Ceph

This is seen when using './make-srpm.sh' on Fedora 32 and running a subsequent
'rpmbuild -ba' on the source rpm produced.

-- Performing Test HAVE_UNALIGNED_ACCESS - Failed
CMake Error at cmake/modules/CephChecks.cmake:140 (message):
  Unaligned access is required
Call Stack (most recent call first):
  CMakeLists.txt:95 (include)

The actual fatal error reported in CMakeError.log is the following.

Compiler executable checksum: 61a79f744777569dee61fe7e7cf9806a
In file included from /usr/include/c++/10/ext/string_conversions.h:41,
                 from /usr/include/c++/10/bits/basic_string.h:6535,
                 from /usr/include/c++/10/string:55,
                 from /usr/include/c++/10/bits/locale_classes.h:40,
                 from /usr/include/c++/10/bits/ios_base.h:41,
                 from /usr/include/c++/10/streambuf:41,
                 from /usr/include/c++/10/bits/streambuf_iterator.h:35,
                 from /usr/include/c++/10/iterator:66,
                 from /home/brad/working/rpmbuild/BUILD/ceph-15.0.0-19450-ga0e82efeea6/build/CMakeFiles/CMakeTmp/src.cxx:3:
/usr/include/c++/10/cstdlib:75:15: fatal error: stdlib.h: No such file or directory
   75 | #include_next <stdlib.h>
      |               ^~~~~~~~~~
compilation terminated.

I could not reproduce this on the same machine doing a build 'in tree' even with
identical arguments to cmake, g++, etc.

After some head scratching I added the following patch and started a new build.

diff --git a/cmake/modules/CephChecks.cmake b/cmake/modules/CephChecks.cmake
index ca86dcbc73d..a5487520991 100644
--- a/cmake/modules/CephChecks.cmake
+++ b/cmake/modules/CephChecks.cmake
@@ -96,7 +96,7 @@ CHECK_STRUCT_HAS_MEMBER("struct stat" st_mtimespec.tv_nsec sys/stat.h
 if(NOT CMAKE_CROSSCOMPILING)
   include(CheckCXXSourceRuns)
   cmake_push_check_state()
-  set(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} -std=c++17")
+  set(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} -v -std=c++17")
   if(WIN32)
     set(CMAKE_REQUIRED_LIBRARIES ws2_32)
   endif()

This shows the issue is related to
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70129 I believe.

Failed build extract from CMakeError.log done under 'rpmbuild'.

GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
Versions of loaded plugins: 
 annobin: Version ANNOBIN_VERSION
ignoring nonexistent directory "/usr/lib/gcc/x86_64-redhat-linux/10/include-fixed" 
ignoring nonexistent directory "/usr/lib/gcc/x86_64-redhat-linux/10/../../../../x86_64-redhat-linux/include" 
ignoring duplicate directory "/usr/include" 
ignoring duplicate directory "/usr/include" 
  as it is a non-system directory that duplicates a system directory
#include "..." search starts here:
#include <...> search starts here:
 /usr/include
 /usr/lib/gcc/x86_64-redhat-linux/10/../../../../include/c++/10
 /usr/lib/gcc/x86_64-redhat-linux/10/../../../../include/c++/10/x86_64-redhat-linux
 /usr/lib/gcc/x86_64-redhat-linux/10/../../../../include/c++/10/backward
 /usr/lib/gcc/x86_64-redhat-linux/10/include
 /usr/local/include
End of search list.

Output from a successful build.

GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
ignoring nonexistent directory "/usr/lib/gcc/x86_64-redhat-linux/10/include-fixed" 
ignoring nonexistent directory "/usr/lib/gcc/x86_64-redhat-linux/10/../../../../x86_64-redhat-linux/include" 
#include "..." search starts here:
#include <...> search starts here:
 /usr/lib/gcc/x86_64-redhat-linux/10/../../../../include/c++/10
 /usr/lib/gcc/x86_64-redhat-linux/10/../../../../include/c++/10/x86_64-redhat-linux
 /usr/lib/gcc/x86_64-redhat-linux/10/../../../../include/c++/10/backward
 /usr/lib/gcc/x86_64-redhat-linux/10/include
 /usr/local/include
 /usr/include
End of search list.

Note the differences in the search list with '/usr/include' at the end in the
successful build and the beginning for the failed build and the references to
'ignoring duplicate directory "/usr/include"' in the failed case.