Auto merge of #12835 - fasterthanlime:sysroot-abi, r=fasterthanlime

Introduce proc-macro-srv/sysroot-abi

Still a WIP.

This change is tracked by:

  * #12818

crates/proc-macro-api/src/lib.rs

@@ -26,7 +26,7 @@ use crate::{
     process::ProcMacroProcessSrv,
 };
 
-pub use version::{read_dylib_info, RustCInfo};
+pub use version::{read_dylib_info, read_version, RustCInfo};
 
 #[derive(Copy, Clone, Eq, PartialEq, Debug, Serialize, Deserialize)]
 pub enum ProcMacroKind {

crates/proc-macro-api/src/version.rs

@@ -16,6 +16,8 @@ pub struct RustCInfo {
     pub channel: String,
     pub commit: Option<String>,
     pub date: Option<String>,
+    // something like "rustc 1.58.1 (db9d1b20b 2022-01-20)"
+    pub version_string: String,
 }
 
 /// Read rustc dylib information
@@ -68,7 +70,7 @@ pub fn read_dylib_info(dylib_path: &AbsPath) -> io::Result<RustCInfo> {
     }
     let version = (version_numbers[0], version_numbers[1], version_numbers[2]);
 
-    Ok(RustCInfo { version, channel, commit, date })
+    Ok(RustCInfo { version, channel, commit, date, version_string: ver_str })
 }
 
 /// This is used inside read_version() to locate the ".rustc" section
@@ -102,7 +104,7 @@ fn read_section<'a>(dylib_binary: &'a [u8], section_name: &str) -> io::Result<&'
 /// * [some more bytes that we don't really care but about still there] :-)
 /// Check this issue for more about the bytes layout:
 /// <https://github.com/rust-lang/rust-analyzer/issues/6174>
-fn read_version(dylib_path: &AbsPath) -> io::Result<String> {
+pub fn read_version(dylib_path: &AbsPath) -> io::Result<String> {
     let dylib_file = File::open(dylib_path)?;
     let dylib_mmaped = unsafe { Mmap::map(&dylib_file) }?;
 

crates/proc-macro-srv/Cargo.toml

@@ -24,9 +24,13 @@ tt = { path = "../tt", version = "0.0.0" }
 mbe = { path = "../mbe", version = "0.0.0" }
 paths = { path = "../paths", version = "0.0.0" }
 proc-macro-api = { path = "../proc-macro-api", version = "0.0.0" }
+crossbeam = "0.8.1"
 
 [dev-dependencies]
 expect-test = "1.4.0"
 
 # used as proc macro test targets
 proc-macro-test = { path = "../proc-macro-test" }
+
+[features]
+sysroot-abi = []

crates/proc-macro-srv/build.rs

@@ -0,0 +1,25 @@
+//! Determine rustc version `proc-macro-srv` (and thus the sysroot ABI) is
+//! build with and make it accessible at runtime for ABI selection.
+
+use std::{env, fs::File, io::Write, path::PathBuf, process::Command};
+
+fn main() {
+    let mut path = PathBuf::from(env::var_os("OUT_DIR").unwrap());
+    path.push("rustc_version.rs");
+    let mut f = File::create(&path).unwrap();
+
+    let rustc = env::var("RUSTC").expect("proc-macro-srv's build script expects RUSTC to be set");
+    let output = Command::new(rustc).arg("--version").output().expect("rustc --version must run");
+    let version_string = std::str::from_utf8(&output.stdout[..])
+        .expect("rustc --version output must be UTF-8")
+        .trim();
+
+    write!(
+        f,
+        "
+    #[allow(dead_code)]
+    pub(crate) const RUSTC_VERSION_STRING: &str = {version_string:?};
+    "
+    )
+    .unwrap();
+}

crates/proc-macro-srv/src/abis/abi_sysroot/mod.rs

@@ -0,0 +1,102 @@
+//! Proc macro ABI
+
+extern crate proc_macro;
+
+#[allow(dead_code)]
+#[doc(hidden)]
+mod ra_server;
+
+use libloading::Library;
+use proc_macro_api::ProcMacroKind;
+
+use super::PanicMessage;
+
+pub(crate) struct Abi {
+    exported_macros: Vec<proc_macro::bridge::client::ProcMacro>,
+}
+
+impl From<proc_macro::bridge::PanicMessage> for PanicMessage {
+    fn from(p: proc_macro::bridge::PanicMessage) -> Self {
+        Self { message: p.as_str().map(|s| s.to_string()) }
+    }
+}
+
+impl Abi {
+    pub unsafe fn from_lib(lib: &Library, symbol_name: String) -> Result<Abi, libloading::Error> {
+        let macros: libloading::Symbol<'_, &&[proc_macro::bridge::client::ProcMacro]> =
+            lib.get(symbol_name.as_bytes())?;
+        Ok(Self { exported_macros: macros.to_vec() })
+    }
+
+    pub fn expand(
+        &self,
+        macro_name: &str,
+        macro_body: &tt::Subtree,
+        attributes: Option<&tt::Subtree>,
+    ) -> Result<tt::Subtree, PanicMessage> {
+        let parsed_body = ra_server::TokenStream::with_subtree(macro_body.clone());
+
+        let parsed_attributes = attributes.map_or(ra_server::TokenStream::new(), |attr| {
+            ra_server::TokenStream::with_subtree(attr.clone())
+        });
+
+        for proc_macro in &self.exported_macros {
+            match proc_macro {
+                proc_macro::bridge::client::ProcMacro::CustomDerive {
+                    trait_name, client, ..
+                } if *trait_name == macro_name => {
+                    let res = client.run(
+                        &proc_macro::bridge::server::SameThread,
+                        ra_server::RustAnalyzer::default(),
+                        parsed_body,
+                        true,
+                    );
+                    return res.map(|it| it.into_subtree()).map_err(PanicMessage::from);
+                }
+                proc_macro::bridge::client::ProcMacro::Bang { name, client }
+                    if *name == macro_name =>
+                {
+                    let res = client.run(
+                        &proc_macro::bridge::server::SameThread,
+                        ra_server::RustAnalyzer::default(),
+                        parsed_body,
+                        true,
+                    );
+                    return res.map(|it| it.into_subtree()).map_err(PanicMessage::from);
+                }
+                proc_macro::bridge::client::ProcMacro::Attr { name, client }
+                    if *name == macro_name =>
+                {
+                    let res = client.run(
+                        &proc_macro::bridge::server::SameThread,
+                        ra_server::RustAnalyzer::default(),
+                        parsed_attributes,
+                        parsed_body,
+                        true,
+                    );
+                    return res.map(|it| it.into_subtree()).map_err(PanicMessage::from);
+                }
+                _ => continue,
+            }
+        }
+
+        Err(proc_macro::bridge::PanicMessage::String("Nothing to expand".to_string()).into())
+    }
+
+    pub fn list_macros(&self) -> Vec<(String, ProcMacroKind)> {
+        self.exported_macros
+            .iter()
+            .map(|proc_macro| match proc_macro {
+                proc_macro::bridge::client::ProcMacro::CustomDerive { trait_name, .. } => {
+                    (trait_name.to_string(), ProcMacroKind::CustomDerive)
+                }
+                proc_macro::bridge::client::ProcMacro::Bang { name, .. } => {
+                    (name.to_string(), ProcMacroKind::FuncLike)
+                }
+                proc_macro::bridge::client::ProcMacro::Attr { name, .. } => {
+                    (name.to_string(), ProcMacroKind::Attr)
+                }
+            })
+            .collect()
+    }
+}