infer-function-types: fix infer from defaults with inner functions

CHANGELOG.md

@@ -9,6 +9,7 @@
 ### Fixes
 - Handle positional only `/` parameters in overload implementation inference
 - Render inferred literal without `?`
+- Fix infer from defaults for inner functions
 
 ## [1.5.0]
 ### Added

mypy/semanal.py

@@ -3040,7 +3040,7 @@ def analyze_simple_literal_type(
         """Return builtins.int if rvalue is an int literal, etc.
 
         If this is a 'Final' context, we return "Literal[...]" instead."""
-        if self.options.semantic_analysis_only or self.function_stack:
+        if self.options.semantic_analysis_only or self.function_stack and not do_bools:
             # Skip this if we're only doing the semantic analysis pass.
             # This is mostly to avoid breaking unit tests.
             # Also skip inside a function; this is to avoid confusing

test-data/unit/check-based-infer-function-types.test

@@ -468,3 +468,9 @@ def deco(func: T) -> T: ...
 def b(b=True) -> None: ...
 
 reveal_type(b)  # N: Revealed type is "def (b: bool =) -> None"
+
+
+[case testInferFromDefaultNested]
+def f1():
+    def f2(a=True): ...
+    reveal_type(f2)  # N: Revealed type is "def (a: bool =) -> None"