Re-enable LTO

librdkafka.spec

@@ -1,6 +1,6 @@
 Name:		librdkafka
 Version:	1.3.0
-Release:	4%{?dist}
+Release:	5%{?dist}
 Summary:	The Apache Kafka C library
 
 License:	BSD
@@ -35,11 +35,14 @@ using librdkafka.
 %setup -q
 
 %build
-# configure tests try to compile code containing ASMs to a .o file
-# In an LTO world, that always works as compilation does not happen until
-# link time.  As a result we get the wrong results from configure.
-# Disable LTO.
-%define _lto_cflags %{nil}
+# This package has a configure test which uses ASMs, but does not link the
+# resultant .o files.  As such the ASM test is always successful, even on
+# architectures were the ASM is not valid when compiling with LTO.
+#
+# -ffat-lto-objects is sufficient to address this issue.  It is the default
+# for F33, but is expected to only be enabled for packages that need it in
+# F34, so we use it here explicitly
+%define _lto_cflags -flto=auto -ffat-lto-objects
 
 %configure --enable-lz4 \
            --enable-ssl \
@@ -74,11 +77,14 @@ find %{buildroot} -name '*.a' -delete -print
 
 
 %changelog
+* Fri Aug 21 2020 Jeff Law <law@redhat.com> - 1.3.0-5
+- Re-enable LTO
+
 * Tue Jul 28 2020 Fedora Release Engineering <releng@fedoraproject.org> - 1.3.0-4
 - Rebuilt for https://fedoraproject.org/wiki/Fedora_33_Mass_Rebuild
 
 * Tue Jun 30 2020 Jeff Law <law@redhat.com> - 1.3.0-3
-Disable LTO
+- Disable LTO
 
 * Wed Jan 29 2020 Fedora Release Engineering <releng@fedoraproject.org> - 1.3.0-2
 - Rebuilt for https://fedoraproject.org/wiki/Fedora_32_Mass_Rebuild