Add Docs.undocumented_names

NEWS.md

@@ -78,6 +78,7 @@ New library features
   write the output to a stream rather than returning a string ([#48625]).
 * `sizehint!(s, n)` now supports an optional `shrink` argument to disable shrinking ([#51929]).
 * New function `Docs.hasdoc(module, symbol)` tells whether a name has a docstring ([#52139]).
+* New function `Docs.undocumented_names(module; all)` returns a module's undocumented names ([#52413]).
 * Passing an IOBuffer as a stdout argument for Process spawn now works as
   expected, synchronized with `wait` or `success`, so a `Base.BufferStream` is
   no longer required there for correctness to avoid data-races ([#TBD]).

base/docs/Docs.jl

@@ -675,4 +675,19 @@ function hasdoc(binding::Docs.Binding, sig::Type = Union{})
 end
 
 
+"""
+    undocumented_names(mod::Module; all=false)
+
+Return an array of undocumented symbols in `module` (that is, lacking docstrings).
+`all=false` returns only exported symbols; whereas `all=true` also includes
+non-exported symbols, following the behavior of [`names`](@ref).
+
+See also: [`names`](@ref), [`Docs.hasdoc`](@ref).
+"""
+function undocumented_names(mod::Module; all::Bool=false, identifiers::Bool=true)
+    filter!(names(mod; all)) do sym
+        !hasdoc(mod, sym) && (!identifiers || Base.isidentifier(sym))
+    end
+end
+
 end

doc/src/manual/documentation.md

@@ -20,7 +20,8 @@ environments provide a way to access documentation directly:
   under the cursor.
 
 
-`Docs.hasdoc(module, name)::Bool` tells whether a name has a docstring.
+`Docs.hasdoc(module, name)::Bool` tells whether a name has a docstring. `Docs.undocumented_names(module; all)`
+returns the undocumented names in a module.
 
 ## Writing Documentation
 

test/docs.jl

@@ -76,6 +76,25 @@ function break_me_docs end
 @test !isdefined(Base, :_this_name_doesnt_exist_) && !Docs.hasdoc(Base, :_this_name_doesnt_exist_)
 @test isdefined(Base, :_typed_vcat) && !Docs.hasdoc(Base, :_typed_vcat)
 
+"This module has names without documentation."
+module _ModuleWithUndocumentedNames
+export f
+f() = 1
+end
+
+"This module has some documentation."
+module _ModuleWithSomeDocumentedNames
+export f
+"f() is 1."
+f() = 1
+g() = 2
+end
+
+@test Docs.undocumented_names(_ModuleWithUndocumentedNames) == [:f]
+@test isempty(Docs.undocumented_names(_ModuleWithSomeDocumentedNames))
+@test Docs.undocumented_names(_ModuleWithSomeDocumentedNames; all=true) == [:g]
+
+
 # issue #11548
 
 module ModuleMacroDoc