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

src/libsyntax/ext/derive.rs

@@ -0,0 +1,250 @@
+// 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 feature_gate;
+use symbol::Symbol;
+use syntax_pos::Span;
+use codemap;
+
+pub fn is_derive_attr(attr: &ast::Attribute) -> bool {
+    let res = attr.name() == Symbol::intern("derive");
+    res
+}
+
+pub fn derive_attr_trait<'a>(cx: &mut ExtCtxt, attr: &'a ast::Attribute)
+                             -> Option<&'a NestedMetaItem> {
+    if !is_derive_attr(attr) {
+        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();
+
+    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: &mut Vec<ast::Attribute>) {
+    for i in 0..attrs.len() {
+        if !is_derive_attr(&attrs[i]) {
+            continue;
+        }
+
+        let span = attrs[i].span;
+
+        if attrs[i].value_str().is_some() {
+            cx.span_err(span, "unexpected value in `derive`");
+        }
+
+        let traits = attrs[i].meta_item_list().unwrap_or(&[]).to_owned();
+
+        if traits.is_empty() {
+            cx.span_warn(span, "empty trait list in `derive`");
+            continue;
+        }
+        for titem in traits {
+            if titem.word().is_none() {
+                cx.span_err(titem.span, "malformed `derive` entry");
+            }
+        }
+    }
+}
+
+pub fn get_derive_attr(cx: &mut ExtCtxt, attrs: &mut Vec<ast::Attribute>,
+                       is_derive_type: fn(&mut ExtCtxt, &NestedMetaItem) -> bool)
+                       -> Option<ast::Attribute> {
+    for i in 0..attrs.len() {
+        if !is_derive_attr(&attrs[i]) {
+            continue;
+        }
+
+        let span = attrs[i].span;
+
+        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() {
+            if is_derive_type(cx, &traits[j]) {
+                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(span, derive, traits);
+                attrs[i] = cx.attribute(span, mitem);
+            }
+            let derive = Symbol::intern("derive");
+            let mitem = cx.meta_list(span, derive, vec![titem]);
+            return Some(cx.attribute(span, mitem));
+        }
+    }
+    return None;
+}
+
+pub fn get_legacy_derive(cx: &mut ExtCtxt, attrs: &mut Vec<ast::Attribute>)
+                         -> Option<ast::Attribute> {
+    get_derive_attr(cx, attrs, is_legacy_derive).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
+    })
+}
+
+pub fn get_proc_macro_derive(cx: &mut ExtCtxt, attrs: &mut Vec<ast::Attribute>)
+                             -> Option<ast::Attribute> {
+    get_derive_attr(cx, attrs, is_proc_macro_derive)
+}
+
+pub fn get_builtin_derive(cx: &mut ExtCtxt, attrs: &mut Vec<ast::Attribute>)
+                          -> Option<ast::Attribute> {
+    get_derive_attr(cx, attrs, is_builtin_derive)
+}
+
+pub fn is_legacy_derive(cx: &mut ExtCtxt, titem: &NestedMetaItem) -> bool {
+    !is_builtin_derive(cx, titem) && !is_proc_macro_derive(cx, titem)
+}
+
+pub fn is_builtin_derive(cx: &mut ExtCtxt, titem: &NestedMetaItem) -> bool {
+    let tname = titem.name().unwrap();
+    let derive_mode = ast::Path::from_ident(titem.span, ast::Ident::with_empty_ctxt(tname));
+    cx.resolver.resolve_macro(cx.current_expansion.mark, &derive_mode, false).map(|ext| {
+        if let SyntaxExtension::BuiltinDerive(_) = *ext { true } else { false }
+    }).unwrap_or(false)
+}
+
+pub fn is_proc_macro_derive(cx: &mut ExtCtxt, titem: &NestedMetaItem) -> bool {
+    let tname = titem.name().unwrap();
+    let derive_mode = ast::Path::from_ident(titem.span, ast::Ident::with_empty_ctxt(tname));
+    cx.resolver.resolve_macro(cx.current_expansion.mark, &derive_mode, false).map(|ext| {
+        if let SyntaxExtension::ProcMacroDerive(_) = *ext { true } else { false }
+    }).unwrap_or(false)
+}
+
+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_structural_marker(cx: &mut ExtCtxt, attrs: &mut Vec<ast::Attribute>) {
+    if attrs.iter().any(|a| a.name() == "structural_match") {
+        return;
+    }
+
+    let (mut seen_peq, mut seen_eq) = (false, false);
+
+    for i in 0..attrs.len() {
+        if !is_derive_attr(&attrs[i]) {
+            continue;
+        }
+        let traits = attrs[i].meta_item_list().unwrap_or(&[]).to_owned();
+        let span = attrs[i].span;
+
+        let (partial_eq, eq) = (Symbol::intern("PartialEq"), Symbol::intern("Eq"));
+        if !seen_peq && traits.iter().any(|t| t.name() == Some(partial_eq)) {
+            seen_peq = true;
+        }
+
+        if !seen_eq && traits.iter().any(|t| t.name() == Some(eq)) {
+            seen_eq = true;
+        }
+
+        if seen_peq && seen_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));
+            return;
+        }
+    }
+}
+
+pub fn add_copy_clone_marker(cx: &mut ExtCtxt, attrs: &mut Vec<ast::Attribute>) {
+    if attrs.iter().any(|a| a.name() == "rustc_copy_clone_marker") {
+        return;
+    }
+
+    let (mut seen_clone, mut seen_copy) = (false, false);
+
+    for i in 0..attrs.len() {
+        if !is_derive_attr(&attrs[i]) {
+            continue;
+        }
+        let traits = attrs[i].meta_item_list().unwrap_or(&[]).to_owned();
+        let span = attrs[i].span;
+
+        let (copy, clone) = (Symbol::intern("Copy"), Symbol::intern("Clone"));
+        if !seen_clone && traits.iter().any(|t| t.name() == Some(clone)) {
+            seen_clone = true;
+        }
+
+        if !seen_copy && traits.iter().any(|t| t.name() == Some(copy)) {
+            seen_copy = true;
+        }
+
+        if seen_clone && seen_copy {
+            let marker = Symbol::intern("rustc_copy_clone_marker");
+            let span = allow_unstable(cx, span, "derive(Copy, Clone)");
+            let meta = cx.meta_word(span, marker);
+            attrs.push(cx.attribute(span, meta));
+            return;
+        }
+    }
+}