reflection: allow names to return using-ed names (JuliaLang#54609)

This commit makes it possible for `names` to return `using`-ed names as
well:
```julia
julia> using Base: @assume_effects

julia> Symbol("@assume_effects") in names(@__MODULE__; usings=true)
true
```

Currently, to find all names available in a module `A`, the following
steps are needed:
1. Use `names(A; all=true, imported=true)` to get the names defined by
`A` and the names explicitly `import`ed by `A`.
2. Use `jl_module_usings(A)` to get the list of modules `A` has
`using`-ed and then use `names()` to get the names `export`ed by those
modules.

This method is implemented in e.g. REPL completions, but it has a
problem: it could not get the names explicitly `using`-ed by `using B:
...` (JuliaLang#36529, JuliaLang#40356, JuliaDebug/Infiltrator.jl#106, etc.).

This commit adds a new keyword argument `usings::Bool=false` to
`names(A; ...)`, which, when `usings=true` is specified, returns all
names introduced by `using` in `A`.
In other words, `usings=true` not only returns explicitly `using`-ed
names but also incorporates step 2 above into the implementation of
`names`.

By using this new option, we can now use
`names(A; all=true, imported=true, usings=true)` to know all names
available in `A`, without implementing the two-fold steps on application
side.
As example application, this new feature will be used to simplify and
enhance the implementation of REPL completions.

- fixes JuliaLang#36529

Co-authored-by: Nathan Daly <NHDaly@gmail.com>
Co-authored-by: Sebastian Pfitzner <pfitzseb@gmail.com>

NEWS.md

@@ -4,6 +4,9 @@ Julia v1.12 Release Notes
 New language features
 ---------------------
 
+- A new keyword argument `usings::Bool` has been added to `names`. By using this, we can now
+  find all the names available in module `A` by `names(A; all=true, imported=true, usings=true)`. ([#54609])
+
 Language changes
 ----------------
 
@@ -17,7 +20,7 @@ Language changes
    may pave the way for inference to be able to intelligently re-use the old
    results, once the new method is deleted. ([#53415])
 
- - Macro expansion will no longer eargerly recurse into into `Expr(:toplevel)`
+ - Macro expansion will no longer eagerly recurse into into `Expr(:toplevel)`
    expressions returned from macros. Instead, macro expansion of `:toplevel`
    expressions will be delayed until evaluation time. This allows a later
    expression within a given `:toplevel` expression to make use of macros

base/reflection.jl

@@ -77,28 +77,33 @@ function fullname(m::Module)
 end
 
 """
-    names(x::Module; all::Bool = false, imported::Bool = false)
+    names(x::Module; all::Bool=false, imported::Bool=false, usings::Bool=false) -> Vector{Symbol}
 
 Get a vector of the public names of a `Module`, excluding deprecated names.
 If `all` is true, then the list also includes non-public names defined in the module,
 deprecated names, and compiler-generated names.
 If `imported` is true, then names explicitly imported from other modules
-are also included. Names are returned in sorted order.
+are also included.
+If `usings` is true, then names explicitly imported via `using` are also included.
+Names are returned in sorted order.
 
 As a special case, all names defined in `Main` are considered \"public\",
 since it is not idiomatic to explicitly mark names from `Main` as public.
 
 !!! note
     `sym ∈ names(SomeModule)` does *not* imply `isdefined(SomeModule, sym)`.
-    `names` will return symbols marked with `public` or `export`, even if
+    `names` may return symbols marked with `public` or `export`, even if
     they are not defined in the module.
 
+!!! warning
+    `names` may return duplicate names. The duplication happens, e.g. if an `import`ed name
+    conflicts with an already existing identifier.
+
 See also: [`Base.isexported`](@ref), [`Base.ispublic`](@ref), [`Base.@locals`](@ref), [`@__MODULE__`](@ref).
 """
-names(m::Module; all::Bool = false, imported::Bool = false) =
-    sort!(unsorted_names(m; all, imported))
-unsorted_names(m::Module; all::Bool = false, imported::Bool = false) =
-    ccall(:jl_module_names, Array{Symbol,1}, (Any, Cint, Cint), m, all, imported)
+names(m::Module; kwargs...) = sort!(unsorted_names(m; kwargs...))
+unsorted_names(m::Module; all::Bool=false, imported::Bool=false, usings::Bool=false) =
+    ccall(:jl_module_names, Array{Symbol,1}, (Any, Cint, Cint, Cint), m, all, imported, usings)
 
 """
     isexported(m::Module, s::Symbol) -> Bool

src/module.c

@@ -991,10 +991,19 @@ JL_DLLEXPORT jl_value_t *jl_module_usings(jl_module_t *m)
     return (jl_value_t*)a;
 }
 
-JL_DLLEXPORT jl_value_t *jl_module_names(jl_module_t *m, int all, int imported)
+uint8_t _binding_is_from_explicit_using(jl_binding_t *b) {
+    jl_binding_t *owner = jl_atomic_load_relaxed(&b->owner);
+    return (owner != NULL && owner != b && !b->imported);
+}
+
+void _append_symbol_to_bindings_array(jl_array_t* a, jl_sym_t *name) {
+    jl_array_grow_end(a, 1);
+    //XXX: change to jl_arrayset if array storage allocation for Array{Symbols,1} changes:
+    jl_array_ptr_set(a, jl_array_dim0(a)-1, (jl_value_t*)name);
+}
+
+void append_module_names(jl_array_t* a, jl_module_t *m, int all, int imported, int usings)
 {
-    jl_array_t *a = jl_alloc_array_1d(jl_array_symbol_type, 0);
-    JL_GC_PUSH1(&a);
     jl_svec_t *table = jl_atomic_load_relaxed(&m->bindings);
     for (size_t i = 0; i < jl_svec_len(table); i++) {
         jl_binding_t *b = (jl_binding_t*)jl_svecref(table, i);
@@ -1003,15 +1012,39 @@ JL_DLLEXPORT jl_value_t *jl_module_names(jl_module_t *m, int all, int imported)
         jl_sym_t *asname = b->globalref->name;
         int hidden = jl_symbol_name(asname)[0]=='#';
         int main_public = (m == jl_main_module && !(asname == jl_eval_sym || asname == jl_include_sym));
-        if ((b->publicp ||
+        if (((b->publicp) ||
              (imported && b->imported) ||
+             (usings && _binding_is_from_explicit_using(b)) ||
              (jl_atomic_load_relaxed(&b->owner) == b && !b->imported && (all || main_public))) &&
-            (all || (!b->deprecated && !hidden))) {
-            jl_array_grow_end(a, 1);
-            // n.b. change to jl_arrayset if array storage allocation for Array{Symbols,1} changes:
-            jl_array_ptr_set(a, jl_array_dim0(a)-1, (jl_value_t*)asname);
+            (all || (!b->deprecated && !hidden)))
+            _append_symbol_to_bindings_array(a, asname);
+    }
+}
+
+void append_exported_names(jl_array_t* a, jl_module_t *m, int all)
+{
+    jl_svec_t *table = jl_atomic_load_relaxed(&m->bindings);
+    for (size_t i = 0; i < jl_svec_len(table); i++) {
+        jl_binding_t *b = (jl_binding_t*)jl_svecref(table, i);
+        if ((void*)b == jl_nothing)
+            break;
+        if (b->exportp && (all || !b->deprecated))
+            _append_symbol_to_bindings_array(a, b->globalref->name);
+    }
+}
+
+JL_DLLEXPORT jl_value_t *jl_module_names(jl_module_t *m, int all, int imported, int usings)
+{
+    jl_array_t *a = jl_alloc_array_1d(jl_array_symbol_type, 0);
+    JL_GC_PUSH1(&a);
+    append_module_names(a, m, all, imported, usings);
+    if (usings) {
+        // If `usings` is specified, traverse the list of `using`-ed modules and incorporate
+        // the names exported by those modules into the list.
+        for(int i=(int)m->usings.len-1; i >= 0; --i) {
+            jl_module_t *usinged = module_usings_getidx(m, i);
+            append_exported_names(a, usinged, all);
         }
-        table = jl_atomic_load_relaxed(&m->bindings);
     }
     JL_GC_POP();
     return (jl_value_t*)a;

test/reflection.jl

@@ -125,11 +125,18 @@ not_const = 1
 # For curmod_*
 include("testenv.jl")
 
+module TestMod36529
+    x36529 = 0
+    y36529 = 1
+    export y36529
+end
+
 module TestMod7648
 using Test
 import Base.convert
 import ..curmod_name, ..curmod
-export a9475, foo9475, c7648, foo7648, foo7648_nomethods, Foo7648
+using ..TestMod36529: x36529   # doesn't import TestMod36529 or y36529, even though it's exported
+export a9475, c7648, f9475, foo7648, foo7648_nomethods, Foo7648
 
 const c7648 = 8
 d7648 = 9
@@ -142,10 +149,11 @@ module TestModSub9475
     using Test
     using ..TestMod7648
     import ..curmod_name
-    export a9475, foo9475
+    export a9475, f9475, f54609
     a9475 = 5
     b9475 = 7
-    foo9475(x) = x
+    f9475(x) = x
+    f54609(x) = x
     let
         @test Base.binding_module(@__MODULE__, :a9475) == @__MODULE__
         @test Base.binding_module(@__MODULE__, :c7648) == TestMod7648
@@ -169,18 +177,104 @@ let
     @test Base.binding_module(TestMod7648, :d7648) == TestMod7648
     @test Base.binding_module(TestMod7648, :a9475) == TestMod7648.TestModSub9475
     @test Base.binding_module(TestMod7648.TestModSub9475, :b9475) == TestMod7648.TestModSub9475
-    @test Set(names(TestMod7648))==Set([:TestMod7648, :a9475, :foo9475, :c7648, :foo7648, :foo7648_nomethods, :Foo7648])
-    @test Set(names(TestMod7648, all = true)) == Set([:TestMod7648, :TestModSub9475, :a9475, :foo9475, :c7648, :d7648, :f7648,
-                                                :foo7648, Symbol("#foo7648"), :foo7648_nomethods, Symbol("#foo7648_nomethods"),
-                                                :Foo7648, :eval, Symbol("#eval"), :include, Symbol("#include")])
-    @test Set(names(TestMod7648, all = true, imported = true)) == Set([:TestMod7648, :TestModSub9475, :a9475, :foo9475, :c7648, :d7648, :f7648,
-                                                      :foo7648, Symbol("#foo7648"), :foo7648_nomethods, Symbol("#foo7648_nomethods"),
-                                                      :Foo7648, :eval, Symbol("#eval"), :include, Symbol("#include"),
-                                                      :convert, :curmod_name, :curmod])
+    defaultset = Set(Symbol[:Foo7648, :TestMod7648, :a9475, :c7648, :f9475, :foo7648, :foo7648_nomethods])
+    allset = defaultset ∪ Set(Symbol[
+        Symbol("#eval"), Symbol("#foo7648"), Symbol("#foo7648_nomethods"), Symbol("#include"),
+        :TestModSub9475, :d7648, :eval, :f7648, :include])
+    imported = Set(Symbol[:convert, :curmod_name, :curmod])
+    usings_from_Test = Set(Symbol[
+        Symbol("@inferred"), Symbol("@test"), Symbol("@test_broken"), Symbol("@test_deprecated"),
+        Symbol("@test_logs"), Symbol("@test_nowarn"), Symbol("@test_skip"), Symbol("@test_throws"),
+        Symbol("@test_warn"), Symbol("@testset"), :GenericArray, :GenericDict, :GenericOrder,
+        :GenericSet, :GenericString, :LogRecord, :Test, :TestLogger, :TestSetException,
+        :detect_ambiguities, :detect_unbound_args])
+    usings_from_Base = delete!(Set(names(Module(); usings=true)), :anonymous) # the name of the anonymous module itself
+    usings = Set(Symbol[:x36529, :TestModSub9475, :f54609]) ∪ usings_from_Test ∪ usings_from_Base
+    @test Set(names(TestMod7648)) == defaultset
+    @test Set(names(TestMod7648, all=true)) == allset
+    @test Set(names(TestMod7648, all=true, imported=true)) == allset ∪ imported
+    @test Set(names(TestMod7648, usings=true)) == defaultset ∪ usings
+    @test Set(names(TestMod7648, all=true, usings=true)) == allset ∪ usings
     @test isconst(TestMod7648, :c7648)
     @test !isconst(TestMod7648, :d7648)
 end
 
+# tests for `names(...; usings=true)`
+
+baremodule Test54609Simple
+module Inner
+export exported
+global exported::Int = 1
+global unexported::Int = 0
+end
+using Base: @assume_effects
+using .Inner
+end
+let usings = names(Test54609Simple; usings=true)
+    @test Symbol("@assume_effects") ∈ usings
+    @test :Base ∉ usings
+    @test :exported ∈ usings
+    @test :unexported ∉ usings
+end # baremodule Test54609Simple
+
+baremodule _Test54609Complex
+export exported_new
+using Base: @deprecate_binding
+global exported_new = nothing
+@deprecate_binding exported_old exported_new
+end # baremodule _Test54609Complex
+baremodule Test54609Complex
+using .._Test54609Complex
+end # baremodule Test54609Complex
+let usings = names(Test54609Complex; usings=true)
+    @test :exported_new ∈ usings
+    @test :exported_old ∉ usings
+    @test :_Test54609Complex ∈ usings # should include the `using`ed module itself
+    usings_all = names(Test54609Complex; usings=true, all=true)
+    @test :exported_new ∈ usings_all
+    @test :exported_old ∈ usings_all # deprecated names should be included with `all=true`
+end
+
+module TestMod54609
+module M1
+    const m1_x = 1
+    export m1_x
+end
+module M2
+    const m2_x = 1
+    export m2_x
+end
+module A
+    module B
+        f(x) = 1
+        secret = 1
+        module Inner2 end
+    end
+    module C
+        x = 1
+        y = 2
+        export y
+    end
+    using .B: f
+    using .C
+    using ..M1
+    import ..M2
+end
+end # module TestMod54609
+let defaultset = Set((:A,))
+    imported = Set((:M2,))
+    usings_from_Base = delete!(Set(names(Module(); usings=true)), :anonymous) # the name of the anonymous module itself
+    usings = Set((:A, :f, :C, :y, :M1, :m1_x)) ∪ usings_from_Base
+    allset = Set((:A, :B, :C, :eval, :include, Symbol("#eval"), Symbol("#include")))
+    @test Set(names(TestMod54609.A)) == defaultset
+    @test Set(names(TestMod54609.A, imported=true)) == defaultset ∪ imported
+    @test Set(names(TestMod54609.A, usings=true)) == defaultset ∪ usings
+    @test Set(names(TestMod54609.A, all=true)) == allset
+    @test Set(names(TestMod54609.A, all=true, usings=true)) == allset ∪ usings
+    @test Set(names(TestMod54609.A, imported=true, usings=true)) == defaultset ∪ imported ∪ usings
+    @test Set(names(TestMod54609.A, all=true, imported=true, usings=true)) == allset ∪ imported ∪ usings
+end
+
 let
     using .TestMod7648
     @test Base.binding_module(@__MODULE__, :a9475) == TestMod7648.TestModSub9475
@@ -189,10 +283,10 @@ let
     @test parentmodule(foo7648, (Any,)) == TestMod7648
     @test parentmodule(foo7648) == TestMod7648
     @test parentmodule(foo7648_nomethods) == TestMod7648
-    @test parentmodule(foo9475, (Any,)) == TestMod7648.TestModSub9475
-    @test parentmodule(foo9475) == TestMod7648.TestModSub9475
+    @test parentmodule(f9475, (Any,)) == TestMod7648.TestModSub9475
+    @test parentmodule(f9475) == TestMod7648.TestModSub9475
     @test parentmodule(Foo7648) == TestMod7648
-    @test parentmodule(first(methods(foo9475))) == TestMod7648.TestModSub9475
+    @test parentmodule(first(methods(f9475))) == TestMod7648.TestModSub9475
     @test parentmodule(first(methods(foo7648))) == TestMod7648
     @test nameof(Foo7648) === :Foo7648
     @test basename(functionloc(foo7648, (Any,))[1]) == "reflection.jl"