[groff] 40/50: Check for m4 program at configuration time.

[G. Branden Robinson]

gbranden pushed a commit to branch master
in repository groff.

commit ffb985975130d2d94a7f6ac287dc373c2e60fc34
Author: G. Branden Robinson <g.branden.robinson@gmail.com>
AuthorDate: Fri May 20 08:29:51 2022 -0500

    Check for m4 program at configuration time.
    
    * m4/groff.m4 (GROFF_PROG_M4): Define new macro to perform the check and
      error out if the program is missing.
    
    * configure.ac: Call the new macro.
    
    * tmac/tmac.am (tmac/groff_man.7.man,
      tmac/groff_man_style.7.man): Use the new implicitly AC_SUBST-ed
      variable `M4` to run the program.
    
    * NEWS: Document build dependency.
---
 ChangeLog    | 11 +++++++++++
 NEWS         |  4 ++++
 configure.ac |  1 +
 m4/groff.m4  |  9 +++++++++
 tmac/tmac.am |  4 ++--
 5 files changed, 27 insertions(+), 2 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index b4ba6d06..9a9ca6c9 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,14 @@
+2022-05-20  G. Branden Robinson <g.branden.robinson@gmail.com>
+
+       Check for m4 program at configuration time.
+
+       * m4/groff.m4 (GROFF_PROG_M4): Define new macro to perform the
+       check and error out if the program is missing.
+       * configure.ac: Call the new macro.
+       * tmac/tmac.am (tmac/groff_man.7.man,
+       tmac/groff_man_style.7.man): Use the new implicitly AC_SUBST-ed
+       variable `M4` to run the program.
+
 2022-05-20  G. Branden Robinson <g.branden.robinson@gmail.com>
 
        * m4/groff.m4 (GROFF_PROG_YACC): Update wording of error
diff --git a/NEWS b/NEWS
index 052b6985..b84902e6 100644
--- a/NEWS
+++ b/NEWS
@@ -423,6 +423,10 @@ o Because all generated forms of groff's Texinfo manual 
are now included
 o Building groff from its distribution archive no longer requires byacc
   (or GNU Bison) to be installed.
 
+o m4 is now required to build.  Any m4 that implements the features
+  documented in the Version 7 Unix m4(1) man page, and the `-D` option,
+  should suffice.
+
 o New 'configure' options --{en,dis}able-groff-allocator control whether
   groff uses its own malloc/free-wrapping allocator to implement all C++
   new/delete operations.  groff has used this allocator for over 30
diff --git a/configure.ac b/configure.ac
index 9b69b41d..eea5a847 100644
--- a/configure.ac
+++ b/configure.ac
@@ -65,6 +65,7 @@ GROFF_PRINT
 GROFF_REFERDIR_DEFAULT
 AC_PROG_EGREP
 GROFF_PROG_YACC
+GROFF_PROG_M4
 GROFF_MAKEINFO
 GROFF_TEXI2DVI
 AC_PROG_RANLIB
diff --git a/m4/groff.m4 b/m4/groff.m4
index cc8fa515..f6719195 100644
--- a/m4/groff.m4
+++ b/m4/groff.m4
@@ -73,6 +73,15 @@ AC_DEFUN([GROFF_PERL],
    AX_PROG_PERL_VERSION([$PERLVERSION], true, \
      AC_MSG_ERROR([perl version is too old], 1))])
 
+# We need m4 to generate some man pages.
+
+AC_DEFUN([GROFF_PROG_M4], [
+  AC_CHECK_PROGS([M4], [m4], [missing])
+  if test "$M4" = missing
+  then
+    AC_MSG_ERROR([could not find 'm4'], 1)
+  fi
+])
 
 # We need makeinfo from Texinfo 5.0 or newer, for @codequoteundirected.
 # The minor version checking logic is present for future needs.
diff --git a/tmac/tmac.am b/tmac/tmac.am
index c1a428e0..c79b38ad 100644
--- a/tmac/tmac.am
+++ b/tmac/tmac.am
@@ -231,11 +231,11 @@ $(M4CHECK): tmac/groff_man.7.man.in
          $(tmac_srcdir)/groff_man.7.man.in > $@
 
 tmac/groff_man.7.man: tmac/groff_man.7.man.in $(M4CHECK)
-       $(AM_V_GEN)m4 -D_groff_man_not_style \
+       $(AM_V_GEN)$(M4) -D_groff_man_not_style \
          $(tmac_srcdir)/groff_man.7.man.in > $@
 
 tmac/groff_man_style.7.man: tmac/groff_man.7.man.in $(M4CHECK)
-       $(AM_V_GEN)m4 -D_groff_man_style \
+       $(AM_V_GEN)$(M4) -D_groff_man_style \
          $(tmac_srcdir)/groff_man.7.man.in > $@
 
 # The installation of groff compatibility wrappers for vendor-provided