From b1df2ae82e6a2190ab2bfa330cb37e43ab0a727b Mon Sep 17 00:00:00 2001 From: Ralf Jung Date: Thu, 16 Aug 2018 10:30:56 +0200 Subject: [PATCH] fix computing layout when calling virtual fn --- src/librustc_mir/interpret/terminator/mod.rs | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-) diff --git a/src/librustc_mir/interpret/terminator/mod.rs b/src/librustc_mir/interpret/terminator/mod.rs index 5ceff57bfee4..9b7df90979d3 100644 --- a/src/librustc_mir/interpret/terminator/mod.rs +++ b/src/librustc_mir/interpret/terminator/mod.rs @@ -384,10 +384,16 @@ impl<'a, 'mir, 'tcx, M: Machine<'mir, 'tcx>> EvalContext<'a, 'mir, 'tcx, M> { ptr_align )?.to_ptr()?; let instance = self.memory.get_fn(fn_ptr)?; + + // We have to patch the self argument, in particular get the layout + // expected by the actual function. Cannot just use "field 0" due to + // Box. let mut args = args.to_vec(); - let layout = args[0].layout.field(&self, 0)?; - args[0].layout = layout; - args[0].op = Operand::Immediate(Value::Scalar(ptr.into())); + let pointee = args[0].layout.ty.builtin_deref(true).unwrap().ty; + let fake_fat_ptr_ty = self.tcx.mk_mut_ptr(pointee); + args[0].layout = self.layout_of(fake_fat_ptr_ty)?.field(&self, 0)?; + args[0].op = Operand::Immediate(Value::Scalar(ptr.into())); // strip vtable + trace!("Patched self operand to {:#?}", args[0]); // recurse with concrete function self.eval_fn_call(instance, destination, &args, span, sig) }