Fix Windows DLL link errors: force instantiation of Ref<string> adapters

StringRef, ConstStringRef, and ConstStringListRef are exported
(FTXUI_EXPORT(SCREEN)), but every one of their member functions --
including ones inherited from Ref<string>/ConstRef<string> -- is defined
inline in the header and never odr-used from within libftxui-screen
itself. MSVC only emits (and therefore dllexports) an inline member
function into the DLL that first odr-uses it, so consumers linking
against the dllimport declaration got LNK2001 unresolved externals.

Add ref.cpp to the screen library across all build systems (CMake,
Bazel, Meson) with a throwaway function that exercises every member,
forcing MSVC to instantiate and export them.

Author: ArthurSonzogni

BUILD.bazel

@@ -45,6 +45,7 @@ ftxui_cc_library(
         "src/ftxui/screen/string_internal.hpp",
         "src/ftxui/screen/terminal.cpp",
         "src/ftxui/screen/util.hpp",
+        "src/ftxui/util/ref.cpp",
     ],
     hdrs = [
         "include/ftxui/screen/box.hpp",

CMakeLists.txt

@@ -49,6 +49,8 @@ add_library(screen
   include/ftxui/screen/string.hpp
   include/ftxui/screen/surface.hpp
   include/ftxui/util/export.hpp
+  include/ftxui/util/ref.hpp
+  src/ftxui/util/ref.cpp
   src/ftxui/screen/box.cpp
   src/ftxui/screen/color.cpp
   src/ftxui/screen/color_info.cpp

src/ftxui/screen/meson.build

@@ -6,4 +6,5 @@ screen_sources = files(
   'screen.cpp',
   'string.cpp',
   'terminal.cpp',
+  '../util/ref.cpp',
 )

src/ftxui/util/ref.cpp

@@ -0,0 +1,49 @@
+// Copyright 2026 Arthur Sonzogni. All rights reserved.
+// Use of this source code is governed by the MIT license that can be found in
+// the LICENSE file.
+#include "ftxui/util/ref.hpp"
+
+#include <utility>
+
+namespace ftxui {
+
+namespace {
+
+// StringRef, ConstStringRef, and ConstStringListRef are exported
+// (FTXUI_EXPORT(SCREEN)), but all of their member functions -- including
+// ones inherited from Ref<string>/ConstRef<string> -- are defined inline in
+// the header and never odr-used from within libftxui-screen itself. On
+// Windows, MSVC only emits (and therefore dllexports) an inline member
+// function into the DLL that first odr-uses it; otherwise consumers linking
+// against the dllimport declaration get an unresolved external symbol. This
+// function exists solely to force that instantiation.
+[[maybe_unused]] void ForceSymbolInstantiation() {
+  StringRef s = "a";
+  StringRef s2(s);
+  StringRef s3(std::move(s2));
+  s = s3;
+  s = std::move(s3);
+  (void)s();
+  (void)*s;
+  (void)s.operator->();
+
+  ConstStringRef c = "a";
+  ConstStringRef c2(c);
+  ConstStringRef c3(std::move(c2));
+  c = c3;
+  c = std::move(c3);
+  (void)c();
+  (void)*c;
+
+  ConstStringListRef l;
+  ConstStringListRef l2(l);
+  ConstStringListRef l3(std::move(l2));
+  l = l3;
+  l = std::move(l3);
+  (void)l.size();
+  (void)l[0];
+}
+
+}  // namespace
+
+}  // namespace ftxui