Introduce static_to_shared_library function (#6092)

The static_to_shared_library function takes an existing static library
and produces a shared library based on it.

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

@@ -1,64 +0,0 @@
-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

@@ -58,11 +58,6 @@ 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'
@@ -76,8 +71,6 @@ def install(self, spec, prefix):
                  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' % (
@@ -87,10 +80,12 @@ def install(self, spec, prefix):
                  spec['ncurses'].prefix.lib),
              'MYLIBS=-lncursesw',
              'CC=%s -std=gnu99' % spack_cc,
-             'LUA_DSO=liblua.%s' % (
-                 dso_suffix),
              'install')
 
+        static_to_shared_library(join_path(prefix.lib, 'liblua.a'),
+                                 arguments=['-lm'], version=self.version,
+                                 compat_version=self.version.up_to(2))
+
         with working_dir(os.path.join('luarocks', 'luarocks')):
             configure('--prefix=' + prefix, '--with-lua=' + prefix)
             make('build')