Brad Fitzpatrick 82cfea90ca all: fix JSON serialization under Go 1.27's finalized encoding/json/v2 ... Go 1.27 enables GOEXPERIMENT=jsonv2 by default: encoding/json is now backed by the json/v2 machinery, and github.com/go-json-experiment/json compiles as a thin alias of the standard library's encoding/json/v2. Several tag options and behaviors we relied on did not make the cut for the final Go 1.27 API, breaking tailscaled at runtime and four packages' tests. This change adapts to the final API while keeping the wire format byte-for-byte identical on all Go versions. First, the `format` tag option was demoted to experimental. Its mere presence in a struct tag now makes marshaling and unmarshaling fail at runtime. tailcfg.SSHAction.SessionDuration had `format:nano` (added in a2dc517d7 to pin the v1 representation), so on Go 1.27 any netmap containing an SSH policy failed to decode, breaking every PollNetMap. Remove the option here and in net/speedtest; time.Duration still marshals as int64 nanoseconds under encoding/json on all Go versions (Go 1.27's v1 mode sets FormatDurationAsNano by default), so old clients and servers are unaffected. Add a regression test locking in the exact wire format. Consequently, invert the cmd/vet jsontags rule: it previously required an explicit `format` tag on time.Duration fields, which is now exactly wrong. It now rejects any `format` tag option, which would have caught this bug in CI. Second, the `inline` tag option was renamed to `embed`. The standard library silently ignores `inline`, while the pinned go-json-experiment module (used on Go 1.26) only knows `inline`. Specify both options in types/prefs and logtail; each implementation ignores the option it does not know, producing identical output. Drop `inline` once we require Go 1.27. Third, encoding/json (v1) now dispatches to MarshalJSONTo and UnmarshalJSONFrom methods and its v1 options flow into nested jsonv2.MarshalEncode calls. Types whose v1 methods deliberately routed through jsonv2 for v2 semantics (types/opt.Value, the types/prefs preference types) would silently change wire format (e.g. nil slices becoming null). Pin jsonv2.DefaultOptionsV2 in their jsonv2 methods so the representation is the same regardless of the entry point. Finally, json.Marshal costs one more allocation under Go 1.27, tripping the types/logger.AsJSON alloc test. Switch its fmt.Formatter to jsonv2.MarshalWrite with explicit v1 options, which writes directly to the fmt.State: one allocation on both toolchains with unchanged output. Depaware files pick up the go-json-experiment/json/v1 options shim as a new dependency of types/logger. With this change, go test ./... passes with both Go 1.26.5 and go1.27rc2. Updates #20220 Fixes #20528 Fixes #20254 Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com> Change-Id: I694c7d57fd81e55a579c579e9be10032bca569d4		2026-07-19 09:58:50 -07:00
..
prefs_example	ipn: remove the last traces of Prefs.AllowSingleHosts	2026-06-26 15:31:38 +01:00
item.go	types/ptr: deprecate ptr.To, use Go 1.26 new	2026-03-05 20:13:18 -08:00
list.go	types/ptr: deprecate ptr.To, use Go 1.26 new	2026-03-05 20:13:18 -08:00
map.go	types/ptr: deprecate ptr.To, use Go 1.26 new	2026-03-05 20:13:18 -08:00
options.go	all: remove AUTHORS file and references to it	2026-01-23 15:49:45 -08:00
prefs_clone_test.go	types/ptr: deprecate ptr.To, use Go 1.26 new	2026-03-05 20:13:18 -08:00
prefs_test.go	all: remove AUTHORS file and references to it	2026-01-23 15:49:45 -08:00
prefs_view_test.go	all: remove AUTHORS file and references to it	2026-01-23 15:49:45 -08:00
prefs.go	all: fix JSON serialization under Go 1.27's finalized encoding/json/v2	2026-07-19 09:58:50 -07:00
struct_list.go	types/ptr: deprecate ptr.To, use Go 1.26 new	2026-03-05 20:13:18 -08:00
struct_map.go	types/ptr: deprecate ptr.To, use Go 1.26 new	2026-03-05 20:13:18 -08:00