From d78efdd98d68ce604fe41a959803a711ec4f0e78 Mon Sep 17 00:00:00 2001
From: Luca Toniolo <10792599+grandixximo@users.noreply.github.com>
Date: Sat, 30 May 2026 22:15:18 +0800
Subject: [PATCH] build: hard-fail configure if asciidoctor is missing

The manpage build rule in docs/src/Submakefile invokes asciidoctor for
every halcompile-built manpage, independent of
--enable-build-documentation.  The configure probe for it was nested
inside `if BUILD_DOCS = yes`, so a plain `./configure
--enable-run-in-place` (no docs opt-in) silently passed and later
crashed make with `asciidoctor: command not found` (issue #4084).

Move the probe out of the BUILD_DOCS gate and promote the warning to a
hard error pointing at the package name on Debian / Fedora / RubyGems.
The PDF / HTML / Rouge probes stay gated since they only matter when
--enable-build-documentation was passed.
---
 src/configure.ac | 21 ++++++++++++---------
 1 file changed, 12 insertions(+), 9 deletions(-)

diff --git a/src/configure.ac b/src/configure.ac
index 3d00a98eb54..68396f2630b 100644
--- a/src/configure.ac
+++ b/src/configure.ac
@@ -1067,16 +1067,19 @@ AC_ARG_ENABLE(build-documentation,
 # --enable-build-documentation=html).  =html itself warn-and-disables
 # only the missing PDF tools; users who want PDF best-effort can pass
 # =html and rebuild after installing the missing tools.
-if ( test "$BUILD_DOCS" = "yes" ) ; then
-    AC_PATH_PROG(ASCIIDOCTOR,asciidoctor,"none")
-    if ( test "none" = "$ASCIIDOCTOR" ) ; then
-        AC_MSG_WARN([no asciidoctor, documentation cannot be built
-install with "sudo apt-get install asciidoctor"])
-        BUILD_DOCS=no
-        BUILD_DOCS_PDF=no
-        BUILD_DOCS_HTML=no
-    fi
+# asciidoctor is required unconditionally: the manpage build rule in
+# docs/src/Submakefile invokes it for every halcompile-built manpage
+# (5axisgui.1 etc.), independent of --enable-build-documentation.
+# Without it `make` later dies with "asciidoctor: command not found"
+# in the middle of the build.  Hard-fail at configure time instead.
+AC_PATH_PROG(ASCIIDOCTOR,asciidoctor,"none")
+if ( test "none" = "$ASCIIDOCTOR" ) ; then
+    AC_MSG_ERROR([no asciidoctor, manpages cannot be built
+install with "sudo apt-get install asciidoctor" on Debian / Ubuntu,
+"sudo dnf install rubygem-asciidoctor" on Fedora, or "gem install asciidoctor"])
+fi
 
+if ( test "$BUILD_DOCS" = "yes" ) ; then
     if ( test "$BUILD_DOCS" = "yes" ) ; then
         AC_PATH_PROG(GS,gs,"none")
         if ( test "none" = "$GS" ) ; then