[libc] Make libc_errno point to internal errno for non-public builds.

The macro llvmlibc_errno has also been removed. This change completes
the switch to using a hermetic errno for unit tests.

Fixes #61037

Reviewed By: lntue

Differential Revision: https://reviews.llvm.org/D146005

libc/src/errno/CMakeLists.txt

@@ -4,7 +4,6 @@ add_entrypoint_object(
     libc_errno.cpp
   HDRS
     libc_errno.h     # Include this
-    llvmlibc_errno.h # DEPRECATED: Will be removed soon
   DEPENDS
     libc.include.errno
 )

libc/src/errno/libc_errno.cpp

@@ -9,17 +9,19 @@
 namespace __llvm_libc {
 
 extern "C" {
+#ifdef LIBC_COPT_PUBLIC_PACKAGING
 // TODO: Declare __llvmlibc_errno only under LIBC_COPT_PUBLIC_PACKAGING and
 // __llvmlibc_internal_errno otherwise.
-//
 // In overlay mode, this will be an unused thread local variable as libc_errno
 // will resolve to errno from the system libc's errno.h. In full build mode
 // however, libc_errno will resolve to this thread local variable via the errno
 // macro defined in LLVM libc's public errno.h header file.
 // TODO: Use a macro to distinguish full build and overlay build which can be
 //       used to exclude __llvmlibc_errno under overlay build.
 thread_local int __llvmlibc_errno;
+#else
 thread_local int __llvmlibc_internal_errno;
+#endif
 } // extern "C"
 
 } // namespace __llvm_libc

libc/src/errno/libc_errno.h

@@ -29,7 +29,7 @@ extern thread_local int __llvmlibc_internal_errno;
 // libc_errno, this header file will be "shipped" via an add_entrypoint_object
 // target. At which point libc_errno, should point to __llvmlibc_internal_errno
 // if LIBC_COPT_PUBLIC_PACKAGING is not defined.
-#define libc_errno errno
+#define libc_errno __llvm_libc::__llvmlibc_internal_errno
 
 } // namespace __llvm_libc
 #endif

libc/test/CMakeLists.txt

@@ -9,6 +9,8 @@ add_header_library(
   errno_setter_matcher
   HDRS
     ErrnoSetterMatcher.h
+  DEPENDS
+    libc.src.errno.errno
 )
 
 add_custom_target(check-libc)

libc/test/ErrnoSetterMatcher.h

@@ -9,9 +9,9 @@
 #ifndef LLVM_LIBC_TEST_ERRNOSETTERMATCHER_H
 #define LLVM_LIBC_TEST_ERRNOSETTERMATCHER_H
 
+#include "src/errno/libc_errno.h"
 #include "test/UnitTest/Test.h"
 
-#include <errno.h>
 #include <string.h>
 
 namespace __llvm_libc {
@@ -42,8 +42,8 @@ template <typename T> class ErrnoSetterMatcher : public Matcher<T> {
 
   bool match(T Got) {
     ActualReturn = Got;
-    ActualErrno = errno;
-    errno = 0;
+    ActualErrno = libc_errno;
+    libc_errno = 0;
     return Got == ExpectedReturn && ActualErrno == ExpectedErrno;
   }
 };