Prevent line breaking at = or in after trivial patterns

src/expr.rs

@@ -1307,20 +1307,28 @@ fn rewrite_pat_expr(context: &RewriteContext,
                                         offset + extra_offset + spacer.len());
 
         if let Some(expr_string) = expr_rewrite {
+            let pat_simple =
+                pat.and_then(|p| p.rewrite(context, context.config.max_width, Indent::empty()))
+                    .map(|s| pat_is_simple(&s));
+
+            if pat.is_none() || pat_simple.unwrap_or(false) || !expr_string.contains('\n') {
                 result.push_str(spacer);
                 result.push_str(&expr_string);
                 return Some(result);
             }
         }
+    }
+
+    let nested = context.nested_context();
 
     // The expression won't fit on the current line, jump to next.
     result.push('\n');
-    result.push_str(&pat_offset.to_string(context.config));
+    result.push_str(&nested.block_indent.to_string(context.config));
 
     let expr_rewrite =
-        expr.rewrite(context,
-                     try_opt!(context.config.max_width.checked_sub(pat_offset.width())),
-                     pat_offset);
+        expr.rewrite(&nested,
+                     try_opt!(context.config.max_width.checked_sub(nested.block_indent.width())),
+                     nested.block_indent);
     result.push_str(&try_opt!(expr_rewrite));
 
     Some(result)

tests/source/expr.rs

@@ -285,3 +285,16 @@ fn complex_if_else() {
         yo();
     }
 }
+
+fn issue1106() {
+    {
+    if let hir::ItemEnum(ref enum_def, ref generics) = self.ast_map.expect_item(enum_node_id).node {
+    }
+    }
+
+    for entry in
+    WalkDir::new(path)
+        .into_iter()
+        .filter_entry(|entry| exclusions.filter_entry(entry)) {
+    }
+}

tests/target/expr.rs

@@ -55,8 +55,8 @@ fn foo() -> bool {
     }
 
     if let (some_very_large,
-            tuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuple) = 1111 +
-                                                                                         2222 {}
+            tuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuple) =
+        1111 + 2222 {}
 
     if let (some_very_large,
             tuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuple) = 1 + 2 + 3 {
@@ -290,3 +290,16 @@ fn complex_if_else() {
         yo();
     }
 }
+
+fn issue1106() {
+    {
+        if let hir::ItemEnum(ref enum_def, ref generics) =
+            self.ast_map.expect_item(enum_node_id).node {
+        }
+    }
+
+    for entry in WalkDir::new(path)
+        .into_iter()
+        .filter_entry(|entry| exclusions.filter_entry(entry)) {
+    }
+}

tests/target/loop.rs

@@ -21,8 +21,8 @@ fn main() {
     while aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa {
     }
 
-    'b: for xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx in some_iter(arg1,
-                                                                                        arg2) {
+    'b: for xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx in
+        some_iter(arg1, arg2) {
         // do smth
     }