feat(tui): graduate the +tui feature

This was previously disabled due to build issues on windows.
Any reasonable platform can now be expected to have the necessary
interfaces to build and run the TUI subsystem.

Runtime quality issues of using the TUI (on any new platform) are not
relevant here. Just run Nvim in an external UI instead of the TUI as always.

6 files changed, 25 insertions, 50 deletions

diff --git a/CMakeLists.txt b/CMakeLists.txt
index c3f490fc83..cb5cb09595 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -498,34 +498,30 @@ if(MSGPACK_HAS_FLOAT32)
   add_definitions(-DNVIM_MSGPACK_HAS_FLOAT32)
 endif()
 
-option(FEAT_TUI "Enable the Terminal UI" ON)
-
-if(FEAT_TUI)
-  find_package(UNIBILIUM 2.0 REQUIRED)
-  include_directories(SYSTEM ${UNIBILIUM_INCLUDE_DIRS})
-
-  list(APPEND CMAKE_REQUIRED_INCLUDES "${UNIBILIUM_INCLUDE_DIRS}")
-  list(APPEND CMAKE_REQUIRED_LIBRARIES "${UNIBILIUM_LIBRARIES}")
-  check_c_source_compiles("
-  #include <unibilium.h>
-
-  int
-  main(void)
-  {
-    unibi_str_from_var(unibi_var_from_str(\"\"));
-    return unibi_num_from_var(unibi_var_from_num(0));
-  }
-  " UNIBI_HAS_VAR_FROM)
-  list(REMOVE_ITEM CMAKE_REQUIRED_INCLUDES "${UNIBILIUM_INCLUDE_DIRS}")
-  list(REMOVE_ITEM CMAKE_REQUIRED_LIBRARIES "${UNIBILIUM_LIBRARIES}")
-  if(UNIBI_HAS_VAR_FROM)
-    add_definitions(-DNVIM_UNIBI_HAS_VAR_FROM)
-  endif()
+find_package(UNIBILIUM 2.0 REQUIRED)
+include_directories(SYSTEM ${UNIBILIUM_INCLUDE_DIRS})
+
+list(APPEND CMAKE_REQUIRED_INCLUDES "${UNIBILIUM_INCLUDE_DIRS}")
+list(APPEND CMAKE_REQUIRED_LIBRARIES "${UNIBILIUM_LIBRARIES}")
+check_c_source_compiles("
+#include <unibilium.h>
 
-  find_package(LibTermkey 0.22 REQUIRED)
-  include_directories(SYSTEM ${LIBTERMKEY_INCLUDE_DIRS})
+int
+main(void)
+{
+  unibi_str_from_var(unibi_var_from_str(\"\"));
+  return unibi_num_from_var(unibi_var_from_num(0));
+}
+" UNIBI_HAS_VAR_FROM)
+list(REMOVE_ITEM CMAKE_REQUIRED_INCLUDES "${UNIBILIUM_INCLUDE_DIRS}")
+list(REMOVE_ITEM CMAKE_REQUIRED_LIBRARIES "${UNIBILIUM_LIBRARIES}")
+if(UNIBI_HAS_VAR_FROM)
+  add_definitions(-DNVIM_UNIBI_HAS_VAR_FROM)
 endif()
 
+find_package(LibTermkey 0.22 REQUIRED)
+include_directories(SYSTEM ${LIBTERMKEY_INCLUDE_DIRS})
+
 find_package(LIBVTERM 0.3 REQUIRED)
 include_directories(SYSTEM ${LIBVTERM_INCLUDE_DIRS})
 
diff --git a/cmake.config/config.h.in b/cmake.config/config.h.in
index 59be83fb5e..283a1d0c47 100644
--- a/cmake.config/config.h.in
+++ b/cmake.config/config.h.in
@@ -56,8 +56,6 @@
 #endif
 #cmakedefine HAVE_FORKPTY
 
-#cmakedefine FEAT_TUI
-
 #ifndef UNIT_TESTING
 #cmakedefine LOG_LIST_ACTIONS
 #endif
diff --git a/runtime/doc/news.txt b/runtime/doc/news.txt
index f5ebacdf98..25e753aaed 100644
--- a/runtime/doc/news.txt
+++ b/runtime/doc/news.txt
@@ -118,6 +118,10 @@ The following changes to existing APIs or features add new behavior.
   thread was used). This is not supposed to be a visible change to the user,
   but might be the cause of subtle changes of behavior and bugs.
 
+  Previously, the TUI could be disabled as a build time feature (+tui/-tui),
+  resulting in a nvim binary which only could be run headless or embedded
+  in an external process. As of this version, TUI is always avalibale.
+
 ==============================================================================
 REMOVED FEATURES                                                 *news-removed*
 
diff --git a/src/nvim/CMakeLists.txt b/src/nvim/CMakeLists.txt
index 92f75dbf75..6b92d0caa8 100755
--- a/src/nvim/CMakeLists.txt
+++ b/src/nvim/CMakeLists.txt
@@ -110,9 +110,6 @@ foreach(subdir
         viml
         viml/parser
        )
-  if(${subdir} MATCHES "tui" AND NOT FEAT_TUI)
-    continue()
-  endif()
 
   file(MAKE_DIRECTORY ${GENERATED_DIR}/${subdir})
   file(MAKE_DIRECTORY ${GENERATED_INCLUDES_DIR}/${subdir})
diff --git a/src/nvim/ui.c b/src/nvim/ui.c
index f40d8b52ca..33c7d0c1fe 100644
--- a/src/nvim/ui.c
+++ b/src/nvim/ui.c
@@ -128,32 +128,16 @@ static UI *builtin_ui = NULL;
 void ui_free_all_mem(void)
 {
   kv_destroy(call_buf);
-# ifdef FEAT_TUI
   if (builtin_ui) {
     tui_free_all_mem(builtin_ui);
     builtin_ui = NULL;
   }
-# endif
 }
 #endif
 
 void ui_builtin_start(void)
 {
-#ifdef FEAT_TUI
   builtin_ui = tui_start();
-#else
-  fprintf(stderr, "Nvim headless-mode started.\n");
-  size_t len;
-  char **addrs = server_address_list(&len);
-  if (addrs != NULL) {
-    fprintf(stderr, "Listening on:\n");
-    for (size_t i = 0; i < len; i++) {
-      fprintf(stderr, "\t%s\n", addrs[i]);
-    }
-    xfree(addrs);
-  }
-  fprintf(stderr, "Press CTRL+C to exit.\n");
-#endif
 }
 
 UI *ui_get_by_index(int idx)
diff --git a/src/nvim/version.c b/src/nvim/version.c
index 98719fce4a..92122b2523 100644
--- a/src/nvim/version.c
+++ b/src/nvim/version.c
@@ -69,11 +69,7 @@ static char *features[] = {
   "-iconv",
 #endif
 
-#ifdef FEAT_TUI
   "+tui",
-#else
-  "-tui",
-#endif
   NULL
 };