Expand attribute macros on statements and expressions.

Retains the `stmt_expr_attributes` feature requirement for attributes on expressions.

closes #41475
cc #38356

src/libsyntax/parse/parser.rs

@@ -4601,6 +4601,9 @@ impl<'a> Parser<'a> {
 
     /// Parse a statement, including the trailing semicolon.
     pub fn parse_full_stmt(&mut self, macro_legacy_warnings: bool) -> PResult<'a, Option<Stmt>> {
+        // skip looking for a trailing semicolon when we have an interpolated statement
+        maybe_whole!(self, NtStmt, |x| Some(x));
+
         let mut stmt = match self.parse_stmt_without_recovery(macro_legacy_warnings)? {
             Some(stmt) => stmt,
             None => return Ok(None),