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Update usage of `syn` in Procedural Macros chapter 

This makes 2 changes:
1. It updates the versions of `syn` and `quote` to the latest versions.
2. It updates the code to not use the deprecated type alias `syn::MacroInput` and instead use the preferred `syn::DeriveInput`. `MacroInput` will be removed in the next breaking version of `syn`. See https://github.com/dtolnay/syn/pull/173
This commit is contained in:
Michael Layzell 2017-06-07 10:39:27 -04:00 committed by GitHub
parent 7a999ef48f
commit 94946f20ce
1 changed files with 5 additions and 5 deletions
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10
first-edition/src/procedural-macros.md
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@ -153,7 +153,7 @@ In this case, we're keeping it as simple as possible.
Great, so let's write `impl_hello_world(&ast)`. Great, so let's write `impl_hello_world(&ast)`.
```rust,ignore ```rust,ignore
fn impl_hello_world(ast: &syn::MacroInput) -> quote::Tokens { fn impl_hello_world(ast: &syn::DeriveInput) -> quote::Tokens {
let name = &ast.ident; let name = &ast.ident;
quote! { quote! {
impl HelloWorld for #name { impl HelloWorld for #name {
@ -167,7 +167,7 @@ fn impl_hello_world(ast: &syn::MacroInput) -> quote::Tokens {
So this is where quotes comes in. The `ast` argument is a struct that gives us So this is where quotes comes in. The `ast` argument is a struct that gives us
a representation of our type (which can be either a `struct` or an `enum`). a representation of our type (which can be either a `struct` or an `enum`).
Check out the [docs](https://docs.rs/syn/0.10.5/syn/struct.MacroInput.html), Check out the [docs](https://docs.rs/syn/0.11.11/syn/struct.DeriveInput.html),
there is some useful information there. We are able to get the name of the there is some useful information there. We are able to get the name of the
type using `ast.ident`. The `quote!` macro lets us write up the Rust code type using `ast.ident`. The `quote!` macro lets us write up the Rust code
that we wish to return and convert it into `Tokens`. `quote!` lets us use some that we wish to return and convert it into `Tokens`. `quote!` lets us use some
@ -181,8 +181,8 @@ So I think that's it. Oh, well, we do need to add dependencies for `syn` and
```toml ```toml
[dependencies] [dependencies]
syn = "0.10.5" syn = "0.11.11"
quote = "0.3.10" quote = "0.3.15"
``` ```
That should be it. Let's try to compile `hello-world`. That should be it. Let's try to compile `hello-world`.
@ -254,7 +254,7 @@ But how do we tell the user, that we do not accept enums?
The idiomatic way to report errors in procedural macros is to panic: The idiomatic way to report errors in procedural macros is to panic:
```rust,ignore ```rust,ignore
fn impl_hello_world(ast: &syn::MacroInput) -> quote::Tokens { fn impl_hello_world(ast: &syn::DeriveInput) -> quote::Tokens {
let name = &ast.ident; let name = &ast.ident;
// Check if derive(HelloWorld) was specified for a struct // Check if derive(HelloWorld) was specified for a struct
if let syn::Body::Struct(_) = ast.body { if let syn::Body::Struct(_) = ast.body {