Allow allman style braces in suspicious_else_formatting

clippy_lints/src/formatting.rs

@@ -215,9 +215,22 @@ fn check_else(cx: &EarlyContext<'_>, expr: &Expr) {
         // the snippet should look like " else \n    " with maybe comments anywhere
         // it’s bad when there is a ‘\n’ after the “else”
         if let Some(else_snippet) = snippet_opt(cx, else_span);
-        if let Some(else_pos) = else_snippet.find("else");
-        if else_snippet[else_pos..].contains('\n');
+        if let Some((pre_else, post_else)) = else_snippet.split_once("else");
+        if let Some((_, post_else_post_eol)) = post_else.split_once('\n');
+
         then {
+            // Allow allman style braces `} \n else \n {`
+            if_chain! {
+                if is_block(else_);
+                if let Some((_, pre_else_post_eol)) = pre_else.split_once('\n');
+                // Exactly one eol before and after the else
+                if !pre_else_post_eol.contains('\n');
+                if !post_else_post_eol.contains('\n');
+                then {
+                    return;
+                }
+            }
+
             let else_desc = if is_if(else_) { "if" } else { "{..}" };
             span_lint_and_note(
                 cx,

tests/ui/suspicious_else_formatting.rs

@@ -40,6 +40,7 @@ fn main() {
     {
     }
 
+    // This is fine, though weird. Allman style braces on the else.
     if foo() {
     }
     else
@@ -76,4 +77,29 @@ fn main() {
     }
     if foo() {
     }
+
+    // Almost Allman style braces. Lint these.
+    if foo() {
+    }
+
+    else
+    {
+
+    }
+
+    if foo() {
+    }
+    else
+
+    {
+
+    }
+
+    // #3864 - Allman style braces
+    if foo()
+    {
+    }
+    else
+    {
+    }
 }

tests/ui/suspicious_else_formatting.stderr

@@ -41,37 +41,50 @@ LL | |     {
    |
    = note: to remove this lint, remove the `else` or remove the new line between `else` and `{..}`
 
-error: this is an `else {..}` but the formatting might hide it
-  --> $DIR/suspicious_else_formatting.rs:44:6
+error: this is an `else if` but the formatting might hide it
+  --> $DIR/suspicious_else_formatting.rs:51:6
    |
-LL |       }
+LL |       } else
    |  ______^
-LL | |     else
-LL | |     {
+LL | |     if foo() { // the span of the above error should continue here
    | |____^
    |
-   = note: to remove this lint, remove the `else` or remove the new line between `else` and `{..}`
+   = note: to remove this lint, remove the `else` or remove the new line between `else` and `if`
 
 error: this is an `else if` but the formatting might hide it
-  --> $DIR/suspicious_else_formatting.rs:50:6
+  --> $DIR/suspicious_else_formatting.rs:56:6
    |
-LL |       } else
+LL |       }
    |  ______^
+LL | |     else
 LL | |     if foo() { // the span of the above error should continue here
    | |____^
    |
    = note: to remove this lint, remove the `else` or remove the new line between `else` and `if`
 
-error: this is an `else if` but the formatting might hide it
-  --> $DIR/suspicious_else_formatting.rs:55:6
+error: this is an `else {..}` but the formatting might hide it
+  --> $DIR/suspicious_else_formatting.rs:83:6
    |
 LL |       }
    |  ______^
+LL | |
 LL | |     else
-LL | |     if foo() { // the span of the above error should continue here
+LL | |     {
    | |____^
    |
-   = note: to remove this lint, remove the `else` or remove the new line between `else` and `if`
+   = note: to remove this lint, remove the `else` or remove the new line between `else` and `{..}`
+
+error: this is an `else {..}` but the formatting might hide it
+  --> $DIR/suspicious_else_formatting.rs:91:6
+   |
+LL |       }
+   |  ______^
+LL | |     else
+LL | |
+LL | |     {
+   | |____^
+   |
+   = note: to remove this lint, remove the `else` or remove the new line between `else` and `{..}`
 
-error: aborting due to 8 previous errors
+error: aborting due to 9 previous errors