From 0673c265df80f66552d1f09bce7512c9595fbee7 Mon Sep 17 00:00:00 2001
From: Andreas Sturmlechner <asturm@gentoo.org>
Date: Tue, 17 Dec 2024 23:46:31 +0100
Subject: [PATCH] ecm.eclass: Introduce _ecm_handbook_optional() to support
 BUILD_DOC

Signed-off-by: Andreas Sturmlechner <asturm@gentoo.org>
---
 eclass/ecm.eclass | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/eclass/ecm.eclass b/eclass/ecm.eclass
index 2ca2b3a9e5..78a28adda2 100644
--- a/eclass/ecm.eclass
+++ b/eclass/ecm.eclass
@@ -595,6 +595,18 @@ ecm_src_prepare() {
 	fi
 }
 
+# @FUNCTION: _ecm_handbook_optional
+# @DESCRIPTION:
+# Use with ECM_HANDBOOK=optional; ticks either -DBUILD_DOC if available,
+# or -DCMAKE_DISABLE_FIND_PACKAGE_KF${_KFSLOT}DocTools
+_ecm_handbook_optional() {
+	if grep -Eq "option.*BUILD_DOC" CMakeLists.txt; then
+		echo "-DBUILD_DOC=$(usex handbook)"
+	else
+		echo "-DCMAKE_DISABLE_FIND_PACKAGE_KF${_KFSLOT}DocTools=$(usex !handbook)"
+	fi
+}
+
 # @FUNCTION: ecm_src_configure
 # @DESCRIPTION:
 # Wrapper for cmake_src_configure with extra logic for magic handling of
@@ -621,7 +633,7 @@ ecm_src_configure() {
 	fi
 
 	if [[ ${ECM_HANDBOOK} = optional ]] ; then
-		cmakeargs+=( -DCMAKE_DISABLE_FIND_PACKAGE_KF${_KFSLOT}DocTools=$(usex !handbook) )
+		cmakeargs+=( $(_ecm_handbook_optional) )
 	fi
 
 	if in_iuse designer && [[ ${ECM_DESIGNERPLUGIN} = true ]]; then