[vcpkg] Enable reentrant vcpkg calls (#13751)

* [vcpkg] Enable recursive vcpkg calls

Via envvars VCPKG_COMMAND and VCPKG_X_RECURSIVE_DATA. Child processes can call vcpkg via "$VCPKG_COMMAND <args>" in limited internal circumstances.

* [vcpkg] Address CR comments

* [vcpkg] Do not move through Optional<&> into Optional<T>

Co-authored-by: Robert Schumacher <roschuma@microsoft.com>

1 files changed, 21 insertions, 0 deletions

diff --git a/toolsrc/src/vcpkg-test/optional.cpp b/toolsrc/src/vcpkg-test/optional.cpp
index f3c61387f..520867f2c 100644
--- a/toolsrc/src/vcpkg-test/optional.cpp
+++ b/toolsrc/src/vcpkg-test/optional.cpp
@@ -58,6 +58,27 @@ TEST_CASE ("ref conversion", "[optional]")
     REQUIRE(cref_1.get() == &x);
 }
 
+TEST_CASE ("value conversion", "[optional]")
+{
+    using vcpkg::Optional;
+
+    Optional<long> j = 1;
+    Optional<int> i = j;
+    Optional<const char*> cstr = "hello, world!";
+    Optional<std::string> cppstr = cstr;
+
+    std::vector<int> v{1, 2, 3};
+    Optional<std::vector<int>&> o_v(v);
+    REQUIRE(o_v.has_value());
+    REQUIRE(o_v.get()->size() == 3);
+    Optional<std::vector<int>> o_w(std::move(o_v));
+    REQUIRE(o_w.has_value());
+    REQUIRE(o_w.get()->size() == 3);
+    // Moving from Optional<&> should not move the underlying object
+    REQUIRE(o_v.has_value());
+    REQUIRE(o_v.get()->size() == 3);
+}
+
 TEST_CASE ("common_projection", "[optional]")
 {
     using vcpkg::Util::common_projection;