docs: safety comments on more FFI functions

Author: morrisonlevi

datadog-profiling-ffi/src/profiles/datatypes.rs

@@ -419,7 +419,11 @@ pub unsafe extern "C" fn ddog_prof_Profile_new(
     profile_new(sample_types, period, None)
 }
 
-/// Same as `ddog_profile_new` but also configures a `string_storage` for the profile.
+/// Same as [ddog_prof_Profile_new] but also configures a `string_storage` for
+/// the profile.
+///
+/// # Safety
+/// Has all same safety conditions as [ddog_prof_Profile_new].
 #[no_mangle]
 #[must_use]
 /// TODO: @ivoanjo Should this take a `*mut ManagedStringStorage` like Profile APIs do?
@@ -809,6 +813,14 @@ pub unsafe extern "C" fn ddog_prof_Profile_serialize(
     .into()
 }
 
+/// Borrows FFI Vec as an FFI Slice.
+///
+/// # Safety
+/// The input needs to be a valid reference to an FFI Vec, and the slice needs
+/// to be used in a way consistent with the lifetime and safety rules. Some
+/// things to avoid:
+///  - Do not modify the Vec at all while the Slice is alive.
+///  - Do not drop the Vec while the Slice is alive.
 #[must_use]
 #[no_mangle]
 pub unsafe extern "C" fn ddog_Vec_U8_as_slice(vec: &ddcommon_ffi::Vec<u8>) -> Slice<u8> {

datadog-profiling-ffi/src/profiles/interning_api.rs

@@ -407,14 +407,9 @@ pub unsafe extern "C" fn ddog_prof_Profile_get_generation(
 }
 
 /// This functions returns whether the given generations are equal.
-///
-/// # Safety: No safety requirements
 #[must_use]
 #[no_mangle]
-pub unsafe extern "C" fn ddog_prof_Profile_generations_are_equal(
-    a: Generation,
-    b: Generation,
-) -> bool {
+pub extern "C" fn ddog_prof_Profile_generations_are_equal(a: Generation, b: Generation) -> bool {
     a == b
 }