refactor: make freetype flags void for non-freetype backend

This is an attempt to use `void` as type for Freetype Load Flags when
backend does not use these flags.

src/config.zig

@@ -1,6 +1,8 @@
 const builtin = @import("builtin");
 
 const formatter = @import("config/formatter.zig");
+const font = @import("font/main.zig");
+const options = font.options;
 pub const Config = @import("config/Config.zig");
 pub const string = @import("config/string.zig");
 pub const edit = @import("config/edit.zig");
@@ -9,6 +11,18 @@ pub const url = @import("config/url.zig");
 pub const FileFormatter = formatter.FileFormatter;
 pub const entryFormatter = formatter.entryFormatter;
 pub const formatEntry = formatter.formatEntry;
+pub const FreetypeLoadFlags = switch (options.backend) {
+    .freetype,
+    .fontconfig_freetype,
+    .coretext_freetype,
+    => Config.FreetypeLoadFlags,
+
+    .coretext,
+    .coretext_harfbuzz,
+    .coretext_noshape,
+    .web_canvas,
+    => void,
+};
 
 // Field types
 pub const ClipboardAccess = Config.ClipboardAccess;

src/font/Collection.zig

@@ -452,7 +452,18 @@ pub const LoadOptions = struct {
     /// for this is owned by the user and is not freed by the collection.
     metric_modifiers: Metrics.ModifierSet = .{},
 
-    freetype_load_flags: config.Config.FreetypeLoadFlags = .{},
+    freetype_load_flags: config.FreetypeLoadFlags = switch (font.options.backend) {
+        .freetype,
+        .fontconfig_freetype,
+        .coretext_freetype,
+        => .{},
+
+        .coretext,
+        .coretext_harfbuzz,
+        .coretext_noshape,
+        .web_canvas,
+        => {},
+    },
 
     pub fn deinit(self: *LoadOptions, alloc: Allocator) void {
         _ = self;

src/font/SharedGridSet.zig

@@ -428,7 +428,7 @@ pub const DerivedConfig = struct {
     @"adjust-strikethrough-position": ?Metrics.Modifier,
     @"adjust-strikethrough-thickness": ?Metrics.Modifier,
     @"adjust-cursor-thickness": ?Metrics.Modifier,
-    @"freetype-load-flags": configpkg.Config.FreetypeLoadFlags,
+    @"freetype-load-flags": configpkg.FreetypeLoadFlags,
 
     /// Initialize a DerivedConfig. The config should be either a
     /// config.Config or another DerivedConfig to clone from.
@@ -463,7 +463,18 @@ pub const DerivedConfig = struct {
             .@"adjust-strikethrough-position" = config.@"adjust-strikethrough-position",
             .@"adjust-strikethrough-thickness" = config.@"adjust-strikethrough-thickness",
             .@"adjust-cursor-thickness" = config.@"adjust-cursor-thickness",
-            .@"freetype-load-flags" = config.@"freetype-load-flags",
+            .@"freetype-load-flags" = switch (font.options.backend) {
+                .freetype,
+                .fontconfig_freetype,
+                .coretext_freetype,
+                => config.@"freetype-load-flags",
+
+                .coretext,
+                .coretext_harfbuzz,
+                .coretext_noshape,
+                .web_canvas,
+                => {},
+            },
 
             // This must be last so the arena contains all our allocations
             // from above since Zig does assignment in order.
@@ -503,7 +514,18 @@ pub const Key = struct {
     /// font grid.
     font_size: DesiredSize = .{ .points = 12 },
 
-    load_flags: configpkg.Config.FreetypeLoadFlags = .{},
+    load_flags: configpkg.FreetypeLoadFlags = switch (font.options.backend) {
+        .freetype,
+        .fontconfig_freetype,
+        .coretext_freetype,
+        => .{},
+
+        .coretext,
+        .coretext_harfbuzz,
+        .coretext_noshape,
+        .web_canvas,
+        => {},
+    },
 
     const style_offsets_len = std.enums.directEnumArrayLen(Style, 0);
     const StyleOffsets = [style_offsets_len]usize;

src/font/face.zig

@@ -2,7 +2,7 @@ const std = @import("std");
 const builtin = @import("builtin");
 const options = @import("main.zig").options;
 pub const Metrics = @import("face/Metrics.zig");
-const FreetypeLoadFlags = @import("../config/Config.zig").FreetypeLoadFlags;
+const config = @import("../config.zig");
 const freetype = @import("face/freetype.zig");
 const coretext = @import("face/coretext.zig");
 pub const web_canvas = @import("face/web_canvas.zig");
@@ -31,7 +31,7 @@ pub const default_dpi = if (builtin.os.tag == .macos) 72 else 96;
 pub const Options = struct {
     size: DesiredSize,
     metric_modifiers: ?*const Metrics.ModifierSet = null,
-    freetype_load_flags: FreetypeLoadFlags,
+    freetype_load_flags: config.FreetypeLoadFlags,
 };
 
 /// The desired size for loading a font.

src/font/face/freetype.zig

@@ -18,7 +18,7 @@ const Library = font.Library;
 const convert = @import("freetype_convert.zig");
 const fastmem = @import("../../fastmem.zig");
 const quirks = @import("../../quirks.zig");
-const FreetypeLoadFlags = @import("../../config/Config.zig").FreetypeLoadFlags;
+const config = @import("../../config.zig");
 
 const log = std.log.scoped(.font_face);
 
@@ -36,7 +36,7 @@ pub const Face = struct {
     metrics: font.face.Metrics,
 
     /// Metrics for this font face. These are useful for renderers.
-    load_flags: FreetypeLoadFlags,
+    load_flags: config.FreetypeLoadFlags,
 
     /// Set quirks.disableDefaultFontFeatures
     quirks_disable_default_font_features: bool = false,