Auto merge of #38099 - GuillaumeGomez:cast_suggestions, r=nikomatsakis · rust-lang/rust@439c312 (original) (raw)
`@@ -14,8 +14,13 @@ use rustc::ty::Ty;
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`use rustc::infer::{InferOk};
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`use rustc::traits::ObligationCause;
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``
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use syntax_pos::Span;
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use syntax::ast;
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use syntax_pos::{self, Span};
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`use rustc::hir;
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use rustc::hir::def::Def;
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use rustc::ty::{self, AssociatedItem};
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use super::method::probe;
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``
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`impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
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`// Requires that the two types unify, and prints an error message if
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`@@ -27,7 +32,7 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
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`self.register_predicates(obligations);
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`},
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`Err(e) => {
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``
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self.report_mismatched_types(&cause, expected, actual, e);
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self.report_mismatched_types(&cause, expected, actual, e).emit();
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`}
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`}
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`}
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`@@ -46,7 +51,7 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
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`self.register_predicates(obligations);
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`},
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`Err(e) => {
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``
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self.report_mismatched_types(cause, expected, actual, e);
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self.report_mismatched_types(cause, expected, actual, e).emit();
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`}
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`}
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`}
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`@@ -57,7 +62,65 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
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`if let Err(e) = self.try_coerce(expr, checked_ty, expected) {
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`let cause = self.misc(expr.span);
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`let expr_ty = self.resolve_type_vars_with_obligations(checked_ty);
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self.report_mismatched_types(&cause, expected, expr_ty, e);
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let mode = probe::Mode::MethodCall;
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let suggestions = self.probe_for_return_type(syntax_pos::DUMMY_SP,
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mode,
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expected,
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checked_ty,
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ast::DUMMY_NODE_ID);
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let mut err = self.report_mismatched_types(&cause, expected, expr_ty, e);
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if suggestions.len() > 0 {
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err.help(&format!("here are some functions which \
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might fulfill your needs:\n - {}",
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self.get_best_match(&suggestions)));
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};
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err.emit();
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}
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}
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fn format_method_suggestion(&self, method: &AssociatedItem) -> String {
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format!(".{}({})",
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method.name,
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if self.has_no_input_arg(method) {
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""
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} else {
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"..."
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})
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}
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fn display_suggested_methods(&self, methods: &[AssociatedItem]) -> String {
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methods.iter()
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.take(5)
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.map(|method| self.format_method_suggestion(&*method))
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.collect::<Vec>()
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.join("\n - ")
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}
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fn get_best_match(&self, methods: &[AssociatedItem]) -> String {
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let no_argument_methods: Vec<_> =
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methods.iter()
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.filter(|ref x| self.has_no_input_arg(&*x))
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.map(|x| x.clone())
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.collect();
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if no_argument_methods.len() > 0 {
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self.display_suggested_methods(&no_argument_methods)
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} else {
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self.display_suggested_methods(&methods)
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}
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}
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// This function checks if the method isn't static and takes other arguments than self.
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fn has_no_input_arg(&self, method: &AssociatedItem) -> bool {
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match method.def() {
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Def::Method(def_id) => {
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match self.tcx.item_type(def_id).sty {
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ty::TypeVariants::TyFnDef(_, _, fty) => {
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fty.sig.skip_binder().inputs().len() == 1
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}
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_ => false,
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}
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}
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_ => false,
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`}
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`}
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`}
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