Rewrite SyntaxEnv #11228

sfackler · 2013-12-31T01:48:16Z

I'd really like to be able to do something like

struct MapChain<'next, K, V> {
    info: BlockInfo,
    map: HashMap<K, V>,
    next: Option<&'next mut MapChain<'next, K, V>
}

but I can't get the lifetimes to work out.

sfackler · 2013-12-31T01:48:25Z

cc @pcwalton

I'd really like to be able to do something like struct MapChain<'next, K, V> { info: BlockInfo, map: HashMap<K, V>, next: Option<&'next mut MapChain<'next, K, V> } but I can't get the lifetimes to work out.

huonw · 2013-12-31T01:50:29Z

Did you try something like

struct MapChain<'this, 'next, K, V> { 
    ... 
    next: Option<&'this mut MapChain<'next, K, V>> 
}

which will be more flexible because the lifetimes are more independent.

sfackler · 2013-12-31T03:53:44Z

@huonw I was thinking about that, but I think it's actually impossible to define if the lifetimes of the pointer and the struct aren't the same. The struct declaration in next is missing a lifetime parameter, right?

huonw · 2013-12-31T05:12:07Z

Oh, of course.

alexcrichton · 2013-12-31T08:07:48Z

This all looks really good to me, but that comes with a grain of salt because I have no idea what's going on in this part of the compiler. I think @jclements has done work on macros in the past, but it looks like @pcwalton's also done a fair bit of work in this part of the compiler, and I'd defer to them for looking over what's going on.

sfackler · 2014-01-01T23:56:30Z

ping @pcwalton

I'd really like to be able to do something like ```rust struct MapChain<'next, K, V> { info: BlockInfo, map: HashMap<K, V>, next: Option<&'next mut MapChain<'next, K, V> } ``` but I can't get the lifetimes to work out.

This is a first pass on support for procedural macros that aren't hardcoded into libsyntax. It is **not yet ready to merge** but I've opened a PR to have a chance to discuss some open questions and implementation issues. Example ======= Here's a silly example showing off the basics: my_synext.rs ```rust #[feature(managed_boxes, globs, macro_registrar, macro_rules)]; extern mod syntax; use syntax::ast::{Name, token_tree}; use syntax::codemap::Span; use syntax::ext::base::*; use syntax::parse::token; #[macro_export] macro_rules! exported_macro (() => (2)) #[macro_registrar] pub fn macro_registrar(register: |Name, SyntaxExtension|) { register(token::intern(&"make_a_1"), NormalTT(@SyntaxExpanderTT { expander: SyntaxExpanderTTExpanderWithoutContext(expand_make_a_1), span: None, } as @SyntaxExpanderTTTrait, None)); } pub fn expand_make_a_1(cx: &mut ExtCtxt, sp: Span, tts: &[token_tree]) -> MacResult { if !tts.is_empty() { cx.span_fatal(sp, "make_a_1 takes no arguments"); } MRExpr(quote_expr!(cx, 1i)) } ``` main.rs: ```rust #[feature(phase)]; #[phase(syntax)] extern mod my_synext; fn main() { assert_eq!(1, make_a_1!()); assert_eq!(2, exported_macro!()); } ``` Overview ======= Crates that contain syntax extensions need to define a function with the following signature and annotation: ```rust #[macro_registrar] pub fn registrar(register: |ast::Name, ext::base::SyntaxExtension|) { ... } ``` that should call the `register` closure with each extension it defines. `macro_rules!` style macros can be tagged with `#[macro_export]` to be exported from the crate as well. Crates that wish to use externally loadable syntax extensions load them by adding the `#[phase(syntax)]` attribute to an `extern mod`. All extensions registered by the specified crate are loaded with the same scoping rules as `macro_rules!` macros. If you want to use a crate both for syntax extensions and normal linkage, you can use `#[phase(syntax, link)]`. Open questions =========== * ~~Does the `macro_crate` syntax make sense? It wraps an entire `extern mod` declaration which looks a bit weird but is nice in the sense that the crate lookup logic can be identical between normal external crates and external macro crates. If the `extern mod` syntax, changes, this will get it for free, etc.~~ Changed to a `phase` attribute. * ~~Is the magic name `macro_crate_registration` the right way to handle extension registration? It could alternatively be handled by a function annotated with `#[macro_registration]` I guess.~~ Switched to an attribute. * The crate loading logic lives inside of librustc, which means that the syntax extension infrastructure can't directly access it. I've worked around this by passing a `CrateLoader` trait object from the driver to libsyntax that can call back into the crate loading logic. It should be possible to pull things apart enough that this isn't necessary anymore, but it will be an enormous refactoring project. I think we'll need to create a couple of new libraries: libsynext libmetadata/ty and libmiddle. * Item decorator extensions can be loaded but the `deriving` decorator itself can't be extended so you'd need to do e.g. `#[deriving_MyTrait] #[deriving(Clone)]` instead of `#[deriving(MyTrait, Clone)]`. Is this something worth bothering with for now? Remaining work =========== - [x] ~~There is not yet support for rustdoc downloading and compiling referenced macro crates as it does for other referenced crates. This shouldn't be too hard I think.~~ - [x] ~~This is not testable at stage1 and sketchily testable at stages above that. The stage *n* rustc links against the stage *n-1* libsyntax and librustc. Unfortunately, crates in the test/auxiliary directory link against the stage *n* libstd, libextra, libsyntax, etc. This causes macro crates to fail to properly dynamically link into rustc since names end up being mangled slightly differently. In addition, when rustc is actually installed onto a system, there are actually do copies of libsyntax, libstd, etc: the ones that user code links against and a separate set from the previous stage that rustc itself uses. By this point in the bootstrap process, the two library versions *should probably* be binary compatible, but it doesn't seem like a sure thing. Fixing this is apparently hard, but necessary to properly cross compile as well and is being tracked in #11145.~~ The offending tests are ignored during `check-stage1-rpass` and `check-stage1-cfail`. When we get a snapshot that has this commit, I'll look into how feasible it'll be to get them working on stage1. - [x] ~~`macro_rules!` style macros aren't being exported. Now that the crate loading infrastructure is there, this should just require serializing the AST of the macros into the crate metadata and yanking them out again, but I'm not very familiar with that part of the compiler.~~ - [x] ~~The `macro_crate_registration` function isn't type-checked when it's loaded. I poked around in the `csearch` infrastructure a bit but didn't find any super obvious ways of checking the type of an item with a certain name. Fixing this may also eliminate the need to `#[no_mangle]` the registration function.~~ Now that the registration function is identified by an attribute, typechecking this will be like typechecking other annotated functions. - [x] ~~The dynamic libraries that are loaded are never unloaded. It shouldn't require too much work to tie the lifetime of the `DynamicLibrary` object to the `MapChain` that its extensions are loaded into.~~ - [x] ~~The compiler segfaults sometimes when loading external crates. The `DynamicLibrary` reference and code objects from that library are both put into the same hash table. When the table drops, due to the random ordering the library sometimes drops before the objects do. Once #11228 lands it'll be easy to fix this.~~

…with_test, r=flip1995 test that we correctly detect panics in intergation tests should be merged after rust-lang/rust-clippy#11225 changelog: add test for integration tests

Rewrite SyntaxEnv

b74613b

I'd really like to be able to do something like struct MapChain<'next, K, V> { info: BlockInfo, map: HashMap<K, V>, next: Option<&'next mut MapChain<'next, K, V> } but I can't get the lifetimes to work out.

sfackler mentioned this pull request Jan 3, 2014

RFC: Externally loadable syntax extensions #11151

Merged

6 tasks

bors closed this Jan 3, 2014

bors merged commit b74613b into rust-lang:master Jan 3, 2014

sfackler deleted the syntaxenv branch May 15, 2014 05:03

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Rewrite SyntaxEnv #11228

Rewrite SyntaxEnv #11228

sfackler commented Dec 31, 2013

sfackler commented Dec 31, 2013

huonw commented Dec 31, 2013

sfackler commented Dec 31, 2013

huonw commented Dec 31, 2013

alexcrichton commented Dec 31, 2013

sfackler commented Jan 1, 2014

Rewrite SyntaxEnv #11228

Rewrite SyntaxEnv #11228

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sfackler commented Dec 31, 2013

sfackler commented Dec 31, 2013

huonw commented Dec 31, 2013

sfackler commented Dec 31, 2013

huonw commented Dec 31, 2013

alexcrichton commented Dec 31, 2013

sfackler commented Jan 1, 2014