runtime(rust): improve loading time

fixes: #17745
closes: #17749

Signed-off-by: Christian Brabandt <cb@256bit.org>

runtime/autoload/rustfmt.vim

@@ -1,6 +1,8 @@
 " Author: Stephen Sugden <stephen@stephensugden.com>
 " Last Modified: 2023-09-11
-" Last Change:   2025 Mar 31 by Vim project (rename s:RustfmtConfigOptions())
+" Last Change:
+" 2025 Mar 31 by Vim project (rename s:RustfmtConfigOptions())
+" 2025 Jul 14 by Vim project (don't parse rustfmt version automatically #17745)
 "
 " Adapted from https://github.com/fatih/vim-go
 " For bugs, patches and license go to https://github.com/rust-lang/rust.vim
@@ -22,6 +24,12 @@ if !exists("g:rustfmt_fail_silently")
 endif
 
 function! rustfmt#DetectVersion()
+    let s:rustfmt_version = "0"
+    let s:rustfmt_help = ""
+    let s:rustfmt_unstable_features = ""
+    if !get(g:, 'rustfmt_detect_version', 0)
+        return s:rustfmt_version
+    endif
     " Save rustfmt '--help' for feature inspection
     silent let s:rustfmt_help = system(g:rustfmt_command . " --help")
     let s:rustfmt_unstable_features = s:rustfmt_help =~# "--unstable-features"
@@ -30,9 +38,7 @@ function! rustfmt#DetectVersion()
     silent let l:rustfmt_version_full = system(g:rustfmt_command . " --version")
     let l:rustfmt_version_list = matchlist(l:rustfmt_version_full,
         \    '\vrustfmt ([0-9]+[.][0-9]+[.][0-9]+)')
-    if len(l:rustfmt_version_list) < 3
+    if len(l:rustfmt_version_list) >= 3
-        let s:rustfmt_version = "0"
-    else
         let s:rustfmt_version = l:rustfmt_version_list[1]
     endif
     return s:rustfmt_version
@@ -63,6 +69,12 @@ function! s:RustfmtWriteMode()
 endfunction
 
 function! rustfmt#RustfmtConfigOptions()
+    let default = '--edition 2018'
+
+    if !get(g:, 'rustfmt_find_toml', 0)
+        return default
+    endif
+
     let l:rustfmt_toml = findfile('rustfmt.toml', expand('%:p:h') . ';')
     if l:rustfmt_toml !=# ''
         return '--config-path '.shellescape(fnamemodify(l:rustfmt_toml, ":p"))
@@ -74,7 +86,7 @@ function! rustfmt#RustfmtConfigOptions()
     endif
 
     " Default to edition 2018 in case no rustfmt.toml was found.
-    return '--edition 2018'
+    return default
 endfunction
 
 function! s:RustfmtCommandRange(filename, line1, line2)

runtime/doc/ft_rust.txt

@@ -159,7 +159,20 @@ g:rustfmt_emit_files~
 	determines whether to run rustfmt with '--emit=files' (when 1 is
 	provided) instead of '--write-mode=overwrite'. >
 	    let g:rustfmt_emit_files = 0
-
+<
+                                                       *g:rustfmt_detect_version*
+g:rustfmt_detect_version~
+	When set to 1, will try to parse the version output from "rustfmt".
+	Disabled by default for performance reasons
+>
+	    let g:rustfmt_detect_version = 1
+<
+                                                       *g:rustfmt_find_toml*
+g:rustfmt_emit_files~
+	When set to 1, will try to find "rustfmt.toml" file by searching from
+	current path upwards.  Disabled by default for performance reasons
+>
+	    let g:rustfmt_find_toml = 1
 <
                                                           *g:rust_playpen_url*
 g:rust_playpen_url~

runtime/doc/tags

@@ -7851,8 +7851,10 @@ g:rustc_path	ft_rust.txt	/*g:rustc_path*
 g:rustfmt_autosave	ft_rust.txt	/*g:rustfmt_autosave*
 g:rustfmt_autosave_if_config_present	ft_rust.txt	/*g:rustfmt_autosave_if_config_present*
 g:rustfmt_command	ft_rust.txt	/*g:rustfmt_command*
+g:rustfmt_detect_version	ft_rust.txt	/*g:rustfmt_detect_version*
 g:rustfmt_emit_files	ft_rust.txt	/*g:rustfmt_emit_files*
 g:rustfmt_fail_silently	ft_rust.txt	/*g:rustfmt_fail_silently*
+g:rustfmt_find_toml	ft_rust.txt	/*g:rustfmt_find_toml*
 g:rustfmt_options	ft_rust.txt	/*g:rustfmt_options*
 g:statusline_winid	options.txt	/*g:statusline_winid*
 g:syntax_on	syntax.txt	/*g:syntax_on*