Implement suggestions for traits to import.
For a call like `foo.bar()` where the method `bar` can't be resolved, the compiler will search for traits that have methods with name `bar` to give a more informative error, providing a list of possibilities. Closes #7643.
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parent
af506fa5d1
commit
06ad8bb872
7 changed files with 249 additions and 2 deletions
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@ -174,6 +174,9 @@ impl Session {
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pub fn fileline_note(&self, sp: Span, msg: &str) {
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self.diagnostic().fileline_note(sp, msg)
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}
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pub fn fileline_help(&self, sp: Span, msg: &str) {
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self.diagnostic().fileline_help(sp, msg)
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}
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pub fn note(&self, msg: &str) {
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self.diagnostic().handler().note(msg)
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}
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@ -29,7 +29,7 @@ use syntax::codemap::Span;
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pub use self::MethodError::*;
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pub use self::CandidateSource::*;
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pub use self::suggest::report_error;
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pub use self::suggest::{report_error, AllTraitsVec};
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mod confirm;
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mod doc;
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@ -11,14 +11,21 @@
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//! Give useful errors and suggestions to users when a method can't be
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//! found or is otherwise invalid.
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use CrateCtxt;
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use astconv::AstConv;
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use check::{self, FnCtxt};
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use middle::ty::{self, Ty};
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use middle::def;
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use metadata::{csearch, cstore, decoder};
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use util::ppaux::UserString;
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use syntax::ast;
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use syntax::{ast, ast_util};
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use syntax::codemap::Span;
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use std::cell;
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use std::cmp::Ordering;
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use super::{MethodError, CandidateSource, impl_method, trait_method};
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pub fn report_error<'a, 'tcx>(fcx: &FnCtxt<'a, 'tcx>,
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@ -67,6 +74,8 @@ pub fn report_error<'a, 'tcx>(fcx: &FnCtxt<'a, 'tcx>,
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report_candidates(fcx, span, method_name, static_sources);
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}
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suggest_traits_to_import(fcx, span, rcvr_ty, method_name)
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}
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MethodError::Ambiguity(sources) => {
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@ -120,3 +129,159 @@ pub fn report_error<'a, 'tcx>(fcx: &FnCtxt<'a, 'tcx>,
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}
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}
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}
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pub type AllTraitsVec = Vec<TraitInfo>;
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fn suggest_traits_to_import<'a, 'tcx>(fcx: &FnCtxt<'a, 'tcx>,
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span: Span,
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_rcvr_ty: Ty<'tcx>,
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method_name: ast::Name)
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{
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let tcx = fcx.tcx();
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let mut candidates = all_traits(fcx.ccx)
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.filter(|info| trait_method(tcx, info.def_id, method_name).is_some())
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.collect::<Vec<_>>();
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if candidates.len() > 0 {
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// sort from most relevant to least relevant
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candidates.sort_by(|a, b| a.cmp(b).reverse());
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let method_ustring = method_name.user_string(tcx);
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span_help!(fcx.sess(), span,
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"methods from traits can only be called if the trait is implemented \
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and in scope; the following trait{s} define{inv_s} a method `{name}`:",
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s = if candidates.len() == 1 {""} else {"s"},
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inv_s = if candidates.len() == 1 {"s"} else {""},
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name = method_ustring);
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for (i, trait_info) in candidates.iter().enumerate() {
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// provide a good-as-possible span; the span of
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// the trait if it is local, or the span of the
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// method call itself if not
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let trait_span = fcx.tcx().map.def_id_span(trait_info.def_id, span);
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fcx.sess().fileline_help(trait_span,
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&*format!("candidate #{}: `{}`",
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i + 1,
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ty::item_path_str(fcx.tcx(), trait_info.def_id)))
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}
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}
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}
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#[derive(Copy)]
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pub struct TraitInfo {
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def_id: ast::DefId,
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}
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impl TraitInfo {
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fn new(def_id: ast::DefId) -> TraitInfo {
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TraitInfo {
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def_id: def_id,
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}
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}
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}
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impl PartialEq for TraitInfo {
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fn eq(&self, other: &TraitInfo) -> bool {
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self.cmp(other) == Ordering::Equal
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}
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}
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impl Eq for TraitInfo {}
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impl PartialOrd for TraitInfo {
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fn partial_cmp(&self, other: &TraitInfo) -> Option<Ordering> { Some(self.cmp(other)) }
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}
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impl Ord for TraitInfo {
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fn cmp(&self, other: &TraitInfo) -> Ordering {
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// accessible traits are more important/relevant than
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// inaccessible ones, local crates are more important than
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// remote ones (local: cnum == 0), and NodeIds just for
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// totality.
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let lhs = (other.def_id.krate, other.def_id.node);
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let rhs = (self.def_id.krate, self.def_id.node);
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lhs.cmp(&rhs)
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}
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}
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/// Retrieve all traits in this crate and any dependent crates.
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fn all_traits<'a>(ccx: &'a CrateCtxt) -> AllTraits<'a> {
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if ccx.all_traits.borrow().is_none() {
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use syntax::visit;
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let mut traits = vec![];
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// Crate-local:
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//
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// meh.
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struct Visitor<'a, 'b: 'a, 'tcx: 'a + 'b> {
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traits: &'a mut AllTraitsVec,
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}
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impl<'v,'a, 'b, 'tcx> visit::Visitor<'v> for Visitor<'a, 'b, 'tcx> {
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fn visit_item(&mut self, i: &'v ast::Item) {
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match i.node {
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ast::ItemTrait(..) => {
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self.traits.push(TraitInfo::new(ast_util::local_def(i.id)));
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}
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_ => {}
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}
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visit::walk_item(self, i)
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}
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}
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visit::walk_crate(&mut Visitor {
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traits: &mut traits
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}, ccx.tcx.map.krate());
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// Cross-crate:
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fn handle_external_def(traits: &mut AllTraitsVec,
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ccx: &CrateCtxt,
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cstore: &cstore::CStore,
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dl: decoder::DefLike) {
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match dl {
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decoder::DlDef(def::DefTrait(did)) => {
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traits.push(TraitInfo::new(did));
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}
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decoder::DlDef(def::DefMod(did)) => {
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csearch::each_child_of_item(cstore, did, |dl, _, _| {
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handle_external_def(traits, ccx, cstore, dl)
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})
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}
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_ => {}
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}
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}
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let cstore = &ccx.tcx.sess.cstore;
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cstore.iter_crate_data(|&mut: cnum, _| {
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csearch::each_top_level_item_of_crate(cstore, cnum, |dl, _, _| {
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handle_external_def(&mut traits, ccx, cstore, dl)
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})
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});
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*ccx.all_traits.borrow_mut() = Some(traits);
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}
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let borrow = ccx.all_traits.borrow();
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assert!(borrow.is_some());
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AllTraits {
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borrow: borrow,
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idx: 0
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}
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}
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struct AllTraits<'a> {
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borrow: cell::Ref<'a Option<AllTraitsVec>>,
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idx: usize
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}
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impl<'a> Iterator for AllTraits<'a> {
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type Item = TraitInfo;
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fn next(&mut self) -> Option<TraitInfo> {
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let AllTraits { ref borrow, ref mut idx } = *self;
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// ugh.
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borrow.as_ref().unwrap().get(*idx).map(|info| {
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*idx += 1;
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*info
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})
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}
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}
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@ -108,6 +108,8 @@ use syntax::print::pprust::*;
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use syntax::{ast, ast_map, abi};
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use syntax::ast_util::local_def;
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use std::cell::RefCell;
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mod check;
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mod rscope;
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mod astconv;
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@ -123,6 +125,11 @@ struct TypeAndSubsts<'tcx> {
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struct CrateCtxt<'a, 'tcx: 'a> {
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// A mapping from method call sites to traits that have that method.
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trait_map: ty::TraitMap,
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/// A vector of every trait accessible in the whole crate
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/// (i.e. including those from subcrates). This is used only for
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/// error reporting, and so is lazily initialised and generally
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/// shouldn't taint the common path (hence the RefCell).
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all_traits: RefCell<Option<check::method::AllTraitsVec>>,
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tcx: &'a ty::ctxt<'tcx>,
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}
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let time_passes = tcx.sess.time_passes();
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let ccx = CrateCtxt {
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trait_map: trait_map,
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all_traits: RefCell::new(None),
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tcx: tcx
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};
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@ -118,6 +118,9 @@ impl SpanHandler {
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pub fn fileline_note(&self, sp: Span, msg: &str) {
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self.handler.custom_emit(&self.cm, FileLine(sp), msg, Note);
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}
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pub fn fileline_help(&self, sp: Span, msg: &str) {
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self.handler.custom_emit(&self.cm, FileLine(sp), msg, Help);
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}
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pub fn span_bug(&self, sp: Span, msg: &str) -> ! {
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self.handler.emit(Some((&self.cm, sp)), msg, Bug);
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panic!(ExplicitBug);
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38
src/test/auxiliary/no_method_suggested_traits.rs
Normal file
38
src/test/auxiliary/no_method_suggested_traits.rs
Normal file
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@ -0,0 +1,38 @@
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// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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pub use reexport::Reexported;
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pub mod foo {
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pub trait PubPub {
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fn method(&self);
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}
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}
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pub mod bar {
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trait PubPriv {
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fn method(&self);
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}
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}
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mod qux {
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pub trait PrivPub {
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fn method(&self);
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}
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}
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mod quz {
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trait PrivPriv {
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fn method(&self);
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}
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}
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mod reexport {
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pub trait Reexported {
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fn method(&self);
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}
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}
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30
src/test/compile-fail/no-method-suggested-traits.rs
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30
src/test/compile-fail/no-method-suggested-traits.rs
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@ -0,0 +1,30 @@
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// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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// aux-build:no_method_suggested_traits.rs
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extern crate no_method_suggested_traits;
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mod foo {
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trait Bar { //~ HELP `foo::Bar`
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fn method(&self);
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}
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}
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fn main() {
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1u32.method();
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//~^ ERROR does not implement
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//~^^ HELP the following traits define a method `method`
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//~^^^ HELP `no_method_suggested_traits::foo::PubPub`
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//~^^^^ HELP `no_method_suggested_traits::reexport::Reexported`
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//~^^^^^ HELP `no_method_suggested_traits::bar::PubPriv`
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//~^^^^^^ HELP `no_method_suggested_traits::qux::PrivPub`
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//~^^^^^^^ HELP `no_method_suggested_traits::quz::PrivPriv`
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}
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