GH-48631: [R] Non-API calls: 'ATTRIB', 'SET_ATTRIB' (#48634)

### Rationale for this change

CRAN complains about non-API calls

### What changes are included in this PR?

Update those items to use alternative approaches

### Are these changes tested?

Well, if the tests pass I think we're good?

### Are there any user-facing changes?

Nope

### Summary of AI changes

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Have added comments inline regarding assumptions behind changes, and where I questioned those to try to verify it.

Sources referenced in approach:
  - Rdatatable/data.table#7487 - similar fixes
  - https://cran.r-project.org/doc/manuals/r-release/R-ints.html on `DUPLICATE_ATTRIB`

* GitHub Issue: #48631

Authored-by: Nic Crane <thisisnic@gmail.com>
Signed-off-by: Nic Crane <thisisnic@gmail.com>

Author: thisisnic

r/src/altrep.cpp

@@ -149,8 +149,8 @@ struct AltrepVectorBase {
   // What gets printed on .Internal(inspect(<the altrep object>))
   static Rboolean Inspect(SEXP alt, int pre, int deep, int pvec,
                           void (*inspect_subtree)(SEXP, int, int, int)) {
-    SEXP data_class_sym = CAR(ATTRIB(ALTREP_CLASS(alt)));
-    const char* class_name = CHAR(PRINTNAME(data_class_sym));
+    SEXP class_sym = R_altrep_class_name(alt);
+    const char* class_name = CHAR(PRINTNAME(class_sym));
 
     if (IsMaterialized(alt)) {
       Rprintf("materialized %s len=%ld\n", class_name,
@@ -574,11 +574,10 @@ struct AltrepFactor : public AltrepVectorBase<AltrepFactor> {
     // the representation integer vector
     SEXP dup = PROTECT(Rf_shallow_duplicate(Materialize(alt)));
 
-    // additional attributes from the altrep
-    SEXP atts = PROTECT(Rf_duplicate(ATTRIB(alt)));
-    SET_ATTRIB(dup, atts);
+    // copy attributes from the altrep object
+    DUPLICATE_ATTRIB(dup, alt);
 
-    UNPROTECT(2);
+    UNPROTECT(1);
     return dup;
   }
 
@@ -1094,9 +1093,7 @@ SEXP MakeAltrepVector(const std::shared_ptr<ChunkedArray>& chunked_array) {
 
 bool is_arrow_altrep(SEXP x) {
   if (ALTREP(x)) {
-    SEXP info = ALTREP_CLASS_SERIALIZED_CLASS(ALTREP_CLASS(x));
-    SEXP pkg = ALTREP_SERIALIZED_CLASS_PKGSYM(info);
-
+    SEXP pkg = R_altrep_class_package(x);
     if (pkg == symbols::arrow) return true;
   }
 
@@ -1160,8 +1157,8 @@ sexp test_arrow_altrep_is_materialized(sexp x) {
     return Rf_ScalarLogical(NA_LOGICAL);
   }
 
-  sexp data_class_sym = CAR(ATTRIB(ALTREP_CLASS(x)));
-  std::string class_name(CHAR(PRINTNAME(data_class_sym)));
+  SEXP class_sym = R_altrep_class_name(x);
+  std::string class_name(CHAR(PRINTNAME(class_sym)));
 
   int result = NA_LOGICAL;
   if (class_name == "arrow::array_dbl_vector") {
@@ -1191,8 +1188,8 @@ bool test_arrow_altrep_force_materialize(sexp x) {
     stop("x is already materialized");
   }
 
-  sexp data_class_sym = CAR(ATTRIB(ALTREP_CLASS(x)));
-  std::string class_name(CHAR(PRINTNAME(data_class_sym)));
+  SEXP class_sym = R_altrep_class_name(x);
+  std::string class_name(CHAR(PRINTNAME(class_sym)));
 
   if (class_name == "arrow::array_dbl_vector") {
     arrow::r::altrep::AltrepVectorPrimitive<REALSXP>::Materialize(x);

r/src/arrow_cpp11.h

@@ -39,11 +39,6 @@
 #define ARROW_R_DCHECK(EXPR)
 #endif
 
-// For context, see:
-// https://github.com/r-devel/r-svn/blob/6418faeb6f5d87d3d9b92b8978773bc3856b4b6f/src/main/altrep.c#L37
-#define ALTREP_CLASS_SERIALIZED_CLASS(x) ATTRIB(x)
-#define ALTREP_SERIALIZED_CLASS_PKGSYM(x) CADR(x)
-
 #if (R_VERSION < R_Version(3, 5, 0))
 #define LOGICAL_RO(x) ((const int*)LOGICAL(x))
 #define INTEGER_RO(x) ((const int*)INTEGER(x))
@@ -55,6 +50,16 @@
 #define DATAPTR(x) (void*)STRING_PTR(x)
 #endif
 
+// R_altrep_class_name and R_altrep_class_package don't exist before R 4.6
+#if R_VERSION < R_Version(4, 6, 0)
+inline SEXP R_altrep_class_name(SEXP x) {
+  return ALTREP(x) ? CAR(ATTRIB(ALTREP_CLASS(x))) : R_NilValue;
+}
+inline SEXP R_altrep_class_package(SEXP x) {
+  return ALTREP(x) ? CADR(ATTRIB(ALTREP_CLASS(x))) : R_NilValue;
+}
+#endif
+
 namespace arrow {
 namespace r {