do not combine if multiple exprs of the same kind

Author: pitaj

Diff for: src/doc/style-guide/src/expressions.md

@@ -850,8 +850,51 @@ let x = func(an_expr, another_expr, SomeStruct {
 
 Apply this behavior recursively.
 
+```rust
+foo(an_expr, bar(another_expr, SomeStruct(SomeEnum::Variant {
+    field: this_is_long,
+    another_field: 123,
+})));
+
+Thing(an_expr, do_something_with(another_expr, [
+    one,
+    two,
+    three,
+]));
+```
+
+Do not apply the combining behavior if one of the prior arguments is the
+same kind of expression as the last argument.
+
+```rust
+// The `[h, v + 0.1, 0.0]` sub-array is not combinable, because
+// there is a previous sub-array in the outer array.
+func(an_expr, &[
+    [h - 0.1, v, 0.0],
+    [h + 0.1, v, 0.0],
+    [h, v + 0.1, 0.0],
+]);
+
+// The `Thing` field struct expression is not combinable, because
+// there is a previous field struct expression in the arguments to `run`.
+func(an_expr, run(
+    Foo { x: 1, y: 2, z: 3 },
+    Bar { x: 1, y: 2, z: 3 },
+    Thing { x: 1, y: 2, z: 3 },
+));
+
+// The `(more_exprs, last_expr)` tuple is not combinable, because
+// there is a previous tuple in the array.
+func(an_expr, [
+    (another_expr, third_expr),
+    (expr_four, fifth_expr),
+    (more_exprs, last_expr),
+]);
+```
+
 If the last argument is a multi-line closure with an explicit block,
-only apply the combining behavior if there are no other closure arguments.
+only apply the combining behavior if there are no other closure arguments,
+regardless of whether they have explicit blocks or occupy multiple lines.
 
 ```rust
 // Combinable