P1091R3 Extending structured bindings to be more like variable declar…

…ations

[dcl.stc] Convert new text to singular to match the context.

source/declarations.tex

@@ -183,9 +183,11 @@
 \pnum
 A \grammarterm{simple-declaration} with an \grammarterm{identifier-list} is called
 a \defn{structured binding declaration}\iref{dcl.struct.bind}.
-The \grammarterm{decl-specifier-seq} shall
-contain only the \grammarterm{type-specifier} \tcode{auto}\iref{dcl.spec.auto}
-and \grammarterm{cv-qualifier}{s}.
+If the \grammarterm{decl-specifier-seq} contains
+any \grammarterm{decl-specifier} other than
+\tcode{static}, \tcode{thread_local}, \tcode{auto}\iref{dcl.spec.auto}, or
+\grammarterm{cv-qualifier}{s},
+the program is ill-formed.
 The \grammarterm{initializer} shall be
 of the form ``\tcode{=} \grammarterm{assignment-expression}'',
 of the form ``\tcode{\{} \grammarterm{assignment-expression} \tcode{\}}'',
@@ -370,17 +372,21 @@
 The \tcode{thread_local} specifier
 indicates that the named entity has thread storage duration\iref{basic.stc.thread}. It
 shall be applied only
-to the declaration of a variable of namespace
-or block scope or to the declaration of a static data member.
+to the declaration of a variable of namespace or block scope,
+to a structured binding declaration\iref{dcl.struct.bind}, or
+to the declaration of a static data member.
 When \tcode{thread_local} is applied to a variable of block scope the
 \grammarterm{storage-class-specifier} \tcode{static} is implied if no other
 \grammarterm{storage-class-specifier} appears in the
 \grammarterm{decl-specifier-seq}.
 
 \pnum
 \indextext{restriction!\idxcode{static}}%
-The \tcode{static} specifier shall be applied only to the declaration of a variable or
-function or to the declaration of an anonymous union\iref{class.union.anon}. There can be no
+The \tcode{static} specifier shall be applied only
+to the declaration of a variable or function,
+to a structured binding declaration\iref{dcl.struct.bind}, or
+to the declaration of an anonymous union\iref{class.union.anon}.
+There can be no
 \tcode{static} function declarations within a block, nor any
 \tcode{static} function parameters. A \tcode{static} specifier used in
 the declaration of a variable declares the variable to have static storage
@@ -6117,12 +6123,20 @@
 of the
 \grammarterm{identifier-list} as names\iref{basic.scope.declarative}
 of \defn{structured binding}{s}.
-Let \cv{} denote the
-\grammarterm{cv-qualifier}{s} in the \grammarterm{decl-specifier-seq}. First, a
-variable with a unique name \tcode{e} is introduced. If the
+Let \cv{} denote the \grammarterm{cv-qualifier}{s} in
+the \grammarterm{decl-specifier-seq} and
+\placeholder{S} consist of the \grammarterm{storage-class-specifier}{s} of
+the \grammarterm{decl-specifier-seq} (if any).
+First, a variable with a unique name \tcode{e} is introduced. If the
 \grammarterm{assignment-expression} in the \grammarterm{initializer}
-has array type \tcode{A} and no \grammarterm{ref-qualifier} is present, \tcode{e}
-has type \cv{}~\tcode{A} and each element is copy-initialized or direct-initialized
+has array type \tcode{A} and no \grammarterm{ref-qualifier} is present,
+\tcode{e} is defined by
+
+\begin{ncbnf}
+\opt{attribute-specifier-seq} \placeholder{S} \cv{} \terminal{A e ;}
+\end{ncbnf}
+
+and each element is copy-initialized or direct-initialized
 from the corresponding element of the \grammarterm{assignment-expression} as specified
 by the form of the \grammarterm{initializer}.
 Otherwise, \tcode{e}
@@ -6189,13 +6203,19 @@
 Ordinary unqualified lookup\iref{basic.lookup.unqual} is not performed.
 \end{note}
 In either case, \tcode{e} is an lvalue if the type of the entity \tcode{e}
-is an lvalue reference and an xvalue otherwise. Given the type $\tcode{T}_i$
-designated by \tcode{std::tuple_element<i, E>::type},
-variables are introduced with unique names $\tcode{r}_i$
-of type ``reference to $\tcode{T}_i$''
-initialized with the initializer~(\ref{dcl.init.ref}),
-where the reference is an lvalue reference if the initializer is
-an lvalue and an rvalue reference otherwise.
+is an lvalue reference and an xvalue otherwise.
+Given the type $\tcode{T}_i$ designated by
+\tcode{std::tuple_element<i, E>::type} and
+the type $\tcode{U}_i$ designated by
+either \tcode{$\tcode{T}_i$\&} or \tcode{$\tcode{T}_i$\&\&},
+where $\tcode{U}_i$ is an lvalue reference if
+the initializer is an lvalue and an rvalue reference otherwise,
+variables are introduced with unique names $\tcode{r}_i$ as follows:
+
+\begin{ncbnf}
+\placeholder{S} \terminal{U$_i$ r$_i$ =} initializer \terminal{;}
+\end{ncbnf}
+
 Each $\tcode{v}_i$ is the name of an lvalue of type $\tcode{T}_i$
 that refers to the object bound to $\tcode{r}_i$;
 the referenced type is $\tcode{T}_i$.

source/expressions.tex

@@ -2164,9 +2164,7 @@
 captured by a \grammarterm{lambda-expression} is odr-used\iref{basic.def.odr} in the scope
 containing the \grammarterm{lambda-expression}.
 If a \grammarterm{lambda-expression}
-explicitly captures an entity that is not odr-usable
-or
-captures a structured binding (explicitly or implicitly),
+explicitly captures an entity that is not odr-usable,
 the program is
 ill-formed.
 \begin{example}
@@ -2298,7 +2296,8 @@
 static_assert([](int n) { return [&n] { return ++n; }(); }(3) == 4);
 \end{codeblock}
 \end{example}
-A bit-field or a member of an anonymous union shall not be captured by reference.
+A bit-field, a structured binding, or a member of an anonymous union
+shall not be captured by reference.
 
 \pnum
 An \grammarterm{id-expression} within