waffle: Remove default values for platform and gl_api

The default values were chosen during CMake configuration time. This was
a recipe for disaster. libwaffle built by different people would have
significant behavioral differences.

- Remove the CMake options waffle_default_{platform,gl_api}.
- Remove the macros WAFFLE_{PLATFORM,GL_API}_DEFAULT.
- Require the user provide attributes WAFFLE_{PLATFORM,GL_API} to
  waffle_init().

Signed-off-by: Chad Versace <chad.versace@linux.intel.com>

3 files changed, 23 insertions, 80 deletions

diff --git a/CMakeLists.txt b/CMakeLists.txt
index a73aab8..ba39a27 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -59,26 +59,6 @@ set(waffle_install_docdir "${CMAKE_INSTALL_PREFIX}/share/doc/waffle"
     CACHE PATH "Directory where documentation will be installed")
 
 #
-# Set waffle_default_platform.
-#
-
-if(CMAKE_SYSTEM_NAME STREQUAL "Linux")
-    set(waffle_default_platform_choices "x11_egl (just one choice for now)")
-    set(waffle_default_platform_regex "x11_egl")
-    set(waffle_default_platform "NOTFOUND"
-        CACHE STRING "One of ${waffle_default_platform_choices}")
-endif(CMAKE_SYSTEM_NAME STREQUAL "Linux")
-
-#
-# Set waffle_default_gl_api.
-#
-
-set(waffle_default_gl_api_choices "gl, gles1, gles2")
-set(waffle_default_gl_api_regex "gl|gles1|gles2")
-set(waffle_default_gl_api "NOTFOUND"
-    CACHE STRING "One of ${waffle_default_gl_api_choices}")
-
-#
 # Set waffle_has_{platform}.
 #
 
@@ -113,33 +93,6 @@ else(waffle_has_x11_egl)
     set(waffle_has_x11 FALSE)
 endif(waffle_has_x11_egl)
 
-# ----------------------------------------------
-# Validate waffle options
-# ----------------------------------------------
-
-#
-# Validate waffle_default_platform.
-#
-
-if(NOT DEFINED waffle_default_platform)
-    message(FATAL_ERROR "Option waffle_default_platform is not defined. Must be one of ${waffle_default_platform_choices}.")
-endif(NOT DEFINED waffle_default_platform)
-
-if(NOT waffle_default_platform MATCHES ${waffle_default_platform_regex})
-    message(FATAL_ERROR "Option waffle_default_platform has bad value '${waffle_default_platform}'. Must be one of ${waffle_default_platform_choices}.")
-endif(NOT waffle_default_platform MATCHES ${waffle_default_platform_regex})
-
-#
-# Validate waffle_default_gl_api.
-#
-
-if(NOT DEFINED waffle_default_gl_api)
-    message(FATAL_ERROR "Option waffle_default_gl_api is not defined. Must be one of ${waffle_default_gl_api_choices}.")
-endif(NOT DEFINED waffle_default_gl_api)
-
-if(NOT waffle_default_gl_api MATCHES ${waffle_default_gl_api_regex})
-    message(FATAL_ERROR "Option waffle_default_gl_api has bad value '${waffle_default_gl_api}'. Must be one of ${waffle_default_gl_api_choices}.")
-endif(NOT waffle_default_gl_api MATCHES ${waffle_default_gl_api_regex})
 
 # ------------------------------------------------------------------------------
 # Compiler Flags
@@ -155,30 +108,6 @@ set(CMAKE_C_FLAGS_DEBUG "-g3 -O0 -DDEBUG")
 set(CMAKE_C_FLAGS_RELEASE "-g1 -02 -DNDEBUG")
 
 #
-# Define WAFFLE_PLATFORM_DEFAULT.
-#
-
-if(waffle_default_platform STREQUAL "glx")
-    add_definitions(-DWAFFLE_PLATFORM_DEFAULT=WAFFLE_PLATFORM_GLX)
-elseif(waffle_default_platform STREQUAL "wayland")
-    add_definitions(-DWAFFLE_PLATFORM_DEFAULT=WAFFLE_PLATFORM_WAYLAND)
-elseif(waffle_default_platform STREQUAL "x11_egl")
-    add_definitions(-DWAFFLE_PLATFORM_DEFAULT=WAFFLE_PLATFORM_X11_EGL)
-endif(waffle_default_platform STREQUAL "glx")
-
-#
-# Define macro WAFFLE_GL_API_DEFAULT.
-#
-
-if(waffle_default_gl_api STREQUAL "gl")
-    add_definitions(-DWAFFLE_GL_API_DEFAULT=WAFFLE_GL)
-elseif(waffle_default_gl_api STREQUAL "gles1")
-    add_definitions(-DWAFFLE_GL_API_DEFAULT=WAFFLE_GLES1)
-elseif(waffle_default_gl_api STREQUAL "gles2")
-    add_definitions(-DWAFFLE_GL_API_DEFAULT=WAFFLE_GLES2)
-endif(waffle_default_gl_api STREQUAL "gl")
-
-#
 # Define macros WAFFLE_HAS_{PLATFORM}.
 #
 # Android is not in this list because it uses a separate build system.
@@ -243,10 +172,6 @@ if(DEFINED waffle_X11-xcb_library)
     message("    X11-xcb: ${waffle_X11-xcb_library}")
 endif(DEFINED waffle_X11-xcb_library)
 message("")
-message("Defaults:")
-message("    default platform: ${waffle_default_platform}")
-message("    default GL API: ${waffle_default_gl_api}")
-message("")
 message("Build type:")
 message("    ${CMAKE_BUILD_TYPE}")
 message("")
diff --git a/include/waffle/waffle_init.h b/include/waffle/waffle_init.h
index 544589e..a45155b 100644
--- a/include/waffle/waffle_init.h
+++ b/include/waffle/waffle_init.h
@@ -45,6 +45,11 @@ extern "C" {
 ///     inherently invalid due to platform or API incompatibilities; for
 ///     example, desktop OpenGL is not available on Android.
 ///
+/// @par Required Attributes
+///
+///     - WAFFLE_PLATFORM
+///     - WAFFLE_GL_API
+///
 /// @par Example: Invalid Attribute List
 ///
 ///     The following is an invalid attribute list because desktop OpenGL is not
@@ -65,7 +70,8 @@ extern "C" {
 ///         to waffle_init(), but has not been reset with waffle_finish().
 ///
 ///     - WAFFLE_BAD_ATTRIBUTE @n
-///         An item in @a attrib_list is unrecognized or has an invalid value.
+///         An item in @a attrib_list is unrecognized, missing, or has an
+///         invalid value.
 ///
 ///     - WAFFLE_INCOMPATIBLE_ATTRIBUTES @n
 ///         The attribute list contains attributes that conflict with each
diff --git a/src/waffle/api/waffle_init.c b/src/waffle/api/waffle_init.c
index 28cf00e..d266a41 100644
--- a/src/waffle/api/waffle_init.c
+++ b/src/waffle/api/waffle_init.c
@@ -27,10 +27,8 @@ waffle_init_parse_attrib_list(
         int *gl_api)
 {
     const int32_t *i;
-
-    // Set defaults.
-    *platform = WAFFLE_PLATFORM_DEFAULT;
-    *gl_api = WAFFLE_GL_API_DEFAULT;
+    bool found_platform = false;
+    bool found_gl_api = false;
 
     for (i = attrib_list; *i != 0; i += 2) {
         const int32_t attr = i[0];
@@ -54,6 +52,7 @@ waffle_init_parse_attrib_list(
 #ifdef WAFFLE_HAS_X11_EGL
                     case WAFFLE_PLATFORM_X11_EGL:
 #endif
+                        found_platform = true;
                         *platform = value;
                         break;
                     default:
@@ -69,6 +68,7 @@ waffle_init_parse_attrib_list(
                     case WAFFLE_GL:
                     case WAFFLE_GLES1:
                     case WAFFLE_GLES2:
+                        found_gl_api = true;
                         *gl_api = value;
                         break;
                     default:
@@ -85,6 +85,18 @@ waffle_init_parse_attrib_list(
         }
     }
 
+    if (!found_platform) {
+        wcore_errorf(WAFFLE_BAD_ATTRIBUTE,
+                     "attribute list is missing WAFFLE_PLATFORM");
+        return false;
+    }
+
+    if (!found_gl_api) {
+        wcore_errorf(WAFFLE_BAD_ATTRIBUTE,
+                     "attribute list is missing WAFFLE_GL_API");
+        return false;
+    }
+
     return true;
 }