[thread.jthread.cons] Revert editorial change from "if INVOKE(...) is a

valid expression" to checking is_invocable_v.

It's unclear that this is exactly equivalent, and it seems less clear,
as the "INVOKE(...)" expression is used again a couple of paragraphs
later.

Author: zygoloid

source/threads.tex

@@ -1433,12 +1433,18 @@
 \begin{itemdescr}
 \pnum
 \requires
-\tcode{F} and each $\tcode{T}_i$ in \tcode{Args} shall meet the
+\tcode{F} and each $\tcode{T}_i$ in \tcode{Args} meet the
 \oldconcept{MoveConstructible} requirements.
 Either
-\tcode{is_invocable_v<decay_t<F>, stop_token, decay_t<Args>...>} is true,
-or
-\tcode{is_invocable_v<decay_t<F>, decay_t<Args>...>} is true.
+\begin{codeblock}
+@\placeholdernc{INVOKE}@(@\placeholdernc{decay-copy}@(std::forward<F>(f)), get_stop_token(),
+       @\placeholdernc{decay-copy}@(std::forward<Args>(args))...)
+\end{codeblock}
+is a valid expression or
+\begin{codeblock}
+@\placeholdernc{INVOKE}@(@\placeholdernc{decay-copy}@(std::forward<F>(f)), @\placeholdernc{decay-copy}@(std::forward<Args>(args))...)
+\end{codeblock}
+is a valid expression.
 
 \pnum
 \constraints
@@ -1449,21 +1455,15 @@
 Initializes \tcode{ssource} and
 constructs an object of type \tcode{jthread}.
 The new thread of execution executes
-        \tcode{%
-                \placeholdernc{INVOKE}(\brk{}%
-                \placeholdernc{decay-copy}(\brk{}%
-                std::forward<F>(f)),
-                get_stop_token(),
-                \placeholdernc{decay-copy}(\brk{}%
-                std::forward\brk{}<Args>(\brk{}args))...)}
+\begin{codeblock}
+@\placeholdernc{INVOKE}@(@\placeholdernc{decay-copy}@(std::forward<F>(f)), get_stop_token(),
+       @\placeholdernc{decay-copy}@(std::forward<Args>(args))...)
+\end{codeblock}
 if that expression is well-formed,
 otherwise
-        \tcode{%
-                \placeholdernc{INVOKE}(\brk{}%
-                \placeholdernc{decay-copy}(\brk{}%
-                std::forward\brk{}<F>\brk{}(f)),
-                \placeholdernc{decay-copy}(\brk{}%
-                std::forward<Args>(\brk{}args))...)}
+\begin{codeblock}
+@\placeholdernc{INVOKE}@(@\placeholdernc{decay-copy}@(std::forward<F>(f)), @\placeholdernc{decay-copy}@(std::forward<Args>(args))...)
+\end{codeblock}
 with the calls to
 \tcode{\placeholder{decay-copy}} being evaluated in the constructing thread.
 Any return value from this invocation is ignored.