lua: Build a shared library (#6008)

Patch is inspired by Arch Linux and Homebrew.

var/spack/repos/builtin/packages/lua/liblua-shared.patch

@@ -0,0 +1,64 @@
+diff -ru a/Makefile b/Makefile
+--- a/Makefile	2017-10-27 23:49:02.821830453 +0200
++++ b/Makefile	2017-10-27 23:50:45.697634413 +0200
+@@ -41,7 +41,7 @@
+ # What to install.
+ TO_BIN= lua luac
+ TO_INC= lua.h luaconf.h lualib.h lauxlib.h lua.hpp
+-TO_LIB= liblua.a
++TO_LIB= liblua.a $(LUA_DSO).$(R)
+ TO_MAN= lua.1 luac.1
+ 
+ # Lua version and release.
+@@ -52,7 +52,7 @@
+ all:	$(PLAT)
+ 
+ $(PLATS) clean:
+-	cd src && $(MAKE) $@
++	cd src && $(MAKE) $@ V=$(V) R=$(R)
+ 
+ test:	dummy
+ 	src/lua -v
+@@ -63,6 +63,8 @@
+ 	cd src && $(INSTALL_DATA) $(TO_INC) $(INSTALL_INC)
+ 	cd src && $(INSTALL_DATA) $(TO_LIB) $(INSTALL_LIB)
+ 	cd doc && $(INSTALL_DATA) $(TO_MAN) $(INSTALL_MAN)
++	ln -sf $(LUA_DSO).$(R) $(INSTALL_LIB)/$(LUA_DSO).$(V)
++	ln -sf $(LUA_DSO).$(R) $(INSTALL_LIB)/$(LUA_DSO)
+ 
+ uninstall:
+ 	cd src && cd $(INSTALL_BIN) && $(RM) $(TO_BIN)
+diff -ru a/src/Makefile b/src/Makefile
+--- a/src/Makefile	2017-10-27 23:49:02.823830467 +0200
++++ b/src/Makefile	2017-10-27 23:50:01.923284014 +0200
+@@ -29,6 +29,8 @@
+ PLATS= aix bsd c89 freebsd generic linux macosx mingw posix solaris
+ 
+ LUA_A=	liblua.a
++LUA_SO= liblua.so
++LUA_DYLIB= liblua.dylib
+ CORE_O=	lapi.o lcode.o lctype.o ldebug.o ldo.o ldump.o lfunc.o lgc.o llex.o \
+ 	lmem.o lobject.o lopcodes.o lparser.o lstate.o lstring.o ltable.o \
+ 	ltm.o lundump.o lvm.o lzio.o
+@@ -43,7 +45,7 @@
+ LUAC_O=	luac.o
+ 
+ ALL_O= $(BASE_O) $(LUA_O) $(LUAC_O)
+-ALL_T= $(LUA_A) $(LUA_T) $(LUAC_T)
++ALL_T= $(LUA_A) $(LUA_T) $(LUAC_T) $(LUA_DSO)
+ ALL_A= $(LUA_A)
+ 
+ # Targets start here.
+@@ -59,6 +61,12 @@
+ 	$(AR) $@ $(BASE_O)
+ 	$(RANLIB) $@
+ 
++$(LUA_SO): $(CORE_O) $(LIB_O)
++	$(CC) -shared -ldl -Wl,-soname,$(LUA_SO).$(V) -o $@.$(R) $^ -lm $(MYLDFLAGS)
++
++$(LUA_DYLIB): $(CORE_O) $(LIB_O)
++	$(CC) -dynamiclib -install_name @LUA_PREFIX@/lib/$(LUA_DYLIB).$(V) -compatibility_version $(V) -current_version $(R) -o $@.$(R) $^
++
+ $(LUA_T): $(LUA_O) $(LUA_A)
+ 	$(CC) -o $@ $(LDFLAGS) $(LUA_O) $(LUA_A) $(LIBS)
+ 

var/spack/repos/builtin/packages/lua/package.py

@@ -58,24 +58,37 @@ class Lua(Package):
         destination="luarocks",
         placement='luarocks')
 
+    # Based on patches from Arch Linux and Homebrew:
+    # https://git.archlinux.org/svntogit/packages.git/tree/trunk/liblua.so.patch?h=packages/lua
+    # https://github.com/Homebrew/homebrew-core/blob/master/Formula/lua.rb
+    patch('liblua-shared.patch')
+
     def install(self, spec, prefix):
         if spec.satisfies("platform=darwin"):
             target = 'macosx'
         else:
             target = 'linux'
         make('INSTALL_TOP=%s' % prefix,
+             'MYCFLAGS=%s' % (
+                 self.compiler.pic_flag),
              'MYLDFLAGS=-L%s -L%s' % (
                  spec['readline'].prefix.lib,
                  spec['ncurses'].prefix.lib),
              'MYLIBS=-lncursesw',
              'CC=%s -std=gnu99' % spack_cc,
+             'LUA_DSO=liblua.%s' % (
+                 dso_suffix),
              target)
         make('INSTALL_TOP=%s' % prefix,
+             'MYCFLAGS=%s' % (
+                 self.compiler.pic_flag),
              'MYLDFLAGS=-L%s -L%s' % (
                  spec['readline'].prefix.lib,
                  spec['ncurses'].prefix.lib),
              'MYLIBS=-lncursesw',
              'CC=%s -std=gnu99' % spack_cc,
+             'LUA_DSO=liblua.%s' % (
+                 dso_suffix),
              'install')
 
         with working_dir(os.path.join('luarocks', 'luarocks')):