Add a descriptive test

Author: DavisVaughan

cpp11test/R/cpp11.R

@@ -223,3 +223,11 @@ rcpp_sum_dbl_accumulate_ <- function(x_sxp) {
 rcpp_grow_ <- function(n_sxp) {
   .Call(`_cpp11test_rcpp_grow_`, n_sxp)
 }
+
+test_destruction_inner <- function() {
+  invisible(.Call(`_cpp11test_test_destruction_inner`))
+}
+
+test_destruction_outer <- function() {
+  invisible(.Call(`_cpp11test_test_destruction_outer`))
+}

cpp11test/src/cpp11.cpp

@@ -422,10 +422,26 @@ extern "C" SEXP _cpp11test_rcpp_grow_(SEXP n_sxp) {
     return cpp11::as_sexp(rcpp_grow_(cpp11::as_cpp<cpp11::decay_t<SEXP>>(n_sxp)));
   END_CPP11
 }
+// test-protect-nested.cpp
+void test_destruction_inner();
+extern "C" SEXP _cpp11test_test_destruction_inner() {
+  BEGIN_CPP11
+    test_destruction_inner();
+    return R_NilValue;
+  END_CPP11
+}
+// test-protect-nested.cpp
+void test_destruction_outer();
+extern "C" SEXP _cpp11test_test_destruction_outer() {
+  BEGIN_CPP11
+    test_destruction_outer();
+    return R_NilValue;
+  END_CPP11
+}
 
 extern "C" {
 /* .Call calls */
-extern SEXP run_testthat_tests(SEXP);
+extern SEXP run_testthat_tests(void *);
 
 static const R_CallMethodDef CallEntries[] = {
     {"_cpp11test_col_sums",                 (DL_FUNC) &_cpp11test_col_sums,                 1},
@@ -483,6 +499,8 @@ static const R_CallMethodDef CallEntries[] = {
     {"_cpp11test_sum_int_for2_",            (DL_FUNC) &_cpp11test_sum_int_for2_,            1},
     {"_cpp11test_sum_int_for_",             (DL_FUNC) &_cpp11test_sum_int_for_,             1},
     {"_cpp11test_sum_int_foreach_",         (DL_FUNC) &_cpp11test_sum_int_foreach_,         1},
+    {"_cpp11test_test_destruction_inner",   (DL_FUNC) &_cpp11test_test_destruction_inner,   0},
+    {"_cpp11test_test_destruction_outer",   (DL_FUNC) &_cpp11test_test_destruction_outer,   0},
     {"_cpp11test_upper_bound",              (DL_FUNC) &_cpp11test_upper_bound,              2},
     {"run_testthat_tests",                  (DL_FUNC) &run_testthat_tests,                  1},
     {NULL, NULL, 0}

cpp11test/src/test-protect-nested.cpp

@@ -0,0 +1,81 @@
+#include "cpp11/function.hpp"
+#include "cpp11/protect.hpp"
+#include "testthat.h"
+
+#ifdef HAS_UNWIND_PROTECT
+
+/*
+ * See https://github.com/r-lib/cpp11/pull/327 for full details.
+ *
+ * - `cpp11::package("cpp11test")["test_destruction_outer"]` uses
+ *   `unwind_protect()` to call R level `test_destruction_outer()` but no entry
+ *   macros are set up. Instead we are going to catch exceptions that get here
+ *   with `expect_error_as()`.
+ *
+ *   - Call R level `test_destruction_outer()` to set up `BEGIN_CPP11` /
+ *     `END_CPP11` entry macros.
+ *
+ *   - C++ `test_destruction_outer()` goes through `unwind_protect()` to call
+ *     the R level `test_destruction_inner()`.
+ *
+ *     - R level `test_destruction_inner()` sets up its own `BEGIN_CPP11` /
+ *       `END_CPP11` entry macros.
+ *
+ *     - C++ `test_destruction_inner()` goes through `unwind_protect()` to call
+ *       `Rf_error()` (i.e., we are nested within `unwind_protect()`s!).
+ *
+ *     - `longjmp()` is caught from inner `unwind_protect()`, and an exception
+ *       is thrown which is caught by the inner entry macros, allowing us to run
+ *       the destructor of `x`, then we let R continue the unwind process.
+ *
+ *   - This `longjmp()`s again and is caught by the outer `unwind_protect()`, an
+ *     exception is thrown which is caught by the outer entry macros, and we let
+ *     R continue the unwind process one more time.
+ *
+ * - This `longjmp()` is caught by `cpp11::package()`'s `unwind_protect()`,
+ *   an exception is thrown, and that is caught by `expect_error_as()`.
+ */
+
+// Global variable to detect if the destructor has been run or not
+static bool destructed = false;
+
+class HasDestructor {
+ public:
+  ~HasDestructor();
+};
+
+HasDestructor::~HasDestructor() {
+  // Destructor has run!
+  destructed = true;
+}
+
+[[cpp11::register]] void test_destruction_inner() {
+  // Expect that `x`'s destructor gets to run on the way out
+  HasDestructor x{};
+  cpp11::stop("oh no!");
+}
+
+[[cpp11::register]] void test_destruction_outer() {
+  const auto test_destruction_inner =
+    cpp11::package("cpp11test")["test_destruction_inner"];
+  test_destruction_inner();
+}
+
+context("unwind_protect-nested-C++") {
+  test_that(
+    "nested `unwind_protect()` (with entry macros set up) will run destructors"
+    "(#327)") {
+    const auto fn = [&] {
+      const auto test_destruction_outer =
+        cpp11::package("cpp11test")["test_destruction_outer"];
+      test_destruction_outer();
+    };
+
+    expect_error_as(fn(), cpp11::unwind_exception);
+    expect_true(destructed);
+
+    destructed = false;
+  }
+}
+
+#endif