Add support for static linking.

Use `make STATIC=1` to build a static library.

Some language ecosystems, like those of Rust, have a convention of
static linking in order to make binaries easier to distribute. In those
environments, this feature helps libui fit in more easily.

In order to prevent internal symbols from linking, we first create an
intermediate object file with `ld -r` and strip private symbols from it
before using `ar` to create the library.

GNUmakefile

@@ -46,9 +46,14 @@ export DESTDIR
 # other important variables
 export OBJDIR
 export OUTDIR
+export STATIC
+
+ifneq (,$(STATIC))
+STATICLIB = STATICLIB=1
+endif
 
 libui:
-	@$(MAKE) -f build/GNUmakefile.libui inlibuibuild=1
+	@$(MAKE) -f build/GNUmakefile.libui inlibuibuild=1 $(STATICLIB)
 
 clean:
 	rm -rf $(OBJDIR) $(OUTDIR)

build/GNUbasegcc.mk

@@ -50,12 +50,7 @@ else
 	reallinker = $(CXX)
 endif
 
-$(OUT): $(OFILES) | $(OUTDIR)
-	@$(reallinker) -o $(OUT) $(OFILES) $(LDFLAGS)
-ifeq ($(USESSONAME),1)
-	@ln -sf $(NAME)$(SUFFIX) $(OUTNOSONAME)
-endif
-	@echo ====== Linked $(OUT)
+include $(OS)/GNUosspecificlink.mk
 
 .SECONDEXPANSION:
 

build/GNUbasemsvc.mk

@@ -69,7 +69,11 @@ OUT = $(OUTDIR)/$(NAME)$(SUFFIX)
 # TODO use $(CC), $(CXX), $(LD), and s$(RC)
 
 $(OUT): $(OFILES) | $(OUTDIR)
+ifeq (,$(STATICLIB))
 	@link -out:$(OUT) $(OFILES) $(LDFLAGS)
+else
+	@lib -out:$(OUT) $(OFILES)
+endif
 	@echo ====== Linked $(OUT)
 
 .SECONDEXPANSION:

build/GNUmakefile.example

@@ -30,7 +30,11 @@ SUFFIX = $(EXESUFFIX)
 
 # TODO merge with the one in build/GNUmakefile.test
 ifeq ($(TOOLCHAIN),gcc)
-	LDFLAGS += -L$(OUTDIR) -lui
+	ifeq (,$(STATIC))
+		LDFLAGS += -L$(OUTDIR) -lui
+	else
+		LDFLAGS += -L$(OUTDIR) -lui $(NATIVE_UI_LDFLAGS)
+	endif
 	# see build/GNUmakefile.test
 	ifeq ($(OS),darwin)
 		LDFLAGS += -Wl,-rpath,@executable_path/

build/GNUmakefile.libui

@@ -17,10 +17,14 @@ HFILES += \
 	ui_$(OS)$(OSHSUFFIX)
 
 NAME = libui
+ifeq (,$(STATIC))
 SUFFIX = $(LIBSUFFIX)
 ifeq ($(USESSONAME),1)
 	SUFFIX = $(SONAMEEXT)
 endif
+else
+SUFFIX = $(STATICLIBSUFFIX)
+endif
 
 ifeq ($(TOOLCHAIN),gcc)
 	# make every symbol hidden by default except _UI_EXTERN ones

darwin/GNUfiles.mk

@@ -42,10 +42,7 @@ HFILES += \
 # LONGTERM split into a separate file or put in GNUmakefile.libui somehow?
 
 # flags for Cocoa
-LDFLAGS += \
-	-lobjc \
-	-framework Foundation \
-	-framework AppKit
+LDFLAGS += $(NATIVE_UI_LDFLAGS)
 
 # flags for OS X versioning
 CFLAGS += \
@@ -57,9 +54,11 @@ CXXFLAGS += \
 LDFLAGS += \
 	-mmacosx-version-min=10.8
 
+ifeq (,$(STATIC))
 # flags for building a shared library
 LDFLAGS += \
 	-dynamiclib
+endif
 
 # on warning about undefined symbols:
 # the gcc flags don't work with Apple's linker

darwin/GNUosspecific.mk

@@ -3,6 +3,7 @@
 EXESUFFIX =
 LIBSUFFIX = .dylib
 OSHSUFFIX = .h
+STATICLIBSUFFIX = .a
 TOOLCHAIN = gcc
 
 USESSONAME = 1
@@ -11,3 +12,9 @@ SONAMEEXT = .$(SOVERSION)$(LIBSUFFIX)
 # note the explicit need for @rpath
 # LONGTERM -current_version, -compatibility_version
 SONAMEFLAG = -Wl,-install_name,@rpath/
+
+NATIVE_UI_LDFLAGS += \
+	-lobjc \
+	-framework Foundation \
+	-framework AppKit
+

darwin/GNUosspecificlink.mk

@@ -0,0 +1,15 @@
+# 28 may 2016
+
+$(OUT): $(OFILES) | $(OUTDIR)
+ifeq (,$(STATICLIB))
+	@$(reallinker) -o $(OUT) $(OFILES) $(LDFLAGS)
+ifeq ($(USESSONAME),1)
+	@ln -sf $(NAME)$(SUFFIX) $(OUTNOSONAME)
+endif
+else
+	nm -m $(OFILES) | sed -E -n 's/^[0-9a-f]* \([A-Z_]+,[a-z_]+\) external //p' > $(OBJDIR)/symbols
+	$(LD) -exported_symbols_list $(OBJDIR)/symbols -r $(OFILES) -o $(OUT:%.a=%.o)
+	$(AR) rcs $(OUT) $(OUT:%.a=%.o)
+endif
+	@echo ====== Linked $(OUT)
+

unix/GNUfiles.mk

@@ -43,17 +43,16 @@ HFILES += \
 # LONGTERM split into a separate file or put in GNUmakefile.libui somehow?
 
 # flags for GTK+
-CFLAGS += \
-	`pkg-config --cflags gtk+-3.0`
-CXXFLAGS += \
-	`pkg-config --cflags gtk+-3.0`
-LDFLAGS += \
-	`pkg-config --libs gtk+-3.0` -lm -ldl
+CFLAGS += $(NATIVE_UI_CFLAGS)
+CXXFLAGS += $(NATIVE_UI_CXXFLAGS)
+LDFLAGS += $(NATIVE_UI_LDFLAGS)
 
 # flags for building a shared library
 # OS X does support -shared but it has a preferred name for this so let's use that there instead; hence this is not gcc-global
+ifeq (,$(STATIC))
 LDFLAGS += \
 	-shared
+endif
 
 # flags for warning on undefined symbols
 # this is not gcc-global because OS X doesn't support these flags

unix/GNUosspecific.mk

@@ -3,6 +3,7 @@
 EXESUFFIX =
 LIBSUFFIX = .so
 OSHSUFFIX = .h
+STATICLIBSUFFIX = .a
 TOOLCHAIN = gcc
 
 # LONGTERM clean up all the NAMEs and SUFFIXs and NOSOSUFFIXs or whatever it was
@@ -11,3 +12,11 @@ SOVERSION = $(SOVERSION0)
 SONAMEEXT = $(LIBSUFFIX).$(SOVERSION)
 # this is not gcc-global because OS X uses a different filename format
 SONAMEFLAG = -Wl,-soname,
+
+NATIVE_UI_CFLAGS = \
+	`pkg-config --cflags gtk+-3.0`
+NATIVE_UI_CXXFLAGS = \
+	`pkg-config --cflags gtk+-3.0`
+NATIVE_UI_LDFLAGS = \
+	`pkg-config --libs gtk+-3.0` -lm -ldl
+

unix/GNUosspecificlink.mk

@@ -0,0 +1,15 @@
+# 28 may 2016
+
+$(OUT): $(OFILES) | $(OUTDIR)
+ifeq (,$(STATICLIB))
+	@$(reallinker) -o $(OUT) $(OFILES) $(LDFLAGS)
+ifeq ($(USESSONAME),1)
+	@ln -sf $(NAME)$(SUFFIX) $(OUTNOSONAME)
+endif
+else
+	$(LD) -r $(OFILES) -o $(OUT:%.a=%.o)
+	objcopy --localize-hidden $(OUT:%.a=%.o)
+	$(AR) rcs $(OUT) $(OUT:%.a=%.o)
+endif
+	@echo ====== Linked $(OUT)
+

windows/GNUfiles.mk

@@ -73,8 +73,10 @@ LDFLAGS += \
 	user32.lib kernel32.lib usp10.lib gdi32.lib comctl32.lib uxtheme.lib msimg32.lib comdlg32.lib d2d1.lib dwrite.lib ole32.lib oleaut32.lib oleacc.lib uuid.lib
 
 # flags for building a shared library
+ifeq (,$(STATIC))
 LDFLAGS += \
 	-dll
+endif
 
 # TODO flags for warning on undefined symbols
 

windows/GNUosspecific.mk

@@ -3,6 +3,7 @@
 EXESUFFIX = .exe
 LIBSUFFIX = .dll
 OSHSUFFIX = .h
+STATICLIBSUFFIX = .lib
 TOOLCHAIN = msvc
 
 USESSONAME = 0