Allow modules to optionally import nothing at all - final bits (#42154)

Exclude modules own name from empty modules

NEWS.md

@@ -5,7 +5,7 @@ Julia v1.8 Release Notes
 New language features
 ---------------------
 
-* `Module(:name, false, false)` can be used to create a `module` that does not import `Core`. ([#40110])
+* `Module(:name, false, false)` can be used to create a `module` that contains no names (it does not import `Base` or `Core` and does not contain a reference to itself). ([#40110, #42154])
 * `@inline` and `@noinline` annotations can be used within a function body to give an extra
   hint about the inlining cost to the compiler. ([#41312])
 * `@inline` and `@noinline` annotations can now be applied to a function callsite or block

base/boot.jl

@@ -428,7 +428,7 @@ eval(Core, :(InterConditional(slot::Int, @nospecialize(vtype), @nospecialize(els
 eval(Core, :(MethodMatch(@nospecialize(spec_types), sparams::SimpleVector, method::Method, fully_covers::Bool) =
     $(Expr(:new, :MethodMatch, :spec_types, :sparams, :method, :fully_covers))))
 
-Module(name::Symbol=:anonymous, std_imports::Bool=true, using_core::Bool=true) = ccall(:jl_f_new_module, Ref{Module}, (Any, Bool, Bool), name, std_imports, using_core)
+Module(name::Symbol=:anonymous, std_imports::Bool=true, default_names::Bool=true) = ccall(:jl_f_new_module, Ref{Module}, (Any, Bool, Bool), name, std_imports, default_names)
 
 function _Task(@nospecialize(f), reserved_stack::Int, completion_future)
     return ccall(:jl_new_task, Ref{Task}, (Any, Any, Int), f, completion_future, reserved_stack)

base/docs/basedocs.jl

@@ -2813,6 +2813,13 @@ StridedVecOrMat
     Module
 
 A `Module` is a separate global variable workspace. See [`module`](@ref) and the [manual section about modules](@ref modules) for details.
+
+    Module(name::Symbol=:anonymous, std_imports=true, default_names=true)
+
+Return a module with the specified name. A `baremodule` corresponds to `Module(:ModuleName, false)`
+
+An empty module containing no names at all can be created with `Module(:ModuleName, false, false)`.
+This module will not import `Base` or `Core` and does not contain a reference to itself.
 """
 Module
 

doc/src/manual/modules.md

@@ -303,7 +303,7 @@ include(p) = Base.include(Mod, p)
 end
 ```
 
-If even `Core` is not wanted, a module that imports nothing at all can be defined with `Module(:YourNameHere, false, false)` and code can be evaluated into it with [`@eval`](@ref) or [`Core.eval`](@ref).
+If even `Core` is not wanted, a module that imports nothing and defines no names at all can be defined with `Module(:YourNameHere, false, false)` and code can be evaluated into it with [`@eval`](@ref) or [`Core.eval`](@ref).
 
 ### Standard modules
 

src/module.c

@@ -11,7 +11,7 @@
 extern "C" {
 #endif
 
-JL_DLLEXPORT jl_module_t *jl_new_module_(jl_sym_t *name, uint8_t using_core)
+JL_DLLEXPORT jl_module_t *jl_new_module_(jl_sym_t *name, uint8_t default_names)
 {
     jl_task_t *ct = jl_current_task;
     const jl_uuid_t uuid_zero = {0, 0};
@@ -36,11 +36,13 @@ JL_DLLEXPORT jl_module_t *jl_new_module_(jl_sym_t *name, uint8_t using_core)
     htable_new(&m->bindings, 0);
     arraylist_new(&m->usings, 0);
     JL_GC_PUSH1(&m);
-    if (jl_core_module && using_core) {
+    if (jl_core_module && default_names) {
         jl_module_using(m, jl_core_module);
     }
     // export own name, so "using Foo" makes "Foo" itself visible
-    jl_set_const(m, name, (jl_value_t*)m);
+    if (default_names) {
+        jl_set_const(m, name, (jl_value_t*)m);
+    }
     jl_module_export(m, name);
     JL_GC_POP();
     return m;
@@ -56,10 +58,10 @@ uint32_t jl_module_next_counter(jl_module_t *m)
     return jl_atomic_fetch_add(&m->counter, 1);
 }
 
-JL_DLLEXPORT jl_value_t *jl_f_new_module(jl_sym_t *name, uint8_t std_imports, uint8_t using_core)
+JL_DLLEXPORT jl_value_t *jl_f_new_module(jl_sym_t *name, uint8_t std_imports, uint8_t default_names)
 {
     // TODO: should we prohibit this during incremental compilation?
-    jl_module_t *m = jl_new_module_(name, using_core);
+    jl_module_t *m = jl_new_module_(name, default_names);
     JL_GC_PUSH1(&m);
     m->parent = jl_main_module; // TODO: this is a lie
     jl_gc_wb(m, m->parent);