pycode: Detect @overload decorators

2 files changed, 37 insertions, 0 deletions

diff --git a/sphinx/pycode/__init__.py b/sphinx/pycode/__init__.py
index 4879fb349..963680a54 100644
--- a/sphinx/pycode/__init__.py
+++ b/sphinx/pycode/__init__.py
@@ -12,6 +12,7 @@ import re
 import tokenize
 import warnings
 from importlib import import_module
+from inspect import Signature
 from io import StringIO
 from os import path
 from typing import Any, Dict, IO, List, Tuple, Optional
@@ -145,6 +146,7 @@ class ModuleAnalyzer:
         self.annotations = None  # type: Dict[Tuple[str, str], str]
         self.attr_docs = None    # type: Dict[Tuple[str, str], List[str]]
         self.finals = None       # type: List[str]
+        self.overloads = None    # type: Dict[str, List[Signature]]
         self.tagorder = None     # type: Dict[str, int]
         self.tags = None         # type: Dict[str, Tuple[str, int, int]]
 
@@ -163,6 +165,7 @@ class ModuleAnalyzer:
 
             self.annotations = parser.annotations
             self.finals = parser.finals
+            self.overloads = parser.overloads
             self.tags = parser.definitions
             self.tagorder = parser.deforders
         except Exception as exc:
diff --git a/sphinx/pycode/parser.py b/sphinx/pycode/parser.py
index 3762c72cc..ec89a3616 100644
--- a/sphinx/pycode/parser.py
+++ b/sphinx/pycode/parser.py
@@ -12,12 +12,14 @@ import itertools
 import re
 import sys
 import tokenize
+from inspect import Signature
 from token import NAME, NEWLINE, INDENT, DEDENT, NUMBER, OP, STRING
 from tokenize import COMMENT, NL
 from typing import Any, Dict, List, Optional, Tuple
 
 from sphinx.pycode.ast import ast  # for py37 or older
 from sphinx.pycode.ast import parse, unparse
+from sphinx.util.inspect import signature_from_ast
 
 
 comment_re = re.compile('^\\s*#: ?(.*)\r?\n?$')
@@ -232,8 +234,10 @@ class VariableCommentPicker(ast.NodeVisitor):
         self.previous = None            # type: ast.AST
         self.deforders = {}             # type: Dict[str, int]
         self.finals = []                # type: List[str]
+        self.overloads = {}             # type: Dict[str, List[Signature]]
         self.typing = None              # type: str
         self.typing_final = None        # type: str
+        self.typing_overload = None     # type: str
         super().__init__()
 
     def get_qualname_for(self, name: str) -> Optional[List[str]]:
@@ -257,6 +261,12 @@ class VariableCommentPicker(ast.NodeVisitor):
         if qualname:
             self.finals.append(".".join(qualname))
 
+    def add_overload_entry(self, func: ast.FunctionDef) -> None:
+        qualname = self.get_qualname_for(func.name)
+        if qualname:
+            overloads = self.overloads.setdefault(".".join(qualname), [])
+            overloads.append(signature_from_ast(func))
+
     def add_variable_comment(self, name: str, comment: str) -> None:
         qualname = self.get_qualname_for(name)
         if qualname:
@@ -285,6 +295,22 @@ class VariableCommentPicker(ast.NodeVisitor):
 
         return False
 
+    def is_overload(self, decorators: List[ast.expr]) -> bool:
+        overload = []
+        if self.typing:
+            overload.append('%s.overload' % self.typing)
+        if self.typing_overload:
+            overload.append(self.typing_overload)
+
+        for decorator in decorators:
+            try:
+                if unparse(decorator) in overload:
+                    return True
+            except NotImplementedError:
+                pass
+
+        return False
+
     def get_self(self) -> ast.arg:
         """Returns the name of first argument if in function."""
         if self.current_function and self.current_function.args.args:
@@ -310,6 +336,8 @@ class VariableCommentPicker(ast.NodeVisitor):
                 self.typing = name.asname or name.name
             elif name.name == 'typing.final':
                 self.typing_final = name.asname or name.name
+            elif name.name == 'typing.overload':
+                self.typing_overload = name.asname or name.name
 
     def visit_ImportFrom(self, node: ast.ImportFrom) -> None:
         """Handles Import node and record it to definition orders."""
@@ -318,6 +346,8 @@ class VariableCommentPicker(ast.NodeVisitor):
 
             if node.module == 'typing' and name.name == 'final':
                 self.typing_final = name.asname or name.name
+            elif node.module == 'typing' and name.name == 'overload':
+                self.typing_overload = name.asname or name.name
 
     def visit_Assign(self, node: ast.Assign) -> None:
         """Handles Assign node and pick up a variable comment."""
@@ -417,6 +447,8 @@ class VariableCommentPicker(ast.NodeVisitor):
             self.add_entry(node.name)  # should be called before setting self.current_function
             if self.is_final(node.decorator_list):
                 self.add_final_entry(node.name)
+            if self.is_overload(node.decorator_list):
+                self.add_overload_entry(node)
             self.context.append(node.name)
             self.current_function = node
             for child in node.body:
@@ -518,6 +550,7 @@ class Parser:
         self.deforders = {}         # type: Dict[str, int]
         self.definitions = {}       # type: Dict[str, Tuple[str, int, int]]
         self.finals = []            # type: List[str]
+        self.overloads = {}         # type: Dict[str, List[Signature]]
 
     def parse(self) -> None:
         """Parse the source code."""
@@ -533,6 +566,7 @@ class Parser:
         self.comments = picker.comments
         self.deforders = picker.deforders
         self.finals = picker.finals
+        self.overloads = picker.overloads
 
     def parse_definition(self) -> None:
         """Parse the location of definitions from the code."""