Avoid creating a second UnwindContext in finalize_definitions

Once UnwindContext sets the personality function it will need to define
a DW.ref.rust_eh_personality function which would cause a duplicate
definition if UnwindContext is called a second time.

Author: bjorn3

src/driver/jit.rs

@@ -84,7 +84,7 @@ pub(crate) fn run_jit(tcx: TyCtxt<'_>, jit_args: Vec<String>) -> ! {
 
  tcx.dcx().abort_if_errors();
 
- jit_module.finalize_definitions();
+letmut jit_module = jit_module.finalize_definitions();
 
 println!(
 "Rustc codegen cranelift will JIT run the executable, because -Cllvm-args=mode=jit was passed"
@@ -104,7 +104,7 @@ pub(crate) fn run_jit(tcx: TyCtxt<'_>, jit_args: Vec<String>) -> ! {
 call_conv: jit_module.target_config().default_call_conv,
 };
 let start_func_id = jit_module.declare_function("main",Linkage::Import,&start_sig).unwrap();
-let finalized_start:*constu8 = jit_module.module.get_finalized_function(start_func_id);
+let finalized_start:*constu8 = jit_module.get_finalized_function(start_func_id);
 
 let f:extern"C"fn(c_int,*const*constc_char) -> c_int =
 unsafe{::std::mem::transmute(finalized_start)};

src/unwind_module.rs

@@ -33,13 +33,10 @@ impl UnwindModule<ObjectModule> {
 
 #[cfg(feature = "jit")]
 implUnwindModule<cranelift_jit::JITModule>{
-pub(crate)fnfinalize_definitions(&mutself){
+pub(crate)fnfinalize_definitions(mutself) -> cranelift_jit::JITModule{
 self.module.finalize_definitions().unwrap();
-let prev_unwind_context = std::mem::replace(
-&mutself.unwind_context,
-UnwindContext::new(&mutself.module,false),
-);
-unsafe{ prev_unwind_context.register_jit(&self.module)};
+unsafe{self.unwind_context.register_jit(&self.module)};
+self.module
 }
 }