fix(libcairo): keep font options storage private

core/libs/prx/libcairo/FontOptions.cpp

@@ -1,23 +1,31 @@
 #include "prx/libcairo/include/InventoryExports.hpp"
 #include <cstdlib>
 
-struct cairo_font_options_t {
+namespace {
+
+struct CairoFontOptionsStorage {
     cairo_antialias_t antialias;
     cairo_subpixel_order_t subpixel_order;
     cairo_hint_style_t hint_style;
     cairo_hint_metrics_t hint_metrics;
 };
 
-namespace {
+const CairoFontOptionsStorage nilOptions{};
 
-const cairo_font_options_t nilOptions{};
+CairoFontOptionsStorage* Storage(cairo_font_options_t* options) {
+    return reinterpret_cast<CairoFontOptionsStorage*>(options);
+}
+
+const CairoFontOptionsStorage* Storage(const cairo_font_options_t* options) {
+    return reinterpret_cast<const CairoFontOptionsStorage*>(options);
+}
 
 bool Invalid(const cairo_font_options_t* options) {
-    return options == nullptr || options == &nilOptions;
+    return options == nullptr || Storage(options) == &nilOptions;
 }
 
 cairo_font_options_t* Nil() {
-    return const_cast<cairo_font_options_t*>(&nilOptions);
+    return reinterpret_cast<cairo_font_options_t*>(const_cast<CairoFontOptionsStorage*>(&nilOptions));
 }
 
 }
@@ -25,14 +33,14 @@ cairo_font_options_t* Nil() {
 extern "C" {
 
 cairo_font_options_t* APS5_VABI cairo_font_options_create() {
-    auto* options = static_cast<cairo_font_options_t*>(std::calloc(1, sizeof(cairo_font_options_t)));
-    return options != nullptr ? options : Nil();
+    auto* options = std::calloc(1, sizeof(CairoFontOptionsStorage));
+    return options != nullptr ? static_cast<cairo_font_options_t*>(options) : Nil();
 }
 
 cairo_font_options_t* APS5_VABI cairo_font_options_copy(const cairo_font_options_t* original) {
     if (Invalid(original)) return Nil();
     auto* options = cairo_font_options_create();
-    if (options != Nil()) *options = *original;
+    if (options != Nil()) *Storage(options) = *Storage(original);
     return options;
 }
 
@@ -41,23 +49,23 @@ void APS5_VABI cairo_font_options_destroy(cairo_font_options_t* options) {
 }
 
 void APS5_VABI cairo_font_options_set_antialias(cairo_font_options_t* options, cairo_antialias_t antialias) {
-    if (!Invalid(options)) options->antialias = antialias;
+    if (!Invalid(options)) Storage(options)->antialias = antialias;
 }
 
 cairo_antialias_t APS5_VABI cairo_font_options_get_antialias(const cairo_font_options_t* options) {
-    return Invalid(options) ? CAIRO_ANTIALIAS_DEFAULT : options->antialias;
+    return Invalid(options) ? CAIRO_ANTIALIAS_DEFAULT : Storage(options)->antialias;
 }
 
 void APS5_VABI cairo_font_options_set_hint_style(cairo_font_options_t* options, cairo_hint_style_t hint_style) {
-    if (!Invalid(options)) options->hint_style = hint_style;
+    if (!Invalid(options)) Storage(options)->hint_style = hint_style;
 }
 
 void APS5_VABI cairo_font_options_set_hint_metrics(cairo_font_options_t* options, cairo_hint_metrics_t hint_metrics) {
-    if (!Invalid(options)) options->hint_metrics = hint_metrics;
+    if (!Invalid(options)) Storage(options)->hint_metrics = hint_metrics;
 }
 
 void APS5_VABI cairo_font_options_set_subpixel_order(cairo_font_options_t* options, cairo_subpixel_order_t subpixel_order) {
-    if (!Invalid(options)) options->subpixel_order = subpixel_order;
+    if (!Invalid(options)) Storage(options)->subpixel_order = subpixel_order;
 }
 
 }