Add a -atomic switch to write and change clang.kak to take advantage

doc/pages/commands.asciidoc

@@ -52,13 +52,20 @@ of the file onto the filesystem
         Otherwise, does nothing.
 
 
-*write[!]* [-sync] [<filename>]::
+*write[!]* [-sync] [-atomic] [<filename>]::
     *alias* w +
     write buffer to <filename> or use its name if filename is not
     given. If the file is write-protected, its permissions are temporarily
     changed to allow saving the buffer and restored afterwards when
     the write! command is used.
 
+    *-sync*:::
+        Synchronise the filesystem after the write
+
+    *-stomic*:::
+        Force writing to a temoprary file then renaming to the target file
+        so that the modification appears automatically.
+
 *write-all* [-sync]::
     *alias* wa +
     write all changed buffers that are associated to a file

rc/tools/clang.kak

@@ -10,7 +10,6 @@ declare-option -docstring "options to pass to the `clang` shell command" \
 declare-option -docstring "directory from which to invoke clang" \
     str clang_directory
 
-declare-option -hidden str clang_tmp_dir
 declare-option -hidden completions clang_completions
 declare-option -hidden line-specs clang_flags
 declare-option -hidden line-specs clang_errors
@@ -22,24 +21,22 @@ The syntaxic errors detected during parsing are shown when auto-diagnostics are
     evaluate-commands %sh{
         dir=$(mktemp -d "${TMPDIR:-/tmp}"/kak-clang.XXXXXXXX)
         mkfifo ${dir}/fifo
-        printf %s\\n "set-option buffer clang_tmp_dir ${dir}"
-        printf %s\\n "evaluate-commands -no-hooks write -sync ${dir}/buf"
-    }
-    # end the previous %sh{} so that its output gets interpreted by kakoune
-    # before launching the following as a background task.
-    evaluate-commands %sh{
-        dir=${kak_opt_clang_tmp_dir}
-        printf %s\\n "evaluate-commands -draft %{
+        printf %s\\n "
+            evaluate-commands -no-hooks write -sync -atomic ${dir}/buf
+            evaluate-commands -draft %{
                 edit! -fifo ${dir}/fifo -debug *clang-output*
                 set-option buffer filetype make
                 set-option buffer make_current_error_line 0
                 hook -once -always buffer BufCloseFifo .* %{ nop %sh{ rm -r ${dir} } }
             }"
+
         # this runs in a detached shell, asynchronously, so that kakoune does
         # not hang while clang is running. As completions references a cursor
         # position and a buffer timestamp, only valid completions should be
         # displayed.
         ((
+            until [ -f ${dir}/buf ]; do :; done # wait for the buffer to be written
+
             if [ -n "$kak_opt_clang_directory" ]; then
                 cd "$kak_opt_clang_directory"
             fi

src/commands.cc

@@ -461,11 +461,14 @@ const CommandDesc force_edit_cmd = {
 };
 
 const ParameterDesc write_params{
-    { { "sync", { false, "force the synchronization of the file onto the filesystem" } } },
+    {
+        { "sync", { false, "force the synchronization of the file onto the filesystem" } },
+        { "atomic", { false, "force the writemethod to replace" } },
+    },
     ParameterDesc::Flags::SwitchesOnlyAtStart, 0, 1
 };
 
-void do_write_buffer(Context& context, Optional<String> filename, WriteFlags flags)
+void do_write_buffer(Context& context, Optional<String> filename, WriteFlags flags, bool atomic = false)
 {
     Buffer& buffer = context.buffer();
 
@@ -479,7 +482,7 @@ void do_write_buffer(Context& context, Optional<String> filename, WriteFlags fla
         throw runtime_error("cannot overwrite the buffer when in readonly mode");
 
     auto effective_filename = not filename ? buffer.name() : parse_filename(*filename);
-    auto mode = context.options()["writemethod"].get<WriteMethod>();
+    auto mode = atomic ? WriteMethod::Replace : context.options()["writemethod"].get<WriteMethod>();
 
     context.hooks().run_hook(Hook::BufWritePre, effective_filename, context);
     write_buffer_to_file(buffer, effective_filename, mode, flags);
@@ -492,7 +495,8 @@ void write_buffer(const ParametersParser& parser, Context& context, const ShellC
     return do_write_buffer(context,
                            parser.positional_count() > 0 ? parser[0] : Optional<String>{},
                            (parser.get_switch("sync") ? WriteFlags::Sync : WriteFlags::None) |
-                           (force ? WriteFlags::Force : WriteFlags::None));
+                           (force ? WriteFlags::Force : WriteFlags::None),
+                           (bool)parser.get_switch("atomic"));
 }
 
 const CommandDesc write_cmd = {