Auto merge of #66647 - petrochenkov:nosynt, r=Centril

rustc_plugin: Remove support for syntactic plugins

This part of the plugin interface was successfully replaced by token-based procedural macros in theory and in practice.

cc #29597
cc #64675
r? @Centril

Cargo.lock

@@ -3802,7 +3802,6 @@ dependencies = [
  "rustc_error_codes",
  "rustc_metadata",
  "syntax",
- "syntax_expand",
  "syntax_pos",
 ]
 

src/doc/unstable-book/src/language-features/plugin.md

@@ -13,7 +13,7 @@ This feature is part of "compiler plugins." It will often be used with the
 ------------------------
 
 `rustc` can load compiler plugins, which are user-provided libraries that
-extend the compiler's behavior with new syntax extensions, lint checks, etc.
+extend the compiler's behavior with new lint checks, etc.
 
 A plugin is a dynamic library crate with a designated *registrar* function that
 registers extensions with `rustc`. Other crates can load these extensions using
@@ -35,134 +35,6 @@ The usual practice is to put compiler plugins in their own crate, separate from
 any `macro_rules!` macros or ordinary Rust code meant to be used by consumers
 of a library.
 
-# Syntax extensions
-
-Plugins can extend Rust's syntax in various ways. One kind of syntax extension
-is the procedural macro. These are invoked the same way as [ordinary
-macros](../../book/macros.md), but the expansion is performed by arbitrary Rust
-code that manipulates syntax trees at
-compile time.
-
-Let's write a plugin
-[`roman_numerals.rs`](https://github.com/rust-lang/rust/blob/master/src/test/ui-fulldeps/auxiliary/roman_numerals.rs)
-that implements Roman numeral integer literals.
-
-```rust,ignore
-#![crate_type="dylib"]
-#![feature(plugin_registrar, rustc_private)]
-
-extern crate syntax;
-extern crate syntax_pos;
-extern crate rustc;
-extern crate rustc_driver;
-
-use syntax::parse::token::{self, Token};
-use syntax::tokenstream::{TokenTree, TokenStream};
-use syntax::ext::base::{ExtCtxt, MacResult, DummyResult, MacEager};
-use syntax_pos::Span;
-use rustc_driver::plugin::Registry;
-
-fn expand_rn(cx: &mut ExtCtxt, sp: Span, args: TokenStream)
-        -> Box<dyn MacResult + 'static> {
-
-    static NUMERALS: &'static [(&'static str, usize)] = &[
-        ("M", 1000), ("CM", 900), ("D", 500), ("CD", 400),
-        ("C",  100), ("XC",  90), ("L",  50), ("XL",  40),
-        ("X",   10), ("IX",   9), ("V",   5), ("IV",   4),
-        ("I",    1)];
-
-    if args.len() != 1 {
-        cx.span_err(
-            sp,
-            &format!("argument should be a single identifier, but got {} arguments", args.len()));
-        return DummyResult::any(sp);
-    }
-
-    let text = match args.into_trees().next().unwrap() {
-        TokenTree::Token(Token { kind: token::Ident(s, _), .. }) => s.to_string(),
-        _ => {
-            cx.span_err(sp, "argument should be a single identifier");
-            return DummyResult::any(sp);
-        }
-    };
-
-    let mut text = &*text;
-    let mut total = 0;
-    while !text.is_empty() {
-        match NUMERALS.iter().find(|&&(rn, _)| text.starts_with(rn)) {
-            Some(&(rn, val)) => {
-                total += val;
-                text = &text[rn.len()..];
-            }
-            None => {
-                cx.span_err(sp, "invalid Roman numeral");
-                return DummyResult::any(sp);
-            }
-        }
-    }
-
-    MacEager::expr(cx.expr_usize(sp, total))
-}
-
-#[plugin_registrar]
-pub fn plugin_registrar(reg: &mut Registry) {
-    reg.register_macro("rn", expand_rn);
-}
-```
-
-Then we can use `rn!()` like any other macro:
-
-```rust,ignore
-#![feature(plugin)]
-#![plugin(roman_numerals)]
-
-fn main() {
-    assert_eq!(rn!(MMXV), 2015);
-}
-```
-
-The advantages over a simple `fn(&str) -> u32` are:
-
-* The (arbitrarily complex) conversion is done at compile time.
-* Input validation is also performed at compile time.
-* It can be extended to allow use in patterns, which effectively gives
-  a way to define new literal syntax for any data type.
-
-In addition to procedural macros, you can define new
-[`derive`](../../reference/attributes/derive.md)-like attributes and other kinds
-of extensions.  See `Registry::register_syntax_extension` and the
-`SyntaxExtension` struct.  For a more involved macro example, see
-[`regex_macros`](https://github.com/rust-lang/regex/blob/master/regex_macros/src/lib.rs).
-
-
-## Tips and tricks
-
-You can use `syntax::parse` to turn token trees into
-higher-level syntax elements like expressions:
-
-```rust,ignore
-fn expand_foo(cx: &mut ExtCtxt, sp: Span, args: &[TokenTree])
-        -> Box<MacResult+'static> {
-
-    let mut parser = cx.new_parser_from_tts(args);
-
-    let expr: P<Expr> = parser.parse_expr();
-```
-
-Looking through [`libsyntax` parser
-code](https://github.com/rust-lang/rust/blob/master/src/libsyntax/parse/parser.rs)
-will give you a feel for how the parsing infrastructure works.
-
-Keep the `Span`s of everything you parse, for better error reporting. You can
-wrap `Spanned` around your custom data structures.
-
-Calling `ExtCtxt::span_fatal` will immediately abort compilation. It's better to
-instead call `ExtCtxt::span_err` and return `DummyResult` so that the compiler
-can continue and find further errors.
-
-To print syntax fragments for debugging, you can use `span_note` together with
-`syntax::print::pprust::*_to_string`.
-
 # Lint plugins
 
 Plugins can extend [Rust's lint

src/librustc_driver/lib.rs

@@ -322,7 +322,7 @@ pub fn run_compiler(
         }
 
         {
-            let (_, _, lint_store) = &*compiler.register_plugins()?.peek();
+            let (_, lint_store) = &*compiler.register_plugins()?.peek();
 
             // Lint plugins are registered; now we can process command line flags.
             if sess.opts.describe_lints {

src/librustc_interface/passes.rs

@@ -37,7 +37,7 @@ use rustc_traits;
 use rustc_typeck as typeck;
 use syntax::{self, ast, visit};
 use syntax::early_buffered_lints::BufferedEarlyLint;
-use syntax_expand::base::{NamedSyntaxExtension, ExtCtxt};
+use syntax_expand::base::ExtCtxt;
 use syntax::mut_visit::MutVisitor;
 use syntax::util::node_count::NodeCounter;
 use syntax::symbol::Symbol;
@@ -119,7 +119,6 @@ pub fn configure_and_expand(
     metadata_loader: Box<MetadataLoaderDyn>,
     krate: ast::Crate,
     crate_name: &str,
-    plugin_info: PluginInfo,
 ) -> Result<(ast::Crate, BoxedResolver)> {
     // Currently, we ignore the name resolution data structures for the purposes of dependency
     // tracking. Instead we will run name resolution and include its output in the hash of each
@@ -137,7 +136,6 @@ pub fn configure_and_expand(
             &crate_name,
             &resolver_arenas,
             &*metadata_loader,
-            plugin_info,
         );
         let mut resolver = match res {
             Err(v) => {
@@ -164,17 +162,13 @@ impl BoxedResolver {
     }
 }
 
-pub struct PluginInfo {
-    syntax_exts: Vec<NamedSyntaxExtension>,
-}
-
 pub fn register_plugins<'a>(
     sess: &'a Session,
     metadata_loader: &'a dyn MetadataLoader,
     register_lints: impl Fn(&Session, &mut lint::LintStore),
     mut krate: ast::Crate,
     crate_name: &str,
-) -> Result<(ast::Crate, PluginInfo, Lrc<lint::LintStore>)> {
+) -> Result<(ast::Crate, Lrc<lint::LintStore>)> {
     krate = time(sess, "attributes injection", || {
         syntax_ext::cmdline_attrs::inject(
             krate, &sess.parse_sess, &sess.opts.debugging_opts.crate_attr
@@ -240,10 +234,9 @@ pub fn register_plugins<'a>(
         }
     });
 
-    let Registry { syntax_exts, llvm_passes, .. } = registry;
-    *sess.plugin_llvm_passes.borrow_mut() = llvm_passes;
+    *sess.plugin_llvm_passes.borrow_mut() = registry.llvm_passes;
 
-    Ok((krate, PluginInfo { syntax_exts }, Lrc::new(lint_store)))
+    Ok((krate, Lrc::new(lint_store)))
 }
 
 fn configure_and_expand_inner<'a>(
@@ -253,7 +246,6 @@ fn configure_and_expand_inner<'a>(
     crate_name: &str,
     resolver_arenas: &'a ResolverArenas<'a>,
     metadata_loader: &'a MetadataLoaderDyn,
-    plugin_info: PluginInfo,
 ) -> Result<(ast::Crate, Resolver<'a>)> {
     time(sess, "pre-AST-expansion lint checks", || {
         lint::check_ast_crate(
@@ -290,10 +282,6 @@ fn configure_and_expand_inner<'a>(
 
     util::check_attr_crate_type(&krate.attrs, &mut resolver.lint_buffer());
 
-    syntax_ext::plugin_macro_defs::inject(
-        &mut krate, &mut resolver, plugin_info.syntax_exts, sess.edition()
-    );
-
     // Expand all macros
     krate = time(sess, "expansion", || {
         let _prof_timer = sess.prof.generic_activity("macro_expand_crate");

src/librustc_interface/queries.rs

@@ -1,5 +1,5 @@
 use crate::interface::{Compiler, Result};
-use crate::passes::{self, BoxedResolver, BoxedGlobalCtxt, PluginInfo};
+use crate::passes::{self, BoxedResolver, BoxedGlobalCtxt};
 
 use rustc_incremental::DepGraphFuture;
 use rustc_data_structures::sync::Lrc;
@@ -79,7 +79,7 @@ pub(crate) struct Queries {
     dep_graph_future: Query<Option<DepGraphFuture>>,
     parse: Query<ast::Crate>,
     crate_name: Query<String>,
-    register_plugins: Query<(ast::Crate, PluginInfo, Lrc<LintStore>)>,
+    register_plugins: Query<(ast::Crate, Lrc<LintStore>)>,
     expansion: Query<(ast::Crate, Steal<Rc<RefCell<BoxedResolver>>>, Lrc<LintStore>)>,
     dep_graph: Query<DepGraph>,
     lower_to_hir: Query<(Steal<hir::map::Forest>, Steal<ResolverOutputs>)>,
@@ -111,7 +111,7 @@ impl Compiler {
         })
     }
 
-    pub fn register_plugins(&self) -> Result<&Query<(ast::Crate, PluginInfo, Lrc<LintStore>)>> {
+    pub fn register_plugins(&self) -> Result<&Query<(ast::Crate, Lrc<LintStore>)>> {
         self.queries.register_plugins.compute(|| {
             let crate_name = self.crate_name()?.peek().clone();
             let krate = self.parse()?.take();
@@ -161,14 +161,13 @@ impl Compiler {
     ) -> Result<&Query<(ast::Crate, Steal<Rc<RefCell<BoxedResolver>>>, Lrc<LintStore>)>> {
         self.queries.expansion.compute(|| {
             let crate_name = self.crate_name()?.peek().clone();
-            let (krate, plugin_info, lint_store) = self.register_plugins()?.take();
+            let (krate, lint_store) = self.register_plugins()?.take();
             passes::configure_and_expand(
                 self.sess.clone(),
                 lint_store.clone(),
                 self.codegen_backend().metadata_loader(),
                 krate,
                 &crate_name,
-                plugin_info,
             ).map(|(krate, resolver)| {
                 (krate, Steal::new(Rc::new(RefCell::new(resolver))), lint_store)
             })

src/librustc_plugin_impl/Cargo.toml

@@ -14,6 +14,5 @@ doctest = false
 rustc = { path = "../librustc" }
 rustc_metadata = { path = "../librustc_metadata" }
 syntax = { path = "../libsyntax" }
-syntax_expand = { path = "../libsyntax_expand" }
 syntax_pos = { path = "../libsyntax_pos" }
 rustc_error_codes = { path = "../librustc_error_codes" }

src/librustc_plugin_impl/lib.rs

@@ -1,55 +1,10 @@
 //! Infrastructure for compiler plugins.
 //!
-//! Plugins are Rust libraries which extend the behavior of `rustc`
-//! in various ways.
-//!
-//! Plugin authors will use the `Registry` type re-exported by
-//! this module, along with its methods. The rest of the module
-//! is for use by `rustc` itself.
-//!
-//! To define a plugin, build a dylib crate with a
-//! `#[plugin_registrar]` function:
-//!
-//! ```no_run
-//! #![crate_name = "myplugin"]
-//! #![crate_type = "dylib"]
-//! #![feature(plugin_registrar)]
-//! #![feature(rustc_private)]
-//!
-//! extern crate rustc_driver;
-//! extern crate syntax;
-//! extern crate syntax_pos;
-//!
-//! use rustc_driver::plugin::Registry;
-//! use syntax_expand::base::{ExtCtxt, MacResult};
-//! use syntax_pos::Span;
-//! use syntax::tokenstream::TokenTree;
-//!
-//! #[plugin_registrar]
-//! pub fn plugin_registrar(reg: &mut Registry) {
-//!     reg.register_macro("mymacro", expand_mymacro);
-//! }
-//!
-//! fn expand_mymacro(cx: &mut ExtCtxt, span: Span, tt: &[TokenTree]) -> Box<MacResult> {
-//!     unimplemented!()
-//! }
-//!
-//! # fn main() {}
-//! ```
-//!
-//! WARNING: We currently don't check that the registrar function
-//! has the appropriate type!
-//!
-//! To use a plugin while compiling another crate:
-//!
-//! ```rust
-//! #![feature(plugin)]
-//! #![plugin(myplugin)]
-//! ```
+//! Plugins are a deprecated way to extend the behavior of `rustc` in various ways.
 //!
 //! See the [`plugin`
 //! feature](https://doc.rust-lang.org/nightly/unstable-book/language-features/plugin.html)
-//! of the Unstable Book for more examples.
+//! of the Unstable Book for some examples.
 
 #![doc(html_root_url = "https://doc.rust-lang.org/nightly/")]
 

src/librustc_plugin_impl/registry.rs

@@ -2,10 +2,6 @@
 
 use rustc::lint::LintStore;
 use rustc::session::Session;
-
-use syntax_expand::base::{SyntaxExtension, SyntaxExtensionKind, NamedSyntaxExtension};
-use syntax_expand::base::MacroExpanderFn;
-use syntax::symbol::Symbol;
 use syntax::ast;
 use syntax_pos::Span;
 
@@ -33,9 +29,6 @@ pub struct Registry<'a> {
     #[doc(hidden)]
     pub krate_span: Span,
 
-    #[doc(hidden)]
-    pub syntax_exts: Vec<NamedSyntaxExtension>,
-
     #[doc(hidden)]
     pub llvm_passes: Vec<String>,
 }
@@ -48,7 +41,6 @@ impl<'a> Registry<'a> {
             lint_store,
             args_hidden: None,
             krate_span,
-            syntax_exts: vec![],
             llvm_passes: vec![],
         }
     }
@@ -67,24 +59,6 @@ impl<'a> Registry<'a> {
         self.args_hidden.as_ref().map(|v| &v[..]).unwrap_or(&[])
     }
 
-    /// Register a syntax extension of any kind.
-    ///
-    /// This is the most general hook into `libsyntax`'s expansion behavior.
-    pub fn register_syntax_extension(&mut self, name: ast::Name, extension: SyntaxExtension) {
-        self.syntax_exts.push((name, extension));
-    }
-
-    /// Register a macro of the usual kind.
-    ///
-    /// This is a convenience wrapper for `register_syntax_extension`.
-    /// It builds for you a `SyntaxExtensionKind::LegacyBang` that calls `expander`,
-    /// and also takes care of interning the macro's name.
-    pub fn register_macro(&mut self, name: &str, expander: MacroExpanderFn) {
-        let kind = SyntaxExtensionKind::LegacyBang(Box::new(expander));
-        let ext = SyntaxExtension::default(kind, self.sess.edition());
-        self.register_syntax_extension(Symbol::intern(name), ext);
-    }
-
     /// Register an LLVM pass.
     ///
     /// Registration with LLVM itself is handled through static C++ objects with