From 5c9194ee7c34053e1f7c0e20472dc25c83c7df9c Mon Sep 17 00:00:00 2001
From: David Hewitt <mail@davidhewitt.dev>
Date: Fri, 19 Apr 2024 12:00:59 +0100
Subject: [PATCH] add `#[track_caller]` to all `Py`/`Bound`/`Borrowed` methods
 which panic

---
 newsfragments/4097.changed.md | 1 +
 src/err/mod.rs                | 1 +
 src/ffi_ptr_ext.rs            | 2 ++
 src/instance.rs               | 9 +++++++++
 src/pycell.rs                 | 2 ++
 5 files changed, 15 insertions(+)
 create mode 100644 newsfragments/4097.changed.md

diff --git a/newsfragments/4097.changed.md b/newsfragments/4097.changed.md
new file mode 100644
index 00000000000..5df526a52e3
--- /dev/null
+++ b/newsfragments/4097.changed.md
@@ -0,0 +1 @@
+Add `#[track_caller]` to all `Py<T>`, `Bound<'py, T>` and `Borrowed<'a, 'py, T>` methods which can panic.
diff --git a/src/err/mod.rs b/src/err/mod.rs
index 8dd16b26b47..a61c8c62d31 100644
--- a/src/err/mod.rs
+++ b/src/err/mod.rs
@@ -1091,6 +1091,7 @@ fn display_downcast_error(
     )
 }
 
+#[track_caller]
 pub fn panic_after_error(_py: Python<'_>) -> ! {
     unsafe {
         ffi::PyErr_Print();
diff --git a/src/ffi_ptr_ext.rs b/src/ffi_ptr_ext.rs
index 3ca8671f1f6..183b0e3734e 100644
--- a/src/ffi_ptr_ext.rs
+++ b/src/ffi_ptr_ext.rs
@@ -39,6 +39,7 @@ impl FfiPtrExt for *mut ffi::PyObject {
     }
 
     #[inline]
+    #[track_caller]
     unsafe fn assume_owned(self, py: Python<'_>) -> Bound<'_, PyAny> {
         Bound::from_owned_ptr(py, self)
     }
@@ -57,6 +58,7 @@ impl FfiPtrExt for *mut ffi::PyObject {
     }
 
     #[inline]
+    #[track_caller]
     unsafe fn assume_borrowed<'a>(self, py: Python<'_>) -> Borrowed<'a, '_, PyAny> {
         Borrowed::from_ptr(py, self)
     }
diff --git a/src/instance.rs b/src/instance.rs
index 88a550ffd30..b2715abe2b9 100644
--- a/src/instance.rs
+++ b/src/instance.rs
@@ -104,6 +104,7 @@ impl<'py> Bound<'py, PyAny> {
     /// - `ptr` must be a valid pointer to a Python object
     /// - `ptr` must be an owned Python reference, as the `Bound<'py, PyAny>` will assume ownership
     #[inline]
+    #[track_caller]
     pub unsafe fn from_owned_ptr(py: Python<'py>, ptr: *mut ffi::PyObject) -> Self {
         Self(py, ManuallyDrop::new(Py::from_owned_ptr(py, ptr)))
     }
@@ -141,6 +142,7 @@ impl<'py> Bound<'py, PyAny> {
     ///
     /// - `ptr` must be a valid pointer to a Python object
     #[inline]
+    #[track_caller]
     pub unsafe fn from_borrowed_ptr(py: Python<'py>, ptr: *mut ffi::PyObject) -> Self {
         Self(py, ManuallyDrop::new(Py::from_borrowed_ptr(py, ptr)))
     }
@@ -242,6 +244,7 @@ where
     /// Panics if the value is currently mutably borrowed. For a non-panicking variant, use
     /// [`try_borrow`](#method.try_borrow).
     #[inline]
+    #[track_caller]
     pub fn borrow(&self) -> PyRef<'py, T> {
         PyRef::borrow(self)
     }
@@ -276,6 +279,7 @@ where
     /// Panics if the value is currently borrowed. For a non-panicking variant, use
     /// [`try_borrow_mut`](#method.try_borrow_mut).
     #[inline]
+    #[track_caller]
     pub fn borrow_mut(&self) -> PyRefMut<'py, T>
     where
         T: PyClass<Frozen = False>,
@@ -573,6 +577,7 @@ impl<'a, 'py> Borrowed<'a, 'py, PyAny> {
     ///   the caller and it is the caller's responsibility to ensure that the reference this is
     ///   derived from is valid for the lifetime `'a`.
     #[inline]
+    #[track_caller]
     pub unsafe fn from_ptr(py: Python<'py>, ptr: *mut ffi::PyObject) -> Self {
         Self(
             NonNull::new(ptr).unwrap_or_else(|| crate::err::panic_after_error(py)),
@@ -1138,6 +1143,7 @@ where
     /// Panics if the value is currently mutably borrowed. For a non-panicking variant, use
     /// [`try_borrow`](#method.try_borrow).
     #[inline]
+    #[track_caller]
     pub fn borrow<'py>(&'py self, py: Python<'py>) -> PyRef<'py, T> {
         self.bind(py).borrow()
     }
@@ -1175,6 +1181,7 @@ where
     /// Panics if the value is currently borrowed. For a non-panicking variant, use
     /// [`try_borrow_mut`](#method.try_borrow_mut).
     #[inline]
+    #[track_caller]
     pub fn borrow_mut<'py>(&'py self, py: Python<'py>) -> PyRefMut<'py, T>
     where
         T: PyClass<Frozen = False>,
@@ -1585,6 +1592,7 @@ impl<T> Py<T> {
     /// # Panics
     /// Panics if `ptr` is null.
     #[inline]
+    #[track_caller]
     pub unsafe fn from_owned_ptr(py: Python<'_>, ptr: *mut ffi::PyObject) -> Py<T> {
         match NonNull::new(ptr) {
             Some(nonnull_ptr) => Py(nonnull_ptr, PhantomData),
@@ -1628,6 +1636,7 @@ impl<T> Py<T> {
     /// # Panics
     /// Panics if `ptr` is null.
     #[inline]
+    #[track_caller]
     pub unsafe fn from_borrowed_ptr(py: Python<'_>, ptr: *mut ffi::PyObject) -> Py<T> {
         match Self::from_borrowed_ptr_or_opt(py, ptr) {
             Some(slf) => slf,
diff --git a/src/pycell.rs b/src/pycell.rs
index a649ad02412..80ccff0a030 100644
--- a/src/pycell.rs
+++ b/src/pycell.rs
@@ -652,6 +652,7 @@ impl<'py, T: PyClass> PyRef<'py, T> {
         self.inner.clone().into_ptr()
     }
 
+    #[track_caller]
     pub(crate) fn borrow(obj: &Bound<'py, T>) -> Self {
         Self::try_borrow(obj).expect("Already mutably borrowed")
     }
@@ -848,6 +849,7 @@ impl<'py, T: PyClass<Frozen = False>> PyRefMut<'py, T> {
     }
 
     #[inline]
+    #[track_caller]
     pub(crate) fn borrow(obj: &Bound<'py, T>) -> Self {
         Self::try_borrow(obj).expect("Already borrowed")
     }