nixpkgs/pkgs/development/compilers/gcc/common/pre-configure.nix
sternenseemann 2d176b593b gcc*: force building a cross compiler if host and target platform differ
gcc's configure system has the nasty habit (for us) of judging for
itself if it is building a cross compiler (or cross compiling), but on
the limited information of the build, host and target platforms' config
which only contains a subset of the information we encode in
`stdenv.*Platform`. The practical consequence was that prior to this
change building `pkgsLLVM.buildPackages.gcc` actually fails because it
refuses to use `--with-headers` with something it believes to not be a
cross compiler.

As a workaround we force the appropriate variable in the configure
script to always be `yes` regardless of its own conditional check.

At some point we probably should report this issue in some capacity, so
future gcc versions don't force us into workarounds like this and
acdc783418.
2021-05-18 00:16:54 +02:00

68 lines
3.3 KiB
Nix

{ lib, version, hostPlatform, targetPlatform
, gnatboot ? null
, langAda ? false
, langJava ? false
, langJit ? false
, langGo }:
assert langJava -> lib.versionOlder version "7";
assert langAda -> gnatboot != null;
lib.optionalString (hostPlatform.isSunOS && hostPlatform.is64bit) ''
export NIX_LDFLAGS=`echo $NIX_LDFLAGS | sed -e s~$prefix/lib~$prefix/lib/amd64~g`
export LDFLAGS_FOR_TARGET="-Wl,-rpath,$prefix/lib/amd64 $LDFLAGS_FOR_TARGET"
export CXXFLAGS_FOR_TARGET="-Wl,-rpath,$prefix/lib/amd64 $CXXFLAGS_FOR_TARGET"
export CFLAGS_FOR_TARGET="-Wl,-rpath,$prefix/lib/amd64 $CFLAGS_FOR_TARGET"
'' + lib.optionalString (lib.versionOlder version "7" && (langJava || langGo)) ''
export lib=$out;
'' + 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
''
# In order to properly install libgccjit on macOS Catalina, strip(1)
# upon installation must not remove external symbols, otherwise the
# install step errors with "symbols referenced by indirect symbol
# table entries that can't be stripped".
+ lib.optionalString (hostPlatform.isDarwin && langJit) ''
export STRIP='strip -x'
''
# HACK: if host and target config are the same, but the platforms are
# actually different we need to convince the configure script that it
# is in fact building a cross compiler although it doesn't believe it.
+ lib.optionalString (targetPlatform.config == hostPlatform.config && targetPlatform != hostPlatform) ''
substituteInPlace configure --replace is_cross_compiler=no is_cross_compiler=yes
''