[R] Fix CopyToR() generated for struct in namespace

Fixes https://sourceforge.net/p/swig/bugs/1147/

Examples/test-suite/common.mk

@@ -315,6 +315,7 @@ CPP_TEST_CASES += \
 	namespace_forward_declaration \
 	namespace_nested \
 	namespace_spaces \
+	namespace_struct \
 	namespace_template \
 	namespace_typedef_class \
 	namespace_typemap \

Examples/test-suite/namespace_struct.i

@@ -0,0 +1,8 @@
+%module namespace_struct
+
+%inline %{
+
+// SWIG/R generated bad code for copyToR for a struct in a namespace in SWIG < 4.1.0
+namespace X { struct Y { int x, y; }; }
+
+%}

Examples/test-suite/r/namespace_struct_runme.R

@@ -0,0 +1,11 @@
+clargs <- commandArgs(trailing=TRUE)
+source(file.path(clargs[1], "unittest.R"))
+
+dyn.load(paste("namespace_struct", .Platform$dynlib.ext, sep=""))
+source("namespace_struct.R")
+cacheMetaData(1)
+
+xy = Y()
+xy$x = as.integer(2)
+xy$y = as.integer(4)
+copyToR(xy)