fix: restore def-line source range before entering function scope so co_firstlineno is correct

Copilot · youknowone · Copilot · commit 629a5fdcd87b · 2026-03-27T16:47:05.000Z
Agent-Logs-Url: https://github.com/RustPython/RustPython/sessions/94701403-2011-4525-88f1-6e06891da6a4 Co-authored-by: youknowone <69878+youknowone@users.noreply.github.com>
diff --git a/Lib/test/test_inspect/test_inspect.py b/Lib/test/test_inspect/test_inspect.py
@@ -961,7 +961,6 @@ def test_range_traceback_toplevel_frame(self):
 class TestDecorators(GetSourceBase):
     fodderModule = mod2
 
-    @unittest.expectedFailure  # TODO: RUSTPYTHON; pass
     def test_wrapped_decorator(self):
         self.assertSourceEqual(mod2.wrapped, 14, 17)
 
@@ -1259,7 +1258,6 @@ def test_class(self):
 class TestComplexDecorator(GetSourceBase):
     fodderModule = mod2
 
-    @unittest.expectedFailure  # TODO: RUSTPYTHON; return foo + bar()
     def test_parens_in_decorator(self):
         self.assertSourceEqual(self.fodderModule.complex_decorated, 273, 275)
 
diff --git a/crates/codegen/src/compile.rs b/crates/codegen/src/compile.rs
@@ -4246,11 +4246,19 @@ impl Compiler {
         is_async: bool,
         type_params: Option<&ast::TypeParams>,
     ) -> CompileResult<()> {
+        // Save the source range of the `def` line before compiling decorators/defaults,
+        // so that the function code object gets the correct co_firstlineno.
+        let def_source_range = self.current_source_range;
+
         self.prepare_decorators(decorator_list)?;
 
         // compile defaults and return funcflags
         let funcflags = self.compile_default_arguments(parameters)?;
 
+        // Restore the `def` line range so that enter_function → push_output → get_source_line_number()
+        // records the `def` keyword's line as co_firstlineno, not the last default-argument line.
+        self.set_source_range(def_source_range);
+
         let is_generic = type_params.is_some();
         let mut num_typeparam_args = 0;
 
diff --git a/extra_tests/snippets/inspect_getsource.py b/extra_tests/snippets/inspect_getsource.py
@@ -0,0 +1,40 @@
+"""Regression tests for inspect.getsource returning full source code."""
+import inspect
+
+
+def a(
+    a=0,
+):
+    pass
+
+
+source = inspect.getsource(a)
+assert "def" in source, f"Expected full source, got: {source!r}"
+
+# Ensure the full definition including the `def` line is present
+assert source.startswith("def a("), f"Source should start with 'def a(', got: {source!r}"
+
+
+# Async function with multi-line parameters
+async def b(
+    x=1,
+    y=2,
+):
+    pass
+
+
+source_b = inspect.getsource(b)
+assert "async def" in source_b, f"Expected 'async def' in source, got: {source_b!r}"
+
+
+# Function with keyword-only defaults
+def c(
+    *,
+    kw=42,
+):
+    pass
+
+
+source_c = inspect.getsource(c)
+assert "def" in source_c, f"Expected full source for kw-only defaults, got: {source_c!r}"
+assert source_c.startswith("def c("), f"Source should start with 'def c(', got: {source_c!r}"
