runtime: document GODEBUG panicnil values

Updates #25448

Change-Id: Ia1b7a376f5175f67e14ad4bd065d6e8ad5250d38
Reviewed-on: https://go-review.googlesource.com/c/go/+/536955
Reviewed-by: Keith Randall <khr@golang.org>
Reviewed-by: Keith Randall <khr@google.com>
Reviewed-by: Carlos Amedee <carlos@golang.org>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Auto-Submit: Keith Randall <khr@golang.org>

diff --git a/src/runtime/extern.go b/src/runtime/extern.go
index 4b3ae63fb5c944ff4036c6fa0b15a9fc08fc8983..e42122fd3a1cd1dadb6a8dbb6a7b10532b7e22ea 100644 (file)
--- a/src/runtime/extern.go
+++ b/src/runtime/extern.go
@@ -152,6 +152,9 @@ It is a comma-separated list of name=val pairs setting these named variables:
        risk in that scenario. Currently not supported on Windows, plan9 or js/wasm. Setting this
        option for some applications can produce large traces, so use with care.
 
+       panicnil: setting panicnil=1 disables the runtime error when calling panic with nil
+       interface value or an untyped nil.
+
        runtimecontentionstacks: setting runtimecontentionstacks=1 enables inclusion of call stacks
        related to contention on runtime-internal locks in the "mutex" profile, subject to the
        MutexProfileFraction setting. When runtimecontentionstacks=0, contention on