DocMeta: Access META binding through invokelatest

Starting in Julia 1.12, global bindings have strict world-age semantics
so this change is required to avoid the warning introduced by
JuliaLang/julia#57133

Author: topolarity

CHANGELOG.md

@@ -3,6 +3,12 @@
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## Unreleased
+
+### Fixed
+
+* `DocMeta` has been updated to respect world-age semantics for bindings, introduced in Julia 1.12. ([#2624])
+
 ## Version [v1.8.0] - 2024-11-07
 
 ### Changed
@@ -1916,6 +1922,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 [#2571]: https://github.com/JuliaDocs/Documenter.jl/issues/2571
 [#2592]: https://github.com/JuliaDocs/Documenter.jl/issues/2592
 [#2593]: https://github.com/JuliaDocs/Documenter.jl/issues/2593
+[#2624]: https://github.com/JuliaDocs/Documenter.jl/issues/2624
 [JuliaLang/julia#36953]: https://github.com/JuliaLang/julia/issues/36953
 [JuliaLang/julia#38054]: https://github.com/JuliaLang/julia/issues/38054
 [JuliaLang/julia#39841]: https://github.com/JuliaLang/julia/issues/39841

src/DocMeta.jl

@@ -15,6 +15,7 @@ module — a special variable is created in each module that has documentation m
 """
 module DocMeta
 import ..Documenter
+import Base: invokelatest
 
 "The unique `Symbol` that is used to store the metadata dictionary in each module."
 const META = gensym(:docmeta)
@@ -31,14 +32,14 @@ const VALIDMETA = Dict{Symbol, Type}(:DocTestSetup => Union{Expr, Symbol})
 """
 """
 function initdocmeta!(m::Module)
-    if !isdefined(m, META)
+    if !invokelatest(isdefined, m, META)
         @debug "Creating documentation metadata dictionary (META=$META) in $m"
         Core.eval(m, :(const $META = $(METATYPE())))
         push!(METAMODULES, m)
     else
         @warn "Existing documentation metadata dictionary (META=$META) in $m. Ignoring."
     end
-    return getfield(m, META)
+    return invokelatest(getfield, m, META)
 end
 
 """
@@ -48,7 +49,7 @@ Returns the documentation metadata dictionary for the module `m`. The dictionary
 considered immutable and assigning values to it is not well-defined. To set documentation
 metadata values, [`DocMeta.setdocmeta!`](@ref) should be used instead.
 """
-getdocmeta(m::Module) = isdefined(m, META) ? getfield(m, META) : METATYPE()
+getdocmeta(m::Module) = invokelatest(isdefined, m, META) ? invokelatest(getfield, m, META) : METATYPE()
 
 """
     getdocmeta(m::Module, key::Symbol, default=nothing)
@@ -74,7 +75,7 @@ function setdocmeta!(m::Module, key::Symbol, value; warn = true, recursive = fal
             setdocmeta!(mod, key, value; warn = warn, recursive = false)
         end
     else
-        isdefined(m, META) || initdocmeta!(m)
+        invokelatest(isdefined, m, META) || initdocmeta!(m)
         meta = getdocmeta(m)
         if warn && haskey(meta, key)
             @warn "$(key) already set for module $m. Overwriting."