434
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1 /* A C macro for emitting link time warnings.
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2 Copyright (C) 1995, 1997, 2000, 2002-2003, 2007, 2009-2010 Free Software
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3 Foundation, Inc.
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4
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5 This program is free software: you can redistribute it and/or modify it
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6 under the terms of the GNU General Public License as published
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7 by the Free Software Foundation; either version 3 of the License, or
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8 (at your option) any later version.
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9
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10 This program is distributed in the hope that it will be useful,
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11 but WITHOUT ANY WARRANTY; without even the implied warranty of
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12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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13 Lesser General Public License for more details.
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14
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15 You should have received a copy of the GNU General Public License
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16 along with this program. If not, see <http://www.gnu.org/licenses/>. */
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17
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18 /* GL_LINK_WARNING("literal string") arranges to emit the literal string as
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19 a linker warning on most glibc systems.
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20 We use a linker warning rather than a preprocessor warning, because
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21 #warning cannot be used inside macros. */
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22 #ifndef GL_LINK_WARNING
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23 /* This works on platforms with GNU ld and ELF object format.
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24 Testing __GLIBC__ is sufficient for asserting that GNU ld is in use.
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25 Testing __ELF__ guarantees the ELF object format.
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26 Testing __GNUC__ is necessary for the compound expression syntax. */
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27 # if defined __GLIBC__ && defined __ELF__ && defined __GNUC__
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28 # define GL_LINK_WARNING(message) \
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29 GL_LINK_WARNING1 (__FILE__, __LINE__, message)
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30 # define GL_LINK_WARNING1(file, line, message) \
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31 GL_LINK_WARNING2 (file, line, message) /* macroexpand file and line */
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32 # define GL_LINK_WARNING2(file, line, message) \
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33 GL_LINK_WARNING3 (file ":" #line ": warning: " message)
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34 # define GL_LINK_WARNING3(message) \
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35 ({ static const char warning[sizeof (message)] \
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36 __attribute__ ((__unused__, \
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37 __section__ (".gnu.warning"), \
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38 __aligned__ (1))) \
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39 = message "\n"; \
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40 (void)0; \
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41 })
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42 # else
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43 # define GL_LINK_WARNING(message) ((void) 0)
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44 # endif
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45 #endif
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