Add a test for foreign_archive of cxx files

test/blackbox-tests/test-cases/foreign_cxx_library.t/dune

@@ -0,0 +1,4 @@
+(executable
+ (name main)
+ (modes byte)
+ (libraries hello_world))

test/blackbox-tests/test-cases/foreign_cxx_library.t/dune-project

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+(lang dune 2.9)

test/blackbox-tests/test-cases/foreign_cxx_library.t/lib/dune

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+(library
+ (name hello_world)
+ (foreign_archives hello_world)
+ (c_library_flags -lstdc++))
+
+(foreign_library
+ (archive_name hello_world)
+ (language cxx)
+ (names hello_world))

test/blackbox-tests/test-cases/foreign_cxx_library.t/lib/hello_world.cpp

@@ -0,0 +1,8 @@
+#include <iostream>
+
+extern "C" void hello_world ();
+
+void hello_world ()
+{
+  std::cout << "Hello World!";
+}

test/blackbox-tests/test-cases/foreign_cxx_library.t/lib/hello_world.ml

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+external hello_world : unit -> unit = "hello_world"

test/blackbox-tests/test-cases/foreign_cxx_library.t/main.ml

@@ -0,0 +1 @@
+Hello_world.hello_world ();;

test/blackbox-tests/test-cases/foreign_cxx_library.t/run.t

@@ -0,0 +1,2 @@
+Building a cxx library should run ocamlmklib with "-lstdc++".
+  $ dune build --verbose 2>&1 | grep -e "ocamlmklib" | grep -qe "-lstdc++"