Makefile.shared: update link_o.darwin rule [from HEAD].

PR: 2306

diff --git a/Makefile.shared b/Makefile.shared
index 3569832f1b92151dfe63ffadf096751830cf031e..ab6532f9fac6a6485be45193f09b4123f8c6405f 100644 (file)
--- a/Makefile.shared
+++ b/Makefile.shared
@@ -135,7 +135,7 @@ LINK_SO_A_VIA_O=    \
   ALL=$$ALLSYMSFLAGS; ALLSYMSFLAGS=; NOALLSYMSFLAGS=; \
   ( $(SET_X); \
     ld $(LDFLAGS) -r -o lib$(LIBNAME).o $$ALL lib$(LIBNAME).a $(LIBEXTRAS) ); \
-  $(LINK_SO) && rm -f $(LIBNAME).o
+  $(LINK_SO) && rm -f lib$(LIBNAME).o
 
 LINK_SO_A_UNPACKED=    \
   UNPACKDIR=link_tmp.$$$$; rm -rf $$UNPACKDIR; mkdir $$UNPACKDIR; \
@@ -207,17 +207,29 @@ link_app.bsd:
        fi; $(LINK_APP)
 
 # For Darwin AKA Mac OS/X (dyld)
-# link_o.darwin produces .so, because we let it use dso_dlfcn module,
-# which has .so extension hard-coded. One can argue that one should
-# develop special dso module for MacOS X. At least manual encourages
-# to use native NSModule(3) API and refers to dlfcn as termporary hack.
+# Originally link_o.darwin produced .so, because it was hard-coded
+# in dso_dlfcn module. At later point dso_dlfcn switched to .dylib
+# extension in order to allow for run-time linking with vendor-
+# supplied shared libraries such as libz, so that link_o.darwin had
+# to be harmonized with it. This caused minor controversy, because
+# it was believed that dlopen can't be used to dynamically load
+# .dylib-s, only so called bundle modules (ones linked with -bundle
+# flag). The belief seems to be originating from pre-10.4 release,
+# where dlfcn functionality was emulated by dlcompat add-on. In
+# 10.4 dlopen was rewritten as native part of dyld and is documented
+# to be capable of loading both dynamic libraries and bundles. In
+# order to provide compatibility with pre-10.4 dlopen, modules are
+# linked with -bundle flag, which makes .dylib extension misleading.
+# It works, because dlopen is [and always was] extension-agnostic.
+# Alternative to this heuristic approach is to develop specific
+# MacOS X dso module relying on whichever "native" dyld interface.
 link_o.darwin:
        @ $(CALC_VERSIONS); \
        SHLIB=lib$(LIBNAME); \
-       SHLIB_SUFFIX=.so; \
+       SHLIB_SUFFIX=.dylib; \
        ALLSYMSFLAGS='-all_load'; \
        NOALLSYMSFLAGS=''; \
-       SHAREDFLAGS="$(CFLAGS) $(SHARED_LDFLAGS)"; \
+       SHAREDFLAGS="$(CFLAGS) `echo $(SHARED_LDFLAGS) | sed s/dynamiclib/bundle/"; \
        if [ -n "$(LIBVERSION)" ]; then \
                SHAREDFLAGS="$$SHAREDFLAGS -current_version $(LIBVERSION)"; \
        fi; \