ae9af212ff
# Overview
This commit makes changes to the `wiggle::from_witx` procedural in order
to allow for escaping strict and reserved Rust keywords.
Additionally, this commit introduces the ability to use a `witx_literal`
field in the `{..}` object provided as an argument to
`wiggle::from_witx`. This field allows for witx documents to be provided
as inline string literals.
Documentation comments are added to the methods of
`wiggle_generate::names::Names` struct responsible for generating
`proc_macro2::Ident` words.
## Keyword Escaping
Today, an interface that includes witx identifiers that conflict with
with Rust syntax will cause the `from_witx` macro to panic at
compilation time.
Here is a small example (adapted from
`/crates/wiggle/tests/keywords.rs`) that demonstrates this issue:
```
;; Attempts to define a module `self`, containing a trait `Self`. Both
;; of these are reserved keywords, and will thus cause a compilation
;; error.
(module $self
(@interface func (export "betchya_cant_implement_this")
)
)
```
Building off of code that (as of `master` today)
[demonstrates a strategy][esc] for escaping keywords, we introduce an
internal `escaping` module to `generate/src/config.rs` that contains
code responsible for escaping Rust keywords in a generalized manner.
[esc]: 0dd77d36f8/crates/wiggle/generate/src/names.rs (L106)
Some code related to special cases, such as accounting for
[`errno::2big`][err] while generating names for enum variants, is moved
into this module as well.
[err]: https://github.com/WebAssembly/WASI/blob/master/phases/snapshot/docs.md#-errno-enumu16
As mentioned in the document comments of this diff, we do not include
weak keywords like `'static` or `union`. Their semantics do not impact
us in the same way from a code generation perspective.
## witx_literal
First, some background. Trait names, type names, and so on use a
camel-cased naming convention. As such, `Self` is the only keyword that
can potentially conflict with these identifiers. (See the [Rust
Reference][key] for a complete list of strict, reserved, and weak
keywords.)
When writing tests, this meant that many tests had to be outlined into
separate files, as items with the name `$self` could not be defined in
the same namespace. As such, it seemed like a worthwhile feature to
implement while the above work was being developed.
The most important function to note is the `load_document` inherent
method added to `WitxConf`, and that `WitxConf` is now an enum
containing either (a) a collection of paths, identical to its current
functionality, or (b) a single string literal.
Note that a witx document given to `from_witx` using a string literal
provided to `from_witx` cannot include `use (..)` directives, per
the `witx::parse` documentation.
(See: https://docs.rs/witx/0.8.5/witx/fn.parse.html)
Two newtypes, `Paths` and `Literal`, are introduced to facilitate the
parsing of `WitxConf` values. Their public API and trait implementations
has been kept to the minimum required to satisfy compilation in order to
limit the scope of this diff. Additional surface for external consumers
can be added in follow-up commits if deemed necessary in review.
wiggle-generate
This is a library crate that implements all of the component parts of
the wiggle proc-macro crate.
Code lives in a separate non-proc-macro crate so that it can be reused in
other settings, e.g. the lucet-wiggle crate.
Code generated by this crate should not have any references to a particular WebAssembly runtime or engine. It should instead expose traits that may be implemented by an engine. Today, it is consumed by both Lucet and Wasmtime.