fix: use c++ memory allocator to match delete calls

Use ::operator new(size) to allocate memory inside C++ instead of using
the Rust libc::malloc. This as the Rust call maps to the C malloc
function rather than the C++ new keyword. As delete keyword is used to
free memory, we also must allocate with new to ensure memory is correctly
managed.

Author: tirithen

build.rs

@@ -198,6 +198,8 @@ fn main() {
             .allowlist_function("clipper_clipperoffset_add_paths64")
             .allowlist_function("clipper_clipperoffset_execute")
             .allowlist_function("clipper_delete_clipperoffset")
+            // Memory allocation
+            .allowlist_function("clipper_allocate")
             .size_t_is_usize(true);
 
         let bindings = builder.generate().expect("unable to generate bindings");

clipper2c/include/clipper2c.h

@@ -510,6 +510,7 @@ void clipper_destruct_svgwriter(ClipperSvgWriter *p);
 void clipper_destruct_svgreader(ClipperSvgReader *p);
 
 // pointer free + destruction
+void* clipper_allocate(size_t size);
 
 void clipper_delete_path64(ClipperPath64 *p);
 void clipper_delete_pathd(ClipperPathD *p);
@@ -527,4 +528,4 @@ void clipper_delete_svgreader(ClipperSvgReader *p);
 
 #ifdef __cplusplus
 }
-#endif
+#endif

clipper2c/src/clipper2c.cpp

@@ -1003,7 +1003,7 @@ extern "C"
   }
 
   // pointer free + destruction
-
+  void* clipper_allocate(size_t size) { return ::operator new(size); }
   void clipper_delete_path64(ClipperPath64 *p) { delete from_c(p); }
   void clipper_delete_pathd(ClipperPathD *p) { delete from_c(p); }
   void clipper_delete_paths64(ClipperPaths64 *p) { delete from_c(p); }
@@ -1020,4 +1020,4 @@ extern "C"
 
 #ifdef __cplusplus
 }
-#endif
+#endif

generated/bindings.rs

@@ -1,5 +1,7 @@
 /* automatically generated by rust-bindgen 0.69.4 */
 
+use std::os::raw::c_void;
+
 #[repr(C)]
 #[derive(Debug, Copy, Clone)]
 pub struct ClipperClipper64 {
@@ -88,10 +90,7 @@ fn bindgen_test_layout_ClipperPointD() {
 }
 #[repr(C)]
 #[derive(Debug, Default, Copy, Clone, Hash, PartialEq, Eq)]
-#[cfg_attr(
-	feature = "serde",
-	derive(serde::Serialize, serde::Deserialize)
-)]
+#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
 pub struct ClipperPoint64 {
     pub x: i64,
     pub y: i64,
@@ -686,6 +685,9 @@ extern "C" {
 extern "C" {
     pub fn clipper_clipperoffset_size() -> usize;
 }
+extern "C" {
+    pub fn clipper_allocate(size: usize) -> *mut c_void;
+}
 extern "C" {
     pub fn clipper_delete_path64(p: *mut ClipperPath64);
 }