[stmt.iter.general] Index an implementation-defined behavior

Author: AlisdairM

source/statements.tex

@@ -577,10 +577,11 @@
 for which the converted controlling expression is a constant expression,
 when interpreted as a \grammarterm{constant-expression}\iref{expr.const}, and
 evaluates to \tcode{true}.
-The \grammarterm{statement} of a trivial infinite loop is replaced with
-a call to the function \tcode{std::this_thread::yield}\iref{thread.thread.this};
-it is implementation-defined whether this replacement occurs
-on freestanding implementations.
+The \grammarterm{statement} of a trivial infinite loop is replaced with a call
+to the function \tcode{std::this_thread::yield}\iref{thread.thread.this}; it is
+\impldef{whether freestanding implementations replace the \grammarterm{statement}
+of a trivial infinite loop with a call to the function \tcode{std::this_thread::yield}}
+whether this replacement occurs on freestanding implementations.
 \begin{note}
 In a freestanding environment,
 concurrent forward progress is not guaranteed;