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Make Func::getN return a Result rather than an Option (#966)

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This allows getN to return a detailed explanation of any type signature
mismatch, and makes it easy to just use `?` on the result of getN rather
than constructing a (necessarily vaguer) error message in the caller.
This commit is contained in:
Josh Triplett
2020-02-22 15:56:23 -08:00
committed by GitHub
parent 48202e0c31
commit aa78d491b0
3 changed files with 86 additions and 65 deletions
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79
crates/api/src/func.rs
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@@ -1,5 +1,6 @@
use crate::callable::{NativeCallable, WasmtimeFn, WrappedCallable};
use crate::{Callable, FuncType, Store, Trap, Val, ValType};
use anyhow::{ensure, Context as _};
use std::fmt;
use std::mem;
use std::panic::{self, AssertUnwindSafe};
@@ -98,7 +99,7 @@ macro_rules! getters {
$(#[$doc])*
#[allow(non_snake_case)]
pub fn $name<$($args,)* R>(&self)
-> Option<impl Fn($($args,)*) -> Result<R, Trap>>
-> anyhow::Result<impl Fn($($args,)*) -> Result<R, Trap>>
where
$($args: WasmTy,)*
R: WasmTy,
@@ -106,23 +107,19 @@ macro_rules! getters {
// Verify all the paramers match the expected parameters, and that
// there are no extra parameters...
let mut params = self.ty().params().iter().cloned();
let n = 0;
$(
if !$args::matches(&mut params) {
return None;
}
let n = n + 1;
$args::matches(&mut params)
.with_context(|| format!("Type mismatch in argument {}", n))?;
)*
if !params.next().is_none() {
return None;
}
ensure!(params.next().is_none(), "Type mismatch: too many arguments (expected {})", n);
// ... then do the same for the results...
let mut results = self.ty().results().iter().cloned();
if !R::matches(&mut results) {
return None;
}
if !results.next().is_none() {
return None;
}
R::matches(&mut results)
.context("Type mismatch in return type")?;
ensure!(results.next().is_none(), "Type mismatch: too many return values (expected 1)");
// ... and then once we've passed the typechecks we can hand out our
// object since our `transmute` below should be safe!
@@ -130,9 +127,9 @@ macro_rules! getters {
wasmtime_runtime::Export::Function { address, vmctx, signature: _} => {
(*address, *vmctx)
}
_ => return None,
_ => panic!("expected function export"),
};
Some(move |$($args: $args),*| -> Result<R, Trap> {
Ok(move |$($args: $args),*| -> Result<R, Trap> {
unsafe {
let f = mem::transmute::<
*const VMFunctionBody,
@@ -447,7 +444,7 @@ pub trait WasmTy {
#[doc(hidden)]
fn push(dst: &mut Vec<ValType>);
#[doc(hidden)]
fn matches(tys: impl Iterator<Item = ValType>) -> bool;
fn matches(tys: impl Iterator<Item = ValType>) -> anyhow::Result<()>;
#[doc(hidden)]
fn from_abi(vmctx: *mut VMContext, abi: Self::Abi) -> Self;
#[doc(hidden)]
@@ -457,8 +454,8 @@ pub trait WasmTy {
impl WasmTy for () {
type Abi = ();
fn push(_dst: &mut Vec<ValType>) {}
fn matches(_tys: impl Iterator<Item = ValType>) -> bool {
true
fn matches(_tys: impl Iterator<Item = ValType>) -> anyhow::Result<()> {
Ok(())
}
#[inline]
fn from_abi(_vmctx: *mut VMContext, abi: Self::Abi) -> Self {
@@ -475,8 +472,14 @@ impl WasmTy for i32 {
fn push(dst: &mut Vec<ValType>) {
dst.push(ValType::I32);
}
fn matches(mut tys: impl Iterator<Item = ValType>) -> bool {
tys.next() == Some(ValType::I32)
fn matches(mut tys: impl Iterator<Item = ValType>) -> anyhow::Result<()> {
let next = tys.next();
ensure!(
next == Some(ValType::I32),
"Type mismatch, expected i32, got {:?}",
next
);
Ok(())
}
#[inline]
fn from_abi(_vmctx: *mut VMContext, abi: Self::Abi) -> Self {
@@ -493,8 +496,14 @@ impl WasmTy for i64 {
fn push(dst: &mut Vec<ValType>) {
dst.push(ValType::I64);
}
fn matches(mut tys: impl Iterator<Item = ValType>) -> bool {
tys.next() == Some(ValType::I64)
fn matches(mut tys: impl Iterator<Item = ValType>) -> anyhow::Result<()> {
let next = tys.next();
ensure!(
next == Some(ValType::I64),
"Type mismatch, expected i64, got {:?}",
next
);
Ok(())
}
#[inline]
fn from_abi(_vmctx: *mut VMContext, abi: Self::Abi) -> Self {
@@ -511,8 +520,14 @@ impl WasmTy for f32 {
fn push(dst: &mut Vec<ValType>) {
dst.push(ValType::F32);
}
fn matches(mut tys: impl Iterator<Item = ValType>) -> bool {
tys.next() == Some(ValType::F32)
fn matches(mut tys: impl Iterator<Item = ValType>) -> anyhow::Result<()> {
let next = tys.next();
ensure!(
next == Some(ValType::F32),
"Type mismatch, expected f32, got {:?}",
next
);
Ok(())
}
#[inline]
fn from_abi(_vmctx: *mut VMContext, abi: Self::Abi) -> Self {
@@ -529,8 +544,14 @@ impl WasmTy for f64 {
fn push(dst: &mut Vec<ValType>) {
dst.push(ValType::F64);
}
fn matches(mut tys: impl Iterator<Item = ValType>) -> bool {
tys.next() == Some(ValType::F64)
fn matches(mut tys: impl Iterator<Item = ValType>) -> anyhow::Result<()> {
let next = tys.next();
ensure!(
next == Some(ValType::F64),
"Type mismatch, expected f64, got {:?}",
next
);
Ok(())
}
#[inline]
fn from_abi(_vmctx: *mut VMContext, abi: Self::Abi) -> Self {
@@ -556,7 +577,7 @@ pub trait WasmRet {
#[doc(hidden)]
fn push(dst: &mut Vec<ValType>);
#[doc(hidden)]
fn matches(tys: impl Iterator<Item = ValType>) -> bool;
fn matches(tys: impl Iterator<Item = ValType>) -> anyhow::Result<()>;
#[doc(hidden)]
fn into_abi(self) -> Self::Abi;
}
@@ -567,7 +588,7 @@ impl<T: WasmTy> WasmRet for T {
T::push(dst)
}
fn matches(tys: impl Iterator<Item = ValType>) -> bool {
fn matches(tys: impl Iterator<Item = ValType>) -> anyhow::Result<()> {
T::matches(tys)
}
@@ -583,7 +604,7 @@ impl<T: WasmTy> WasmRet for Result<T, Trap> {
T::push(dst)
}
fn matches(tys: impl Iterator<Item = ValType>) -> bool {
fn matches(tys: impl Iterator<Item = ValType>) -> anyhow::Result<()> {
T::matches(tys)
}