fort77.html

posix标准英文,html格式

<p>The standard error shall be used only for diagnostic messages. If more than one <i>file</i> operand ending in <b>.f</b> (or
possibly other unspecified suffixes) is given, for each such file:</p>

<pre>
<tt>"%s:\n", &lt;</tt><i>file</i><tt>&gt;
</tt>
</pre>

<p>may be written to allow identification of the diagnostic message with the appropriate input file.</p>

<p>This utility may produce warning messages about certain conditions that do not warrant returning an error (non-zero) exit
value.</p>
</blockquote>

<h4><a name="tag_04_57_12"></a>OUTPUT FILES</h4>

<blockquote>
<p>Object files, listing files, and executable files shall be produced in unspecified formats.</p>
</blockquote>

<h4><a name="tag_04_57_13"></a>EXTENDED DESCRIPTION</h4>

<blockquote>
<h5><a name="tag_04_57_13_01"></a>Standard Libraries</h5>

<p>The <i>fort77</i> utility shall recognize the following <b>-l</b> operand for the standard library:</p>

<dl compact>
<dt><b>-l&nbsp;f</b></dt>

<dd>This library contains all functions referenced in the ANSI&nbsp;X3.9-1978 standard. This operand shall not be required to be
present to cause a search of this library.</dd>
</dl>

<p>In the absence of options that inhibit invocation of the link editor, such as <b>-c</b>, the <i>fort77</i> utility shall cause
the equivalent of a <b>-l&nbsp;f</b> operand to be passed to the link editor as the last <b>-l</b> operand, causing it to be
searched after all other object files and libraries are loaded.</p>

<p>It is unspecified whether the library <b>libf.a</b> exists as a regular file. The implementation may accept as <b>-l</b>
operands names of objects that do not exist as regular files.</p>

<h5><a name="tag_04_57_13_02"></a>External Symbols</h5>

<p>The FORTRAN compiler and link editor shall support the significance of external symbols up to a length of at least 31 bytes;
case folding is permitted. The action taken upon encountering symbols exceeding the implementation-defined maximum symbol length is
unspecified.</p>

<p>The compiler and link editor shall support a minimum of 511 external symbols per source or object file, and a minimum of 4095
external symbols total. A diagnostic message is written to standard output if the implementation-defined limit is exceeded; other
actions are unspecified.</p>
</blockquote>

<h4><a name="tag_04_57_14"></a>EXIT STATUS</h4>

<blockquote>
<p>The following exit values shall be returned:</p>

<dl compact>
<dt>&nbsp;0</dt>

<dd>Successful compilation or link edit.</dd>

<dt>&gt;0</dt>

<dd>An error occurred.</dd>
</dl>
</blockquote>

<h4><a name="tag_04_57_15"></a>CONSEQUENCES OF ERRORS</h4>

<blockquote>
<p>When <i>fort77</i> encounters a compilation error, it shall write a diagnostic to standard error and continue to compile other
source code operands. It shall return a non-zero exit status, but it is implementation-defined whether an object module is created.
If the link edit is unsuccessful, a diagnostic message shall be written to standard error, and <i>fort77</i> shall exit with a
non-zero status.</p>
</blockquote>

<hr>
<div class="box"><em>The following sections are informative.</em></div>

<h4><a name="tag_04_57_16"></a>APPLICATION USAGE</h4>

<blockquote>
<p>None.</p>
</blockquote>

<h4><a name="tag_04_57_17"></a>EXAMPLES</h4>

<blockquote>
<p>The following usage example compiles <b>xyz.f</b> and creates the executable file <b>foo</b>:</p>

<pre>
<tt>fort77 -o foo xyz.f
</tt>
</pre>

<p>The following example compiles <b>xyz.f</b> and creates the object file <b>xyz.o</b>:</p>

<pre>
<tt>fort77 -c xyz.f
</tt>
</pre>

<p>The following example compiles <b>xyz.f</b> and creates the executable file <b>a.out</b>:</p>

<pre>
<tt>fort77 xyz.f
</tt>
</pre>

<p>The following example compiles <b>xyz.f</b>, links it with <b>b.o</b>, and creates the executable <b>a.out</b>:</p>

<pre>
<tt>fort77 xyz.f b.o
</tt>
</pre>
</blockquote>

<h4><a name="tag_04_57_18"></a>RATIONALE</h4>

<blockquote>
<p>The name of this utility was chosen as <i>fort77</i> to parallel the renaming of the C compiler. The name <i>f77</i> was not
chosen to avoid problems with historical implementations. The ANSI&nbsp;X3.9-1978 standard was selected as a normative reference
because the ISO/IEC version of FORTRAN-77 has been superseded by the ISO/IEC&nbsp;1539:1990 standard (Fortran-90).</p>

<p>The file inclusion and symbol definition <b>#define</b> mechanisms used by the <a href="../utilities/c99.html"><i>c99</i></a>
utility were not included in this volume of IEEE&nbsp;Std&nbsp;1003.1-2001-even though they are commonly implemented-since there is
no requirement that the FORTRAN compiler use the C preprocessor.</p>

<p>The <b>-onetrip</b> option was not included in this volume of IEEE&nbsp;Std&nbsp;1003.1-2001, even though many historical
compilers support it, because it is derived from FORTRAN-66; it is an anachronism that should not be perpetuated.</p>

<p>Some implementations produce compilation listings. This aspect of FORTRAN has been left unspecified because there was
controversy concerning the various methods proposed for implementing it: a <b>-V</b> option overlapped with historical vendor
practice and a naming convention of creating files with <b>.l</b> suffixes collided with historical <a href=
"../utilities/lex.html"><i>lex</i></a> file naming practice.</p>

<p>There is no <b>-I</b> option in this version of this volume of IEEE&nbsp;Std&nbsp;1003.1-2001 to specify a directory for file
inclusion. An INCLUDE directive has been a part of the Fortran-90 discussions, but an interface supporting that standard is not in
the current scope.</p>

<p>It is noted that many FORTRAN compilers produce an object module even when compilation errors occur; during a subsequent
compilation, the compiler may patch the object module rather than recompiling all the code. Consequently, it is left to the
implementor whether or not an object file is created.</p>

<p>A reference to MIL-STD-1753 was removed from an early proposal in response to a request from the POSIX FORTRAN-binding standard
developers. It was not the intention of the standard developers to require certification of the FORTRAN compiler, and
IEEE&nbsp;Std&nbsp;1003.9-1992 does not specify the military standard or any special preprocessing requirements. Furthermore, use
of that document would have been inappropriate for an international standard.</p>

<p>The specification of optimization has been subject to changes through early proposals. At one time, <b>-O</b> and <b>-N</b> were
Booleans: optimize and do not optimize (with an unspecified default). Some historical practice led this to be changed to:</p>

<dl compact>
<dt><b>-O</b>&nbsp;0</dt>

<dd>No optimization.</dd>

<dt><b>-O</b>&nbsp;1</dt>

<dd>Some level of optimization.</dd>

<dt><b>-O&nbsp;</b> <i>n</i></dt>

<dd>Other, unspecified levels of optimization.</dd>
</dl>

<p>It is not always clear whether &quot;good code generation&quot; is the same thing as optimization. Simple optimizations of local actions
do not usually affect the semantics of a program. The <b>-O</b> 0 option has been included to accommodate the very particular
nature of scientific calculations in a highly optimized environment; compilers make errors. Some degree of optimization is
expected, even if it is not documented here, and the ability to shut it off completely could be important when porting an
application. An implementation may treat <b>-O</b> 0 as &quot;do less than normal&quot; if it wishes, but this is only meaningful if any of
the operations it performs can affect the semantics of a program. It is highly dependent on the implementation whether doing less
than normal is logical. It is not the intent of the <b>-O</b> 0 option to ask for inefficient code generation, but rather to assure
that any semantically visible optimization is suppressed.</p>

<p>The specification of standard library access is consistent with the C compiler specification. Implementations are not required
to have <b>/usr/lib/libf.a</b>, as many historical implementations do, but if not they are required to recognize <b>f</b> as a
token.</p>

<p>External symbol size limits are in normative text; conforming applications need to know these limits. However, the minimum
maximum symbol length should be taken as a constraint on a conforming application, not on an implementation, and consequently the
action taken for a symbol exceeding the limit is unspecified. The minimum size for the external symbol table was added for similar
reasons.</p>

<p>The CONSEQUENCES OF ERRORS section clearly specifies the behavior of the compiler when compilation or link-edit errors occur.
The behavior of several historical implementations was examined, and the choice was made to be silent on the status of the
executable, or <b>a.out</b>, file in the face of compiler or linker errors. If a linker writes the executable file, then links it
on disk with <a href="../functions/lseek.html"><i>lseek</i>()</a>s and <a href="../functions/write.html"><i>write</i>()</a>s, the
partially linked executable file can be left on disk and its execute bits turned off if the link edit fails. However, if the linker
links the image in memory before writing the file to disk, it need not touch the executable file (if it already exists) because the
link edit fails. Since both approaches are historical practice, a conforming application shall rely on the exit status of
<i>fort77</i>, rather than on the existence or mode of the executable file.</p>

<p>The <b>-g</b> and <b>-s</b> options are not specified as mutually-exclusive. Historically these two options have been
mutually-exclusive, but because both are so loosely specified, it seemed appropriate to leave their interaction unspecified.</p>

<p>The requirement that conforming applications specify compiler options separately is to reserve the multi-character option name
space for vendor-specific compiler options, which are known to exist in many historical implementations. Implementations are not
required to recognize, for example, <b>-gc</b> as if it were <b>-g</b> <b>-c</b>; nor are they forbidden from doing so. The
SYNOPSIS shows all of the options separately to highlight this requirement on applications.</p>

<p>Echoing filenames to standard error is considered a diagnostic message because it would otherwise be difficult to associate an
error message with the erring file. They are described with &quot;may&quot; to allow implementations to use other methods of identifying
files and to parallel the description in <a href="../utilities/c99.html"><i>c99</i></a>.</p>
</blockquote>

<h4><a name="tag_04_57_19"></a>FUTURE DIRECTIONS</h4>

<blockquote>
<p>A compilation system based on the ISO/IEC&nbsp;1539:1990 standard (Fortran-90) may be considered for a future version; it may
have a different utility name from <i>fort77</i>.</p>
</blockquote>

<h4><a name="tag_04_57_20"></a>SEE ALSO</h4>

<blockquote>
<p><a href="ar.html"><i>ar</i></a>, <a href="asa.html"><i>asa</i></a>, <a href="c99.html"><i>c99</i></a>, <a href=
"umask.html"><i>umask</i>()</a>, the System Interfaces volume of IEEE&nbsp;Std&nbsp;1003.1-2001, <i>exec</i></p>
</blockquote>

<h4><a name="tag_04_57_21"></a>CHANGE HISTORY</h4>

<blockquote>
<p>First released in Issue 4.</p>
</blockquote>

<h4><a name="tag_04_57_22"></a>Issue 6</h4>

<blockquote>
<p>This utility is marked as part of the FORTRAN Development Utilities option.</p>

<p>The normative text is reworded to avoid use of the term &quot;must&quot; for application requirements.</p>
</blockquote>

<div class="box"><em>End of informative text.</em></div>

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