Method block_call_arg_ty

cranelift/codegen/src/verifier/mod.rs:1548–1630

(
        &self,
        arg: BlockArg,
        inst: Inst,
        target_type: BlockCallTargetType,
        errors: &mut VerifierErrors,
    )

    }

    fn block_call_arg_ty(
        &self,
        arg: BlockArg,
        inst: Inst,
        target_type: BlockCallTargetType,
        errors: &mut VerifierErrors,
    ) -> Result<Option<Type>, ()> {
        match arg {
            BlockArg::Value(v) => Ok(Some(self.func.dfg.value_type(v))),
            BlockArg::TryCallRet(_) | BlockArg::TryCallExn(_) => {
                // Get the invoked signature.
                let et = match self.func.dfg.insts[inst].exception_table() {
                    Some(et) => et,
                    None => {
                        errors.fatal((
                            inst,
                            self.context(inst),
                            format!(
                                "`retN` block argument in block-call not on `try_call` instruction"
                            ),
                        ))?;
                        unreachable!()
                    }
                };
                let exdata = &self.func.dfg.exception_tables[et];
                let sig = &self.func.dfg.signatures[exdata.signature()];

                match (arg, target_type) {
                    (BlockArg::TryCallRet(i), BlockCallTargetType::ExNormalRet)
                        if (i as usize) < sig.returns.len() =>
                    {
                        Ok(Some(sig.returns[i as usize].value_type))
                    }
                    (BlockArg::TryCallRet(_), BlockCallTargetType::ExNormalRet) => {
                        errors.fatal((
                            inst,
                            self.context(inst),
                            format!("out-of-bounds `retN` block argument"),
                        ))?;
                        unreachable!()
                    }
                    (BlockArg::TryCallRet(_), _) => {
                        errors.fatal((
                            inst,
                            self.context(inst),
                            format!("`retN` block argument used outside normal-return target of `try_call`"),
                        ))?;
                        unreachable!()
                    }
                    (BlockArg::TryCallExn(i), BlockCallTargetType::Exception) => {
                        if let Some(isa) = self.isa {
                            match sig
                                .call_conv
                                .exception_payload_types(isa.pointer_type())
                                .get(i as usize)
                            {
                                Some(ty) => Ok(Some(*ty)),
                                None => {