Error if get_namespace() fails (#396)

Rather than hanging indefinitely when a function is called

NEWS.md

@@ -1,5 +1,8 @@
 # cpp11 (development version)
 
+* `cpp11::package` now errors if given a package name that hasn't been loaded
+  yet. Previously it would cause R to hang indefinitely (#317).
+
 * `cpp11::function` now protects its underlying function, for maximum safety
   (#294).
 

cpp11test/src/test-function.cpp

@@ -36,4 +36,8 @@ context("function-C++") {
 
     close(con);
   }
+
+  test_that("unknown packages cause an error (#317)") {
+    expect_error_as(cpp11::package("definitely_not_a_package"), cpp11::unwind_exception);
+  }
 }

inst/include/cpp11/function.hpp

@@ -68,7 +68,7 @@ class package {
       return R_BaseEnv;
     }
     sexp name_sexp = safe[Rf_install](name);
-    return safe[Rf_findVarInFrame](R_NamespaceRegistry, name_sexp);
+    return safe[detail::r_env_get](R_NamespaceRegistry, name_sexp);
   }
 
   // Either base env or in namespace registry, so no protection needed