[WIP] Expand #[derive(..)]s in the InvocationCollector

src/librustc_metadata/creader.rs

@@ -577,7 +577,7 @@ impl<'a> CrateLoader<'a> {
         use proc_macro::TokenStream;
         use proc_macro::__internal::Registry;
         use rustc_back::dynamic_lib::DynamicLibrary;
-        use syntax_ext::deriving::custom::CustomDerive;
+        use syntax_ext::deriving::custom::ProcMacroDerive;
         use syntax_ext::proc_macro_impl::AttrProcMacro;
 
         let path = match dylib {
@@ -609,8 +609,8 @@ impl<'a> CrateLoader<'a> {
                                       expand: fn(TokenStream) -> TokenStream,
                                       attributes: &[&'static str]) {
                 let attrs = attributes.iter().cloned().map(Symbol::intern).collect();
-                let derive = SyntaxExtension::CustomDerive(
-                    Box::new(CustomDerive::new(expand, attrs))
+                let derive = SyntaxExtension::ProcMacroDerive(
+                    Box::new(ProcMacroDerive::new(expand, attrs))
                 );
                 self.0.push((Symbol::intern(trait_name), Rc::new(derive)));
             }

src/librustc_resolve/build_reduced_graph.rs

@@ -546,7 +546,7 @@ impl<'a> Resolver<'a> {
                       "an `extern crate` loading macros must be at the crate root");
         } else if !self.use_extern_macros && !used &&
                   self.session.cstore.dep_kind(module.def_id().unwrap().krate).macros_only() {
-            let msg = "custom derive crates and `#[no_link]` crates have no effect without \
+            let msg = "proc macro crates and `#[no_link]` crates have no effect without \
                        `#[macro_use]`";
             self.session.span_warn(item.span, msg);
             used = true; // Avoid the normal unused extern crate warning

src/librustc_resolve/macros.rs

@@ -250,6 +250,14 @@ impl<'a> base::Resolver for Resolver<'a> {
         }
         result
     }
+
+    fn resolve_builtin_macro(&mut self, tname: Name) -> Result<Rc<SyntaxExtension>, Determinacy> {
+        match self.builtin_macros.get(&tname).cloned() {
+            Some(binding) => Ok(binding.get_macro(self)),
+            None => Err(Determinacy::Undetermined),
+        }
+    }
+
 }
 
 impl<'a> Resolver<'a> {

src/libsyntax/ext/base.rs

@@ -10,7 +10,7 @@
 
 pub use self::SyntaxExtension::{MultiDecorator, MultiModifier, NormalTT, IdentTT};
 
-use ast::{self, Attribute, Name, PatKind};
+use ast::{self, Attribute, Name, PatKind, MetaItem};
 use attr::HasAttrs;
 use codemap::{self, CodeMap, ExpnInfo, Spanned, respan};
 use syntax_pos::{Span, ExpnId, NO_EXPANSION};
@@ -471,6 +471,9 @@ impl MacResult for DummyResult {
     }
 }
 
+pub type BuiltinDeriveFn =
+    for<'cx> fn(&'cx mut ExtCtxt, Span, &MetaItem, &Annotatable, &mut FnMut(Annotatable));
+
 /// An enum representing the different kinds of syntax extensions.
 pub enum SyntaxExtension {
     /// A syntax extension that is attached to an item and creates new items
@@ -507,7 +510,14 @@ pub enum SyntaxExtension {
     ///
     IdentTT(Box<IdentMacroExpander>, Option<Span>, bool),
 
-    CustomDerive(Box<MultiItemModifier>),
+    /// An attribute-like procedural macro. TokenStream -> TokenStream.
+    /// The input is the annotated item.
+    /// Allows generating code to implement a Trait for a given struct
+    /// or enum item.
+    ProcMacroDerive(Box<MultiItemModifier>),
+
+    /// An attribute-like procedural macro that derives a builtin trait.
+    BuiltinDerive(BuiltinDeriveFn),
 }
 
 pub type NamedSyntaxExtension = (Name, SyntaxExtension);
@@ -526,6 +536,7 @@ pub trait Resolver {
     fn find_attr_invoc(&mut self, attrs: &mut Vec<Attribute>) -> Option<Attribute>;
     fn resolve_macro(&mut self, scope: Mark, path: &ast::Path, force: bool)
                      -> Result<Rc<SyntaxExtension>, Determinacy>;
+    fn resolve_builtin_macro(&mut self, tname: Name) -> Result<Rc<SyntaxExtension>, Determinacy>;
 }
 
 #[derive(Copy, Clone, Debug)]
@@ -552,6 +563,9 @@ impl Resolver for DummyResolver {
                      -> Result<Rc<SyntaxExtension>, Determinacy> {
         Err(Determinacy::Determined)
     }
+    fn resolve_builtin_macro(&mut self, _tname: Name) -> Result<Rc<SyntaxExtension>, Determinacy> {
+        Err(Determinacy::Determined)
+    }
 }
 
 #[derive(Clone)]

src/libsyntax/ext/derive.rs

@@ -0,0 +1,220 @@
+// Copyright 2012-2017 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+use ast::{self, NestedMetaItem};
+use ext::base::{ExtCtxt, SyntaxExtension};
+use ext::build::AstBuilder;
+use ast::Name;
+use feature_gate;
+use symbol::Symbol;
+use syntax_pos::Span;
+use codemap;
+
+pub fn derive_attr_trait<'a>(cx: &mut ExtCtxt, attr: &'a ast::Attribute)
+                             -> Option<&'a NestedMetaItem> {
+    if attr.name() != "derive" {
+        return None;
+    }
+    if attr.value_str().is_some() {
+        cx.span_err(attr.span, "unexpected value in `derive`");
+        return None;
+    }
+
+    let traits = attr.meta_item_list().unwrap_or(&[]);
+
+    if traits.is_empty() {
+        cx.span_warn(attr.span, "empty trait list in `derive`");
+        return None;
+    }
+
+    return traits.get(0);
+}
+
+pub fn verify_derive_attrs(cx: &mut ExtCtxt, attrs: &[ast::Attribute]) {
+    for attr in attrs {
+        if attr.name() != "derive" {
+            continue;
+        }
+
+        if attr.value_str().is_some() {
+            cx.span_err(attr.span, "unexpected value in `derive`");
+        }
+
+        let traits = attr.meta_item_list().unwrap_or(&[]).to_owned();
+
+        if traits.is_empty() {
+            cx.span_warn(attr.span, "empty trait list in `derive`");
+            attr::mark_used(&attr);
+            continue;
+        }
+        for titem in traits {
+            if titem.word().is_none() {
+                cx.span_err(titem.span, "malformed `derive` entry");
+            }
+        }
+    }
+}
+
+#[derive(PartialEq, Debug, Clone, Copy)]
+pub enum DeriveType {
+    Legacy,
+    ProcMacro,
+    Builtin
+}
+
+impl DeriveType {
+    // Classify a derive trait name by resolving the macro.
+    pub fn classify(cx: &mut ExtCtxt, tname: Name) -> Option<DeriveType> {
+        let legacy_derive_name = Symbol::intern(&format!("derive_{}", tname));
+
+        if let Ok(_) = cx.resolver.resolve_builtin_macro(legacy_derive_name) {
+            return Some(DeriveType::Legacy);
+        }
+
+        match cx.resolver.resolve_builtin_macro(tname) {
+            Ok(ext) => match *ext {
+                SyntaxExtension::BuiltinDerive(..) => Some(DeriveType::Builtin),
+                SyntaxExtension::ProcMacroDerive(..) => Some(DeriveType::ProcMacro),
+                _ => None,
+            },
+            Err(_) => Some(DeriveType::ProcMacro),
+        }
+    }
+}
+
+pub fn get_derive_attr(cx: &mut ExtCtxt, attrs: &mut Vec<ast::Attribute>,
+                       derive_type: DeriveType) -> Option<ast::Attribute> {
+    for i in 0..attrs.len() {
+        if attrs[i].name() != "derive" {
+            continue;
+        }
+
+        if attrs[i].value_str().is_some() {
+            continue;
+        }
+
+        let mut traits = attrs[i].meta_item_list().unwrap_or(&[]).to_owned();
+
+        // First, weed out malformed #[derive]
+        traits.retain(|titem| titem.word().is_some());
+
+        let mut titem = None;
+
+        // See if we can find a matching trait.
+        for j in 0..traits.len() {
+            let tname = if let Some(tname) = traits[j].name() {
+                tname
+            } else {
+                continue;
+            };
+
+            if DeriveType::classify(cx, tname) == Some(derive_type) {
+                titem = Some(traits.remove(j));
+                break;
+            }
+        }
+
+        // If we find a trait, remove the trait from the attribute.
+        if let Some(titem) = titem {
+            if traits.len() == 0 {
+                attrs.remove(i);
+            } else {
+                let derive = Symbol::intern("derive");
+                let mitem = cx.meta_list(titem.span, derive, traits);
+                attrs[i] = cx.attribute(titem.span, mitem);
+            }
+            let derive = Symbol::intern("derive");
+            let mitem = cx.meta_list(titem.span, derive, vec![titem]);
+            return Some(cx.attribute(mitem.span, mitem));
+        }
+    }
+    return None;
+}
+
+fn allow_unstable(cx: &mut ExtCtxt, span: Span, attr_name: &str) -> Span {
+    Span {
+        expn_id: cx.codemap().record_expansion(codemap::ExpnInfo {
+            call_site: span,
+            callee: codemap::NameAndSpan {
+                format: codemap::MacroAttribute(Symbol::intern(attr_name)),
+                span: Some(span),
+                allow_internal_unstable: true,
+            },
+        }),
+        ..span
+    }
+}
+
+pub fn add_derived_markers(cx: &mut ExtCtxt, attrs: &mut Vec<ast::Attribute>) {
+    if attrs.is_empty() {
+        return;
+    }
+
+    let titems = attrs.iter().filter(|a| {
+        a.name() == "derive"
+    }).flat_map(|a| {
+        a.meta_item_list().unwrap_or(&[]).iter()
+    }).filter_map(|titem| {
+        titem.name()
+    }).collect::<Vec<_>>();
+
+    let span = attrs[0].span;
+
+    if !attrs.iter().any(|a| a.name() == "structural_match") &&
+        titems.iter().any(|t| *t == "PartialEq") && titems.iter().any(|t| *t == "Eq") {
+        let structural_match = Symbol::intern("structural_match");
+        let span = allow_unstable(cx, span, "derive(PartialEq, Eq)");
+        let meta = cx.meta_word(span, structural_match);
+        attrs.push(cx.attribute(span, meta));
+    }
+
+    if !attrs.iter().any(|a| a.name() == "rustc_copy_clone_marker") &&
+        titems.iter().any(|t| *t == "Copy") && titems.iter().any(|t| *t == "Clone") {
+        let structural_match = Symbol::intern("rustc_copy_clone_marker");
+        let span = allow_unstable(cx, span, "derive(Copy, Clone)");
+        let meta = cx.meta_word(span, structural_match);
+        attrs.push(cx.attribute(span, meta));
+    }
+}
+
+pub fn find_derive_attr(cx: &mut ExtCtxt, attrs: &mut Vec<ast::Attribute>)
+                        -> Option<ast::Attribute> {
+    verify_derive_attrs(cx, attrs);
+    get_derive_attr(cx, attrs, DeriveType::Legacy).and_then(|a| {
+            let titem = derive_attr_trait(cx, &a);
+            if let Some(titem) = titem {
+                let tword = titem.word().unwrap();
+                let tname = tword.name();
+                if !cx.ecfg.enable_custom_derive() {
+                    feature_gate::emit_feature_err(
+                        &cx.parse_sess,
+                         "custom_derive",
+                         titem.span,
+                         feature_gate::GateIssue::Language,
+                         feature_gate::EXPLAIN_CUSTOM_DERIVE
+                    );
+                } else {
+                    let name = Symbol::intern(&format!("derive_{}", tname));
+                    if !cx.resolver.is_whitelisted_legacy_custom_derive(name) {
+                        cx.span_warn(titem.span,
+                                          feature_gate::EXPLAIN_DEPR_CUSTOM_DERIVE);
+                    }
+                    let mitem = cx.meta_word(titem.span, name);
+                    return Some(cx.attribute(mitem.span, mitem));
+                }
+            }
+            None
+    }).or_else(|| {
+        add_derived_markers(cx, attrs);
+        get_derive_attr(cx, attrs, DeriveType::Builtin)
+    }).or_else(|| {
+        get_derive_attr(cx, attrs, DeriveType::ProcMacro)
+    })
+}