_span = start.to(end);
+        
+        lint_duplicate_code(cx, "end", start, lint_end);
+    } else if eval_expr && expr_eq {
+        if let Some(expr) = first_block.expr {
+            let start = get_source_span(expr.span);
 
-        lint_duplicate_code(cx, "end", lint_span);
+            lint_duplicate_code(cx, "end", start, lint_end);
+        };
     }
 }
 

tests/ui/shared_code_in_if_blocks.rs

@@ -169,4 +169,30 @@ fn shared_code_at_end() {
     };
 }
 
+fn expr_with_unit_type() {
+    // This lint should also evaluate equality of the expression if it's return type is `()`
+    let x = 9;
+
+    // Don't lint
+    if x == 9 {
+        let _a = 17;
+        let _b = 49;
+        
+        println!("A message")
+    } else {
+        let _b = 49;
+        
+        println!("A different message message")
+    }
+
+    // lint
+    if x == 7 {
+        let _a = 0;
+
+        println!("We are doppelgänger")
+    } else {
+        println!("We are doppelgänger")
+    }
+}
+
 fn main() {}

tests/ui/shared_code_in_if_blocks.stderr

@@ -122,5 +122,14 @@ LL | |     } else {
    |
    = help: Consider moving the code out of the if statement to prevent code duplication
 
-error: aborting due to 10 previous errors
+error: All if blocks contain the same code at the end
+  --> $DIR/shared_code_in_if_blocks.rs:192:9
+   |
+LL | /         println!("We are doppelgänger")
+LL | |     } else {
+   | |_____^
+   |
+   = help: Consider moving the code out of the if statement to prevent code duplication
+
+error: aborting due to 11 previous errors