input: Binding set clone must deep clone actions

Fixes a crash found in Discord.

Cloning the keybinding set previously shallow copied the actions, but
actions may contain pointers. These pointer values must be deep copied
to avoid dangling references when the underlying memory is freed.

src/input/Binding.zig

@@ -421,6 +421,8 @@ pub const Action = union(enum) {
     ///
     crash: CrashThread,
 
+    pub const Key = @typeInfo(Action).Union.tag_type.?;
+
     pub const CrashThread = enum {
         main,
         io,
@@ -430,6 +432,16 @@ pub const Action = union(enum) {
     pub const CursorKey = struct {
         normal: []const u8,
         application: []const u8,
+
+        pub fn clone(
+            self: CursorKey,
+            alloc: Allocator,
+        ) Allocator.Error!CursorKey {
+            return .{
+                .normal = try alloc.dupe(u8, self.normal),
+                .application = try alloc.dupe(u8, self.application),
+            };
+        }
     };
 
     pub const AdjustSelection = enum {
@@ -773,6 +785,50 @@ pub const Action = union(enum) {
         }
     }
 
+    /// Clone this action with the given allocator. The allocator
+    /// should be an arena-style allocator since fine-grained
+    /// deallocation is not possible.
+    pub fn clone(self: Action, alloc: Allocator) Allocator.Error!Action {
+        return switch (self) {
+            inline else => |value, tag| @unionInit(
+                Action,
+                @tagName(tag),
+                try cloneValue(alloc, value),
+            ),
+        };
+    }
+
+    fn cloneValue(
+        alloc: Allocator,
+        value: anytype,
+    ) Allocator.Error!@TypeOf(value) {
+        return switch (@typeInfo(@TypeOf(value))) {
+            .Void,
+            .Int,
+            .Float,
+            .Enum,
+            => value,
+
+            .Pointer => |info| slice: {
+                comptime assert(info.size == .Slice);
+                break :slice try alloc.dupe(
+                    info.child,
+                    value,
+                );
+            },
+
+            .Struct => |info| if (info.is_tuple)
+                value
+            else
+                try value.clone(alloc),
+
+            else => {
+                @compileLog(@TypeOf(value));
+                @compileError("unexpected type");
+            },
+        };
+    }
+
     /// Returns a hash code that can be used to uniquely identify this
     /// action.
     pub fn hash(self: Action) u64 {
@@ -1101,6 +1157,16 @@ pub const Set = struct {
         action: Action,
         flags: Flags,
 
+        pub fn clone(
+            self: Leaf,
+            alloc: Allocator,
+        ) Allocator.Error!Leaf {
+            return .{
+                .action = try self.action.clone(alloc),
+                .flags = self.flags,
+            };
+        }
+
         pub fn hash(self: Leaf) u64 {
             var hasher = std.hash.Wyhash.init(0);
             self.action.hash(&hasher);
@@ -1390,8 +1456,9 @@ pub const Set = struct {
         // If we have any leaders we need to clone them.
         var it = result.bindings.iterator();
         while (it.next()) |entry| switch (entry.value_ptr.*) {
-            // No data to clone
+            // Leaves could have data to clone (i.e. text actions
-            .leaf => {},
+            // contain allocated strings).
+            .leaf => |*s| s.* = try s.clone(alloc),
 
             // Must be deep cloned.
             .leader => |*s| {
@@ -2128,3 +2195,22 @@ test "set: consumed state" {
     try testing.expect(s.get(.{ .key = .{ .translated = .a } }).?.value_ptr.* == .leaf);
     try testing.expect(s.get(.{ .key = .{ .translated = .a } }).?.value_ptr.*.leaf.flags.consumed);
 }
+
+test "Action: clone" {
+    const testing = std.testing;
+    var arena = std.heap.ArenaAllocator.init(testing.allocator);
+    defer arena.deinit();
+    const alloc = arena.allocator();
+
+    {
+        var a: Action = .ignore;
+        const b = try a.clone(alloc);
+        try testing.expect(b == .ignore);
+    }
+
+    {
+        var a: Action = .{ .text = "foo" };
+        const b = try a.clone(alloc);
+        try testing.expect(b == .text);
+    }
+}