Drop support for R 3.6 and remove dead code (#411)

* Drop support for R 3.6

* NEWS bullet

* Remove dead code from tests

* Remove dead code from `environment.hpp`

* Remove dead code from `protect.hpp`

* Simplify `altrep.hpp` as much as possible

Likely still need to keep it around for compatibility reasons

* NEWS bullet about `altrep.hpp`

* Bring back dummy `HAS_UNWIND_PROTECT` and remove all usage of it

Author: DavisVaughan

.github/workflows/R-CMD-check.yaml

@@ -27,8 +27,6 @@ jobs:
           - {os: macos-latest,   r: 'release'}
 
           - {os: windows-latest, r: 'release'}
-          # Use 3.6 to trigger usage of RTools35
-          - {os: windows-latest, r: '3.6'}
           # use 4.1 to check with rtools40's older compiler
           - {os: windows-latest, r: '4.1'}
 

DESCRIPTION

@@ -18,7 +18,7 @@ License: MIT + file LICENSE
 URL: https://cpp11.r-lib.org, https://github.com/r-lib/cpp11
 BugReports: https://github.com/r-lib/cpp11/issues
 Depends:
-    R (>= 3.6.0)
+    R (>= 4.0.0)
 Suggests:
     bench,
     brio,

NEWS.md

@@ -1,5 +1,16 @@
 # cpp11 (development version)
 
+* Because cpp11 now requires R >=4.0.0 and `R_UnwindProtect()` is always
+  available, `HAS_UNWIND_PROTECT` is no longer useful. Please avoid using it,
+  as we'd like to remove it in the future (#411).
+
+* Because cpp11 now requires R >=4.0.0 and ALTREP is always available, the
+  `cpp11/altrep.hpp` file is no longer useful. Please avoid using `#include "cpp11/altrep.hpp"` and `HAS_ALTREP` as we'd like to remove them in the
+  future (#411).
+
+* cpp11 now requires R >=4.0.0, in line with the
+  [tidyverse version policy](https://www.tidyverse.org/blog/2019/04/r-version-support/) (#411).
+
 # cpp11 0.5.0
 
 ## R non-API related changes

cpp11test/src/safe.cpp

@@ -26,9 +26,7 @@
   if (buf[0] != '\0') {
     Rf_error("%s", buf);
   } else if (err != R_NilValue) {
-#ifdef HAS_UNWIND_PROTECT
     R_ContinueUnwind(err);
-#endif
   }
 
   return R_NilValue;

cpp11test/src/test-as.cpp

@@ -49,11 +49,9 @@ context("as_cpp-C++") {
     auto x5 = cpp11::as_cpp<unsigned long>(r);
     expect_true(x5 == 42UL);
 
-#ifdef HAS_UNWIND_PROTECT
     /* throws a runtime exception if the value is not a integerish one */
     REAL(r)[0] = 42.5;
     expect_error(cpp11::as_cpp<int>(r));
-#endif
 
     UNPROTECT(1);
   }

cpp11test/src/test-doubles.cpp

@@ -233,7 +233,7 @@ context("doubles-C++") {
     UNPROTECT(1);
   }
 
-#if defined(__APPLE__) && defined(R_VERSION) && R_VERSION >= R_Version(3, 5, 0)
+#if defined(__APPLE__)
   test_that("writable::doubles(ALTREP_SEXP)") {
     // ALTREP compact-seq
     auto seq = cpp11::package("base")["seq"];

cpp11test/src/test-integers.cpp

@@ -1,4 +1,3 @@
-#include "Rversion.h"
 #include "cpp11/R.hpp"
 #include "cpp11/doubles.hpp"
 #include "cpp11/function.hpp"
@@ -218,7 +217,7 @@ context("integers-C++") {
     expect_true(x[2] == 3);
   }
 
-#if defined(__APPLE__) && defined(R_VERSION) && R_VERSION >= R_Version(3, 5, 0)
+#if defined(__APPLE__)
   test_that("writable::integers(ALTREP_SEXP)") {
     // ALTREP compact-seq
     auto seq = cpp11::package("base")["seq"];

cpp11test/src/test-protect-nested.cpp

@@ -2,8 +2,6 @@
 #include "cpp11/protect.hpp"
 #include "testthat.h"
 
-#ifdef HAS_UNWIND_PROTECT
-
 /*
  * See https://github.com/r-lib/cpp11/pull/327 for full details.
  *
@@ -77,5 +75,3 @@ context("unwind_protect-nested-C++") {
     destructed = false;
   }
 }
-
-#endif

cpp11test/src/test-protect.cpp

@@ -2,7 +2,6 @@
 #include "cpp11/protect.hpp"
 #include "testthat.h"
 
-#ifdef HAS_UNWIND_PROTECT
 context("unwind_protect-C++") {
   test_that("unwind_protect works if there is no error") {
     SEXP out = PROTECT(cpp11::unwind_protect([&] {
@@ -49,5 +48,3 @@ context("unwind_protect-C++") {
     expect_error_as(cpp11::safe[Rf_allocVector](REALSXP, -1), cpp11::unwind_exception);
   }
 }
-
-#endif

cpp11test/src/test-r_vector.cpp

@@ -7,14 +7,6 @@
 
 #include <algorithm>  // for max_element
 
-#ifdef _WIN32
-#include "Rversion.h"
-#define CPP11_HAS_IS_UTILITIES R_VERSION >= R_Version(4, 0, 0)
-#else
-#define CPP11_HAS_IS_UTILITIES 1
-#endif
-
-#if CPP11_HAS_IS_UTILITIES
 context("r_vector-capabilities-C++") {
   test_that("read only vector capabilities") {
     using cpp11::integers;
@@ -77,7 +69,6 @@ context("r_vector-capabilities-C++") {
     expect_true(std::is_move_assignable<integers::proxy>::value);
   }
 }
-#endif
 
 context("r_vector-C++") {
   test_that("writable vector temporary isn't leaked (integer) (#338)") {