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Merge pull request #82921 from Calvin-L/fix-gcc-on-catalina

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Fix GCC compilation on MacOS 10.15
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Jörg Thalheim 2020-07-23 11:30:23 +01:00 committed by GitHub
commit 9f5d38e751
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32
pkgs/development/compilers/gcc/common/pre-configure.nix
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@ -17,3 +17,35 @@ lib.optionalString (hostPlatform.isSunOS && hostPlatform.is64bit) ''
'' + lib.optionalString langAda ''
export PATH=${gnatboot}/bin:$PATH
''
# NOTE 2020/3/18: This environment variable prevents configure scripts from
# detecting the presence of aligned_alloc on Darwin. There are many facts that
# collectively make this fix necessary:
# - Nix uses a fixed set of standard library headers on all MacOS systems,
# regardless of their actual version. (Nix uses version 10.12 headers.)
# - Nix uses the native standard library binaries for the build system. That
# means the standard library binaries may not exactly match the standard
# library headers.
# - The aligned_alloc procedure is present in MacOS 10.15 (Catalina), but not
# in earlier versions. Therefore on Catalina systems, aligned_alloc is
# linkable (i.e. present in the binary libraries) but not present in the
# headers.
# - Configure scripts detect a procedure's existence by checking whether it is
# linkable. They do not check whether it is present in the headers.
# - GCC throws an error during compilation because aligned_alloc is not
# defined in the headers---even though the linker can see it.
#
# This fix would not be necessary if ANY of the above were false:
# - If Nix used native headers for each different MacOS version, aligned_alloc
# would be in the headers on Catalina.
# - If Nix used the same libary binaries for each MacOS version, aligned_alloc
# would not be in the library binaries.
# - If Catalina did not include aligned_alloc, this wouldn't be a problem.
# - If the configure scripts looked for header presence as well as
# linkability, they would see that aligned_alloc is missing.
# - If GCC allowed implicit declaration of symbols, it would not fail during
# compilation even if the configure scripts did not check header presence.
#
+ lib.optionalString (hostPlatform.isDarwin) ''
export ac_cv_func_aligned_alloc=no
''