add test for fully overlapping overloads

Author: carljm

conformance/results/mypy/overloads_overlap.toml

@@ -4,4 +4,5 @@ errors_diff = """
 """
 output = """
 overloads_overlap.py:14: error: Overloaded function signatures 1 and 2 overlap with incompatible return types  [overload-overlap]
+overloads_overlap.py:36: error: Overloaded function signature 2 will never be matched: signature 1's parameter type(s) are the same or broader  [overload-cannot-match]
 """

conformance/results/pyre/overloads_overlap.toml

@@ -1,10 +1,11 @@
-conformant = "Fail"
+conformant = "Partial"
 notes = """
-Does not check for overlapping overloads with inconsistent return type.
+Does not check for partially overlapping overloads with inconsistent return type.
 """
 conformance_automated = "Fail"
 errors_diff = """
 Line 14: Expected 1 errors
 """
 output = """
+overloads_overlap.py:36:0 Incompatible overload [43]: The overloaded function `full_overlap` on line 36 will never be matched. The signature `(x: bool) -> bool` is the same or broader.
 """

conformance/results/pyre/version.toml

@@ -1,2 +1,2 @@
 version = "pyre 0.9.23"
-test_duration = 6.7
+test_duration = 6.6

conformance/results/pyright/overloads_overlap.toml

@@ -4,4 +4,5 @@ errors_diff = """
 """
 output = """
 overloads_overlap.py:14:5 - error: Overload 1 for "is_one" overlaps overload 2 and returns an incompatible type (reportOverlappingOverload)
+overloads_overlap.py:36:5 - error: Overload 2 for "full_overlap" will never be used because its parameters overlap overload 1 (reportOverlappingOverload)
 """

conformance/results/pytype/overloads_overlap.toml

@@ -1,16 +1,23 @@
 conformant = "Fail"
 notes = """
-Does not check for overlapping overloads with inconsistent return type.
+Does not check for partially or fully overlapping overloads.
 """
 conformance_automated = "Fail"
 errors_diff = """
 Line 14: Expected 1 errors
+Line 36: Expected 1 errors
 Line 22: Unexpected errors ['overloads_overlap.py:22:5: \\x1b[1m\\x1b[31merror\\x1b[39m\\x1b[0m: in is_one: bad return type [bad-return-type]']
+Line 40: Unexpected errors ['overloads_overlap.py:40:12: \\x1b[1m\\x1b[31merror\\x1b[39m\\x1b[0m: in full_overlap: bad return type [bad-return-type]']
 """
 output = """
 overloads_overlap.py:22:5: \u001b[1m\u001b[31merror\u001b[39m\u001b[0m: in is_one: bad return type [bad-return-type]
 
     return x == 1
     \u001b[1m\u001b[31m~~~~~~~~~~~~~\u001b[39m\u001b[0m
 
+overloads_overlap.py:40:12: \u001b[1m\u001b[31merror\u001b[39m\u001b[0m: in full_overlap: bad return type [bad-return-type]
+
+    return 1
+           \u001b[1m\u001b[31m~\u001b[39m\u001b[0m
+
 """

conformance/results/pytype/version.toml

@@ -1,2 +1,2 @@
 version = "pytype 2024.10.11"
-test_duration = 32.1
+test_duration = 30.1

conformance/results/results.html

@@ -165,10 +165,10 @@ <h3>Python Type System Conformance Test Results</h3>
 <div class='tc-time'>1.5sec</div>
 </th>
 <th class='tc-header'><div class='tc-name'>pyre 0.9.23</div>
-<div class='tc-time'>6.7sec</div>
+<div class='tc-time'>6.6sec</div>
 </th>
 <th class='tc-header'><div class='tc-name'>pytype 2024.10.11</div>
-<div class='tc-time'>32.1sec</div>
+<div class='tc-time'>30.1sec</div>
 </th>
 </tr>
 <tr><th class="column" colspan="5">
@@ -693,8 +693,8 @@ <h3>Python Type System Conformance Test Results</h3>
 <tr><th class="column col1">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;overloads_overlap</th>
 <th class="column col2 conformant">Pass</th>
 <th class="column col2 conformant">Pass</th>
-<th class="column col2 not-conformant"><div class="hover-text">Fail<span class="tooltip-text" id="bottom"><p>Does not check for overlapping overloads with inconsistent return type.</p></span></div></th>
-<th class="column col2 not-conformant"><div class="hover-text">Fail<span class="tooltip-text" id="bottom"><p>Does not check for overlapping overloads with inconsistent return type.</p></span></div></th>
+<th class="column col2 partially-conformant"><div class="hover-text">Partial<span class="tooltip-text" id="bottom"><p>Does not check for partially overlapping overloads with inconsistent return type.</p></span></div></th>
+<th class="column col2 not-conformant"><div class="hover-text">Fail<span class="tooltip-text" id="bottom"><p>Does not check for partially or fully overlapping overloads.</p></span></div></th>
 </tr>
 <tr><th class="column" colspan="5">
 <a class="test_group" href="https://typing.readthedocs.io/en/latest/spec/exceptions.html">Exceptions</a>

conformance/tests/overloads_overlap.py

@@ -20,3 +20,21 @@ def is_one(x: int) -> Literal[False]:
 
 def is_one(x: int) -> bool:
     return x == 1
+
+
+# > If all possible sets of arguments accepted by an overload are also always
+# > accepted by an earlier overload, the two overloads are said to "fully overlap".
+# > In this case, the latter overload will never be used. This condition
+# > is indicative of a programming error and should be reported by type
+# > checkers.
+
+@overload
+def full_overlap(x: bool) -> bool:
+    ...
+
+@overload
+def full_overlap(x: Literal[False]) -> int:  # E: overload will never be used due to full overlap
+    ...
+
+def full_overlap(x: bool) -> int:
+    return 1