P1103R3 Merging Modules

source/classes.tex

@@ -2876,7 +2876,7 @@
 A bit-field shall not be a static member.
 \indextext{bit-field!type of}%
 A bit-field shall have integral or enumeration type;
-the bit-field attribute is not part of the type of the class member.
+the bit-field semantic property is not part of the type of the class member.
 The \grammarterm{constant-expression} shall be an integral constant expression
 with a value greater than or equal to zero and
 is called the \defn{width} of the bit-field.

source/compatibility.tex

@@ -1791,6 +1791,20 @@
 
 \rSec2[diff.cpp17.lex]{\ref{lex}: lexical conventions}
 
+\diffref{lex.header}
+\change \grammarterm{header-name} tokens are formed in more contexts.
+\rationale Required for new features.
+\effect When the identifier \tcode{import}
+is followed by a \tcode{<} character,
+a \grammarterm{header-name} token may be formed.
+\begin{example}
+\begin{codeblock}
+template<typename> class import {};
+import<int> f();                // ill-formed; previously well-formed
+::import<int> g();              // OK
+\end{codeblock}
+\end{example}
+
 \diffref{lex.key}
 \change New keywords.
 \rationale Required for new features.
@@ -1862,6 +1876,25 @@
 
 \rSec2[diff.cpp17.basic]{\ref{basic}: basics}
 
+\diffref{basic.link,module.unit,module.import}
+\change New identifiers with special meaning.
+\rationale Required for new features.
+\effect Top-level declarations beginning with
+\tcode{module} or \tcode{import} may
+be either ill-formed or interpreted differently
+in this International Standard.
+\begin{example}
+\begin{codeblock}
+class module;
+module *m1;         // ill-formed; previously well-formed
+::module *m2;       // OK
+
+class import {};
+import j1;          // was variable declaration; now \grammarterm{import-declaration}
+::import j2;        // variable declaration
+\end{codeblock}
+\end{example}
+
 \diffref{intro.races}
 \change Except for the initial release operation,
 a release sequence consists solely of atomic read-modify-write operations.

source/declarations.tex

@@ -25,6 +25,7 @@
     deduction-guide\br
     explicit-instantiation\br
     explicit-specialization\br
+    export-declaration\br
     linkage-specification\br
     namespace-definition\br
     empty-declaration\br
@@ -1031,27 +1032,46 @@
 been declared inline.
 
 \pnum
-An inline function or variable shall be defined in every translation unit in which
-it is odr-used and shall have exactly the same definition in every
-case\iref{basic.def.odr}.
+If an inline function or variable
+is odr-used in a translation unit,
+a definition of it shall be reachable from the end of that translation unit,
+and it shall have exactly the same definition
+in every such translation unit\iref{basic.def.odr}.
 \begin{note}
 A call to the inline function or a use of the inline variable may be encountered before its definition
 appears in the translation unit.
 \end{note}
-If the definition of a function or variable appears in a translation unit before its
+If a definition of a function or variable is reachable
+at the point of its
 first declaration as inline, the program is ill-formed. If a function or variable
-with external linkage is declared inline in one translation unit, it
-shall be declared inline in all translation units in which it appears;
-no diagnostic is required. An inline function or variable with external
-linkage shall have the same address in all translation units.
+with external or module linkage
+is declared inline in one translation unit,
+there shall be a reachable inline declaration
+in all translation units in which it is declared;
+no diagnostic is required.
+An inline function or variable
+with external or module linkage
+shall have the same address in all translation units.
 \begin{note}
 A \tcode{static} local variable in an inline
-function with external linkage always refers to the same object.
+function with external or module linkage
+always refers to the same object.
 A type defined within the body of an inline
-function with external linkage is the
+function with external or module linkage is the
 same type in every translation unit.
 \end{note}
 
+\pnum
+An exported inline function or variable
+shall be defined in the translation unit
+containing its exported declaration,
+outside the \grammarterm{private-module-fragment} (if any).
+\begin{note}
+There is no restriction on the linkage (or absence thereof)
+of entities that the function body of an exported inline function
+can reference. A constexpr function\iref{dcl.constexpr} is implicitly inline.
+\end{note}
+
 \rSec2[dcl.type]{Type specifiers}%
 \indextext{specifier!type|see{type specifier}}
 
@@ -1709,6 +1729,17 @@
 \end{codeblock}
 \end{example}
 
+\pnum
+An exported function
+with a declared return type that uses a placeholder type
+shall be defined in the translation unit
+containing its exported declaration,
+outside the \grammarterm{private-module-fragment} (if any).
+\begin{note}
+There is no restriction on the linkage of
+the deduced return type.
+\end{note}
+
 \pnum
 If the name of an entity with an undeduced placeholder type appears in an
 expression, the program is ill-formed.  Once a
@@ -6642,6 +6673,25 @@
 the definition of a namespace can be split over several parts of one or
 more translation units.
 
+\pnum
+\begin{note}
+A namespace name with external linkage is exported
+if any of its \term{namespace-definition}{s} is exported,
+or if it contains any
+\grammarterm{export-declaration}{s}\iref{module.interface}.
+A namespace is never attached to a module,
+and never has module linkage
+even if it is not exported.
+\end{note}
+\begin{example}
+\begin{codeblock}
+export module M;
+namespace N1 {}                 // \tcode{N1} is not exported
+export namespace N2 {}          // \tcode{N2} is exported
+namespace N3 { export int n; }  // \tcode{N3} is exported
+\end{codeblock}
+\end{example}
+
 \pnum
 The outermost declarative region of a translation unit is a namespace;
 see~\ref{basic.scope.namespace}.

source/lex.tex

@@ -42,8 +42,9 @@
 \begin{note} Previously translated translation units and instantiation
 units can be preserved individually or in libraries. The separate
 translation units of a program communicate\iref{basic.link} by (for
-example) calls to functions whose identifiers have external linkage,
-manipulation of objects whose identifiers have external linkage, or
+example)
+calls to functions whose identifiers have external or module linkage,
+manipulation of objects whose identifiers have external or module linkage, or
 manipulation of data files. Translation units can be separately
 translated and then later linked to produce an executable
 program\iref{basic.link}. \end{note}%
@@ -139,7 +140,18 @@
 semantically analyzed and translated as a translation unit. \begin{note}
 The process of analyzing and translating the tokens may occasionally
 result in one token being replaced by a sequence of other
-tokens\iref{temp.names}.\end{note} \begin{note} Source files, translation
+tokens\iref{temp.names}.\end{note}
+It is
+\impldef{whether the sources for
+module units and header units
+on which the current translation unit has an interface
+dependency are required to be available during translation}
+whether the sources for
+module units and header units
+on which the current translation unit has an interface
+dependency (\ref{module.unit}, \ref{module.import})
+are required to be available.
+\begin{note} Source files, translation
 units and translated translation units need not necessarily be stored as
 files, nor need there be any one-to-one correspondence between these
 entities and any external representation. The description is conceptual
@@ -324,7 +336,20 @@
 characters that could constitute a preprocessing token, even if that
 would cause further lexical analysis to fail,
 except that a \grammarterm{header-name}\iref{lex.header} is only formed
-within a \tcode{\#include} directive\iref{cpp.include}.
+\begin{itemize}
+\item
+within a \tcode{\#include} directive\iref{cpp.include},
+
+\item
+within a \grammarterm{has-include-expression}, or
+
+\item
+outside of any preprocessing directive,
+if applying phase 4 of translation to the sequence
+of preprocessing tokens produced thus far
+is valid and
+results in an \grammarterm{import-seq}\iref{cpp.module}.
+\end{itemize}
 \end{itemize}
 
 \begin{example}
@@ -638,14 +663,17 @@
 \grammarterm{identifier} has a special meaning is resolved to interpret the
 token as a regular \grammarterm{identifier}.
 
-\begin{floattable}{Identifiers with special meaning}{tab:identifiers.special}
-{llll}
-\topline
-\tcode{audit}           &
-\tcode{axiom}           &
-\tcode{final}           &
+\begin{multicolfloattable}{Identifiers with special meaning}{tab:identifiers.special}
+{lll}
+\tcode{audit}           \\
+\tcode{axiom}           \\
+\columnbreak
+\tcode{import}          \\
+\tcode{final}           \\
+\columnbreak
+\tcode{module}          \\
 \tcode{override}        \\
-\end{floattable}
+\end{multicolfloattable}
 
 \pnum
 \indextext{\idxcode{_}|see{character, underscore}}%
@@ -765,8 +793,8 @@
 \tcode{while} \\
 \end{multicolfloattable}
 
-\begin{note} The \tcode{export} and \tcode{register} keywords are unused but
-are reserved for future use.\end{note}
+\begin{note} The \tcode{register} keyword is unused but
+is reserved for future use.\end{note}
 
 \pnum
 Furthermore, the alternative representations shown in

source/macros.tex

@@ -407,6 +407,26 @@
 
 \lstnewenvironment{codeblock}{\CodeBlockSetup}{}
 
+% Left-align listings titles
+\makeatletter
+\def\lst@maketitle{\@makeleftcaption\lst@title@dropdelim}
+\long\def\@makeleftcaption#1#2{%
+  \vskip\abovecaptionskip
+  \sbox\@tempboxa{#1: #2}%
+  \ifdim \wd\@tempboxa >\hsize
+    #1: #2\par
+  \else
+    \global \@minipagefalse
+    \hb@xt@\hsize{%\hfil -- REMOVED
+    \box\@tempboxa\hfil}%
+  \fi
+  \vskip\belowcaptionskip}%
+\makeatother
+
+\lstnewenvironment{codeblocktu}[1]{%
+\lstset{title={%\parabullnum{Bullets1}{0pt}
+#1:}}\CodeBlockSetup}{}
+
 % An environment for command / program output that is not C++ code.
 \lstnewenvironment{outputblock}{\lstset{language=}}{}