signature: Support typing.Optional[T] and refine a bit

The signature was missing "typing.Optional[T]" which has to be wrapped
around any argument with a default value of "None".

This is the only case where the repr of a type looks different than
it was written, because it renders as "typing.Union[T, NoneType]".
Solving that by redefining a few typing structures was way too
hard and too error prone. It was finally solved by a regex replacemet
that is run as a post process in generate_pyi.py .

The enumerations are now even more complete, since toplevel enums
are also included. This had the effect that enums with Python
keywords were revealed, and so the function "createEnumItem" had
to be modified.

The order of creation was also changed to avoid name clashes.

The overall structure was improved, and instead of parsing the
generated signatures to find out if something is a class method,
this is now very cleanly implemented as an inquiry to get_signature().

I tried to make sense of the flags structure that comes with many
enums. PyQt5 has a standard set of "__...__" methods without useful
signature information. I could mimick that as well, but that would
create a whole lot of pointless extra information. We should decide
later if it makes sense to include that. Right now the flags
structures show the class name, only.

This patch will be merged with the 5.14 branch. The additions of this
patch could fortunately be placed into areas which do almost not
overlap with the 5.14 signature additions.

Change-Id: Ie513e15917b04d746ab597fb7a9eb1fd766f7c73
Fixes: PYSIDE-1079
Reviewed-by: Cristian Maureira-Fredes <cristian.maureira-fredes@qt.io>

1 files changed, 34 insertions, 3 deletions

diff --git a/sources/shiboken2/shibokenmodule/files.dir/shibokensupport/signature/layout.py b/sources/shiboken2/shibokenmodule/files.dir/shibokensupport/signature/layout.py
index af8ada065..384273d92 100644
--- a/sources/shiboken2/shibokenmodule/files.dir/shibokensupport/signature/layout.py
+++ b/sources/shiboken2/shibokenmodule/files.dir/shibokensupport/signature/layout.py
@@ -56,7 +56,7 @@ used literally as strings like "signature", "existence", etc.
 """
 
 from textwrap import dedent
-from shibokensupport.signature import inspect
+from shibokensupport.signature import inspect, typing
 from shibokensupport.signature.mapping import ellipsis
 from shibokensupport.signature.lib.tool import SimpleNamespace
 
@@ -162,6 +162,35 @@ def define_nameless_parameter():
 
 NamelessParameter = define_nameless_parameter()
 
+"""
+Note on the "Optional" feature:
+
+When an annotation has a default value that is None, then the
+type has to be wrapped into "typing.Optional".
+
+Note that only the None value creates an Optional expression,
+because the None leaves the domain of the variable.
+Defaults like integer values are ignored: They stay in the domain.
+
+That information would be lost when we use the "..." convention.
+
+Note that the typing module has the remarkable expansion
+
+    Optional[T]    is    Variant[T, NoneType]
+
+We want to avoid that when generating the .pyi file.
+This is done by a regex in generate_pyi.py .
+The following would work in Python 3, but this is a version-dependent
+hack that also won't work in Python 2 and would be _very_ complex.
+"""
+# import sys
+# if sys.version_info[0] == 3:
+#     class hugo(list):pass
+#     typing._normalize_alias["hugo"] = "Optional"
+#     Optional = typing._alias(hugo, typing.T, inst=False)
+# else:
+#     Optional = typing.Optional
+
 
 def make_signature_nameless(signature):
     """
@@ -217,8 +246,6 @@ def create_signature(props, key):
     defaults = props["defaults"][:]
     if not layout.defaults:
         defaults = ()
-    if layout.ellipsis:
-        defaults = (ellipsis,) * len(defaults)
     annotations = props["annotations"].copy()
     if not layout.return_annotation and "return" in annotations:
         del annotations["return"]
@@ -235,6 +262,10 @@ def create_signature(props, key):
         name = name.lstrip("*")
         defpos = idx - len(varnames) + len(defaults)
         default = defaults[defpos] if defpos >= 0 else _empty
+        if default is None:
+            ann = typing.Optional[ann]
+        if default is not _empty and layout.ellipsis:
+            default = ellipsis
         param = inspect.Parameter(name, kind, annotation=ann, default=default)
         params.append(param)
         if kind == _VAR_POSITIONAL: