Because js uses static data structures and is linked into other shared libraries, js must be built as a shared library.

Thanks to Colin Blake <colin@theblakes.com> for the original patch.
Bug #127442 r=bryner

embedding/browser/gtk/tests/Makefile.in

@@ -67,6 +67,7 @@ EXTRA_LIBS	+= $(EXTRA_DSO_LIBS) $(STATIC_EXTRA_LIBS)
 
 endif
 
+EXTRA_LIBS	+= $(MOZ_JS_LIBS)
 EXTRA_LIBS	+= $(MOZ_COMPONENT_LIBS)
 
 include $(topsrcdir)/config/rules.mk

js/src/Makefile.in

@@ -41,14 +41,18 @@ include $(DEPTH)/config/autoconf.mk
 
 MODULE		= js
 LIBRARY_NAME	= mozjs
-EXPORT_LIBRARY = 1
 
 ifeq ($(OS_ARCH),WINNT)
 LIBRARY_NAME	= js$(MOZ_BITS)$(VERSION_NUMBER)
 RESFILE		= js$(MOZ_BITS)40.res
-FORCE_SHARED_LIB = 1
 endif
 
+# JavaScript must be built shared, even for static builds, as it is used by
+# other modules which are always built shared. Failure to do so results in
+# the js code getting copied into xpinstall and jsd as well as mozilla-bin,
+# and then the static data cells used for locking no longer work.
+FORCE_SHARED_LIB = 1
+
 ifdef NS_TRACE_MALLOC
 REQUIRES	= xpcom
 endif

xpfe/bootstrap/Makefile.in

@@ -98,10 +98,6 @@ EXTRA_DSO_LIBS += jsj
 endif
 endif
 
-XP_LIBS		+= \
-		$(MOZ_JS_LIBS) \
-		$(NULL)
-
 else
 include $(topsrcdir)/config/static-config.mk
 
@@ -118,6 +114,7 @@ XP_LIBS		+= $(STATIC_EXTRA_LIBS)
 endif
 
 XP_LIBS		+= \
+		$(MOZ_JS_LIBS) \
 		$(XPCOM_LIBS) \
 		$(NSPR_LIBS) \
 		$(NULL)

xpinstall/packager/packages-static-unix

@@ -32,6 +32,7 @@ bin/defaults/profile/search.rdf
 bin/defaults/profile/mimeTypes.rdf
 
 [xpcom]
+bin/libmozjs.so
 bin/libnspr4.so
 bin/libplc4.so
 bin/libplds4.so