From 23739c6f9694d7fc436967439f170173dbb4c6b4 Mon Sep 17 00:00:00 2001
From: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Date: Mon, 24 Feb 2020 10:22:13 +0100
Subject: [PATCH] build_tools/build_detect_platform: fix C++ tests

Replace -o /dev/null by -o test.o when testing for C++ features such as
-faligned-new otherwise tests will fail with some bugged binutils
(https://sourceware.org/bugzilla/show_bug.cgi?id=19526):

output/host/bin/xtensa-buildroot-linux-uclibc-g++ -faligned-new -x c++ - -o /dev/null <<EOF
            struct alignas(1024) t {int a;};
            int main() {}
EOF
/home/fabrice/buildroot/output/host/lib/gcc/xtensa-buildroot-linux-uclibc/8.3.0/../../../../xtensa-buildroot-linux-uclibc/bin/ld: final link failed: file truncated

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
[Upstream status: https://github.com/facebook/rocksdb/pull/6479]
---
 build_tools/build_detect_platform | 58 +++++++++++++++----------------
 1 file changed, 29 insertions(+), 29 deletions(-)

diff --git a/build_tools/build_detect_platform b/build_tools/build_detect_platform
index 2535d8124..64a0ae76c 100755
--- a/build_tools/build_detect_platform
+++ b/build_tools/build_detect_platform
@@ -245,7 +245,7 @@ if [ "$CROSS_COMPILE" = "true" -o "$FBCODE_BUILD" = "true" ]; then
 else
     if ! test $ROCKSDB_DISABLE_FALLOCATE; then
         # Test whether fallocate is available
-        $CXX $CFLAGS -x c++ - -o /dev/null 2>/dev/null  <<EOF
+        $CXX $CFLAGS -x c++ - -o test.o 2>/dev/null  <<EOF
           #include <fcntl.h>
           #include <linux/falloc.h>
           int main() {
@@ -261,7 +261,7 @@ EOF
     if ! test $ROCKSDB_DISABLE_SNAPPY; then
         # Test whether Snappy library is installed
         # http://code.google.com/p/snappy/
-        $CXX $CFLAGS -x c++ - -o /dev/null 2>/dev/null  <<EOF
+        $CXX $CFLAGS -x c++ - -o test.o 2>/dev/null  <<EOF
           #include <snappy.h>
           int main() {}
 EOF
@@ -276,7 +276,7 @@ EOF
         # Test whether gflags library is installed
         # http://gflags.github.io/gflags/
         # check if the namespace is gflags
-        $CXX $CFLAGS -x c++ - -o /dev/null 2>/dev/null << EOF
+        $CXX $CFLAGS -x c++ - -o test.o 2>/dev/null << EOF
           #include <gflags/gflags.h>
           int main() {}
 EOF
@@ -285,7 +285,7 @@ EOF
             PLATFORM_LDFLAGS="$PLATFORM_LDFLAGS -lgflags"
         else
           # check if namespace is google
-          $CXX $CFLAGS -x c++ - -o /dev/null 2>/dev/null << EOF
+          $CXX $CFLAGS -x c++ - -o test.o 2>/dev/null << EOF
             #include <gflags/gflags.h>
             using namespace google;
             int main() {}
@@ -299,7 +299,7 @@ EOF
 
     if ! test $ROCKSDB_DISABLE_ZLIB; then
         # Test whether zlib library is installed
-        $CXX $CFLAGS $COMMON_FLAGS -x c++ - -o /dev/null 2>/dev/null  <<EOF
+        $CXX $CFLAGS $COMMON_FLAGS -x c++ - -o test.o 2>/dev/null  <<EOF
           #include <zlib.h>
           int main() {}
 EOF
@@ -312,7 +312,7 @@ EOF
 
     if ! test $ROCKSDB_DISABLE_BZIP; then
         # Test whether bzip library is installed
-        $CXX $CFLAGS $COMMON_FLAGS -x c++ - -o /dev/null 2>/dev/null  <<EOF
+        $CXX $CFLAGS $COMMON_FLAGS -x c++ - -o test.o 2>/dev/null  <<EOF
           #include <bzlib.h>
           int main() {}
 EOF
@@ -325,7 +325,7 @@ EOF
 
     if ! test $ROCKSDB_DISABLE_LZ4; then
         # Test whether lz4 library is installed
-        $CXX $CFLAGS $COMMON_FLAGS -x c++ - -o /dev/null 2>/dev/null  <<EOF
+        $CXX $CFLAGS $COMMON_FLAGS -x c++ - -o test.o 2>/dev/null  <<EOF
           #include <lz4.h>
           #include <lz4hc.h>
           int main() {}
@@ -339,7 +339,7 @@ EOF
 
     if ! test $ROCKSDB_DISABLE_ZSTD; then
         # Test whether zstd library is installed
-        $CXX $CFLAGS $COMMON_FLAGS -x c++ - -o /dev/null 2>/dev/null  <<EOF
+        $CXX $CFLAGS $COMMON_FLAGS -x c++ - -o test.o 2>/dev/null  <<EOF
           #include <zstd.h>
           int main() {}
 EOF
@@ -352,7 +352,7 @@ EOF
 
     if ! test $ROCKSDB_DISABLE_NUMA; then
         # Test whether numa is available
-        $CXX $CFLAGS -x c++ - -o /dev/null -lnuma 2>/dev/null  <<EOF
+        $CXX $CFLAGS -x c++ - -o test.o -lnuma 2>/dev/null  <<EOF
           #include <numa.h>
           #include <numaif.h>
           int main() {}
@@ -366,7 +366,7 @@ EOF
 
     if ! test $ROCKSDB_DISABLE_TBB; then
         # Test whether tbb is available
-        $CXX $CFLAGS $LDFLAGS -x c++ - -o /dev/null -ltbb 2>/dev/null  <<EOF
+        $CXX $CFLAGS $LDFLAGS -x c++ - -o test.o -ltbb 2>/dev/null  <<EOF
           #include <tbb/tbb.h>
           int main() {}
 EOF
@@ -379,7 +379,7 @@ EOF
 
     if ! test $ROCKSDB_DISABLE_JEMALLOC; then
         # Test whether jemalloc is available
-        if echo 'int main() {}' | $CXX $CFLAGS -x c++ - -o /dev/null -ljemalloc \
+        if echo 'int main() {}' | $CXX $CFLAGS -x c++ - -o test.o -ljemalloc \
           2>/dev/null; then
             # This will enable some preprocessor identifiers in the Makefile
             JEMALLOC=1
@@ -400,7 +400,7 @@ EOF
     fi
     if ! test $JEMALLOC && ! test $ROCKSDB_DISABLE_TCMALLOC; then
         # jemalloc is not available. Let's try tcmalloc
-        if echo 'int main() {}' | $CXX $CFLAGS -x c++ - -o /dev/null \
+        if echo 'int main() {}' | $CXX $CFLAGS -x c++ - -o test.o \
           -ltcmalloc 2>/dev/null; then
             PLATFORM_LDFLAGS="$PLATFORM_LDFLAGS -ltcmalloc"
             JAVA_LDFLAGS="$JAVA_LDFLAGS -ltcmalloc"
@@ -409,7 +409,7 @@ EOF
 
     if ! test $ROCKSDB_DISABLE_MALLOC_USABLE_SIZE; then
         # Test whether malloc_usable_size is available
-        $CXX $CFLAGS -x c++ - -o /dev/null 2>/dev/null  <<EOF
+        $CXX $CFLAGS -x c++ - -o test.o 2>/dev/null  <<EOF
           #include <malloc.h>
           int main() {
             size_t res = malloc_usable_size(0);
@@ -424,7 +424,7 @@ EOF
 
     if ! test $ROCKSDB_DISABLE_PTHREAD_MUTEX_ADAPTIVE_NP; then
         # Test whether PTHREAD_MUTEX_ADAPTIVE_NP mutex type is available
-        $CXX $CFLAGS -x c++ - -o /dev/null 2>/dev/null  <<EOF
+        $CXX $CFLAGS -x c++ - -o test.o 2>/dev/null  <<EOF
           #include <pthread.h>
           int main() {
             int x = PTHREAD_MUTEX_ADAPTIVE_NP;
@@ -439,7 +439,7 @@ EOF
 
     if ! test $ROCKSDB_DISABLE_BACKTRACE; then
         # Test whether backtrace is available
-        $CXX $CFLAGS -x c++ - -o /dev/null 2>/dev/null  <<EOF
+        $CXX $CFLAGS -x c++ - -o test.o 2>/dev/null  <<EOF
           #include <execinfo.h>
           int main() {
             void* frames[1];
@@ -451,7 +451,7 @@ EOF
             COMMON_FLAGS="$COMMON_FLAGS -DROCKSDB_BACKTRACE"
         else
             # Test whether execinfo library is installed
-            $CXX $CFLAGS -lexecinfo -x c++ - -o /dev/null 2>/dev/null  <<EOF
+            $CXX $CFLAGS -lexecinfo -x c++ - -o test.o 2>/dev/null  <<EOF
               #include <execinfo.h>
               int main() {
                 void* frames[1];
@@ -468,7 +468,7 @@ EOF
 
     if ! test $ROCKSDB_DISABLE_PG; then
         # Test if -pg is supported
-        $CXX $CFLAGS -pg -x c++ - -o /dev/null 2>/dev/null  <<EOF
+        $CXX $CFLAGS -pg -x c++ - -o test.o 2>/dev/null  <<EOF
           int main() {
             return 0;
           }
@@ -480,7 +480,7 @@ EOF
 
     if ! test $ROCKSDB_DISABLE_SYNC_FILE_RANGE; then
         # Test whether sync_file_range is supported for compatibility with an old glibc
-        $CXX $CFLAGS -x c++ - -o /dev/null 2>/dev/null  <<EOF
+        $CXX $CFLAGS -x c++ - -o test.o 2>/dev/null  <<EOF
           #include <fcntl.h>
           int main() {
             int fd = open("/dev/null", 0);
@@ -494,7 +494,7 @@ EOF
 
     if ! test $ROCKSDB_DISABLE_SCHED_GETCPU; then
         # Test whether sched_getcpu is supported
-        $CXX $CFLAGS -x c++ - -o /dev/null 2>/dev/null  <<EOF
+        $CXX $CFLAGS -x c++ - -o test.o 2>/dev/null  <<EOF
           #include <sched.h>
           int main() {
             int cpuid = sched_getcpu();
@@ -508,7 +508,7 @@ EOF
 
     if ! test $ROCKSDB_DISABLE_AUXV_GETAUXVAL; then
         # Test whether getauxval is supported
-        $CXX $CFLAGS -x c++ - -o /dev/null 2>/dev/null  <<EOF
+        $CXX $CFLAGS -x c++ - -o test.o 2>/dev/null  <<EOF
           #include <sys/auxv.h>
           int main() {
             uint64_t auxv = getauxval(AT_HWCAP);
@@ -522,7 +522,7 @@ EOF
 
     if ! test $ROCKSDB_DISABLE_ALIGNED_NEW; then
         # Test whether c++17 aligned-new is supported
-        $CXX $PLATFORM_CXXFLAGS -faligned-new -x c++ - -o /dev/null 2>/dev/null <<EOF
+        $CXX $PLATFORM_CXXFLAGS -faligned-new -x c++ - -o test.o 2>/dev/null <<EOF
             struct alignas(1024) t {int a;};
             int main() {}
 EOF
@@ -536,7 +536,7 @@ fi
 # -Wshorten-64-to-32 breaks compilation on FreeBSD i386
 if ! [ "$TARGET_OS" = FreeBSD -a "$TARGET_ARCHITECTURE" = i386 ]; then
   # Test whether -Wshorten-64-to-32 is available
-  $CXX $CFLAGS -x c++ - -o /dev/null -Wshorten-64-to-32 2>/dev/null  <<EOF
+  $CXX $CFLAGS -x c++ - -o test.o -Wshorten-64-to-32 2>/dev/null  <<EOF
     int main() {}
 EOF
   if [ "$?" = 0 ]; then
@@ -603,7 +603,7 @@ if test "$TRY_SSE_ETC"; then
   TRY_AVX2="-mavx2"
 fi
 
-$CXX $PLATFORM_CXXFLAGS $COMMON_FLAGS $TRY_SSE42 -x c++ - -o /dev/null 2>/dev/null <<EOF
+$CXX $PLATFORM_CXXFLAGS $COMMON_FLAGS $TRY_SSE42 -x c++ - -o test.o 2>/dev/null <<EOF
   #include <cstdint>
   #include <nmmintrin.h>
   int main() {
@@ -617,7 +617,7 @@ elif test "$USE_SSE"; then
   echo "warning: USE_SSE specified but compiler could not use SSE intrinsics, disabling" >&2
 fi
 
-$CXX $PLATFORM_CXXFLAGS $COMMON_FLAGS $TRY_PCLMUL -x c++ - -o /dev/null 2>/dev/null <<EOF
+$CXX $PLATFORM_CXXFLAGS $COMMON_FLAGS $TRY_PCLMUL -x c++ - -o test.o 2>/dev/null <<EOF
   #include <cstdint>
   #include <wmmintrin.h>
   int main() {
@@ -634,7 +634,7 @@ elif test "$USE_SSE"; then
   echo "warning: USE_SSE specified but compiler could not use PCLMUL intrinsics, disabling" >&2
 fi
 
-$CXX $PLATFORM_CXXFLAGS $COMMON_FLAGS $TRY_AVX2 -x c++ - -o /dev/null 2>/dev/null <<EOF
+$CXX $PLATFORM_CXXFLAGS $COMMON_FLAGS $TRY_AVX2 -x c++ - -o test.o 2>/dev/null <<EOF
   #include <cstdint>
   #include <immintrin.h>
   int main() {
@@ -649,7 +649,7 @@ elif test "$USE_SSE"; then
   echo "warning: USE_SSE specified but compiler could not use AVX2 intrinsics, disabling" >&2
 fi
 
-$CXX $PLATFORM_CXXFLAGS $COMMON_FLAGS -x c++ - -o /dev/null 2>/dev/null <<EOF
+$CXX $PLATFORM_CXXFLAGS $COMMON_FLAGS -x c++ - -o test.o 2>/dev/null <<EOF
   #include <cstdint>
   int main() {
     uint64_t a = 0xffffFFFFffffFFFF;
@@ -666,7 +666,7 @@ fi
 # succeed because the cross-compiler flags are added by the Makefile, not this
 # script.
 if [ "$PLATFORM" != IOS ]; then
-  $CXX $COMMON_FLAGS -x c++ - -o /dev/null 2>/dev/null <<EOF
+  $CXX $COMMON_FLAGS -x c++ - -o test.o 2>/dev/null <<EOF
   #if defined(_MSC_VER) && !defined(__thread)
   #define __thread __declspec(thread)
   #endif
@@ -685,7 +685,7 @@ if [ "$FBCODE_BUILD" != "true" -a "$PLATFORM" = OS_LINUX ]; then
   void dummy_func() {}
 EOF
   if [ "$?" = 0 ]; then
-    $CXX $COMMON_FLAGS $PLATFORM_SHARED_LDFLAGS test_dl.o -o /dev/null 2>/dev/null
+    $CXX $COMMON_FLAGS $PLATFORM_SHARED_LDFLAGS test_dl.o -o test.o 2>/dev/null
     if [ "$?" = 0 ]; then
       EXEC_LDFLAGS+="-ldl"
       rm -f test_dl.o
-- 
2.25.0