Steal pointer in pineappl_fktable_optimize instead of returning FkTable

Author: Radonirinaunimi

examples/cpp/evolve-grid.cpp

@@ -280,8 +280,8 @@ int main() {
     pineappl_grid_write(fktable, "evolved-grid.pineappl.lz4");
 
     // optimise the FK table and then write into disk
-    pineappl_fktable* fktable_opt = pineappl_fktable_optimize(fktable, PINEAPPL_FK_ASSUMPTIONS_NF3_SYM);
-    pineappl_grid_write(fktable_opt, "evolved-grid-optimised.pineappl.lz4");
+    pineappl_fktable_optimize(fktable, PINEAPPL_FK_ASSUMPTIONS_NF3_SYM);
+    pineappl_grid_write(fktable, "evolved-grid-optimised.pineappl.lz4");
 
     pineappl_grid_delete(grid);
     pineappl_grid_delete(fktable);

pineappl_capi/src/lib.rs

@@ -2286,12 +2286,9 @@ pub unsafe extern "C" fn pineappl_grid_evolve(
 ///
 /// This function panics if `grid` is not an FK table-like object.
 #[no_mangle]
-pub unsafe extern "C" fn pineappl_fktable_optimize(
-    grid: *mut Grid,
-    assumptions: FkAssumptions,
-) -> Box<FkTable> {
+pub unsafe extern "C" fn pineappl_fktable_optimize(grid: *mut Grid, assumptions: FkAssumptions) {
     let grid = unsafe { &mut *grid };
     let mut fktable = FkTable::try_from(grid.clone()).unwrap();
     fktable.optimize(assumptions);
-    Box::new(fktable)
+    unsafe { std::ptr::replace(grid, fktable.into_grid()) };
 }