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diff --git a/devdocs/gcc~13/c_002b_002b-module-preprocessing.html b/devdocs/gcc~13/c_002b_002b-module-preprocessing.html new file mode 100644 index 00000000..aa56fe74 --- /dev/null +++ b/devdocs/gcc~13/c_002b_002b-module-preprocessing.html @@ -0,0 +1,8 @@ +<div class="subsection-level-extent" id="C_002b_002b-Module-Preprocessing"> <div class="nav-panel"> <p> Next: <a href="c_002b_002b-compiled-module-interface" accesskey="n" rel="next">Compiled Module Interface</a>, Previous: <a href="c_002b_002b-module-mapper" accesskey="p" rel="prev">Module Mapper</a>, Up: <a href="c_002b_002b-modules" accesskey="u" rel="up">C++ Modules</a> [<a href="index#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="indices" title="Index" rel="index">Index</a>]</p> </div> <h1 class="subsection" id="Module-Preprocessing"><span>3.23.2 Module Preprocessing<a class="copiable-link" href="#Module-Preprocessing"> ΒΆ</a></span></h1> <p>Modules affect preprocessing because of header units and include translation. Some uses of the preprocessor as a separate step either do not produce a correct output, or require CMIs to be available. </p> <p>Header units import macros. These macros can affect later conditional inclusion, which therefore can cascade to differing import sets. When preprocessing, it is necessary to load the CMI. If a header unit is unavailable, the preprocessor issues a warning and continue (when not just preprocessing, an error is emitted). Detecting such imports requires preprocessor tokenization of the input stream to phase 4 (macro expansion). </p> <p>Include translation converts <code class="code">#include</code>, <code class="code">#include_next</code> and <code class="code">#import</code> directives to internal <code class="code">import</code> declarations. Whether a particular directive is translated is controlled by the module mapper. Header unit names are canonicalized during preprocessing. </p> <p>Dependency information can be emitted for macro import, extending the functionality of <samp class="option">-MD</samp> and <samp class="option">-MMD</samp> options. Detection of import declarations also requires phase 4 preprocessing, and thus requires full preprocessing (or compilation). </p> <p>The <samp class="option">-M</samp>, <samp class="option">-MM</samp> and <samp class="option">-E -fdirectives-only</samp> options halt preprocessing before phase 4. </p> <p>The <samp class="option">-save-temps</samp> option uses <samp class="option">-fdirectives-only</samp> for preprocessing, and preserve the macro definitions in the preprocessed output. Usually you also want to use this option when explicitly preprocessing a header-unit, or consuming such preprocessed output: </p> <div class="example smallexample"> <pre class="example-preformatted" data-language="cpp">g++ -fmodules-ts -E -fdirectives-only my-header.hh -o my-header.ii +g++ -x c++-header -fmodules-ts -fpreprocessed -fdirectives-only my-header.ii</pre> +</div> </div><div class="_attribution"> + <p class="_attribution-p"> + © Free Software Foundation<br>Licensed under the GNU Free Documentation License, Version 1.3.<br> + <a href="https://gcc.gnu.org/onlinedocs/gcc-13.1.0/gcc/C_002b_002b-Module-Preprocessing.html" class="_attribution-link">https://gcc.gnu.org/onlinedocs/gcc-13.1.0/gcc/C_002b_002b-Module-Preprocessing.html</a> + </p> +</div> |