Windows: use libxml2 from Rtools if found

NEWS.md

@@ -1,5 +1,7 @@
 # xml2 (development version)
 
+* Windows: use libxml2 from Rtools if found
+
 # xml2 1.3.6
 
 * Now compatible with libxml2 2.12.0 and later (@KNnut).

src/Makevars.win

@@ -1,18 +1,24 @@
-VERSION=2.10.3
-RWINLIB=../windows/libxml2-$(VERSION)
-PKG_CPPFLAGS=-I../inst/include -I$(RWINLIB)/include/libxml2 \
-	-DLIBXML_STATIC
+PKG_CONFIG_NAME = libxml-2.0
+PKG_CONFIG ?= $(BINPREF)pkg-config
+PKG_LIBS := $(shell $(PKG_CONFIG) --libs $(PKG_CONFIG_NAME))
+STATIC_CFLAGS = -DLIBXML_STATIC -I../inst/include
 
+ifneq ($(PKG_LIBS),)
+$(info using $(PKG_CONFIG_NAME) from Rtools)
+PKG_CPPFLAGS := $(shell $(PKG_CONFIG) --cflags $(PKG_CONFIG_NAME)) $(STATIC_CFLAGS)
+else
+RWINLIB = ../windows/libxml2-2.10.3
+PKG_CPPFLAGS = -I$(RWINLIB)/include -I$(RWINLIB)/include/libxml2 $(STATIC_CFLAGS)
 PKG_LIBS = -L$(RWINLIB)/lib${subst gcc,,$(COMPILED_BY)}$(R_ARCH) \
-	-L$(RWINLIB)/lib$(R_ARCH)\
-	-lxml2 -llzma -liconv -lz -lws2_32
+	-L$(RWINLIB)/lib$(R_ARCH) -lxml2 -llzma -liconv -lz -lws2_32
+endif
 
-all: clean winlibs
+all: $(SHLIB)
 
-clean:
-	rm -f $(OBJECTS) $(SHLIB)
+$(OBJECTS): $(RWINLIB)
 
-winlibs:
-	"${R_HOME}/bin${R_ARCH_BIN}/Rscript.exe" "../tools/winlibs.R" $(VERSION)
+$(RWINLIB):
+	"${R_HOME}/bin${R_ARCH_BIN}/Rscript.exe" "../tools/winlibs.R"
 
-.PHONY: all winlibs clean
+clean:
+	rm -f $(SHLIB) $(OBJECTS)

tools/winlibs.R

@@ -1,8 +1,6 @@
 # Build against static libraries from rwinlib
-VERSION <- commandArgs(TRUE)
-if(!file.exists(sprintf("../windows/libxml2-%s/include/libxml2/libxml/parser.h", VERSION))){
-  if(getRversion() < "3.3.0") setInternet2()
-  download.file(sprintf("https://github.com/rwinlib/libxml2/archive/v%s.zip", VERSION), "lib.zip", quiet = TRUE)
+if(!file.exists("../windows/libxml2-2.10.3/include/libxml2/libxml/parser.h")){
+  download.file("https://github.com/rwinlib/libxml2/archive/v2.10.3.zip", "lib.zip", quiet = TRUE)
   dir.create("../windows", showWarnings = FALSE)
   unzip("lib.zip", exdir = "../windows")
   unlink("lib.zip")