configure: Improve Vulkan detection

1. Output Vulkan status in summary
2. Add missing "test" call
3. Check for glslc

The glslc check will be necessary later for the code that automatically
compiles the Vulkan glsl source to Spir-V.
Nothing happens if glslc is not available - unless you modify the glsl.

1 files changed, 7 insertions, 4 deletions

diff --git a/configure.ac b/configure.ac
index df3a187a07..8093384b2a 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1321,27 +1321,29 @@ fi
 
 # Check for Vulkan support.
 
-have_vulkan="no"
 if test "x$enable_vulkan" != "xno"; then
       vulkan_error=""
       AC_CHECK_HEADER([vulkan/vulkan.h], [], [vulkan_error="Vulkan header not found"])
       AC_CHECK_LIB([vulkan], [vkCreateInstance], [], [vulkan_error="Vulkan library not found"])
-      if "x$vulkan_error" != "x"; then
+      if test "x$vulkan_result" != "x"; then
           if "x$enable_vulkan" = "xyes"; then
               AC_MSG_ERROR($vulkan_error)
           else
               AC_MSG_WARN($vulkan_error)
           fi
+          vulkan_result="no ($vulkan_error)"
       else
           GDK_EXTRA_LIBS="-lvulkan"
-          have_vulkan="yes"
           GDK_WINDOWING="$GDK_WINDOWING
 #define GDK_WINDOWING_VULKAN"
+          AC_PATH_PROG([GLSLC], [glslc])
+          vulkan_result="yes"
       fi
 else
       AC_MSG_WARN(Vulkan support explicitly disabled)
+      vulkan_result="no (Vulkan support explicitly disabled)"
 fi
-AM_CONDITIONAL(HAVE_VULKAN, test "$have_vulkan" = "yes")
+AM_CONDITIONAL(HAVE_VULKAN, test "$vulkan_result" = "yes")
 
 # Check for Pango flags
 
@@ -2063,6 +2065,7 @@ echo "        GDK backends:         $GDK_BACKENDS"
 if test "$enable_x11_backend" = "yes"; then
 echo "        X11 extensions:       $X_EXTENSIONS"
 fi
+echo "        Vulkan support:       $vulkan_result"
 echo "        Print backends:       $PRINT_BACKENDS"
 echo "        Dynamic modules:      $build_dynamic_modules"
 echo "        Included immodules:   $included_immodules"