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On 04/26/2017 11:03 PM, Walter Dnes wrote: |
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> On Wed, Apr 26, 2017 at 06:01:20AM +0800, Bill Kenworthy wrote |
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> |
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>> That flag isn't mentioned here. |
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> |
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> I checked the source code. It forces the old ABI, so it should work, |
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> compiled with GCC 5.4.0, even on a Gcc 4.9.4 system... |
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> |
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> [CentOS65][pmbuilder][~/pmmaster] grep -r GLIBCXX_USE_CXX11_ABI pmsrc |
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> pmsrc/configure: CXXFLAGS="$CXXFLAGS -D_GLIBCXX_USE_CXX11_ABI=0" |
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> pmsrc/configure: HOST_CXXFLAGS="$HOST_CXXFLAGS -D_GLIBCXX_USE_CXX11_ABI=0" |
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> pmsrc/configure.in: CXXFLAGS="$CXXFLAGS -D_GLIBCXX_USE_CXX11_ABI=0" |
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> pmsrc/configure.in: HOST_CXXFLAGS="$HOST_CXXFLAGS -D_GLIBCXX_USE_CXX11_ABI=0" |
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> |
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Walter, |
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That flag "-D_GLIBCXX_USE_CXX11_ABI=0" is a CPPFLAG. It is only |
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recognized by GCC 5.1.x and higher. And it only works on GCC built with |
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dual ABI support. Gentoo doesn't support the dual ABI builds. |
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Info links : |
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https://gcc.gnu.org/onlinedocs/libstdc++/manual/using_macros.html |
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https://gcc.gnu.org/onlinedocs/libstdc++/manual/abi.html#abi.versioning.__GLIBCXX__ |
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https://gcc.gnu.org/onlinedocs/libstdc++/manual/configure.html |
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On my system, I went ahead with the switch to GCC 5.4.0. |
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The "-D_GLIBCXX_USE_CXX11_ABI=1" CPPFLAG forces GCC to check IF the new |
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ABI should be applied FIRST. NO FORCING the ABI on software that doesn't |
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use it. |
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Putting CPPFLAGS="-D_GLIBCXX_USE_CXX11_ABI=1" in make.conf killed almost |
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all the erorrs in the revdep-rebuild process. |
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Putting that in as a CFLAGS or CXXFLAGS switch caused lots of errors in |
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revdep-rebuild. |
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Thought you might want to know. |
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Corbin |
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