Commit: patch 9.1.1687: filetype: autoconf filetype not always correct

[Christian Brabandt]

patch 9.1.1687: filetype: autoconf filetype not always correct

Commit: https://github.com/vim/vim/commit/2b55474f0a78bd252290578a5774316dc5f60180
Author: Damien Lejay <dam...@lejay.be>
Date: Tue Aug 26 17:09:47 2025 +0200

patch 9.1.1687: filetype: autoconf filetype not always correct

Problem: filetype: autoconf filetype not always correct
Solution: Detect aclocal.m4 as config filetype, detect configure.ac as
config filetype, fall back to POSIX m4 (Damien Lejay).

closes: #18065

Signed-off-by: Damien Lejay <dam...@lejay.be>
Signed-off-by: Christian Brabandt <c...@256bit.org>

diff --git a/runtime/autoload/dist/ft.vim b/runtime/autoload/dist/ft.vim
index 380b97bf4..2172626dc 100644
--- a/runtime/autoload/dist/ft.vim
+++ b/runtime/autoload/dist/ft.vim
@@ -3,7 +3,7 @@ vim9script
# Vim functions for file type detection
#
# Maintainer: The Vim Project <https://github.com/vim/vim>
-# Last Change: 2025 Jul 09
+# Last Change: 2025 Aug 26
# Former Maintainer: Bram Moolenaar <Br...@vim.org>

# These functions are moved here from runtime/filetype.vim to make startup
@@ -599,6 +599,50 @@ export def FTm()
endif
enddef

+# For files ending in *.m4, distinguish:
+# – *.html.m4 files
+# – files in the Autoconf M4 dialect
+# – files in POSIX M4
+export def FTm4()
+ var fname = expand('%:t')
+ var path = expand('%:p:h')
+
+ # Case 0: canonical Autoconf file
+ if fname ==# 'aclocal.m4'
+ setf config
+ return
+ endif
+
+ # Case 1: html.m4
+ if fname =~# 'html\.m4$'
+ setf htmlm4
+ return
+ endif
+
+ # Case 2: repo heuristic (nearby configure.ac)
+ if filereadable(path .. '/../configure.ac') || filereadable(path .. '/configure.ac')
+ setf config
+ return
+ endif
+
+ # Case 3: content heuristic (scan first ~200 lines)
+ # Signals:
+ # - Autoconf macro prefixes: AC_/AM_/AS_/AU_/AT_
+ var n = 1
+ var max = min([200, line('$')])
+ while n <= max
+ var line = getline(n)
+ if line =~# '^\s*A[CMSUT]_'
+ setf config
+ return
+ endif
+ n += 1
+ endwhile
+
+ # Case 4: default to POSIX M4
+ setf m4
+enddef
+
export def FTmake()
# Check if it is a BSD, GNU, or Microsoft Makefile
unlet! b:make_flavor
diff --git a/runtime/filetype.vim b/runtime/filetype.vim
index 1b0e4183f..af21a47fb 100644
--- a/runtime/filetype.vim
+++ b/runtime/filetype.vim
@@ -1,7 +1,7 @@
" Vim support file to detect file types
"
" Maintainer: The Vim Project <https://github.com/vim/vim>
-" Last Change: 2025 Aug 10
+" Last Change: 2025 Aug 26
" Former Maintainer: Bram Moolenaar <Br...@vim.org>

" Listen very carefully, I will say this only once
@@ -219,8 +219,8 @@ au BufNewFile,BufRead *.au3 setf autoit
" Autohotkey
au BufNewFile,BufRead *.ahk setf autohotkey

-" Autotest .at files are actually m4
-au BufNewFile,BufRead *.at setf m4
+" Autotest .at files are actually Autoconf M4
+au BufNewFile,BufRead *.at setf config

" Avenue
au BufNewFile,BufRead *.ave setf ave
@@ -1157,9 +1157,6 @@ au BufNewFile,BufRead *.http setf http
" HTML with Ruby - eRuby
au BufNewFile,BufRead *.erb,*.rhtml setf eruby

-" HTML with M4
-au BufNewFile,BufRead *.html.m4 setf htmlm4
-
" Some template. Used to be HTML Cheetah.
au BufNewFile,BufRead *.tmpl setf template

@@ -1519,8 +1516,8 @@ au BufNewFile,BufRead *.lsl call dist#ft#FTlsl()
au BufNewFile,BufRead *.lss setf lss

" M4
-au BufNewFile,BufRead *.m4
- \ if expand("<afile>") !~? 'html.m4$\|fvwm2rc' | setf m4 | endif
+au BufNewFile,BufRead *.m4 call dist#ft#FTm4()
+
au BufNewFile,BufRead .m4_history setf m4

" MaGic Point
diff --git a/src/testdir/test_filetype.vim b/src/testdir/test_filetype.vim
index 8ac4f54ee..42e4cbcde 100644
--- a/src/testdir/test_filetype.vim
+++ b/src/testdir/test_filetype.vim
@@ -1,5 +1,10 @@
" Test :setfiletype

+" Make VIMRUNTIME and &rtp absolute.
+" Otherwise, a :lcd inside a test would break the relative ../../runtime path.
+let $VIMRUNTIME = fnamemodify($VIMRUNTIME, ':p')
+let &rtp = join(map(split(&rtp, ','), 'fnamemodify(v:val, ":p")'), ',')
+
func Test_backup_strip()
filetype on
let fname = 'Xdetect.js~~~~~~~~~~~'
@@ -186,7 +191,7 @@ def s:GetFilenameChecks(): dict<list<string>>
coco: ['file.atg'],
conaryrecipe: ['file.recipe'],
conf: ['auto.master', 'file.conf', 'texdoc.cnf', '.x11vncrc', '.chktexrc', '.ripgreprc', 'ripgreprc', 'file.ctags'],
- config: ['configure.in', 'configure.ac', '/etc/hostname.file', 'any/etc/hostname.file'],
+ config: ['/etc/hostname.file', 'any/etc/hostname.file', 'configure.in', 'configure.ac', 'alocal.m4', 'file.at'],
confini: ['pacman.conf', 'paru.conf', 'mpv.conf', 'any/.aws/config', 'any/.aws/credentials', 'file.nmconnection',
'any/.gnuradio/grc.conf', 'any/gnuradio/config.conf', 'any/gnuradio/conf.d/modtool.conf'],
context: ['tex/context/any/file.tex', 'file.mkii', 'file.mkiv', 'file.mkvi', 'file.mkxl', 'file.mklx'],
@@ -466,7 +471,7 @@ def s:GetFilenameChecks(): dict<list<string>>
'any/m17n-db/file.ali', 'any/m17n-db/file.cs', 'any/m17n-db/file.dir', 'any/m17n-db/FLT/file.flt', 'any/m17n-db/file.fst', 'any/m17n-db/LANGDATA/file.lnm', 'any/m17n-db/file.mic', 'any/m17n-db/MIM/file.mim', 'any/m17n-db/file.tbl'],
m3build: ['m3makefile', 'm3overrides'],
m3quake: ['file.quake', 'cm3.cfg'],
- m4: ['file.at', '.m4_history'],
+ m4: ['.m4_history'],
mail: ['snd.123', '.letter', '.letter.123', '.followup', '.article', '.article.123', 'pico.123', 'mutt-xx-xxx', 'muttng-xx-xxx', 'ae123.txt', 'file.eml', 'reportbug-file'],
mailaliases: ['/etc/mail/aliases', '/etc/aliases', 'any/etc/aliases', 'any/etc/mail/aliases'],
mailcap: ['.mailcap', 'mailcap'],
@@ -1180,6 +1185,43 @@ endfunc
" Keep sorted.
"""""""""""""""""""""""""""""""""""""""""""""""""

+" Since dist#ft#FTm4() looks around for configure.ac
+" the test needs to isolate itself in a fresh temporary project tree,
+" so that no configure.ac from another test (or from the repo root)
+" accidentally influences detection.
+func Test_autoconf_file()
+ filetype on
+ " Make a fresh sandbox far away from any configure.ac
+ let save_cwd = getcwd()
+ call mkdir('Xproj_autoconf/a/b', 'p')
+ execute 'lcd Xproj_autoconf/a/b'
+
+ try
+ call writefile(['AC_CHECK_HEADERS([stdio.h])'], 'foo.m4', 'D')
+ split foo.m4
+ call assert_equal('config', &filetype)
+ bwipe!
+
+ call writefile(['AS_IF([true], [:])'], 'bar.m4', 'D')
+ split bar.m4
+ call assert_equal('config', &filetype)
+ bwipe!
+
+ call writefile(['AC_INIT([foo],[1.0])'], 'configure.ac')
+ call mkdir('m4', 'p')
+ call writefile([], 'm4/empty.m4', 'D')
+ split m4/empty.m4
+ call assert_equal('config', &filetype)
+ bwipe!
+ finally
+ call delete('m4', 'rf')
+ call delete('configure.ac')
+ execute 'lcd' fnameescape(save_cwd)
+ call delete('Xproj_autoconf', 'rf')
+ filetype off
+ endtry
+endfunc
+
func Test_bas_file()
filetype on

@@ -1925,6 +1967,30 @@ func Test_m_file()
filetype off
endfunc

+" Since dist#ft#FTm4() looks around for configure.ac
+" the test needs to isolate itself in a fresh temporary project tree,
+" so that no configure.ac from another test (or from the repo root)
+" accidentally influences detection.
+func Test_m4_file()
+ filetype on
+ let save_cwd = getcwd()
+
+ " Make a fresh sandbox far away from any configure.ac
+ call mkdir('Xsandbox/level1/level2', 'p')
+ execute 'lcd Xsandbox/level1/level2'
+
+ try
+ call writefile(["define(`FOO', `bar')", "FOO"], 'plain.m4', 'D')
+ split plain.m4
+ call assert_equal('m4', &filetype)
+ bwipe!
+ finally
+ execute 'lcd' fnameescape(save_cwd)
+ call delete('Xsandbox', 'rf')
+ filetype off
+ endtry
+endfunc
+
func Test_mod_file()
filetype on

diff --git a/src/version.c b/src/version.c
index 4f47ec268..309ddf7f7 100644
--- a/src/version.c
+++ b/src/version.c
@@ -724,6 +724,8 @@ static char *(features[]) =

static int included_patches[] =
{ /* Add new patch number below this line */
+/**/
+ 1687,
/**/
1686,
/**/