Add missing SWIGTYPE *const& typemaps

CHANGES.current

@@ -7,6 +7,10 @@ the issue number to the end of the URL: https://github.com/swig/swig/issues/
 Version 4.1.0 (in progress)
 ===========================
 
+2022-10-13: wsfulton
+            [R] Add missing SWIGTYPE *const& typemaps for supporting pointers
+            by const reference.
+
 2022-10-10: wsfulton
             #2160 Fix compile error when using templates with more than one template
             parameter and used as an input parameter in a virtual method in a

Examples/test-suite/r/constant_pointers_runme.R

@@ -0,0 +1,13 @@
+clargs <- commandArgs(trailing=TRUE)
+source(file.path(clargs[1], "unittest.R"))
+
+dyn.load(paste("constant_pointers", .Platform$dynlib.ext, sep=""))
+source("constant_pointers.R")
+cacheMetaData(1)
+
+myb <- B()
+bret = bar(myb)
+bret2 = cbar(myb)
+bret3 = bar(bret2)
+
+q(save="no")

Lib/r/rtype.swg

@@ -14,12 +14,13 @@
 %typemap("rtype") bool, bool * "logical"
 %typemap("rtype") enum SWIGTYPE "character"
 %typemap("rtype") enum SWIGTYPE * "character"
-%typemap("rtype") enum SWIGTYPE *const "character"
+%typemap("rtype") enum SWIGTYPE *const& "character"
 %typemap("rtype") enum SWIGTYPE & "character"
 %typemap("rtype") const enum SWIGTYPE & "character"
 %typemap("rtype") enum SWIGTYPE && "character"
 %typemap("rtype") SWIGTYPE * "$R_class"
 %typemap("rtype") SWIGTYPE *const "$R_class"
+%typemap("rtype") SWIGTYPE *const& "$*R_class"
 %typemap("rtype") SWIGTYPE & "$R_class"
 %typemap("rtype") SWIGTYPE && "$R_class"
 %typemap("rtype") SWIGTYPE "$&R_class"
@@ -93,7 +94,7 @@
 %typemap(scoercein) enum SWIGTYPE *const
   %{  $input = enumToInteger($input, "$R_class"); %}
 
-%typemap(scoercein) SWIGTYPE, SWIGTYPE *, SWIGTYPE *const, SWIGTYPE &, SWIGTYPE &&
+%typemap(scoercein) SWIGTYPE, SWIGTYPE *, SWIGTYPE *const, SWIGTYPE *const&, SWIGTYPE &, SWIGTYPE &&
  %{ if (inherits($input, "ExternalReference")) $input = slot($input,"ref"); %}
 
 /*
@@ -172,6 +173,10 @@ string &, std::string &
   %{ $result <- if (is.null($result)) $result
   else new("$R_class", ref=$result); %}
 
+%typemap(scoerceout) SWIGTYPE *const&
+  %{ $result <- if (is.null($result)) $result
+  else new("$*R_class", ref=$result); %}
+
 
 /* Override the SWIGTYPE * above. */
 %typemap(scoerceout) char,