Move derive macro expansion into the MacroExpander

This removes the expand_derives function, and sprinkles
the functionality throughout the Invocation Collector,
Expander and Resolver.

1 files changed, 218 insertions, 0 deletions

diff --git a/src/libsyntax/ext/derive.rs b/src/libsyntax/ext/derive.rs
new file mode 100644
index 00000000000..946448eaaee
--- /dev/null
+++ b/src/libsyntax/ext/derive.rs
@@ -0,0 +1,218 @@
+// 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::Name;
+use attr;
+use ast::{self, NestedMetaItem}; use ext::base::{ExtCtxt, SyntaxExtension};
+use codemap;
+use ext::build::AstBuilder;
+use feature_gate;
+use symbol::Symbol;
+use syntax_pos::Span;
+
+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) -> DeriveType {
+        let legacy_derive_name = Symbol::intern(&format!("derive_{}", tname));
+
+        if let Ok(_) = cx.resolver.resolve_builtin_macro(legacy_derive_name) {
+            return DeriveType::Legacy;
+        }
+
+        match cx.resolver.resolve_builtin_macro(tname) {
+            Ok(ext) => match *ext {
+                SyntaxExtension::BuiltinDerive(..) => DeriveType::Builtin,
+                _ => DeriveType::ProcMacro,
+            },
+            Err(_) => 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 = match traits[j].name() {
+                Some(tname) => tname,
+                _ => continue,
+            };
+
+            if DeriveType::classify(cx, tname) == 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);
+        titem.and_then(|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
+                );
+                None
+            } 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);
+                Some(cx.attribute(mitem.span, mitem))
+            }
+        })
+    }).or_else(|| {
+        get_derive_attr(cx, attrs, DeriveType::ProcMacro)
+    }).or_else(|| {
+        add_derived_markers(cx, attrs);
+        get_derive_attr(cx, attrs, DeriveType::Builtin)
+    })
+}