From 66d6416e2930dfb0022956cfb607085d20e22d0a Mon Sep 17 00:00:00 2001 From: Matthew Pickering Date: Wed, 16 Jun 2021 20:09:56 +0100 Subject: rts: Pass -Wl,_U,___darwin_check_fd_set_overflow on Darwin Note [fd_set_overflow] ~~~~~~~~~~~~~~~~~~~~~~ In this note is the very sad tale of __darwin_fd_set_overflow. The 8.10.5 release was broken because it was built in an environment where the libraries were provided by XCode 12.*, these libraries introduced a reference to __darwin_fd_set_overflow via the FD_SET macro which is used in Select.c. Unfortunately, this symbol is not available with XCode 11.* which led to a linker error when trying to link anything. This is almost certainly a bug in XCode but we still have to work around it. Undefined symbols for architecture x86_64: "___darwin_check_fd_set_overflow", referenced from: _awaitEvent in libHSrts.a(Select.o) ld: symbol(s) not found for architecture x86_64 One way to fix this is to upgrade your version of xcode, but this would force the upgrade on users prematurely. Fortunately it also seems safe to pass the linker option "-Wl,-U,___darwin_check_fd_set_overflow" because the usage of the symbol is guarded by a guard to check if it's defined. __header_always_inline int __darwin_check_fd_set(int _a, const void *_b) { if ((uintptr_t)&__darwin_check_fd_set_overflow != (uintptr_t) 0) { return __darwin_check_fd_set_overflow(_a, _b, 1); return __darwin_check_fd_set_overflow(_a, _b, 0); } else { return 1; } Across the internet there are many other reports of this issue See: https://github.com/mono/mono/issues/19393 , https://github.com/sitsofe/fio/commit/b6a1e63a1ff607692a3caf3c2db2c3d575ba2320 The issue was originally reported in #19950 Fixes #19950 --- rts/rts.cabal.in | 42 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 42 insertions(+) diff --git a/rts/rts.cabal.in b/rts/rts.cabal.in index 872a9e3493..9c698b09a3 100644 --- a/rts/rts.cabal.in +++ b/rts/rts.cabal.in @@ -400,6 +400,8 @@ library if os(osx) ld-options: "-Wl,-search_paths_first" + -- See Note [fd_set_overflow] + "-Wl,-U,___darwin_check_fd_set_overflow" if !arch(x86_64) && !arch(aarch64) ld-options: -read_only_relocs warning @@ -560,3 +562,43 @@ library posix/Signals.c posix/TTY.c -- posix/*.c -- we do not want itimer + +-- Note [fd_set_overflow] +-- ~~~~~~~~~~~~~~~~~~~~~~ +-- In this note is the very sad tale of __darwin_fd_set_overflow. +-- The 8.10.5 release was broken because it was built in an environment +-- where the libraries were provided by XCode 12.*, these libraries introduced +-- a reference to __darwin_fd_set_overflow via the FD_SET macro which is used in +-- Select.c. Unfortunately, this symbol is not available with XCode 11.* which +-- led to a linker error when trying to link anything. This is almost certainly +-- a bug in XCode but we still have to work around it. + +-- Undefined symbols for architecture x86_64: +-- "___darwin_check_fd_set_overflow", referenced from: +-- _awaitEvent in libHSrts.a(Select.o) +-- ld: symbol(s) not found for architecture x86_64 + +-- One way to fix this is to upgrade your version of xcode, but this would +-- force the upgrade on users prematurely. Fortunately it also seems safe to pass +-- the linker option "-Wl,-U,___darwin_check_fd_set_overflow" because the usage of +-- the symbol is guarded by a guard to check if it's defined. + +-- __header_always_inline int +-- __darwin_check_fd_set(int _a, const void *_b) +-- { +-- if ((uintptr_t)&__darwin_check_fd_set_overflow != (uintptr_t) 0) { +--#if defined(_DARWIN_UNLIMITED_SELECT) || defined(_DARWIN_C_SOURCE) +-- return __darwin_check_fd_set_overflow(_a, _b, 1); +--#else +-- return __darwin_check_fd_set_overflow(_a, _b, 0); +--#endif +-- } else { +-- return 1; +-- } +--} + +-- Across the internet there are many other reports of this issue +-- See: https://github.com/mono/mono/issues/19393 +-- , https://github.com/sitsofe/fio/commit/b6a1e63a1ff607692a3caf3c2db2c3d575ba2320 + +-- The issue was originally reported in #19950 -- cgit v1.2.1