build system: introduce a new feature called build variants.

it allows building a package multiple times in one pass with different build dirs,
based on the same build settings.
replaces templating hacks like the one used in the hostapd package

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@18357 3c298f89-4303-0410-b956-a3cf2f4a3e73

include/package-defaults.mk

@@ -37,6 +37,7 @@ define Package/Default
   KCONFIG:=
   BUILDONLY:=
   URL:=
+  VARIANT:=
 endef
 
 Build/Patch:=$(Build/Patch/Default)

include/package-dumpinfo.mk

@@ -32,7 +32,8 @@ $(if $(MENU),Menu: $(MENU)
 )Version: $(VERSION)
 Depends: $(DEPENDS)
 Provides: $(PROVIDES)
-$(if $(PKG_BUILD_DEPENDS),Build-Depends: $(PKG_BUILD_DEPENDS)
+$(if $(VARIANT),Build-Variant: $(VARIANT)
+)$(if $(PKG_BUILD_DEPENDS),Build-Depends: $(PKG_BUILD_DEPENDS)
 )$(if $(HOST_BUILD_DEPENDS),Build-Depends/host: $(HOST_BUILD_DEPENDS)
 )$(if $(BUILD_TYPES),Build-Types: $(BUILD_TYPES)
 )Section: $(SECTION)

include/subdir.mk

@@ -35,7 +35,9 @@ define subdir
       )
       $(call warn_eval,$(1)/$(bd),t,T,$(1)/$(bd)/$(target): $(if $(QUILT),,$($(1)/$(bd)/$(target)) $(call $(1)//$(target),$(1)/$(bd))))
 	  	$(if $(BUILD_LOG),@mkdir -p $(BUILD_LOG_DIR)/$(1)/$(bd))
-		+$(if $(BUILD_LOG),set -o pipefail;) $$(SUBMAKE) -C $(1)/$(bd) $(target) $(if $(BUILD_LOG),SILENT= 2>&1 | tee $(BUILD_LOG_DIR)/$(1)/$(bd)/$(target).txt) $(if $(findstring $(bd),$($(1)/builddirs-ignore-$(target))), || $(call MESSAGE,   ERROR: $(1)/$(bd) failed to build.))
+        $(foreach variant,$(if $(BUILD_VARIANT),$(BUILD_VARIANT),$(if $($(1)/$(bd)/variants),$($(1)/$(bd)/variants),__default)),
+			+$(if $(BUILD_LOG),set -o pipefail;) $$(SUBMAKE) -C $(1)/$(bd) $(target) BUILD_VARIANT="$(filter-out __default,$(variant))" $(if $(BUILD_LOG),SILENT= 2>&1 | tee $(BUILD_LOG_DIR)/$(1)/$(bd)/$(target).txt) $(if $(findstring $(bd),$($(1)/builddirs-ignore-$(target))), || $(call MESSAGE,   ERROR: $(1)/$(bd) failed to build$(if $(filter-out __default,$(variant)), (build variant: $(variant))).))
+        )
         $$(if $(call debug,$(1)/$(bd),v),,.SILENT: $(1)/$(bd)/$(target))
 
       # legacy targets

scripts/metadata.pl

@@ -620,6 +620,9 @@ sub gen_package_mk() {
 		if ($config) {
 			$pkg->{buildonly} and $config = "";
 			print "package-$config += $pkg->{subdir}$pkg->{src}\n";
+			if ($pkg->{variant}) {
+				print "\$(curdir)/$pkg->{subdir}$pkg->{src}/variants += \$(if $config,$pkg->{variant})\n"
+			}
 			$pkg->{prereq} and print "prereq-$config += $pkg->{subdir}$pkg->{src}\n";
 		}
 

scripts/metadata.pm

@@ -112,6 +112,7 @@ sub parse_package_metadata($) {
 			}
 		};
 		/^Depends: \s*(.+)\s*$/ and $pkg->{depends} = [ split /\s+/, $1 ];
+		/^Build-Variant: \s*(\w+)\s*/ and $pkg->{variant} = $1;
 		/^Build-Only: \s*(.+)\s*$/ and $pkg->{buildonly} = 1;
 		/^Build-Depends: \s*(.+)\s*$/ and $pkg->{builddepends} = [ split /\s+/, $1 ];
 		/^Build-Depends\/(\w+): \s*(.+)\s*$/ and $pkg->{"builddepends/$1"} = [ split /\s+/, $2 ];