Macro call with braces does not require semicolon to be statement

This commit by itself is supposed to have no effect on behavior. All of
the call sites are updated to preserve their previous behavior.

The behavior changes are in the commits that follow.

compiler/rustc_ast/src/util/classify.rs

@@ -42,19 +42,23 @@ use crate::{ast, token::Delimiter};
 ///     _ => m! {} - 1,  // binary subtraction operator
 /// }
 /// ```
-#[allow(non_snake_case)]
-pub fn expr_requires_semi_to_be_stmt_FIXME(e: &ast::Expr) -> bool {
-    !matches!(
-        e.kind,
-        ast::ExprKind::If(..)
-            | ast::ExprKind::Match(..)
-            | ast::ExprKind::Block(..)
-            | ast::ExprKind::While(..)
-            | ast::ExprKind::Loop(..)
-            | ast::ExprKind::ForLoop { .. }
-            | ast::ExprKind::TryBlock(..)
-            | ast::ExprKind::ConstBlock(..)
-    )
+pub fn expr_requires_semi_to_be_stmt(e: &ast::Expr) -> bool {
+    use ast::ExprKind::*;
+
+    match &e.kind {
+        If(..)
+        | Match(..)
+        | Block(..)
+        | While(..)
+        | Loop(..)
+        | ForLoop { .. }
+        | TryBlock(..)
+        | ConstBlock(..) => false,
+
+        MacCall(mac_call) => mac_call.args.delim != Delimiter::Brace,
+
+        _ => true,
+    }
 }
 
 /// If an expression ends with `}`, returns the innermost expression ending in the `}`