Add deprecation

Author: helgee

base/deprecated.jl

@@ -1702,6 +1702,9 @@ end
 
 @eval @deprecate $(Symbol("@schedule")) $(Symbol("@async"))
 
+# PR #27432
+@eval @deprecate $(Symbol("@pure")) $(Symbol("@unsafe_pure")) ex=false
+
 # END 0.7 deprecations
 
 # BEGIN 1.0 deprecations