SDL: cmake: make HEADERS_DIR a required argument of SDL_generate_manpages

From 5be5000fa17a485a6080e061153b7823f5d6385e Mon Sep 17 00:00:00 2001
From: Anonymous Maarten <[EMAIL REDACTED]>
Date: Fri, 29 Sep 2023 03:42:33 +0200
Subject: [PATCH] cmake: make HEADERS_DIR a required argument of
 SDL_generate_manpages

---
 CMakeLists.txt          | 3 ++-
 cmake/sdlmanpages.cmake | 2 +-
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index c244bc09617e..6f03982f3638 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -2804,7 +2804,7 @@ set(SDL_REVISION "" CACHE STRING "Custom SDL revision (overrides SDL_REVISION_SU
 if(NOT SDL_REVISION)
   set(SDL_REVISION_SUFFIX "" CACHE STRING "Suffix for the SDL revision")
   if(EXISTS "${CMAKE_CURRENT_SOURCE_DIR}/VERSION.txt")
-    # If VERSION exists, it contains the SDL version
+    # If VERSION.txt exists, it contains the SDL version
     file(READ "${CMAKE_CURRENT_SOURCE_DIR}/VERSION.txt" SDL_REVISION_CENTER)
     string(STRIP "${SDL_REVISION_CENTER}" SDL_REVISION_CENTER)
   else()
@@ -3364,6 +3364,7 @@ if(NOT SDL_DISABLE_INSTALL)
 
   if(NOT SDL_DISABLE_INSTALL_DOCS)
     SDL_generate_manpages(
+      HEADERS_DIR "${PROJECT_SOURCE_DIR}/include/SDL3"
       SYMBOL "SDL_Init"
       WIKIHEADERS_PL_PATH "${CMAKE_CURRENT_SOURCE_DIR}/build-scripts/wikiheaders.pl"
       REVISION "${SDL_REVISION}"
diff --git a/cmake/sdlmanpages.cmake b/cmake/sdlmanpages.cmake
index cc706dd709fe..dc3ebb6bb6ea 100644
--- a/cmake/sdlmanpages.cmake
+++ b/cmake/sdlmanpages.cmake
@@ -19,7 +19,7 @@ function(SDL_generate_manpages)
   endif()
 
   if(NOT ARG_HEADERS_DIR)
-    set(ARG_HEADERS_DIR "${PROJECT_SOURCE_DIR}/include/SDL3")
+    message(FATAL_ERROR "Missing required HEADERS_DIR argument")
   endif()
 
   # FIXME: get rid of SYMBOL and let the perl script figure out the dependencies