[style 2024] Combine all delimited exprs as last argument

Author: pitaj

src/doc/style-guide/src/editions.md

@@ -36,6 +36,9 @@ For a full history of changes in the Rust 2024 style edition, see the git
 history of the style guide. Notable changes in the Rust 2024 style edition
 include:
 
+- As the last argument of a function call, delimited expressions are generally
+  combinable, regardless of the number of function arguments. Previously only
+  applied with exactly one argument (except for closures with explicit blocks).
 - Miscellaneous `rustfmt` bugfixes.
 
 ## Rust 2015/2018/2021 style edition

src/doc/style-guide/src/expressions.md

@@ -801,11 +801,11 @@ E.g., `&&Some(foo)` matches, `Foo(4, Bar)` does not.
 
 ## Combinable expressions
 
-Where a function call has a single argument, and that argument is formatted
-across multiple-lines, format the outer call as if it were a single-line call,
+When the last argument in a function call is formatted across
+multiple-lines, format the outer call as if it were a single-line call,
 if the result fits. Apply the same combining behaviour to any similar
 expressions which have multi-line, block-indented lists of sub-expressions
-delimited by parentheses (e.g., macros or tuple struct literals). E.g.,
+delimited by parentheses, brackets, or braces. E.g.,
 
 ```rust
 foo(bar(
@@ -831,20 +831,56 @@ let arr = [combinable(
     an_expr,
     another_expr,
 )];
+
+let x = Thing(an_expr, another_expr, match cond {
+    A => 1,
+    B => 2,
+});
+
+let x = format!("Stuff: {}", [
+    an_expr,
+    another_expr,
+]);
 ```
 
 Apply this behavior recursively.
 
-For a function with multiple arguments, if the last argument is a multi-line
-closure with an explicit block, there are no other closure arguments, and all
-the arguments and the first line of the closure fit on the first line, use the
-same combining behavior:
+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.
 
 ```rust
+// Combinable
 foo(first_arg, x, |param| {
     action();
     foo(param)
 })
+// Not combinable, because the closure is not the last argument
+foo(
+    first_arg,
+    |param| {
+        action();
+        foo(param)
+    },
+    whatever,
+)
+// Not combinable, because the first line of the closure does not fit
+foo(
+    first_arg,
+    x,
+    move |very_long_param_causing_line_to_overflow| -> Bar {
+        action();
+        foo(param)
+    },
+)
+// Not combinable, because there is more than one closure argument
+foo(
+    first_arg,
+    |x| x.bar(),
+    |param| {
+        action();
+        foo(param)
+    },
+)
 ```
 
 ## Ranges