Add RPM macros for compiler/linker flags

buildflags.md

@@ -5,8 +5,9 @@ and how to use them.
 
 # Using RPM build flags
 
-At present, the only supported way is to use the `%configure` macro to
-obtain the full complement of flags, like this:
+For packages which use autoconf to set up the build environment, use
+the `%configure` macro to obtain the full complement of flags, like
+this:
 
     %configure
 
@@ -15,9 +16,36 @@ This will invoke the `./configure` with arguments (such as
 
 As a side effect, this will set the environment variables `CFLAGS`,
 `CXXFLAGS`, `FFLAGS`, `FCFLAGS`, and `LDFLAGS`, so they can be used by
-makefiles and other build tools.
+makefiles and other build tools.  (However, existing values for this
+variables are not overwritten.)
 
-For some other build tools besides `autoconf`, separate mechanisms exist:
+If your package does not use autoconf, you can still set the same
+environment variables using
+
+    %set_build_flags
+
+early in the `%build` section.  (Again, existing environment variables
+are not overwritten.)
+
+Individual build flags are also available through RPM macros:
+
+* `%{build_cflags}` for the C compiler flags (also known as the
+  `CFLAGS` variable).  Also historically available as `%{optflags}`.
+  Furthermore, at the start of the `%build` section, the environment
+  variable `RPM_OPT_FLAGS` is set to this value.
+* `%{build_cxxflags} for the C++ compiler flags (usually assigned to
+  the `CXXFLAGS` shell variable).
+* `%{build_fflags} for `FFLAGS` (the Fortran compiler flags, also
+  known as the `FCFLAGS` variable).
+* `{%build_ldflags}` for the link editor (ld) flags, usually known as
+  `LDFLAGS`.  Note that the contents quotes linker arguments using
+  `-Wl`, so this variable is intended for use with the `gcc` compiler
+  driver.  At the start of the `%build` section, the environment
+  variable `RPM_LD_FLAGS` is set to this value.
+
+These RPM macros do not alter shell environment variables.
+
+For some other build tools separate mechanisms exist:
 
 * CMake builds use the the `%cmake` macro from the `cmake-rpm-macros`
   package.

macros

@@ -24,6 +24,46 @@
 %_debugsource_packages  1
 %_debuginfo_subpackages 1
 
+#==============================================================================
+# ---- compiler flags.
+
+# C compiler flags.  This is traditionally called CFLAGS in makefiles.
+# Historically also available as %%{optflags}, and %%build sets the
+# environment variable RPM_OPT_FLAGS to this value.
+%build_cflags %{optflags}
+
+# C++ compiler flags.  This is traditionally called CXXFLAGS in makefiles.
+%build_cxxflags %{optflags}
+
+# Fortran compiler flags.  Makefiles use both FFLAGS and FCFLAGS as
+# the corresponding variable names.
+%build_fflags %{optflags} -I%{_fmoddir}
+
+# Link editor flags.  This is usually called LDFLAGS in makefiles.
+# (Some makefiles use LFLAGS instead.)  The default value assumes that
+# the flags, while intended for ld, are still passed through the gcc
+# compiler driver.  At the beginning of %%build, the environment
+# variable RPM_LD_FLAGS to this value.
+%build_ldflags -Wl,-z,relro %{_ld_symbols_flags} %{_hardened_ldflags}
+
+# Expands to shell code to seot the compiler/linker environment
+# variables CFLAGS, CXXFLAGS, FFLAGS, FCFLAGS, LDFLAGS if they have
+# not been set already.  RPM_OPT_FLAGS and RPM_LD_FLAGS have already
+# been set implicitly at the start of the %%build section.
+%set_build_flags \
+  CFLAGS="${CFLAGS:-%{build_cflags}}" ; export CFLAGS ; \
+  CXXFLAGS="${CXXFLAGS:-%{build_cxxflags}}" ; export CXXFLAGS ; \
+  FFLAGS="${FFLAGS:-%{build_fflags}}" ; export FFLAGS ; \
+  FCFLAGS="${FCFLAGS:-%{build_fflags}}" ; export FCFLAGS ; \
+  LDFLAGS="${LDFLAGS:-%{build_ldflags}}" ; export LDFLAGS
+
+# Deprecated names.  For backwards compatibility only.
+%__global_cflags %{build_cflags}
+%__global_cxxflags %{build_cxxflags}
+%__global_fflags %{build_fflags}
+%__global_fcflags %{build_fflags}
+%__global_ldflags %{build_ldflags}
+
 #==============================================================================
 # ---- configure and makeinstall.
 #
@@ -35,11 +75,7 @@
 # way to turn it back off.
 # %_configure_disable_silent_rules 1
 %configure \
-  CFLAGS="${CFLAGS:-%__global_cflags}" ; export CFLAGS ; \
-  CXXFLAGS="${CXXFLAGS:-%__global_cxxflags}" ; export CXXFLAGS ; \
-  FFLAGS="${FFLAGS:-%__global_fflags}" ; export FFLAGS ; \
-  FCFLAGS="${FCFLAGS:-%__global_fcflags}" ; export FCFLAGS ; \
-  LDFLAGS="${LDFLAGS:-%__global_ldflags}"; export LDFLAGS; \
+  %{set_build_flags}; \
   [ "%_configure_gnuconfig_hack" = 1 ] && for i in $(find $(dirname %{_configure}) -name config.guess -o -name config.sub) ; do \
       [ -f /usr/lib/rpm/redhat/$(basename $i) ] && %{__rm} -f $i && %{__cp} -fv /usr/lib/rpm/redhat/$(basename $i) $i ; \
   done ; \
@@ -178,12 +214,6 @@
 
 %__global_compiler_flags	-O2 -g -pipe -Wall -Werror=format-security -Wp,-D_FORTIFY_SOURCE=2 -Wp,-D_GLIBCXX_ASSERTIONS -fexceptions -fstack-protector-strong -grecord-gcc-switches %{_hardened_cflags} %{_annotated_cflags}
 
-%__global_cflags	%{optflags}
-%__global_cxxflags	%{optflags}
-%__global_fflags	%{optflags} -I%_fmoddir
-%__global_fcflags	%{optflags} -I%_fmoddir
-%__global_ldflags	-Wl,-z,relro %{_ld_symbols_flags} %{_hardened_ldflags}
-
 #==============================================================================
 # ---- Generic auto req/prov filtering macros
 #

redhat-rpm-config.spec

@@ -6,7 +6,7 @@
 
 Summary: Red Hat specific rpm configuration files
 Name: redhat-rpm-config
-Version: 93
+Version: 94
 Release: 1%{?dist}
 # No version specified.
 License: GPL+
@@ -183,6 +183,9 @@ install -p -m 755 -t %{buildroot}%{_rpmconfigdir} kmod.prov
 %{_rpmconfigdir}/macros.d/macros.kmp
 
 %changelog
+* Sun Feb  4 2018 Florian Weimer <fweimer@redhat.com> - 94-1
+- Add RPM macros for compiler/linker flags
+
 * Sat Feb 03 2018 Igor Gnatenko <ignatenkobrain@fedoraproject.org> - 93-1
 - Use newly available /usr/bin/grep