From 6b08e80bd1217c5c2eb6c89604c21faa5b2a156f Mon Sep 17 00:00:00 2001
From: Ian Butterworth <i.r.butterworth@gmail.com>
Date: Mon, 22 Jul 2024 21:43:43 -0400
Subject: [PATCH] document mutable struct const fields (#55203)

Introduced in https://github.com/JuliaLang/julia/pull/43305
---
 base/docs/basedocs.jl | 16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/base/docs/basedocs.jl b/base/docs/basedocs.jl
index 635f1765627fa..00e4a0afb5c0e 100644
--- a/base/docs/basedocs.jl
+++ b/base/docs/basedocs.jl
@@ -1451,8 +1451,20 @@ kw"struct"
     mutable struct
 
 `mutable struct` is similar to [`struct`](@ref), but additionally allows the
-fields of the type to be set after construction. See the manual section on
-[Composite Types](@ref) for more information.
+fields of the type to be set after construction.
+
+Individual fields of a mutable struct can be marked as `const` to make them immutable:
+
+```julia
+mutable struct Baz
+    a::Int
+    const b::Float64
+end
+```
+!!! compat "Julia 1.8"
+    The `const` keyword for fields of mutable structs requires at least Julia 1.8.
+
+See the manual section on [Composite Types](@ref) for more information.
 """
 kw"mutable struct"