P0616R0 Depessimize numeric algorithms with std::move

The wording changes have been applied to the intended place in the current working paper, with LWG approval, despite having been given relative to an older draft in P0616R0.

Author: tkoeppe

source/numerics.tex

@@ -8807,9 +8807,9 @@
 with the initial value
 \tcode{init}
 and then modifies it with
-\tcode{acc = acc + *i}
+\tcode{acc = std::move(acc) + *i}
 or
-\tcode{acc = binary_op(acc, *i)}
+\tcode{acc = binary_op(std::move(acc), *i)}
 for every iterator
 \tcode{i}
 in the range \range{first}{last}
@@ -8961,9 +8961,9 @@
 with the initial value
 \tcode{init}
 and then modifying it with
-\tcode{acc = acc + (*i1) * (*i2)}
+\tcode{acc = std::move(acc) + (*i1) * (*i2)}
 or
-\tcode{acc = binary_op1(acc, binary_op2(*i1, *i2))}
+\tcode{acc = binary_op1(std::move(acc), binary_op2(*i1, *i2))}
 for every iterator
 \tcode{i1}
 in the range \range{first1}{last1}
@@ -9114,7 +9114,7 @@
 \pnum
 \requires
 \tcode{InputIterator}'s value type shall be constructible from the type of \tcode{*first}.
-The result of the expression \tcode{acc + *i} or \tcode{binary_op(acc, *i)} shall be
+The result of the expression \tcode{std::move(acc) + *i} or \tcode{binary_op(std::move(acc), *i)} shall be
 implicitly convertible to \tcode{InputIterator}'s value type. \tcode{acc}
 shall be writable\iref{iterator.requirements.general} to the \tcode{result} output iterator.
 In the ranges
@@ -9130,7 +9130,7 @@
 the function creates an accumulator \tcode{acc} whose type is \tcode{InputIterator}'s
 value type, initializes it with \tcode{*first},
 and assigns the result to \tcode{*result}. For every iterator \tcode{i} in \range{first + 1}{last}
-in order, \tcode{acc} is then modified by \tcode{acc = acc + *i} or \tcode{acc = binary_op(acc, *i)}
+in order, \tcode{acc} is then modified by \tcode{acc = std::move(acc) + *i} or \tcode{acc = binary_op(std::move(acc), *i)}
 and the result is assigned to \tcode{*(result + (i - first))}.
 
 \pnum
@@ -9540,8 +9540,8 @@
 type shall be \tcode{MoveAssignable} (Table~\ref{tab:moveassignable}) and shall
 be constructible from the type of \tcode{*first}. \tcode{acc} (defined below)
 shall be writable\iref{iterator.requirements.general} to the \tcode{result}
-output iterator.  The result of the expression \tcode{val - acc} or
-\tcode{binary_op(val, acc)} shall be writable to the \tcode{result} output iterator.
+output iterator.  The result of the expression \tcode{val - std::move(acc)} or
+\tcode{binary_op(val, std::move(acc))} shall be writable to the \tcode{result} output iterator.
 
 \item
 For the overloads with an \tcode{ExecutionPolicy}, the value type of
@@ -9567,7 +9567,7 @@
 value type, initializes it with \tcode{*first},
 and assigns the result to \tcode{*result}. For every iterator \tcode{i} in \range{first + 1}{last}
 in order, creates an object \tcode{val} whose type is \tcode{InputIterator}'s value type, initializes it
-with \tcode{*i}, computes \tcode{val - acc} or \tcode{binary_op(val, acc)}, assigns the result
+with \tcode{*i}, computes \tcode{val - std::move(acc)} or \tcode{binary_op(val, std::move(acc))}, assigns the result
 to \tcode{*(result + (i - first))}, and move assigns from \tcode{val} to \tcode{acc}.
 
 \pnum