improvement(abi): replace the dispatch table's function pointer sette…

…rs with mutable getters

crates/mun_abi/src/autogen.rs

@@ -119,16 +119,22 @@ impl DispatchTable {
         }
     }
 
-    pub unsafe fn set_ptr_unchecked(&mut self, idx: u32, ptr: *const c_void) {
-        *self.fn_ptrs.offset(idx as isize) = ptr;
-    }
-
-    pub fn set_ptr(&mut self, idx: u32, ptr: *const c_void) -> bool {
+    /// Returns a mutable reference to a function pointer, without doing bounds checking.
+    ///
+    /// This is generally not recommended, use with caution! Calling this method with an
+    /// out-of-bounds index is _undefined behavior_ even if the resulting reference is not used.
+    /// For a safe alternative see [get_ptr_mut](#method.get_ptr_mut).
+    pub unsafe fn get_ptr_unchecked_mut(&self, idx: u32) -> &mut *const c_void {
+        &mut *self.fn_ptrs.offset(idx as isize)
+    }
+
+    /// Returns a mutable reference to a function pointer at the given index, or `None` if out of
+    /// bounds.
+    pub fn get_ptr_mut(&self, idx: u32) -> Option<&mut *const c_void> {
         if idx < self.num_entries {
-            unsafe { self.set_ptr_unchecked(idx, ptr) };
-            true
+            Some(unsafe { self.get_ptr_unchecked_mut(idx) })
         } else {
-            false
+            None
         }
     }
 }
@@ -456,7 +462,7 @@ mod tests {
     }
 
     #[test]
-    fn test_dispatch_table_set_ptr_unchecked() {
+    fn test_dispatch_table_get_ptr_unchecked_mut() {
         let type_name = CString::new(FAKE_TYPE_NAME).expect("Invalid fake type name.");
         let type_info = fake_type_info(&type_name);
 
@@ -467,16 +473,15 @@ mod tests {
         let signatures = &[fn_signature];
         let fn_ptrs = &mut [ptr::null()];
 
-        let mut dispatch_table = fake_dispatch_table(signatures, fn_ptrs);
-        assert_eq!(unsafe { dispatch_table.get_ptr_unchecked(0) }, fn_ptrs[0]);
-
-        let ptr = 0xffffffff as *const c_void;
-        unsafe { dispatch_table.set_ptr_unchecked(0, ptr) };
-        assert_eq!(unsafe { dispatch_table.get_ptr_unchecked(0) }, ptr);
+        let dispatch_table = fake_dispatch_table(signatures, fn_ptrs);
+        assert_eq!(
+            unsafe { dispatch_table.get_ptr_unchecked_mut(0) },
+            &mut fn_ptrs[0]
+        );
     }
 
     #[test]
-    fn test_dispatch_table_set_ptr_none() {
+    fn test_dispatch_table_get_ptr_mut_none() {
         let type_name = CString::new(FAKE_TYPE_NAME).expect("Invalid fake type name.");
         let type_info = fake_type_info(&type_name);
 
@@ -487,15 +492,12 @@ mod tests {
         let signatures = &[fn_signature];
         let fn_ptrs = &mut [ptr::null()];
 
-        let mut dispatch_table = fake_dispatch_table(signatures, fn_ptrs);
-        assert_eq!(dispatch_table.get_ptr(1), None);
-
-        let ptr = 0xffffffff as *const c_void;
-        assert_eq!(dispatch_table.set_ptr(1, ptr), false);
+        let dispatch_table = fake_dispatch_table(signatures, fn_ptrs);
+        assert_eq!(dispatch_table.get_ptr_mut(1), None);
     }
 
     #[test]
-    fn test_dispatch_table_set_ptr_some() {
+    fn test_dispatch_table_get_ptr_mut_some() {
         let type_name = CString::new(FAKE_TYPE_NAME).expect("Invalid fake type name.");
         let type_info = fake_type_info(&type_name);
 
@@ -506,12 +508,8 @@ mod tests {
         let signatures = &[fn_signature];
         let fn_ptrs = &mut [ptr::null()];
 
-        let mut dispatch_table = fake_dispatch_table(signatures, fn_ptrs);
-        assert_eq!(dispatch_table.get_ptr(0), Some(fn_ptrs[0]));
-
-        let ptr = 0xffffffff as *const c_void;
-        assert_eq!(dispatch_table.set_ptr(0, ptr), true);
-        assert_eq!(dispatch_table.get_ptr(0), Some(ptr));
+        let dispatch_table = fake_dispatch_table(signatures, fn_ptrs);
+        assert_eq!(dispatch_table.get_ptr_mut(0), Some(&mut fn_ptrs[0]));
     }
 
     fn fake_assembly_info(