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Hi everyone, |
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|
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I debated about whether to write a news item about c++11 abi. Usually |
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our news items are about some change which requires user intervention. |
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But this is just precautionary. With more packages needing c++11 |
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because of source changes, we may want to inform users about breakage at |
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the ABI level in case they do something like add -std=c++11 to their |
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global CXXFLAGS. |
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|
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Let me know if you think its worth sending out and/or any other suggestions. |
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Title: GCC 4.7 Introduces New c++11 ABI |
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Author: Anthony G. Basile <blueness@g.o> |
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Content-Type: text/plain |
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Posted: 2014-10-20 |
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Revision: 1 |
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News-Item-Format: 1.0 |
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Display-If-Installed: >=sys-devel/gcc-4.7.0 |
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Display-If-Keyword: amd64 |
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Display-If-Keyword: arm |
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Display-If-Keyword: mips |
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Display-If-Keyword: ppc |
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Display-If-Keyword: ppc64 |
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Display-If-Keyword: x86 |
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Display-If-Keyword: amd64-fbsd |
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Display-If-Keyword: x86-fbsd |
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GCC 4.7 introduced the new experimental 2011 ISO C++ standard [1], along |
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with |
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its GNU variant. This new standard is not the default in GCC 4.7, 4.8 |
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or 4.9, |
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the default is still gnu++98, but it can be enabled by passing -std=c++11 or |
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-std=gnu++11 to CXXFLAGS. |
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|
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Users that wish to try c++11 should exercise caution because it is not |
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ABI-compatible with c++98. Thus linking c++98 and c++11 objects is |
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likely to |
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cause breakage. For packages which are self-contained and do not link |
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against |
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any libraries written in C++, there is no problem. However, switching |
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to c++11 |
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and then building packages which link against any of the numerous |
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libraries still |
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in the older ABI, can lead to a crippled system. |
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|
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This is a precautionary news item and the typical user need not do anything. |
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However, as c++11 gains in popularity and the number of packages using it |
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increase, it is important that users understand these precautions. |
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|
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For an ABI compliance checker, and more information about C++ ABIs, see |
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[2]. |
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|
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Ref. |
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[1] http://www.stroustrup.com/C++11FAQ.html |
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[2] http://ispras.linuxbase.org/index.php/ABI_compliance_checker |
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|
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-- |
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Anthony G. Basile, Ph.D. |
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Gentoo Linux Developer [Hardened] |
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E-Mail : blueness@g.o |
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GnuPG FP : 1FED FAD9 D82C 52A5 3BAB DC79 9384 FA6E F52D 4BBA |
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GnuPG ID : F52D4BBA |
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