d8a3d6f378
When dealing with proc macros, there are two very different kinds of errors: * first, usual errors of "proc macro panicked on this particular input" * second, the proc macro server might day if the user, eg, kills it First kind of errors are expected and are a normal output, while the second kind are genuine IO-errors. For this reason, we use a curious nested result here: `Result<Result<T, E1>, E2>` pattern, which is 100% inspired by http://sled.rs/errors.html
89 lines
2.8 KiB
Rust
89 lines
2.8 KiB
Rust
//! RA Proc Macro Server
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//!
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//! This library is able to call compiled Rust custom derive dynamic libraries on arbitrary code.
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//! The general idea here is based on <https://github.com/fedochet/rust-proc-macro-expander>.
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//!
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//! But we adapt it to better fit RA needs:
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//!
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//! * We use `tt` for proc-macro `TokenStream` server, it is easier to manipulate and interact with
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//! RA than `proc-macro2` token stream.
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//! * By **copying** the whole rustc `lib_proc_macro` code, we are able to build this with `stable`
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//! rustc rather than `unstable`. (Although in general ABI compatibility is still an issue)…
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#![allow(unreachable_pub)]
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mod dylib;
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mod abis;
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use std::{
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collections::{hash_map::Entry, HashMap},
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env, fs,
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path::{Path, PathBuf},
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time::SystemTime,
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};
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use proc_macro_api::{
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msg::{ExpandMacro, FlatTree, PanicMessage},
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ProcMacroKind,
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};
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#[derive(Default)]
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pub(crate) struct ProcMacroSrv {
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expanders: HashMap<(PathBuf, SystemTime), dylib::Expander>,
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}
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impl ProcMacroSrv {
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pub fn expand(&mut self, task: ExpandMacro) -> Result<FlatTree, PanicMessage> {
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let expander = self.expander(task.lib.as_ref()).map_err(|err| {
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debug_assert!(false, "should list macros before asking to expand");
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PanicMessage(format!("failed to load macro: {}", err))
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})?;
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let mut prev_env = HashMap::new();
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for (k, v) in &task.env {
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prev_env.insert(k.as_str(), env::var_os(k));
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env::set_var(k, v);
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}
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let macro_body = task.macro_body.to_subtree();
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let attributes = task.attributes.map(|it| it.to_subtree());
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let result = expander
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.expand(&task.macro_name, ¯o_body, attributes.as_ref())
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.map(|it| FlatTree::new(&it));
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for (k, _) in &task.env {
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match &prev_env[k.as_str()] {
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Some(v) => env::set_var(k, v),
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None => env::remove_var(k),
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}
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}
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result.map_err(PanicMessage)
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}
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pub(crate) fn list_macros(
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&mut self,
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dylib_path: &Path,
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) -> Result<Vec<(String, ProcMacroKind)>, String> {
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let expander = self.expander(dylib_path)?;
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Ok(expander.list_macros())
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}
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fn expander(&mut self, path: &Path) -> Result<&dylib::Expander, String> {
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let time = fs::metadata(path).and_then(|it| it.modified()).map_err(|err| {
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format!("Failed to get file metadata for {}: {:?}", path.display(), err)
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})?;
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Ok(match self.expanders.entry((path.to_path_buf(), time)) {
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Entry::Vacant(v) => v.insert(dylib::Expander::new(path).map_err(|err| {
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format!("Cannot create expander for {}: {:?}", path.display(), err)
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})?),
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Entry::Occupied(e) => e.into_mut(),
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})
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}
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}
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pub mod cli;
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#[cfg(test)]
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mod tests;
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