Allow allman style braces in suspicious_else_formatting

Author: Jarcho

clippy_lints/src/formatting.rs

@@ -200,7 +200,7 @@ fn check_unop(cx: &EarlyContext<'_>, expr: &Expr) {
 /// Implementation of the `SUSPICIOUS_ELSE_FORMATTING` lint for weird `else`.
 fn check_else(cx: &EarlyContext<'_>, expr: &Expr) {
     if_chain! {
-        if let ExprKind::If(_, then, Some(else_)) = &expr.kind;
+        if let ExprKind::If(cond, then, Some(else_)) = &expr.kind;
         if is_block(else_) || is_if(else_);
         if !differing_macro_contexts(then.span, else_.span);
         if !then.span.from_expansion() && !in_external_macro(cx.sess, expr.span);
@@ -218,6 +218,17 @@ fn check_else(cx: &EarlyContext<'_>, expr: &Expr) {
         if let Some(else_pos) = else_snippet.find("else");
         if else_snippet[else_pos..].contains('\n');
         then {
+            // Allow allman style braces `if .. \n { \n .. \n } \n else \n { \n .. \n }`
+            if_chain! {
+                if is_block(else_);
+                if else_snippet.starts_with('\n');
+                if let Some(if_snippet) = snippet_opt(cx, cond.span.between(then.span));
+                if if_snippet.contains('\n');
+                then {
+                    return;
+                }
+            }
+
             let else_desc = if is_if(else_) { "if" } else { "{..}" };
             span_lint_and_note(
                 cx,

tests/ui/suspicious_else_formatting.rs

@@ -76,4 +76,14 @@ fn main() {
     }
     if foo() {
     }
+
+    // #3864 - allman style braces
+    if foo()
+    {
+        // stuff
+    }
+    else
+    {
+        // other stuff
+    }
 }