Add a bootstrap build option; enable bootstrap

ldc 1.0.0 and newer need a working D compiler to build, causing a
circular dependency on itself. To make it possible to bootstrap ldc,
upstream is going to keep on supporting 0.17.x for building newer ldc
versions as this is the last version that only needs a C++ compiler for
building.

This commit adds a bootstrap define to allow boostrapping with ldc
version 0.17.2.

ldc.spec

@@ -5,6 +5,11 @@
 %global ldc_version 1.1.0
 %global root        %{name}-%ldc_version-beta3-src
 
+# Enable this for bootstrapping with an older version that doesn't require a
+# working D compiler to build itself
+%global bootstrap 1
+%global bootstrap_version 0.17.2
+
 %undefine _hardened_build
 
 Name:           ldc
@@ -19,11 +24,16 @@ Group:          Development/Languages
 License:        BSD
 URL:            https://github.com/ldc-developers/ldc
 Source0:        https://github.com/ldc-developers/ldc/releases/download/v%ldc_version-beta3/%{name}-%ldc_version-beta3-src.tar.gz
+%if 0%{?bootstrap}
+Source1:        https://github.com/ldc-developers/ldc/releases/download/v%{bootstrap_version}/%{name}-%{bootstrap_version}-src.tar.gz
+%endif
 Source3:        macros.%{name}
 
 ExclusiveArch:  %{ldc_arches}
 
+%if ! 0%{?bootstrap}
 BuildRequires:  ldc
+%endif
 BuildRequires:  llvm-devel >= 3.0
 BuildRequires:  libconfig, libconfig-devel
 BuildRequires:  cmake
@@ -170,12 +180,24 @@ mkdir geany_config
 rm -fr %root/runtime/phobos/etc/c/zlib
 
 %build
+%if 0%{?bootstrap}
+tar xf %{SOURCE1}
+mkdir build-bootstrap
+pushd build-bootstrap
+cmake ../%{name}-%{bootstrap_version}-src
+make %{?_smp_mflags}
+popd
+%endif
+
 mkdir build
 pushd build
     %cmake    -DMULTILIB:BOOL=OFF -DBUILD_SHARED_LIBS:BOOL=ON       \
               -DINCLUDE_INSTALL_DIR:PATH=%{_includedir}/d           \
               -DSYSCONF_INSTALL_DIR:PATH=%{_sysconfdir}             \
               -DCMAKE_INSTALL_PREFIX:PATH=%{_prefix}                \
+%if 0%{?bootstrap}
+              -DD_COMPILER:PATH=`pwd`/../build-bootstrap/bin/ldmd2  \
+%endif
               --enable-optimized ..
     make %{?_smp_mflags} VERBOSE=2
 popd
@@ -246,6 +268,7 @@ install -m0644 phobos.d.tags %{buildroot}/%{_datadir}/geany/tags/
 %changelog
 * Mon Oct 31 2016 Kalev Lember <klember@redhat.com> - 1:1.1.0-0.1.beta3
 - Update to 1.1.0 beta3
+- Add a bootstrap build option; enable bootstrap
 
 * Mon Oct 31 2016 Kalev Lember <klember@redhat.com> - 1:0.17.2-3
 - Move ldc_arches macro to redhat-rpm-config

sources

@@ -1 +1,2 @@
+df585811aa29d0e00d3ccb0d469dad30  ldc-0.17.2-src.tar.gz
 7d796d7195df23a44136bd2ea74d23f3  ldc-1.1.0-beta3-src.tar.gz