amaranth.hdl: start all private names with an underscore.

This change completes commit 9dc0617e and makes all the tests pass.
It corresponds with the ongoing langauge reference documentation effort.

Fixes #781.

tests/test_hdl_ast.py

@@ -1,7 +1,7 @@
 import warnings
 from enum import Enum, EnumMeta
 
-from amaranth.hdl.ast import *
+from amaranth.hdl._ast import *
 from amaranth.lib.enum import Enum as AmaranthEnum
 
 from .utils import *
@@ -1024,10 +1024,10 @@ class ArrayTestCase(FHDLTestCase):
             @ValueCastable.lowermethod
             def as_value(self):
                 return Signal()
-            
+
             def shape():
                 return unsigned(1)
-        
+
         a = Array([1,2,3])
         a[MyValue()]
 

tests/test_hdl_cd.py

@@ -1,4 +1,4 @@
-from amaranth.hdl.cd import *
+from amaranth.hdl._cd import *
 
 from .utils import *
 

tests/test_hdl_dsl.py

@@ -3,9 +3,9 @@
 import sys
 from collections import OrderedDict
 
-from amaranth.hdl.ast import *
-from amaranth.hdl.cd import *
-from amaranth.hdl.dsl import *
+from amaranth.hdl._ast import *
+from amaranth.hdl._cd import *
+from amaranth.hdl._dsl import *
 from amaranth.lib.enum import Enum
 
 from .utils import *

tests/test_hdl_ir.py

@@ -2,10 +2,10 @@
 
 from collections import OrderedDict
 
-from amaranth.hdl.ast import *
-from amaranth.hdl.cd import *
-from amaranth.hdl.ir import *
-from amaranth.hdl.mem import *
+from amaranth.hdl._ast import *
+from amaranth.hdl._cd import *
+from amaranth.hdl._ir import *
+from amaranth.hdl._mem import *
 
 from .utils import *
 

tests/test_hdl_mem.py

@@ -1,7 +1,7 @@
 # amaranth: UnusedElaboratable=no
 
-from amaranth.hdl.ast import *
-from amaranth.hdl.mem import *
+from amaranth.hdl._ast import *
+from amaranth.hdl._mem import *
 
 from .utils import *
 

tests/test_hdl_rec.py

@@ -2,7 +2,7 @@ import warnings
 
 from enum import Enum
 
-from amaranth.hdl.ast import *
+from amaranth.hdl._ast import *
 with warnings.catch_warnings():
     warnings.filterwarnings(action="ignore", category=DeprecationWarning)
     from amaranth.hdl.rec import *

tests/test_hdl_xfrm.py

@@ -2,13 +2,13 @@
 
 import warnings
 
-from amaranth.hdl.ast import *
-from amaranth.hdl.cd import *
-from amaranth.hdl.dsl import *
-from amaranth.hdl.ir import *
-from amaranth.hdl.xfrm import *
-from amaranth.hdl.mem import *
-from amaranth.hdl.mem import MemoryInstance
+from amaranth.hdl._ast import *
+from amaranth.hdl._cd import *
+from amaranth.hdl._dsl import *
+from amaranth.hdl._ir import *
+from amaranth.hdl._xfrm import *
+from amaranth.hdl._mem import *
+from amaranth.hdl._mem import MemoryInstance
 
 from .utils import *
 from amaranth._utils import _ignore_deprecated

tests/test_lib_data.py

@@ -3,7 +3,7 @@ import operator
 from unittest import TestCase
 
 from amaranth.hdl import *
-from amaranth.hdl.ast import ShapeCastable
+from amaranth.hdl._ast import ShapeCastable
 from amaranth.lib.data import *
 from amaranth.sim import Simulator
 

tests/test_lib_wiring.py

@@ -4,7 +4,7 @@ import unittest
 from types import SimpleNamespace as NS
 
 from amaranth import *
-from amaranth.hdl.ast import ValueCastable
+from amaranth.hdl._ast import ValueCastable
 from amaranth.lib import data, enum
 from amaranth.lib.wiring import Flow, In, Out, Member
 from amaranth.lib.wiring import SignatureError, SignatureMembers, FlippedSignatureMembers

tests/test_sim.py

@@ -3,14 +3,14 @@ import warnings
 from contextlib import contextmanager
 
 from amaranth._utils import flatten
-from amaranth.hdl.ast import *
-from amaranth.hdl.cd import  *
-from amaranth.hdl.mem import *
+from amaranth.hdl._ast import *
+from amaranth.hdl._cd import  *
+from amaranth.hdl._mem import *
 with warnings.catch_warnings():
     warnings.filterwarnings(action="ignore", category=DeprecationWarning)
     from amaranth.hdl.rec import *
-from amaranth.hdl.dsl import  *
-from amaranth.hdl.ir import *
+from amaranth.hdl._dsl import  *
+from amaranth.hdl._ir import *
 from amaranth.sim import *
 
 from .utils import *
@@ -695,10 +695,10 @@ class SimulatorIntegrationTestCase(FHDLTestCase):
             @ValueCastable.lowermethod
             def as_value(self):
                 return Signal()
-            
+
             def shape():
                 return unsigned(1)
-        
+
         a = Array([1,2,3])
         a[MyValue()]
 

tests/test_tracer.py

@@ -1,4 +1,4 @@
-from amaranth.hdl.ast import *
+from amaranth.hdl._ast import *
 from types import SimpleNamespace
 
 from .utils import *

tests/utils.py

@@ -6,8 +6,8 @@ import textwrap
 import traceback
 import unittest
 
-from amaranth.hdl.ast import *
-from amaranth.hdl.ir import *
+from amaranth.hdl._ast import *
+from amaranth.hdl._ir import *
 from amaranth.back import rtlil
 from amaranth._toolchain import require_tool