[libc] Make the errno macro resolve to the thread local variable directly.

[sivachandra]

Summary

With modern architectures having a thread pointer and language supporting
thread locals, there is no reason to use a function intermediary to access
the thread local errno value.

The entrypoint corresponding to errno has been replaced with an object
library as there is no formal entrypoint for errno anymore.

[michaelrj]

LGTM

[jeffbailey]

I spent a bit of time just trying to think of if there's a more straightforward way to do the dummy_errno. Something like a base library of support services to gloss over which libc it's built against. I couldn't think of any (and it would be outside the scope of this CL).

libc/config/linux/aarch64/entrypoints.txt

set(TARGET_LIBC_ENTRYPOINTS
     libc.src.ctype.ispunct
     libc.src.ctype.isspace
     libc.src.ctype.isupper
     libc.src.ctype.isxdigit
     libc.src.ctype.toascii
     libc.src.ctype.tolower
     libc.src.ctype.toupper
     
-    # errno.h entrypoints
-    libc.src.errno.__errno_location
-
     # fcntl.h entrypoints
     libc.src.fcntl.creat
     libc.src.fcntl.open
     libc.src.fcntl.openat
 
     # string.h entrypoints
     libc.src.string.bcmp
     libc.src.string.bzero

libc/config/linux/api.td

def NullMacro : MacroDef<"NULL"> {
   let Defn = [{
     #define __need_NULL
     #include <stddef.h>
   }];
 }
 
 def ErrnoMacro : MacroDef<"errno"> {
   let Defn = [{
-    #ifdef __cplusplus
-    extern "C"
-    #endif
-    int *__errno_location();
-    #define errno (*__errno_location())
+    extern _Thread_local int __llvmlibc_errno;
+    #define errno __llvmlibc_errno
   }];
 }
 
 def AssertAPI : PublicAPI<"assert.h"> {
   let Macros = [
     AssertMacro,
     StaticAssertMacro,
   ];

libc/config/linux/x86_64/entrypoints.txt

set(TARGET_LIBC_ENTRYPOINTS
     libc.src.ctype.ispunct
     libc.src.ctype.isspace
     libc.src.ctype.isupper
     libc.src.ctype.isxdigit
     libc.src.ctype.toascii
     libc.src.ctype.tolower
     libc.src.ctype.toupper
 
-    # errno.h entrypoints
-    libc.src.errno.__errno_location
-
     # fcntl.h entrypoints
     libc.src.fcntl.creat
     libc.src.fcntl.open
     libc.src.fcntl.openat
 
     # string.h entrypoints
     libc.src.string.bcmp
     libc.src.string.bzero

libc/include/__llvm-libc-common.h

 #define _Alignas alignas
 
 #undef _Static_assert
 #define _Static_assert static_assert
 
 #undef _Alignof
 #define _Alignof alignof
 
+#undef _Thread_local
+#define _Thread_local thread_local
+
 #else // not __cplusplus
 
 #undef __BEGIN_C_DECLS
 #define __BEGIN_C_DECLS
 
 #undef __END_C_DECLS
 #define __END_C_DECLS
 
 #undef __restrict
 #define __restrict restrict // C99 and above support the restrict keyword.
 
 #endif // __cplusplus
 
 #endif // LLVM_LIBC___COMMON_H

libc/spec/llvm_libc_ext.td

HeaderSpec Assert = HeaderSpec<
               "__assert_fail",
               RetValSpec<NoReturn>,
               [ArgSpec<ConstCharPtr>, ArgSpec<ConstCharPtr>, ArgSpec<UnsignedType>, ArgSpec<ConstCharPtr>]
 
           >,
       ]
   >;
 
-  HeaderSpec Errno = HeaderSpec<
-      "errno.h",
-      [], // Macros
-      [], // Types
-      [], // Enumerations
-      [
-          FunctionSpec<
-              "__errno_location",
-              RetValSpec<IntPtr>,
-              [ArgSpec<VoidType>]
-
-          >,
-      ]
-  >;
-
   let Headers = [
     String,
     Assert,
-    Errno,
   ];
 }

libc/src/__support/CMakeLists.txt

 
 add_header_library(
   str_to_integer
   HDRS
     str_to_integer.h
   DEPENDS
     .ctype_utils
     libc.include.errno
-    libc.src.errno.__errno_location
+    libc.src.errno.errno
     libc.src.__support.CPP.standalone_cpp
 )
 
 add_header_library(
   high_precision_decimal
   HDRS
     high_precision_decimal.h
   DEPENDS
     .str_to_integer
 )
 
 add_header_library(
   str_to_float
   HDRS
     str_to_float.h
   DEPENDS
     .str_to_integer
     .ctype_utils
     .high_precision_decimal
     libc.include.errno
-    libc.src.errno.__errno_location
+    libc.src.errno.errno
     libc.src.__support.CPP.standalone_cpp
     libc.src.__support.FPUtil.fputil
 )
 
 add_header_library(
   integer_operations
   HDRS
     integer_operations.h
 )
 
 add_subdirectory(File)
 add_subdirectory(FPUtil)
 add_subdirectory(OSUtil)

libc/src/__support/FPUtil/CMakeLists.txt

HDRS
     UInt.h
     XFloat.h
   DEPENDS
     libc.include.math
     libc.include.errno
     libc.include.fenv
     libc.src.__support.common
     libc.src.__support.CPP.standalone_cpp
-    libc.src.errno.__errno_location
+    libc.src.errno.errno
 )
 
 add_header_library(
   sqrt
   HDRS
     sqrt.h
   DEPENDS
     .fputil
     libc.src.__support.FPUtil.generic.sqrt
 )
 
 add_subdirectory(generic)

libc/src/__support/File/CMakeLists.txt

 add_object_library(
   file
   SRCS
     file.cpp
   HDRS
     file.h
   DEPENDS
-    libc.src.errno.__errno_location
+    libc.include.errno
+    libc.src.errno.errno
 )

libc/src/errno/CMakeLists.txt

 if (LLVM_LIBC_FULL_BUILD)
-add_entrypoint_object(
-  __errno_location
+add_object_library(
+  errno
   SRCS
-    __errno_location.cpp
+    errno.cpp
   HDRS
-    __errno_location.h
     llvmlibc_errno.h
 )
 else()
-add_entrypoint_object(
-  __errno_location
+add_object_library(
+  errno
   SRCS
     dummy_errno.cpp
   HDRS
     dummy_errno.h
 )
 endif()

libc/src/errno/__errno_location.h

-//===-- Implementation header for __errno_location --------------*- C++ -*-===//
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-//===----------------------------------------------------------------------===//
-
-#ifndef LLVM_LIBC_SRC_ERRNO_ERRNO_LOCATION_H
-#define LLVM_LIBC_SRC_ERRNO_ERRNO_LOCATION_H
-
-namespace __llvm_libc {
-
-int *__errno_location();
-
-} // namespace __llvm_libc
-
-#endif // LLVM_LIBC_SRC_ERRNO_ERRNO_LOCATION_H

libc/src/errno/__errno_location.cpp

-//===-- Implementation of __errno_location --------------------------------===//
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-//===----------------------------------------------------------------------===//
-
-#include "src/errno/__errno_location.h"
-
-#include "src/__support/common.h"
-
-namespace __llvm_libc {
-
-static thread_local int errno = 0;
-
-// __errno_location is not really an entry point but we still want it to behave
-// like an entry point because the errno macro resolves to the C symbol
-// "__errno_location".
-LLVM_LIBC_FUNCTION(int *, __errno_location, ()) { return &errno; }
-
-} // namespace __llvm_libc

libc/src/errno/errno.cpp

+//===-- Implementation of __errno_location --------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+thread_local int __llvmlibc_errno = 0;

libc/src/errno/llvmlibc_errno.h

 //===-- Implementation header for errno -------------------------*- C++ -*-===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
-#include "src/errno/__errno_location.h"
-
 #ifndef LLVM_LIBC_SRC_ERRNO_LLVMLIBC_ERRNO_H
 #define LLVM_LIBC_SRC_ERRNO_LLVMLIBC_ERRNO_H
 
 // Internal code should use this and not use the errno macro from the
 // public header.
-#define llvmlibc_errno (*__llvm_libc::__errno_location())
+extern thread_local int __llvmlibc_errno;
+#define llvmlibc_errno __llvmlibc_errno
 
 #endif // LLVM_LIBC_SRC_ERRNO_LLVMLIBC_ERRNO_H

libc/src/fcntl/linux/CMakeLists.txt

 add_entrypoint_object(
   creat
   SRCS
     creat.cpp
   HDRS
     ../creat.h
   DEPENDS
     libc.include.errno
     libc.include.fcntl
     libc.src.__support.OSUtil.osutil
-    libc.src.errno.__errno_location
+    libc.src.errno.errno
 )
 
 add_entrypoint_object(
   open
   SRCS
     open.cpp
   HDRS
     ../open.h
   DEPENDS
     libc.include.errno
     libc.include.fcntl
     libc.src.__support.OSUtil.osutil
-    libc.src.errno.__errno_location
+    libc.src.errno.errno
 )
 
 add_entrypoint_object(
   openat
   SRCS
     openat.cpp
   HDRS
     ../openat.h
   DEPENDS
     libc.include.errno
     libc.include.fcntl
     libc.src.__support.OSUtil.osutil
-    libc.src.errno.__errno_location
+    libc.src.errno.errno
 )

libc/src/math/generic/CMakeLists.txt

add_object_library(
   math_utils
   SRCS
     math_utils.cpp
   HDRS
     math_utils.h
   DEPENDS
     libc.include.errno
     libc.include.math
-    libc.src.errno.__errno_location
+    libc.src.errno.errno
 )
 
 add_object_library(
   sincosf_utils
   HDRS
     sincosf_utils.h
   SRCS
     sincosf_data.cpp
   DEPENDS
     .math_utils
 )
 
 add_entrypoint_object(
   cosf
   SRCS
     cosf.cpp
   HDRS
     ../cosf.h
   DEPENDS
     .sincosf_utils
     libc.include.math
-    libc.src.errno.__errno_location
+    libc.src.errno.errno
   COMPILE_OPTIONS
     -O3
 )
 
 add_entrypoint_object(
   sinf
   SRCS
     sinf.cpp
   HDRS
     ../sinf.h
   DEPENDS
     .sincosf_utils
     libc.include.math
-    libc.src.errno.__errno_location
+    libc.src.errno.errno
     libc.src.__support.FPUtil.fputil
   COMPILE_OPTIONS
     -O3
 )
 
 add_entrypoint_object(
   sincosf
   SRCS
     sincosf.cpp
   HDRS
     ../sincosf.h
   DEPENDS
     .sincosf_utils
     libc.include.math
-    libc.src.errno.__errno_location
+    libc.src.errno.errno
   COMPILE_OPTIONS
     -O3
 )
 
 add_entrypoint_object(
   fabs
   SRCS
     fabs.cpp

libc/src/signal/linux/CMakeLists.txt

add_entrypoint_object(
   HDRS
     signal.h
     ../sigaction.h
   DEPENDS
     .__restore
     libc.include.signal
     libc.include.sys_syscall
     libc.src.__support.OSUtil.osutil
-    libc.src.errno.__errno_location
+    libc.src.errno.errno
 )
 
 add_entrypoint_object(
   sigprocmask
   SRCS
     sigprocmask.cpp
   HDRS
     signal.h
     ../sigprocmask.h
   DEPENDS
     libc.include.signal
     libc.include.sys_syscall
     libc.src.__support.OSUtil.osutil
-    libc.src.errno.__errno_location
+    libc.src.errno.errno
 )
 
 add_entrypoint_object(
   sigemptyset
   SRCS
     sigemptyset.cpp
   HDRS
     signal.h
     ../sigemptyset.h
   DEPENDS
     libc.include.errno
     libc.include.signal
-    libc.src.errno.__errno_location
+    libc.src.errno.errno
 )
 
 add_entrypoint_object(
   sigaddset
   SRCS
     sigaddset.cpp
   HDRS
     signal.h
     ../sigaddset.h
   DEPENDS
     libc.include.errno
     libc.include.signal
-    libc.src.errno.__errno_location
+    libc.src.errno.errno
 )
 
 add_entrypoint_object(
   signal
   SRCS
     signal.cpp
   HDRS
     signal.h
     ../signal.h
   DEPENDS
     .sigaction
     libc.include.signal
 )
 
 add_entrypoint_object(
   sigfillset
   SRCS
     sigfillset.cpp
   HDRS
     signal.h
     ../sigfillset.h
   DEPENDS
     libc.include.errno
     libc.include.signal
-    libc.src.errno.__errno_location
+    libc.src.errno.errno
 )
 
 add_entrypoint_object(
   sigdelset
   SRCS
     sigdelset.cpp
   HDRS
     signal.h
     ../sigdelset.h
   DEPENDS
     libc.include.errno
     libc.include.signal
-    libc.src.errno.__errno_location
+    libc.src.errno.errno
 )

libc/src/sys/mman/linux/CMakeLists.txt

 add_entrypoint_object(
   mmap
   SRCS
     mmap.cpp
   HDRS
     ../mmap.h
   DEPENDS
     libc.include.sys_mman
     libc.include.sys_syscall
     libc.src.__support.OSUtil.osutil
-    libc.src.errno.__errno_location
+    libc.src.errno.errno
 )
 
 add_entrypoint_object(
   munmap
   SRCS
     munmap.cpp
   HDRS
     ../munmap.h
   DEPENDS
     libc.include.sys_mman
     libc.include.sys_syscall
     libc.src.__support.OSUtil.osutil
-    libc.src.errno.__errno_location
+    libc.src.errno.errno
 )

libc/src/sys/stat/linux/CMakeLists.txt

 add_entrypoint_object(
   mkdir
   SRCS
     mkdir.cpp
   HDRS
     ../mkdir.h
   DEPENDS
     libc.include.fcntl
     libc.include.sys_stat
     libc.include.sys_syscall
     libc.src.__support.OSUtil.osutil
-    libc.src.errno.__errno_location
+    libc.src.errno.errno
 )
 
 add_entrypoint_object(
   mkdirat
   SRCS
     mkdirat.cpp
   HDRS
     ../mkdirat.h
   DEPENDS
     libc.include.sys_stat
     libc.include.sys_syscall
     libc.src.__support.OSUtil.osutil
-    libc.src.errno.__errno_location
+    libc.src.errno.errno
 )

libc/src/threads/linux/CMakeLists.txt

HDRS
     ../thrd_create.h
   DEPENDS
     .threads_utils
     libc.include.errno
     libc.include.sys_syscall
     libc.include.threads
     libc.src.__support.common
     libc.src.__support.OSUtil.osutil
-    libc.src.errno.__errno_location
+    libc.src.errno.errno
     libc.src.sys.mman.mmap
   COMPILE_OPTIONS
     -O3
     -fno-omit-frame-pointer # This allows us to sniff out the thread args from
                             # the new thread's stack reliably.
 )
 
 add_entrypoint_object(

libc/src/time/CMakeLists.txt

 add_object_library(
   time_utils
   SRCS
     time_utils.cpp
   HDRS
     time_utils.h
   DEPENDS
     libc.include.errno
     libc.include.time
-    libc.src.errno.__errno_location
+    libc.src.errno.errno
 )
 
 add_entrypoint_object(
   asctime
   SRCS
     asctime.cpp
   HDRS
     asctime.h
add_entrypoint_object(
   SRCS
     mktime.cpp
   HDRS
     mktime.h
   DEPENDS
     .time_utils
     libc.include.errno
     libc.include.time
-    libc.src.errno.__errno_location
+    libc.src.errno.errno
 )

libc/src/unistd/linux/CMakeLists.txt

 add_entrypoint_object(
   close
   SRCS
     close.cpp
   HDRS
     ../close.h
   DEPENDS
     libc.include.unistd
     libc.include.sys_syscall
     libc.src.__support.OSUtil.osutil
-    libc.src.errno.__errno_location
+    libc.src.errno.errno
 )
 
 add_entrypoint_object(
   fsync
   SRCS
     fsync.cpp
   HDRS
     ../fsync.h
   DEPENDS
     libc.include.unistd
     libc.include.sys_syscall
     libc.src.__support.OSUtil.osutil
-    libc.src.errno.__errno_location
+    libc.src.errno.errno
 )
 
 add_entrypoint_object(
   read
   SRCS
     read.cpp
   HDRS
     ../read.h
   DEPENDS
     libc.include.unistd
     libc.include.sys_syscall
     libc.src.__support.OSUtil.osutil
-    libc.src.errno.__errno_location
+    libc.src.errno.errno
 )
 
 add_entrypoint_object(
   rmdir
   SRCS
     rmdir.cpp
   HDRS
     ../rmdir.h
   DEPENDS
     libc.include.fcntl
     libc.include.unistd
     libc.include.sys_syscall
     libc.src.__support.OSUtil.osutil
-    libc.src.errno.__errno_location
+    libc.src.errno.errno
 )
 
 add_entrypoint_object(
   unlink
   SRCS
     unlink.cpp
   HDRS
     ../unlink.h
   DEPENDS
     libc.include.fcntl
     libc.include.unistd
     libc.include.sys_syscall
     libc.src.__support.OSUtil.osutil
-    libc.src.errno.__errno_location
+    libc.src.errno.errno
 )
 
 add_entrypoint_object(
   unlinkat
   SRCS
     unlinkat.cpp
   HDRS
     ../unlinkat.h
   DEPENDS
     libc.include.fcntl
     libc.include.unistd
     libc.include.sys_syscall
     libc.src.__support.OSUtil.osutil
-    libc.src.errno.__errno_location
+    libc.src.errno.errno
 )
 
 add_entrypoint_object(
   write
   SRCS
     write.cpp
   HDRS
     ../write.h
   DEPENDS
     libc.include.unistd
     libc.include.sys_syscall
     libc.src.__support.OSUtil.osutil
-    libc.src.errno.__errno_location
+    libc.src.errno.errno
 )

libc/test/loader/linux/CMakeLists.txt

 #  SRC
 #    tls_test.cpp
 #  DEPENDS
 #    libc.config.linux.app_h
 #    libc.include.errno
 #    libc.include.sys_mman
 #    libc.loader.linux.crt1
 #    libc.src.assert.__assert_fail
-#    libc.src.errno.__errno_location
+#    libc.src.errno.errno
 #    libc.src.sys.mman.mmap
 #)

libc/test/src/__support/File/CMakeLists.txt

 
 add_libc_unittest(
   file_test
   SUITE
     libc_support_unittests
   SRCS
     file_test.cpp
   DEPENDS
+    libc.include.errno
     libc.include.stdio
     libc.include.stdlib
     libc.src.__support.File.file
 )
 
 target_link_libraries(
   libc.test.src.__support.File.file_test PRIVATE LibcMemoryHelpers
 )

libc/test/src/errno/CMakeLists.txt

 if(NOT LLVM_LIBC_FULL_BUILD)
   return()
 endif()
 
 add_libc_testsuite(libc_errno_unittests)
 
 add_libc_unittest(
   errno_test
   SUITE
     libc_errno_unittests
   SRCS
     errno_test.cpp
   DEPENDS
-    libc.src.errno.__errno_location
+    libc.src.errno.errno
 )

libc/test/src/math/CMakeLists.txt

SUITE
     libc_math_unittests
   SRCS
     lround_test.cpp
   HDRS
     RoundToIntegerTest.h
   DEPENDS
     libc.include.errno
     libc.include.math
-    libc.src.errno.__errno_location
+    libc.src.errno.errno
     libc.src.fenv.feclearexcept
     libc.src.fenv.feraiseexcept
     libc.src.fenv.fetestexcept
     libc.src.math.lround
     libc.src.__support.FPUtil.fputil
 )
 
 add_fp_unittest(
   lroundf_test
   NEED_MPFR
   SUITE
     libc_math_unittests
   SRCS
     lroundf_test.cpp
   HDRS
     RoundToIntegerTest.h
   DEPENDS
     libc.include.errno
     libc.include.math
-    libc.src.errno.__errno_location
+    libc.src.errno.errno
     libc.src.fenv.feclearexcept
     libc.src.fenv.feraiseexcept
     libc.src.fenv.fetestexcept
     libc.src.math.lroundf
     libc.src.__support.FPUtil.fputil
 )
 
 add_fp_unittest(
   lroundl_test
   NEED_MPFR
   SUITE
     libc_math_unittests
   SRCS
     lroundl_test.cpp
   HDRS
     RoundToIntegerTest.h
   DEPENDS
     libc.include.errno
     libc.include.math
-    libc.src.errno.__errno_location
+    libc.src.errno.errno
     libc.src.fenv.feclearexcept
     libc.src.fenv.feraiseexcept
     libc.src.fenv.fetestexcept
     libc.src.math.lroundl
     libc.src.__support.FPUtil.fputil
 )
 
 add_fp_unittest(
   llround_test
   NEED_MPFR
   SUITE
     libc_math_unittests
   SRCS
     llround_test.cpp
   HDRS
     RoundToIntegerTest.h
   DEPENDS
     libc.include.errno
     libc.include.math
-    libc.src.errno.__errno_location
+    libc.src.errno.errno
     libc.src.fenv.feclearexcept
     libc.src.fenv.feraiseexcept
     libc.src.fenv.fetestexcept
     libc.src.math.llround
     libc.src.__support.FPUtil.fputil
 )
 
 add_fp_unittest(
   llroundf_test
   NEED_MPFR
   SUITE
     libc_math_unittests
   SRCS
     llroundf_test.cpp
   HDRS
     RoundToIntegerTest.h
   DEPENDS
     libc.include.errno
     libc.include.math
-    libc.src.errno.__errno_location
+    libc.src.errno.errno
     libc.src.fenv.feclearexcept
     libc.src.fenv.feraiseexcept
     libc.src.fenv.fetestexcept
     libc.src.math.llroundf
     libc.src.__support.FPUtil.fputil
 )
 
 add_fp_unittest(
   llroundl_test
   NEED_MPFR
   SUITE
     libc_math_unittests
   SRCS
     llroundl_test.cpp
   HDRS
     RoundToIntegerTest.h
   DEPENDS
     libc.include.errno
     libc.include.math
-    libc.src.errno.__errno_location
+    libc.src.errno.errno
     libc.src.fenv.feclearexcept
     libc.src.fenv.feraiseexcept
     libc.src.fenv.fetestexcept
     libc.src.math.llroundl
     libc.src.__support.FPUtil.fputil
 )
 
 add_fp_unittest(

libc/test/src/signal/CMakeLists.txt

 add_libc_unittest(
   sigprocmask_test
   SUITE
     libc_signal_unittests
   SRCS
     sigprocmask_test.cpp
   DEPENDS
     libc.include.errno
-    libc.src.errno.__errno_location
+    libc.src.errno.errno
     libc.src.signal.raise
     libc.src.signal.sigaddset
     libc.src.signal.sigemptyset
     libc.src.signal.sigprocmask
     libc.test.errno_setter_matcher
 )
 
 add_libc_unittest(
add_libc_unittest(
   signal_test
   SUITE
     libc_signal_unittests
   SRCS
     signal_test.cpp
   DEPENDS
     libc.include.errno
     libc.include.signal
-    libc.src.errno.__errno_location
+    libc.src.errno.errno
     libc.src.signal.raise
     libc.src.signal.signal
     libc.test.errno_setter_matcher
 )
 
 add_libc_unittest(
   sigfillset_test
   SUITE

libc/test/src/sys/mman/linux/CMakeLists.txt

 add_libc_testsuite(libc_sys_mman_unittests)
 
 add_libc_unittest(
   mmap_test
   SUITE
     libc_sys_mman_unittests
   SRCS
     mmap_test.cpp
   DEPENDS
     libc.include.errno
     libc.include.sys_mman
-    libc.src.errno.__errno_location
+    libc.src.errno.errno
     libc.src.sys.mman.mmap
     libc.src.sys.mman.munmap
     libc.test.errno_setter_matcher
 )

libc/test/src/threads/CMakeLists.txt

 add_libc_unittest(
   thrd_test
   SUITE
     libc_threads_unittests
   SRCS
     thrd_test.cpp
   DEPENDS
     libc.include.threads
-    libc.src.errno.__errno_location
+    libc.src.errno.errno
     libc.src.threads.thrd_create
     libc.src.threads.thrd_join
 )
 
 add_libc_unittest(
   mtx_test
   SUITE
     libc_threads_unittests
   SRCS
     mtx_test.cpp
   DEPENDS
     libc.include.threads
-    libc.src.errno.__errno_location
+    libc.src.errno.errno
     libc.src.threads.mtx_destroy
     libc.src.threads.mtx_init
     libc.src.threads.mtx_lock
     libc.src.threads.mtx_unlock
     libc.src.threads.thrd_create
     libc.src.threads.thrd_join
 )