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use check::FnCtxt;
use rustc::ty::Ty;
use rustc::infer::{InferOk};
use rustc::traits::ObligationCause;
use syntax::ast;
use syntax_pos::{self, Span};
use rustc::hir;
use rustc::hir::def::Def;
use rustc::ty::{self, AssociatedItem};
use errors::DiagnosticBuilder;
use super::method::probe;
impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
pub fn demand_suptype(&self, sp: Span, expected: Ty<'tcx>, actual: Ty<'tcx>) {
let cause = self.misc(sp);
match self.sub_types(false, &cause, actual, expected) {
Ok(InferOk { obligations, value: () }) => {
self.register_predicates(obligations);
},
Err(e) => {
self.report_mismatched_types(&cause, expected, actual, e).emit();
}
}
}
pub fn demand_eqtype(&self, sp: Span, expected: Ty<'tcx>, actual: Ty<'tcx>) {
if let Some(mut err) = self.demand_eqtype_diag(sp, expected, actual) {
err.emit();
}
}
pub fn demand_eqtype_diag(&self,
sp: Span,
expected: Ty<'tcx>,
actual: Ty<'tcx>) -> Option<DiagnosticBuilder<'tcx>> {
self.demand_eqtype_with_origin(&self.misc(sp), expected, actual)
}
pub fn demand_eqtype_with_origin(&self,
cause: &ObligationCause<'tcx>,
expected: Ty<'tcx>,
actual: Ty<'tcx>) -> Option<DiagnosticBuilder<'tcx>> {
match self.eq_types(false, cause, actual, expected) {
Ok(InferOk { obligations, value: () }) => {
self.register_predicates(obligations);
None
},
Err(e) => {
Some(self.report_mismatched_types(cause, expected, actual, e))
}
}
}
pub fn demand_coerce(&self, expr: &hir::Expr, checked_ty: Ty<'tcx>, expected: Ty<'tcx>) {
let expected = self.resolve_type_vars_with_obligations(expected);
if let Err(e) = self.try_coerce(expr, checked_ty, expected) {
let cause = self.misc(expr.span);
let expr_ty = self.resolve_type_vars_with_obligations(checked_ty);
let mode = probe::Mode::MethodCall;
let suggestions = self.probe_for_return_type(syntax_pos::DUMMY_SP,
mode,
expected,
checked_ty,
ast::DUMMY_NODE_ID);
let mut err = self.report_mismatched_types(&cause, expected, expr_ty, e);
if suggestions.len() > 0 {
err.help(&format!("here are some functions which \
might fulfill your needs:\n{}",
self.get_best_match(&suggestions).join("\n")));
};
err.emit();
}
}
fn format_method_suggestion(&self, method: &AssociatedItem) -> String {
format!("- .{}({})",
method.name,
if self.has_no_input_arg(method) {
""
} else {
"..."
})
}
fn display_suggested_methods(&self, methods: &[AssociatedItem]) -> Vec<String> {
methods.iter()
.take(5)
.map(|method| self.format_method_suggestion(&*method))
.collect::<Vec<String>>()
}
fn get_best_match(&self, methods: &[AssociatedItem]) -> Vec<String> {
let no_argument_methods: Vec<_> =
methods.iter()
.filter(|ref x| self.has_no_input_arg(&*x))
.map(|x| x.clone())
.collect();
if no_argument_methods.len() > 0 {
self.display_suggested_methods(&no_argument_methods)
} else {
self.display_suggested_methods(&methods)
}
}
fn has_no_input_arg(&self, method: &AssociatedItem) -> bool {
match method.def() {
Def::Method(def_id) => {
match self.tcx.item_type(def_id).sty {
ty::TypeVariants::TyFnDef(_, _, sig) => {
sig.inputs().skip_binder().len() == 1
}
_ => false,
}
}
_ => false,
}
}
}