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<H1> 13.12 Pragma Restrictions</H1>
<DIV Class="Paranum"><FONT SIZE=-2>1</FONT></DIV>
<DIV Class="Normal"> A <FONT FACE="Arial, Helvetica">pragma</FONT>
Restrictions expresses the user's intent to abide by certain restrictions.
This may facilitate the construction of simpler run-time environments.
</DIV>
<H4 ALIGN=CENTER>Syntax</H4>
<DIV Class="Paranum"><FONT SIZE=-2>2</FONT></DIV>
<DIV Class="SyntaxIndented" Style="margin-bottom: 0.2em">The form of
a <FONT FACE="Arial, Helvetica">pragma</FONT> Restrictions is as follows:
</DIV>
<DIV Class="Paranum"><FONT SIZE=-2>3</FONT></DIV>
<DIV Class="SyntaxIndented"> <B>pragma</B> <A NAME="I4446"></A>Restrictions(<A NAME="I4447"></A><FONT FACE="Arial, Helvetica">restriction</FONT>{,
<A NAME="I4448"></A><FONT FACE="Arial, Helvetica">restriction</FONT>});</DIV>
<DIV Class="Paranum"><FONT SIZE=-2>4</FONT></DIV>
<DIV Class="SyntaxIndented"><FONT FACE="Arial, Helvetica">restriction<A NAME="I4449"></A>
::= </FONT><I>restriction_</I><A NAME="I4450"></A><FONT FACE="Arial, Helvetica">identifier</FONT><BR>
| <I>restriction_parameter_</I><A NAME="I4451"></A><FONT FACE="Arial, Helvetica">identifier</FONT> => <A NAME="I4452"></A><FONT FACE="Arial, Helvetica">expression</FONT></DIV>
<H4 ALIGN=CENTER>Name Resolution Rules</H4>
<DIV Class="Paranum"><FONT SIZE=-2>5</FONT></DIV>
<DIV Class="Normal"> <A NAME="I4453"></A>Unless otherwise specified
for a particular restriction, the <FONT FACE="Arial, Helvetica">expression</FONT>
is expected to be of any integer type. </DIV>
<H4 ALIGN=CENTER>Legality Rules</H4>
<DIV Class="Paranum"><FONT SIZE=-2>6</FONT></DIV>
<DIV Class="Normal"> Unless otherwise specified for a particular restriction,
the <FONT FACE="Arial, Helvetica">expression</FONT> shall be static,
and its value shall be nonnegative. </DIV>
<H4 ALIGN=CENTER>Static Semantics</H4>
<DIV Class="Paranum"><FONT SIZE=-2>7</FONT></DIV>
<DIV Class="Normal"> The set of <FONT FACE="Arial, Helvetica">restrictions</FONT>
is implementation defined. </DIV>
<H4 ALIGN=CENTER>Post-Compilation Rules</H4>
<DIV Class="Paranum"><FONT SIZE=-2>8</FONT></DIV>
<DIV Class="Normal"> <A NAME="I4454"></A><A NAME="I4455"></A>A <FONT FACE="Arial, Helvetica">pragma</FONT>
Restrictions is a configuration pragma; unless otherwise specified for
a particular restriction, a partition shall obey the restriction if a
<FONT FACE="Arial, Helvetica">pragma</FONT> Restrictions applies to any
compilation unit included in the partition.</DIV>
<DIV Class="Paranum"><FONT SIZE=-2>8.1/1</FONT></DIV>
<DIV Class="Normal" Style="margin-bottom: 0.4em"> For the purpose
of checking whether a partition contains constructs that violate any
restriction (unless specified otherwise for a particular restriction):</DIV>
<DIV Class="Paranum"><FONT SIZE=-2>8.2/1</FONT></DIV>
<UL Class="Bulleted"><LI TYPE=DISC>Generic instances are logically expanded at the point of
instantiation;</LI></UL>
<DIV Class="Paranum"><FONT SIZE=-2>8.3/1</FONT></DIV>
<UL Class="Bulleted"><LI TYPE=DISC>If an object of a type is declared or allocated and not
explicitly initialized, then all expressions appearing in the definition
for the type and any of its ancestors are presumed to be used;</LI></UL>
<DIV Class="Paranum"><FONT SIZE=-2>8.4/1</FONT></DIV>
<UL Class="Bulleted"><LI TYPE=DISC>A <FONT FACE="Arial, Helvetica">default_expression</FONT>
for a formal parameter or a generic formal object is considered to be
used if and only if the corresponding actual parameter is not provided
in a given call or instantiation. </LI></UL>
<H4 ALIGN=CENTER>Implementation Permissions</H4>
<DIV Class="Paranum"><FONT SIZE=-2>9</FONT></DIV>
<DIV Class="Normal"> An implementation may place limitations on the
values of the <FONT FACE="Arial, Helvetica">expression</FONT> that are
supported, and limitations on the supported combinations of restrictions.
The consequences of violating such limitations are implementation defined.
</DIV>
<DIV Class="Paranum"><FONT SIZE=-2>9.1/1</FONT></DIV>
<DIV Class="Normal"> An implementation is permitted to omit restriction
checks for code that is recognized at compile time to be unreachable
and for which no code is generated.</DIV>
<DIV Class="Paranum"><FONT SIZE=-2>9.2/1</FONT></DIV>
<DIV Class="Normal"> Whenever enforcement of a restriction is not
required prior to execution, an implementation may nevertheless enforce
the restriction prior to execution of a partition to which the restriction
applies, provided that every execution of the partition would violate
the restriction. </DIV>
<DIV Class="NotesHeader"><FONT SIZE=-1>NOTES</FONT></DIV>
<DIV Class="Paranum"><FONT SIZE=-2>10</FONT></DIV>
<DIV Class="Notes"><FONT SIZE=-1>28 Restrictions intended
to facilitate the construction of efficient tasking run-time systems
are defined in <A HREF="RM-D-7.html">D.7</A>. Safety- and security-related
restrictions are defined in <A HREF="RM-H-4.html">H.4</A>.</FONT></DIV>
<DIV Class="Paranum"><FONT SIZE=-2>11</FONT></DIV>
<DIV Class="Notes"><FONT SIZE=-1>29 An implementation has
to enforce the restrictions in cases where enforcement is required, even
if it chooses not to take advantage of the restrictions in terms of efficiency.
</FONT></DIV>
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