+// Copyright 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 fmt_macros::{Parser, Piece, Position};
+
+use hir::def_id::DefId;
+use ty::{self, TyCtxt};
+use util::common::ErrorReported;
+use util::nodemap::FxHashMap;
+
+use syntax_pos::Span;
+use syntax_pos::symbol::InternedString;
+
+pub struct OnUnimplementedFormatString(InternedString);
+pub struct OnUnimplementedInfo {
+ pub label: OnUnimplementedFormatString
+}
+
+impl<'a, 'gcx, 'tcx> OnUnimplementedInfo {
+ pub fn of_item(tcx: TyCtxt<'a, 'gcx, 'tcx>,
+ trait_def_id: DefId,
+ impl_def_id: DefId,
+ span: Span)
+ -> Result<Option<Self>, ErrorReported>
+ {
+ let attrs = tcx.get_attrs(impl_def_id);
+
+ let attr = if let Some(item) =
+ attrs.into_iter().find(|a| a.check_name("rustc_on_unimplemented"))
+ {
+ item
+ } else {
+ return Ok(None);
+ };
+
+ let span = attr.span.substitute_dummy(span);
+ if let Some(label) = attr.value_str() {
+ Ok(Some(OnUnimplementedInfo {
+ label: OnUnimplementedFormatString::try_parse(
+ tcx, trait_def_id, label.as_str(), span)?
+ }))
+ } else {
+ struct_span_err!(
+ tcx.sess, span, E0232,
+ "this attribute must have a value")
+ .span_label(attr.span, "attribute requires a value")
+ .note(&format!("eg `#[rustc_on_unimplemented = \"foo\"]`"))
+ .emit();
+ Err(ErrorReported)
+ }
+ }
+}
+
+impl<'a, 'gcx, 'tcx> OnUnimplementedFormatString {
+ pub fn try_parse(tcx: TyCtxt<'a, 'gcx, 'tcx>,
+ trait_def_id: DefId,
+ from: InternedString,
+ err_sp: Span)
+ -> Result<Self, ErrorReported>
+ {
+ let result = OnUnimplementedFormatString(from);
+ result.verify(tcx, trait_def_id, err_sp)?;
+ Ok(result)
+ }
+
+ fn verify(&self,
+ tcx: TyCtxt<'a, 'gcx, 'tcx>,
+ trait_def_id: DefId,
+ span: Span)
+ -> Result<(), ErrorReported>
+ {
+ let name = tcx.item_name(trait_def_id).as_str();
+ let generics = tcx.generics_of(trait_def_id);
+ let parser = Parser::new(&self.0);
+ let types = &generics.types;
+ let mut result = Ok(());
+ for token in parser {
+ match token {
+ Piece::String(_) => (), // Normal string, no need to check it
+ Piece::NextArgument(a) => match a.position {
+ // `{Self}` is allowed
+ Position::ArgumentNamed(s) if s == "Self" => (),
+ // `{ThisTraitsName}` is allowed
+ Position::ArgumentNamed(s) if s == name => (),
+ // So is `{A}` if A is a type parameter
+ Position::ArgumentNamed(s) => match types.iter().find(|t| {
+ t.name == s
+ }) {
+ Some(_) => (),
+ None => {
+ span_err!(tcx.sess, span, E0230,
+ "there is no type parameter \
+ {} on trait {}",
+ s, name);
+ result = Err(ErrorReported);
+ }
+ },
+ // `{:1}` and `{}` are not to be used
+ Position::ArgumentIs(_) => {
+ span_err!(tcx.sess, span, E0231,
+ "only named substitution \
+ parameters are allowed");
+ result = Err(ErrorReported);
+ }
+ }
+ }
+ }
+
+ result
+ }
+
+ pub fn format(&self,
+ tcx: TyCtxt<'a, 'gcx, 'tcx>,
+ trait_ref: ty::TraitRef<'tcx>)
+ -> String
+ {
+ let name = tcx.item_name(trait_ref.def_id).as_str();
+ let trait_str = tcx.item_path_str(trait_ref.def_id);
+ let generics = tcx.generics_of(trait_ref.def_id);
+ let generic_map = generics.types.iter().map(|param| {
+ (param.name.as_str().to_string(),
+ trait_ref.substs.type_for_def(param).to_string())
+ }).collect::<FxHashMap<String, String>>();
+
+ let parser = Parser::new(&self.0);
+ parser.map(|p| {
+ match p {
+ Piece::String(s) => s,
+ Piece::NextArgument(a) => match a.position {
+ Position::ArgumentNamed(s) => match generic_map.get(s) {
+ Some(val) => val,
+ None if s == name => {
+ &trait_str
+ }
+ None => {
+ bug!("broken on_unimplemented {:?} for {:?}: \
+ no argument matching {:?}",
+ self.0, trait_ref, s)
+ }
+ },
+ _ => {
+ bug!("broken on_unimplemented {:?} - bad \
+ format arg", self.0)
+ }
+ }
+ }
+ }).collect()
+ }
+}