P2393R1 Cleaning up integer-class types

Author: jensmaurer

source/algorithms.tex

@@ -246,6 +246,13 @@
 return n;
 \end{codeblock}
 
+\pnum
+In the description of the algorithms,
+given an iterator \tcode{a} whose difference type is \tcode{D}, and
+an expression \tcode{n} of integer-like type other than \cv{} \tcode{D},
+the semantics of \tcode{a + n} and \tcode{a - n} are, respectively,
+those of \tcode{a + D(n)} and \tcode{a - D(n)}.
+
 \pnum
 In the description of algorithm return values,
 a sentinel value \tcode{s} denoting the end of a range \range{i}{s}

source/iterators.tex

@@ -1333,35 +1333,86 @@
 
 \pnum
 A type \tcode{I} is an \defnadj{integer-class}{type}
-if it is in a set of \impldef{integer-class type} class types
+if it is in a set of \impldef{integer-class type} types
 that behave as integer types do, as defined below.
+\begin{note}
+An integer-class type is not necessarily a class type.
+\end{note}
 
 \pnum
 The range of representable values of an integer-class type
 is the continuous set of values over which it is defined.
-The values 0 and 1 are part of the range of every integer-class type.
-If any negative numbers are part of the range,
-the type is a \defnadj{signed-integer-class}{type};
-otherwise, it is an \defnadj{unsigned-integer-class}{type}.
+For any integer-class type,
+its range of representable values is
+either $-2^{N-1}$ to $2^{N-1}-1$ (inclusive) for some integer $N$,
+in which case it is a \defnadj{signed-integer-class}{type}, or
+$0$ to $2^{N}-1$ (inclusive) for some integer $N$,
+in which case it is an \defnadj{unsigned-integer-class}{type}.
+In both cases, $N$ is called
+the \defnx{width}{width!of integer class type} of the integer-class type.
+The width of an integer-class type is greater than
+that of every integral type of the same signedness.
+
+\pnum
+A type \tcode{I} other than \cv{}~\tcode{bool} is \defn{integer-like}
+if it models \tcode{\libconcept{integral}<I>} or
+if it is an integer-class type.
+An integer-like type \tcode{I} is \defn{signed-integer-like}
+if it models \tcode{\libconcept{signed_integral}<I>} or
+if it is a signed-integer-class type.
+An integer-like type \tcode{I} is \defn{unsigned-integer-like}
+if it models \tcode{\libconcept{unsigned_integral}<I>} or
+if it is an unsigned-integer-class type.
 
 \pnum
 For every integer-class type \tcode{I},
-let \tcode{B(I)} be a hypothetical extended integer type
-of the same signedness with the smallest width\iref{basic.fundamental}
-capable of representing the same range of values.
-The width of \tcode{I} is equal to the width of \tcode{B(I)}.
+let \tcode{B(I)} be a unique hypothetical extended integer type
+of the same signedness with the same width\iref{basic.fundamental} as \tcode{I}.
+\begin{note}
+The corresponding hypothetical specialization \tcode{numeric_limits<B(I)>}
+meets the requirements on \tcode{numeric_limits} specializations
+for integral types\iref{numeric.limits}.
+\end{note}
+For every integral type \tcode{J}, let \tcode{B(J)} be the same type as \tcode{J}.
 
 \pnum
-Let \tcode{a} and \tcode{b} be objects of integer-class type \tcode{I},
-let \tcode{x} and \tcode{y} be objects of type \tcode{B(I)} as described above
-that represent the same values as \tcode{a} and \tcode{b} respectively, and
+Expressions of integer-class type are
+explicitly convertible to any integer-like type, and
+implicitly convertible to any integer-class type
+of equal or greater width and the same signedness.
+Expressions of integral type are
+both implicitly and explicitly convertible to any integer-class type.
+Conversions between integral and integer-class types
+and between two integer-class types do not exit via an exception.
+The result of such a conversion is the unique value of the destination type
+that is congruent to the source modulo $2^N$,
+where $N$ is the width of the destination type.
+
+\pnum
+Let \tcode{a} be an object of integer-class type \tcode{I},
+let \tcode{b} be an object of integer-like type \tcode{I2}
+such that the expression \tcode{b} is implicitly convertible to \tcode{I},
+let \tcode{x} and \tcode{y} be, respectively,
+objects of type \tcode{B(I)} and \tcode{B(I2)} as described above
+that represent the same values as \tcode{a} and \tcode{b}, and
 let \tcode{c} be an lvalue of any integral type.
 \begin{itemize}
 \item
-  For every unary operator \tcode{@} for which the expression \tcode{@x}
+The expressions \tcode{a++} and \tcode{a--} shall be prvalues of type \tcode{I}
+whose values are equal to
+that of \tcode{a} prior to the evaluation of the expressions.
+The expression \tcode{a++} shall modify the value of \tcode{a}
+by adding \tcode{1} to it.
+The expression \tcode{a--} shall modify the value of \tcode{a}
+by subtracting \tcode{1} from it.
+\item
+The expressions \tcode{++a}, \tcode{--a}, and \tcode{\&a} shall be
+expression-equivalent to
+\tcode{a += 1}, \tcode{a -= 1}, and \tcode{addressof(a)}, respectively.
+\item
+  For every \grammarterm{unary-operator} \tcode{@} other than \tcode{\&} for which the expression \tcode{@x}
   is well-formed, \tcode{@a} shall also be well-formed
-  and have the same value, effects, and value category as \tcode{@x}
-  provided that value is representable by \tcode{I}.
+  and have the same value, effects, and value category as \tcode{@x}.
   If \tcode{@x} has type \tcode{bool}, so too does \tcode{@a};
   if \tcode{@x} has type \tcode{B(I)}, then \tcode{@a} has type \tcode{I}.
 \item
@@ -1371,22 +1422,27 @@
   shall have the same value and effects as \tcode{c @= x}.
   The expression \tcode{c @= a} shall be an lvalue referring to \tcode{c}.
 \item
-  For every binary operator \tcode{@} for which \tcode{x @ y} is well-formed,
-  \tcode{a @ b} shall also be well-formed and
-  shall have the same value, effects, and value category as \tcode{x @ y}
-  provided that value is representable by \tcode{I}.
-  If \tcode{x @ y} has type \tcode{bool}, so too does \tcode{a @ b};
-  if \tcode{x @ y} has type \tcode{B(I)}, then \tcode{a @ b} has type \tcode{I}.
+For every assignment operator \tcode{@=}
+for which \tcode{x @= y} is well-formed,
+\tcode{a @= b} shall also be well-formed and
+shall have the same effects as \tcode{x @= y},
+except that the value that would be stored into \tcode{x}
+is stored into \tcode{a}.
+The expression \tcode{a @= b} shall be an lvalue referring to \tcode{a}.
+\item
+  For every non-assignment binary operator \tcode{@}
+  for which \tcode{x @ y} and \tcode{y @ x} are well-formed,
+  \tcode{a @ b} and \tcode{b @ a} shall also be well-formed and
+  shall have the same value, effects, and value category as
+  \tcode{x @ y} and \tcode{y @ x}, respectively.
+  If \tcode{x @ y} or \tcode{y @ x} has type \tcode{B(I)},
+  then \tcode{a @ b} or \tcode{b @ a}, respectively, has type \tcode{I};
+  if \tcode{x @ y} or \tcode{y @ x} has type \tcode{B(I2)},
+  then \tcode{a @ b} or \tcode{b @ a}, respectively, has type \tcode{I2};
+  if \tcode{x @ y} or \tcode{y @ x} has any other type,
+  then \tcode{a @ b} or \tcode{b @ a}, respectively, has that type.
 \end{itemize}
 
-\pnum
-Expressions of integer-class type are
-explicitly convertible to any integral type.
-Expressions of integral type are
-both implicitly and explicitly convertible to any integer-class type.
-Conversions between integral and integer-class types
-do not exit via an exception.
-
 \pnum
 An expression \tcode{E} of integer-class type \tcode{I} is
 contextually convertible to \tcode{bool}
@@ -1395,44 +1451,26 @@
 \pnum
 All integer-class types model
 \libconcept{regular}\iref{concepts.object} and
-\libconcept{totally_ordered}\iref{concept.totallyordered}.
+\tcode{\libconcept{three_way_comparable}<strong_ordering>}\iref{cmp.concept}.
 
 \pnum
 A value-initialized object of integer-class type has value 0.
 
 \pnum
 For every (possibly cv-qualified) integer-class type \tcode{I},
-\tcode{numeric_limits<I>} is specialized such that:
-\begin{itemize}
-\item
-  \tcode{numeric_limits<I>::is_specialized} is \tcode{true},
-\item
-  \tcode{numeric_limits<I>::is_signed} is \tcode{true}
-  if and only if \tcode{I} is a signed-integer-class type,
-\item
-  \tcode{numeric_limits<I>::is_integer} is \tcode{true},
-\item
-  \tcode{numeric_limits<I>::is_exact} is \tcode{true},
-\item
-  \tcode{numeric_limits<I>::digits} is equal to the width of the integer-class type,
-\item
-  \tcode{numeric_limits<I>::digits10} is equal to \tcode{static_cast<int>(digits * log10(2))}, and
-\item
-  \tcode{numeric_limits<I>::min()} and \tcode{numeric_limits<I>::max()} return
-  the lowest and highest representable values of \tcode{I}, respectively, and
-  \tcode{numeric_limits<I>::lowest()} returns \tcode{numeric_limits<I>::\brk{}min()}.
-\end{itemize}
-
-\pnum
-A type \tcode{I} other than \cv{}~\tcode{bool} is \defn{integer-like}
-if it models \tcode{\libconcept{integral}<I>} or
-if it is an integer-class type.
-An integer-like type \tcode{I} is \defn{signed-integer-like}
-if it models \tcode{\libconcept{signed_integral}<I>} or
-if it is a signed-integer-class type.
-An integer-like type \tcode{I} is \defn{unsigned-integer-like}
-if it models \tcode{\libconcept{unsigned_integral}<I>} or
-if it is an unsigned-integer-class type.
+\tcode{numeric_limits<I>} is specialized such that
+each static data member \tcode{m}
+has the same value as \tcode{numeric_limits<B(I)>::m}, and
+each static member function \tcode{f}
+returns \tcode{I(numeric_limits<B(I)>::f())}.
+
+\pnum
+For any two integer-like types \tcode{I1} and \tcode{I2},
+at least one of which is an integer-class type,
+\tcode{common_type_t<I1, I2>} denotes an integer-class type
+whose width is not less than that of \tcode{I1} or \tcode{I2}.
+If both \tcode{I1} and \tcode{I2} are signed-integer-like types,
+then \tcode{common_type_t<I1, I2>} is also a signed-integer-like type.
 
 \pnum
 \tcode{\exposid{is-integer-like}<I>} is \tcode{true}

source/ranges.tex

@@ -1708,7 +1708,7 @@
 Equivalent to:
 \begin{itemize}
 \item If \exposid{StoreSize} is \tcode{true},
-\tcode{subrange(r, ranges::size(r))}.
+\tcode{subrange(r, static_cast<decltype(\exposid{size_})>(ranges::size(r)))}.
 \item Otherwise, \tcode{subrange(ranges::begin(r), ranges::end(r))}.
 \end{itemize}
 \end{itemdescr}
@@ -4654,7 +4654,7 @@
         if constexpr (@\libconcept{random_access_range}@<V>)
           return ranges::begin(@\exposid{base_}@);
         else {
-          auto sz = size();
+          auto sz = range_difference_t<V>(size());
           return counted_iterator(ranges::begin(@\exposid{base_}@), sz);
         }
       } else
@@ -4666,7 +4666,7 @@
         if constexpr (@\libconcept{random_access_range}@<const V>)
           return ranges::begin(@\exposid{base_}@);
         else {
-          auto sz = size();
+          auto sz = range_difference_t<V>(size());
           return counted_iterator(ranges::begin(@\exposid{base_}@), sz);
         }
       } else
@@ -4676,7 +4676,7 @@
     constexpr auto end() requires (!@\exposconcept{simple-view}@<V>) {
       if constexpr (@\libconcept{sized_range}@<V>) {
         if constexpr (@\libconcept{random_access_range}@<V>)
-          return ranges::begin(@\exposid{base_}@) + size();
+          return ranges::begin(@\exposid{base_}@) + range_difference_t<V>(size());
         else
           return default_sentinel;
       } else
@@ -4686,7 +4686,7 @@
     constexpr auto end() const requires @\libconcept{range}@<const V> {
       if constexpr (@\libconcept{sized_range}@<const V>) {
         if constexpr (@\libconcept{random_access_range}@<const V>)
-          return ranges::begin(@\exposid{base_}@) + size();
+          return ranges::begin(@\exposid{base_}@) + range_difference_t<V>(size());
         else
           return default_sentinel;
       } else
@@ -6646,7 +6646,7 @@
 \begin{itemize}
 \item
 If \tcode{T} models \libconcept{contiguous_iterator},
-then \tcode{span(to_address(E), static_cast<D>(F))}.
+then \tcode{span(to_address(E), static_cast<size_t>(static_-\linebreak{}cast<D>(F)))}.
 
 \item
 Otherwise, if \tcode{T} models \libconcept{random_access_iterator},