Inject typed literal build-option values into a module

build.zig

@@ -113,8 +113,13 @@ fn findOption(name: []const u8) ?spec.Option {
     return null;
 }
 
-fn addBuildOptions(b: *std.Build, module_name: []const u8, option_names: []const []const u8) ?*std.Build.Step.Options {
-    if (option_names.len == 0) return null;
+fn addBuildOptions(
+    b: *std.Build,
+    module_name: []const u8,
+    option_names: []const []const u8,
+    option_values: []const spec.OptionValue,
+) ?*std.Build.Step.Options {
+    if (option_names.len == 0 and option_values.len == 0) return null;
 
     const options = b.addOptions();
     for (option_names) |name| {
@@ -135,6 +140,30 @@ fn addBuildOptions(b: *std.Build, module_name: []const u8, option_names: []const
         }
     }
 
+    // Injected literal values, for options modules a repo's build.zig would
+    // normally synthesize (e.g. tigerbeetle's vsr_options).
+    for (option_values) |ov| {
+        if (std.mem.eql(u8, ov.kind, "bool")) {
+            options.addOption(bool, ov.name, ov.bool_value);
+        } else if (std.mem.eql(u8, ov.kind, "string")) {
+            options.addOption([]const u8, ov.name, ov.string_value);
+        } else if (std.mem.eql(u8, ov.kind, "u32")) {
+            options.addOption(u32, ov.name, ov.u32_value);
+        } else if (std.mem.eql(u8, ov.kind, "opt_commit")) {
+            // A ?[40]u8 git commit hash: the 40-char value, or null.
+            if (ov.commit_value) |commit| {
+                var buf: [40]u8 = undefined;
+                if (commit.len != 40) @panic("opt_commit value must be exactly 40 characters");
+                @memcpy(&buf, commit[0..40]);
+                options.addOption(?[40]u8, ov.name, buf);
+            } else {
+                options.addOption(?[40]u8, ov.name, null);
+            }
+        } else {
+            @panic("unsupported option_value kind");
+        }
+    }
+
     _ = module_name;
     return options;
 }
@@ -315,7 +344,7 @@ pub fn build(b: *std.Build) void {
             .optimize = m.optimize,
         });
         applyNative(b, mod, m.native);
-        if (addBuildOptions(b, m.name, m.build_options)) |options| {
+        if (addBuildOptions(b, m.name, m.build_options, m.option_values)) |options| {
             mod.addOptions(m.build_options_import, options);
         }
         modules.put(m.name, mod) catch unreachable;

build_spec_test.zig

@@ -115,6 +115,18 @@ test "package imports and artifacts name their package surfaces" {
             }
             try testing.expect(found);
         }
+        for (m.option_values) |ov| {
+            try testing.expect(ov.name.len > 0);
+            // kind is one of the four supported tags; opt_commit is null or 40.
+            const ok = std.mem.eql(u8, ov.kind, "bool") or
+                std.mem.eql(u8, ov.kind, "string") or
+                std.mem.eql(u8, ov.kind, "u32") or
+                std.mem.eql(u8, ov.kind, "opt_commit");
+            try testing.expect(ok);
+            if (std.mem.eql(u8, ov.kind, "opt_commit")) {
+                if (ov.commit_value) |c| try testing.expect(c.len == 40);
+            }
+        }
     }
 }
 

gen_build_spec.sh

@@ -70,6 +70,15 @@ pub const PackageArtifact = struct {
     backend: ?[]const u8,
 };
 
+pub const OptionValue = struct {
+    name: []const u8,
+    kind: []const u8,
+    bool_value: bool,
+    string_value: []const u8,
+    u32_value: u32,
+    commit_value: ?[]const u8,
+};
+
 pub const Native = struct {
     c_sources: []const []const u8,
     include_dirs: []const []const u8,
@@ -97,6 +106,7 @@ pub const Module = struct {
     pkg_imports: []const PackageImport,
     pkg_artifacts: []const PackageArtifact,
     build_options: []const []const u8,
+    option_values: []const OptionValue,
     build_options_import: []const u8,
     native: Native,
     optimize: std.builtin.OptimizeMode,
@@ -272,6 +282,25 @@ def zig_pkg_artifacts(items):
 def zig_bool(v):
     return 'true' if v else 'false'
 
+def zig_option_values(items):
+    if not items:
+        return '&.{}'
+    rendered = []
+    for item in items:
+        kind = item['kind']
+        commit = item.get('commit')
+        commit_field = 'null' if (kind != 'opt_commit' or not commit) else zig_string(commit)
+        rendered.append(
+            '.{ .name = ' + zig_string(item['name'])
+            + ', .kind = ' + zig_string(kind)
+            + ', .bool_value = ' + zig_bool(item.get('bool_value', False))
+            + ', .string_value = ' + zig_string(item.get('string_value', ''))
+            + ', .u32_value = ' + str(int(item.get('u32_value', 0)))
+            + ', .commit_value = ' + commit_field
+            + ' }'
+        )
+    return '&.{ ' + ', '.join(rendered) + ' }'
+
 def zig_native(item):
     item = item or {}
     return '''.{{
@@ -315,6 +344,7 @@ for name, m in mods.items():
     pkg_imports_str = zig_pkg_imports(m.get('pkg_imports', []))
     pkg_artifacts_str = zig_pkg_artifacts(m.get('pkg_artifacts', []))
     build_options_str = zig_string_list(m.get('build_options', []))
+    option_values_str = zig_option_values(m.get('option_values', []))
     native_str = zig_native(m.get('native', {}))
     print(f'''    .{{
         .name = {zig_string(name)},
@@ -330,6 +360,7 @@ for name, m in mods.items():
         .pkg_imports = {pkg_imports_str},
         .pkg_artifacts = {pkg_artifacts_str},
         .build_options = {build_options_str},
+        .option_values = {option_values_str},
         .build_options_import = {zig_string(m.get('build_options_import', 'build-options'))},
         .native = {native_str},
         .optimize = {opt},

schema.cue

@@ -51,6 +51,22 @@ package build
 	backend?: string
 }
 
+// A literal, typed value injected into a module's build-options module (the
+// one imported under build_options_import). Unlike #Option, which surfaces a
+// CLI flag, an #OptionValue is a fixed value the build config supplies so a
+// module that does @import("<options>") compiles without the project's own
+// build.zig. Used to reproduce generated options like tigerbeetle's
+// vsr_options. `kind` selects which typed field is emitted.
+#OptionValue: {
+	name: string
+	kind: "bool" | "string" | "u32" | "opt_commit"
+	bool_value:   bool | *false
+	string_value: string | *""
+	u32_value:    uint32 | *0
+	// opt_commit emits a ?[40]u8: a 40-char hex string, or "" for null.
+	commit: string | *""
+}
+
 #Package: {
 	url?: string
 	hash?: string
@@ -98,6 +114,7 @@ package build
 	pkg_imports: [...#PackageImport] | *[]
 	pkg_artifacts: [...#PackageArtifact] | *[]
 	build_options: [...string] | *[]
+	option_values: [...#OptionValue] | *[]
 	build_options_import: string | *"build-options"
 	native: #Native | *{}