Merge 2019-07 CWG Motion 19

P1152R4 Deprecating volatile

Fixes #2999.

Author: zygoloid

source/declarations.tex

@@ -3350,6 +3350,8 @@
 \indextext{parameter!\idxcode{void}}%
 Except for this special case, a parameter shall not have type \term{cv}
 \tcode{void}.
+A parameter with \tcode{volatile}-qualified type is deprecated;
+see~\ref{depr.volatile.type}.
 If the
 \grammarterm{parameter-declaration-clause}
 \indextext{argument type!unknown}%
@@ -3509,6 +3511,10 @@
 There shall be no arrays of functions, although there can be arrays of pointers
 to functions.
 
+\pnum
+A \tcode{volatile}-qualified return type is deprecated;
+see~\ref{depr.volatile.type}.
+
 \pnum
 Types shall not be defined in return or parameter types.
 
@@ -6521,6 +6527,8 @@
 the \grammarterm{decl-specifier-seq} and
 \placeholder{S} consist of the \grammarterm{storage-class-specifier}{s} of
 the \grammarterm{decl-specifier-seq} (if any).
+A \cv{} that includes \tcode{volatile} is deprecated;
+see~\ref{depr.volatile.type}.
 First, a variable with a unique name \exposid{e} is introduced. If the
 \grammarterm{assignment-expression} in the \grammarterm{initializer}
 has array type \tcode{A} and no \grammarterm{ref-qualifier} is present,

source/expressions.tex

@@ -3309,8 +3309,10 @@
 \end{note}
 The operand shall be a modifiable lvalue. The type of the operand shall
 be an arithmetic type other than \cv{}~\tcode{bool},
-or a pointer to a complete object type. The value
-of the operand object is modified by adding \tcode{1} to it.
+or a pointer to a complete object type.
+An operand with \tcode{volatile}-qualified type is deprecated;
+see~\ref{depr.volatile.type}.
+The value of the operand object is modified by adding \tcode{1} to it.
 The
 \indextext{value computation}%
 value computation of the \tcode{++} expression is sequenced before the
@@ -4265,6 +4267,8 @@
 The operand shall be a modifiable lvalue. The type of the operand shall
 be an arithmetic type other than \cv{}~\tcode{bool},
 or a pointer to a completely-defined object type.
+An operand with \tcode{volatile}-qualified type is deprecated;
+see~\ref{depr.volatile.type}.
 The result is the updated operand; it is an lvalue, and it is a
 bit-field if the operand is a bit-field.
 The expression \tcode{++x} is equivalent to \tcode{x+=1}.
@@ -6690,10 +6694,20 @@
 resulting value of the bit-field is
 \impldefplain{value of bit-field that cannot represent!assigned value}.
 
+\pnum
+A simple assignment whose left operand is of
+a \tcode{volatile}-qualified non-class type
+is deprecated\iref{depr.volatile.type}
+unless the assignment is either a discarded-value expression or
+appears in an unevaluated context.
+
 \pnum
 The behavior of an expression of the form \tcode{E1 \placeholder{op}= E2}
 is equivalent to \tcode{E1 = E1 \placeholder{op} E2} except
-that \tcode{E1} is evaluated only once. In \tcode{+=} and \tcode{-=},
+that \tcode{E1} is evaluated only once.
+Such expressions are deprecated
+if \tcode{E1} has \tcode{volatile}-qualified type; see~\ref{depr.volatile.type}.
+In \tcode{+=} and \tcode{-=},
 \tcode{E1} shall either have arithmetic type or be a pointer to a
 possibly cv-qualified completely-defined object type. In all other
 cases, \tcode{E1} shall have arithmetic type.

source/future.tex

@@ -91,6 +91,27 @@
 \end{codeblock}
 \end{example}
 
+\rSec1[depr.volatile.type]{Deprecated \tcode{volatile} types}
+
+\pnum
+Postfix \tcode{++} and \tcode{\dcr} expressions\iref{expr.post.incr} and
+prefix \tcode{++} and \tcode{\dcr} expressions\iref{expr.pre.incr}
+of \tcode{volatile}-qualified arithmetic and pointer types are deprecated.
+
+\pnum
+Certain assignments
+where the left operand is a \tcode{volatile}-qualified non-class type
+are deprecated; see~\ref{expr.ass}.
+
+\pnum
+A function type\iref{dcl.fct}
+with a parameter with \tcode{volatile}-qualified type or
+with a \tcode{volatile}-qualified return type is deprecated.
+
+\pnum
+A structured binding\iref{dcl.struct.bind} of a \tcode{volatile}-qualified type
+is deprecated.
+
 \rSec1[depr.static.constexpr]{Redeclaration of \tcode{static constexpr} data members}
 
 \pnum