addTarget

    pub fn addTarget(wip: *Wip, t: std.Target) !TargetQuery.Index {
        const gpa = wip.gpa;
        const cpu_name: String = try wip.addString(t.cpu.model.name);

        const os_version_min: TargetQuery.OsVersion, const os_version_max: TargetQuery.OsVersion, const glibc_version: ?String, const android_api_level: ?u32 = switch (t.os.versionRange()) {
            .none => .{
                .none,
                .none,
                null,
                null,
            },
            .semver => |range| .{
                .{ .semver = try wip.addSemVer(range.min) },
                .{ .semver = try wip.addSemVer(range.max) },
                null,
                null,
            },
            .hurd => |hurd| .{
                .{ .semver = try wip.addSemVer(hurd.range.min) },
                .{ .semver = try wip.addSemVer(hurd.range.max) },
                try wip.addSemVer(hurd.glibc),
                null,
            },
            .linux => |linux| .{
                .{ .semver = try wip.addSemVer(linux.range.min) },
                .{ .semver = try wip.addSemVer(linux.range.max) },
                try wip.addSemVer(linux.glibc),
                linux.android,
            },
            .windows => |range| .{
                .{ .windows = range.min },
                .{ .windows = range.max },
                null,
                null,
            },
        };
        const dynamic_linker: ?String = if (t.dynamic_linker.get()) |dl| try wip.addString(dl) else null;
        const cpu_features_add_empty = t.cpu.features.isEmpty();
        const result_index = try wip.addExtra(TargetQuery, .{
            .flags = .{
                .cpu_arch = .init(t.cpu.arch),
                .cpu_model = .explicit,
                .cpu_features_add = !cpu_features_add_empty,
                .cpu_features_sub = false,
                .os_tag = .init(t.os.tag),
                .abi = .init(t.abi),
                .object_format = .init(t.ofmt),
                .os_version_min = os_version_min,
                .os_version_max = os_version_max,
                .glibc_version = glibc_version != null,
                .android_api_level = android_api_level != null,
                .dynamic_linker = dynamic_linker != null,
            },
            .cpu_features_add = .{ .value = if (cpu_features_add_empty) null else t.cpu.features },
            .cpu_features_sub = .{ .value = null },
            .glibc_version = .{ .value = glibc_version },
            .android_api_level = .{ .value = android_api_level },
            .dynamic_linker = .{ .value = dynamic_linker },
            .cpu_name = .{ .value = cpu_name },
            .os_version_min = .{ .u = os_version_min },
            .os_version_max = .{ .u = os_version_max },
        });

        // Deduplicate.
        const gop = try wip.targets_table.getOrPutContext(gpa, result_index, @as(TargetsTableContext, .{
            .extra = wip.extra.items,
        }));
        if (gop.found_existing) {
            wip.extra.items.len = @backingInt(result_index);
            return gop.key_ptr.*;
        } else {
            return result_index;
        }
    }