docs: Improve man page compression code in CMake

The existing code would fail on the second CMake run when gzip wasn't
actually installed, as well as on the first build. The behaviour is
modified as follows:

- ENABLE_MAN_PAGE_COMPRESSION is made a variable, instead of an option
- Its default value is derived from ${GZIP_FOUND}

1 files changed, 11 insertions, 24 deletions

diff --git a/host/docs/CMakeLists.txt b/host/docs/CMakeLists.txt
index cf691a787..8df7c1069 100644
--- a/host/docs/CMakeLists.txt
+++ b/host/docs/CMakeLists.txt
@@ -151,45 +151,32 @@ endif(NOT WIN32)
 
 set(MAN_PAGES_DEPS "NOT_WIN32")
 
-# check to see if ENABLE_MAN_PAGE_COMPRESSION was set in the cmake
-# call, one way or the other
-if(ENABLE_MAN_PAGE_COMPRESSION)
-  set(MAN_PAGE_COMPRESSION_FORCE TRUE)
-else()
-  set(MAN_PAGE_COMPRESSION_FORCE FALSE)
-endif()
-
-option(ENABLE_MAN_PAGE_COMPRESSION "Compress Man Pages if installed." ON)
+# Quietly see if we have GZip, if not, we can skip trying to compress
+# the man pages
+find_package(GZip QUIET)
+set(ENABLE_MAN_PAGE_COMPRESSION ${GZIP_FOUND} CACHE BOOL "Compress Man Pages")
 
 message(STATUS "")
 if(ENABLE_MAN_PAGE_COMPRESSION)
-    find_package(GZip QUIET)
+    # If gzip is not found, this will force failure in
+    # LIBUHD_REGISTER_COMPONENT for ENABLE_MAN_PAGES
+    list(APPEND MAN_PAGES_DEPS "GZIP_FOUND")
     if(GZIP_FOUND)
         message(STATUS "Found GZip: ${GZIP_EXECUTABLE}")
         message(STATUS "")
-        list(APPEND MAN_PAGES_DEPS "GZIP_FOUND")
         message(STATUS "Compressed Man Pages enabled")
     else()
-        message(STATUS "GZip compression program - not found")
+        message(FATAL_ERROR
+                "ENABLE_MAN_PAGE_COMPRESSION is set, "
+                "but GZip compression program not found!")
         message(STATUS "")
-        # was using compressed man pages forced?
-        if(MAN_PAGE_COMPRESSION_FORCE)
-            # yes: GZIP wasn't found
-            # force failure in LIBUHD_REGISTER_COMPONENT for ENABLE_MAN_PAGES
-            list(APPEND MAN_PAGES_DEPS "GZIP_FOUND")
-            message(STATUS "Compressed Man Pages force enabled")
-        else()
-            # no not forced; just don't use compression
-            message(STATUS "Compressed Man Pages optional; disabling")
-        endif()
     endif()
 else()
-    message(STATUS "Compressed Man Pages force disabled")
+    message(STATUS "Compressed Man Pages disabled")
 endif(ENABLE_MAN_PAGE_COMPRESSION)
 message(STATUS "  Override with -DENABLE_MAN_PAGE_COMPRESSION=ON/OFF")
 
 LIBUHD_REGISTER_COMPONENT("Man Pages" ENABLE_MAN_PAGES ON "${MAN_PAGES_DEPS}" OFF OFF)
-
 if(ENABLE_MAN_PAGES)
     #Generate man pages; either compressed or not
     if(ENABLE_MAN_PAGE_COMPRESSION)