[expr.prim.fold] Disable character protrusion for a bnf block where it would break alignment

Author: tkoeppe

source/expressions.tex

@@ -1322,6 +1322,8 @@
 \end{bnf}
 
 \begin{bnf}
+%% Ed. note: character protrusion would misalign operators with leading `-`.
+\microtypesetup{protrusion=false}
 \nontermdef{fold-operator} \textnormal{one of}\br
     \terminal{+ }\quad\terminal{- }\quad\terminal{* }\quad\terminal{/ }\quad\terminal{\% }\quad\terminal{\caret{} }\quad\terminal{\& }\quad\terminal{| }\quad\terminal{<< }\quad\terminal{>> }\br
     \terminal{+=}\quad\terminal{-=}\quad\terminal{*=}\quad\terminal{/=}\quad\terminal{\%=}\quad\terminal{\caret=}\quad\terminal{\&=}\quad\terminal{|=}\quad\terminal{<<=}\quad\terminal{>>=}\quad\terminal{=}\br