Preemptively unset WAYLAND_DISPLAY

CHANGELOG.md

@@ -6,6 +6,17 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic
 Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [Unreleased]
+
+### Changed
+
+- Yabridge now preemptively unsets the `WAYLAND_DISPLAY` environment variable
+  when launching Wine. Upstream Wine currently does not yet have a Wayland
+  driver, but future versions may. When that happens yabridge's X11 window
+  embedding would otherwise suddenly start breaking spectacularly. This change
+  makes sure that Wine will keep using X11 even if Wayland support becomes
+  available at some point.
+
 ## [5.0.4] - 2023-02-23
 
 ### Fixed

src/common/process.cpp

@@ -174,6 +174,13 @@ void ProcessEnvironment::insert(const std::string& key,
     variables_.push_back(key + "=" + value);
 }
 
+size_t ProcessEnvironment::erase(const std::string& key) {
+    return std::erase_if(variables_, [&key](const std::string& variable) {
+        return variable.starts_with(key) && variable.size() > key.size() &&
+               variable[key.size()] == '=';
+    });
+}
+
 char* const* ProcessEnvironment::make_environ() const {
     recreated_environ_.clear();
 

src/common/process.h

@@ -101,6 +101,14 @@ class ProcessEnvironment {
      */
     void insert(const std::string& key, const std::string& value);
 
+    /**
+     * Remove an environment variable from the environment. Returns the number
+     * of elements erased (to stay consistent with the STL map interface). This
+     * can be higher than 1 if the map contains duplicate or overwritten
+     * environment variables.
+     */
+    size_t erase(const std::string& key);
+
     /**
      * Create an environ-like object from the updated environment that can be
      * passed to the `exec*e()` functions. These pointers will be invalidated

src/plugin/utils.cpp

@@ -70,6 +70,14 @@ ProcessEnvironment PluginInfo::create_host_env() const {
                },
                wine_prefix_);
 
+    // As of writing upstream Wine does not yet have a Wayland driver, but one
+    // is in the process of being merged. If this ever becomes enabled by
+    // default on distros, Wine could suddenly start using using Wayland instead
+    // of X11. This would break yabridge's embedding and drag-and-drop handling.
+    // So we'll preemptively avoid this by unsetting the `WAYLAND_DISPLAY`
+    // environment variable.
+    env.erase("WAYLAND_DISPLAY");
+
     return env;
 }
 

src/plugin/utils.h

@@ -79,6 +79,9 @@ struct PluginInfo {
      * `WINEPREFIX` was already set then nothing will be changed. Otherwise
      * we'll set `WINEPREFIX` to the detected Wine prefix, or it will be left
      * unset if we could not detect a prefix.
+     *
+     * This also unsets `WAYLAND_DISPLAY` so if Wine has been compiled with
+     * Wayland support, it won't suddenly start using that over X11.
      */
     ProcessEnvironment create_host_env() const;
 

tools/yabridgectl/src/util.rs

@@ -356,6 +356,10 @@ pub fn verify_wine_setup(config: &mut Config) -> Result<()> {
     let wine_binary = env::var("WINELOADER").unwrap_or_else(|_| String::from("wine"));
     let wine_version_output = Command::new(&wine_binary)
         .arg("--version")
+        // NOTE: This mimics the setup used in `PluginInfo::create_host_env()`. The X11 window
+        //       embedding will break when future Wine versions start defaulting to a native Wayland
+        //       driver, so we'll prevent that from happening.
+        .env_remove("WAYLAND_DISPLAY")
         .output()
         .with_context(|| {
             format!(