You can not select more than 25 topics Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.

Weak-Pragmas.html 4.3KB

3 years ago
123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103
  1. <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
  2. <html>
  3. <!-- Copyright (C) 1988-2020 Free Software Foundation, Inc.
  4. Permission is granted to copy, distribute and/or modify this document
  5. under the terms of the GNU Free Documentation License, Version 1.3 or
  6. any later version published by the Free Software Foundation; with the
  7. Invariant Sections being "Funding Free Software", the Front-Cover
  8. Texts being (a) (see below), and with the Back-Cover Texts being (b)
  9. (see below). A copy of the license is included in the section entitled
  10. "GNU Free Documentation License".
  11. (a) The FSF's Front-Cover Text is:
  12. A GNU Manual
  13. (b) The FSF's Back-Cover Text is:
  14. You have freedom to copy and modify this GNU Manual, like GNU
  15. software. Copies published by the Free Software Foundation raise
  16. funds for GNU development. -->
  17. <!-- Created by GNU Texinfo 6.5, http://www.gnu.org/software/texinfo/ -->
  18. <head>
  19. <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
  20. <title>Weak Pragmas (Using the GNU Compiler Collection (GCC))</title>
  21. <meta name="description" content="Weak Pragmas (Using the GNU Compiler Collection (GCC))">
  22. <meta name="keywords" content="Weak Pragmas (Using the GNU Compiler Collection (GCC))">
  23. <meta name="resource-type" content="document">
  24. <meta name="distribution" content="global">
  25. <meta name="Generator" content="makeinfo">
  26. <link href="index.html#Top" rel="start" title="Top">
  27. <link href="Option-Index.html#Option-Index" rel="index" title="Option Index">
  28. <link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
  29. <link href="Pragmas.html#Pragmas" rel="up" title="Pragmas">
  30. <link href="Diagnostic-Pragmas.html#Diagnostic-Pragmas" rel="next" title="Diagnostic Pragmas">
  31. <link href="Structure_002dLayout-Pragmas.html#Structure_002dLayout-Pragmas" rel="prev" title="Structure-Layout Pragmas">
  32. <style type="text/css">
  33. <!--
  34. a.summary-letter {text-decoration: none}
  35. blockquote.indentedblock {margin-right: 0em}
  36. blockquote.smallindentedblock {margin-right: 0em; font-size: smaller}
  37. blockquote.smallquotation {font-size: smaller}
  38. div.display {margin-left: 3.2em}
  39. div.example {margin-left: 3.2em}
  40. div.lisp {margin-left: 3.2em}
  41. div.smalldisplay {margin-left: 3.2em}
  42. div.smallexample {margin-left: 3.2em}
  43. div.smalllisp {margin-left: 3.2em}
  44. kbd {font-style: oblique}
  45. pre.display {font-family: inherit}
  46. pre.format {font-family: inherit}
  47. pre.menu-comment {font-family: serif}
  48. pre.menu-preformatted {font-family: serif}
  49. pre.smalldisplay {font-family: inherit; font-size: smaller}
  50. pre.smallexample {font-size: smaller}
  51. pre.smallformat {font-family: inherit; font-size: smaller}
  52. pre.smalllisp {font-size: smaller}
  53. span.nolinebreak {white-space: nowrap}
  54. span.roman {font-family: initial; font-weight: normal}
  55. span.sansserif {font-family: sans-serif; font-weight: normal}
  56. ul.no-bullet {list-style: none}
  57. -->
  58. </style>
  59. </head>
  60. <body lang="en">
  61. <a name="Weak-Pragmas"></a>
  62. <div class="header">
  63. <p>
  64. Next: <a href="Diagnostic-Pragmas.html#Diagnostic-Pragmas" accesskey="n" rel="next">Diagnostic Pragmas</a>, Previous: <a href="Structure_002dLayout-Pragmas.html#Structure_002dLayout-Pragmas" accesskey="p" rel="prev">Structure-Layout Pragmas</a>, Up: <a href="Pragmas.html#Pragmas" accesskey="u" rel="up">Pragmas</a> &nbsp; [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Option-Index.html#Option-Index" title="Index" rel="index">Index</a>]</p>
  65. </div>
  66. <hr>
  67. <a name="Weak-Pragmas-1"></a>
  68. <h4 class="subsection">6.62.12 Weak Pragmas</h4>
  69. <p>For compatibility with SVR4, GCC supports a set of <code>#pragma</code>
  70. directives for declaring symbols to be weak, and defining weak
  71. aliases.
  72. </p>
  73. <dl compact="compact">
  74. <dt><code>#pragma weak <var>symbol</var></code></dt>
  75. <dd><a name="index-pragma_002c-weak"></a>
  76. <p>This pragma declares <var>symbol</var> to be weak, as if the declaration
  77. had the attribute of the same name. The pragma may appear before
  78. or after the declaration of <var>symbol</var>. It is not an error for
  79. <var>symbol</var> to never be defined at all.
  80. </p>
  81. </dd>
  82. <dt><code>#pragma weak <var>symbol1</var> = <var>symbol2</var></code></dt>
  83. <dd><p>This pragma declares <var>symbol1</var> to be a weak alias of <var>symbol2</var>.
  84. It is an error if <var>symbol2</var> is not defined in the current
  85. translation unit.
  86. </p></dd>
  87. </dl>
  88. </body>
  89. </html>