Add --whole-archive to include all store implementations (when BUILD_SHARED_LIBS=false)

mk/libraries.mk

@@ -50,6 +50,11 @@ endif
 #   target andwill not be listed in the make help output. This is
 #   useful for libraries built solely for testing, for example.
 #
+# - $(1)_WHOLE_ARCHIVE: if defined, the whole archive of the static
+#   library will be used. This is necessary when using global
+#   constructors such as setting up a RegisterStoreImplementation.
+#   Only applies when BUILD_SHARED_LIBS=0.
+#
 # - BUILD_SHARED_LIBS: if equal to ‘1’, a dynamic library will be
 #   built, otherwise a static library.
 define build-library
@@ -127,7 +132,32 @@ define build-library
     $$($(1)_PATH): $$($(1)_OBJS) | $$(_d)/
 	$(trace-ar) $(AR) crs $$@ $$?
 
-    $(1)_LDFLAGS_USE += $$($(1)_PATH) $$($(1)_LDFLAGS)
+    # Special care is needed to support C++ global initializers, used
+    # in RegisterStoreImplementation. The .init section needs to be in
+    # the linked executable for it find the registered stores. On
+    # Linux systems systems, wrap the linked object archive with whole
+    # archive flags. Note that --whole-archive is only supported with
+    # the bfd, gold, and lld linkers. The macOS ld64 linker has a
+    # -force_load that seems to work similarly, but takes one argument
+    # instead of a group of arguments.
+
+    ifdef $(1)_WHOLE_ARCHIVE
+      ifeq ($(OS), Linux)
+        $(1)_LDFLAGS_USE += -Wl,--whole-archive
+      else ifeq ($(OS), Darwin)
+        $(1)_LDFLAGS_USE += -Wl,-force_load
+      endif
+    endif
+
+    $(1)_LDFLAGS_USE += $$($(1)_PATH)
+
+    ifdef $(1)_WHOLE_ARCHIVE
+      ifeq ($(OS), Linux)
+        $(1)_LDFLAGS_USE += -Wl,--no-whole-archive
+      endif
+    endif
+
+    $(1)_LDFLAGS_USE += $$($(1)_LDFLAGS)
 
     $(1)_INSTALL_PATH := $$(libdir)/$$($(1)_NAME).a
 

src/libexpr/local.mk

@@ -15,6 +15,8 @@ ifneq ($(OS), FreeBSD)
  libexpr_LDFLAGS += -ldl
 endif
 
+libexpr_WHOLE_ARCHIVE = 1
+
 # The dependency on libgc must be propagated (i.e. meaning that
 # programs/libraries that use libexpr must explicitly pass -lgc),
 # because inline functions in libexpr's header files call libgc.

src/libfetchers/local.mk

@@ -9,3 +9,6 @@ libfetchers_SOURCES := $(wildcard $(d)/*.cc)
 libfetchers_CXXFLAGS += -I src/libutil -I src/libstore
 
 libfetchers_LIBS = libutil libstore libnixrust
+
+libfetchers_WHOLE_ARCHIVE = 1
+

src/libstore/local.mk

@@ -13,6 +13,8 @@ ifneq ($(OS), FreeBSD)
  libstore_LDFLAGS += -ldl
 endif
 
+libstore_WHOLE_ARCHIVE = 1
+
 ifeq ($(OS), Darwin)
 libstore_FILES = sandbox-defaults.sb sandbox-minimal.sb sandbox-network.sb
 endif