use check::FnCtxt;
-use rustc::ty::Ty;
-use rustc::infer::{InferOk};
+use rustc::infer::InferOk;
use rustc::traits::ObligationCause;
use syntax::ast;
use syntax_pos::{self, Span};
use rustc::hir;
+use rustc::hir::print;
use rustc::hir::def::Def;
-use rustc::ty::{self, AssociatedItem};
-use errors::DiagnosticBuilder;
+use rustc::ty::{self, Ty, AssociatedItem};
+use errors::{DiagnosticBuilder, CodeMapper};
use super::method::probe;
// Requires that the two types unify, and prints an error message if
// they don't.
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) {
+ self.demand_suptype_diag(sp, expected, actual).map(|mut e| e.emit());
+ }
+
+ pub fn demand_suptype_diag(&self,
+ sp: Span,
+ expected: Ty<'tcx>,
+ actual: Ty<'tcx>) -> Option<DiagnosticBuilder<'tcx>> {
+ let cause = &self.misc(sp);
+ match self.at(cause, self.param_env).sup(expected, actual) {
Ok(InferOk { obligations, value: () }) => {
self.register_predicates(obligations);
+ None
},
Err(e) => {
- self.report_mismatched_types(&cause, expected, actual, e).emit();
+ Some(self.report_mismatched_types(&cause, expected, actual, e))
}
}
}
cause: &ObligationCause<'tcx>,
expected: Ty<'tcx>,
actual: Ty<'tcx>) -> Option<DiagnosticBuilder<'tcx>> {
- match self.eq_types(false, cause, actual, expected) {
+ match self.at(cause, self.param_env).eq(expected, actual) {
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>)
+ -> Ty<'tcx> {
+ let (ty, err) = self.demand_coerce_diag(expr, checked_ty, expected);
+ if let Some(mut err) = err {
+ err.emit();
+ }
+ ty
+ }
+
// Checks that the type of `expr` can be coerced to `expected`.
- pub fn demand_coerce(&self, expr: &hir::Expr, checked_ty: Ty<'tcx>, expected: Ty<'tcx>) {
+ //
+ // NB: This code relies on `self.diverges` to be accurate. In
+ // particular, assignments to `!` will be permitted if the
+ // diverges flag is currently "always".
+ pub fn demand_coerce_diag(&self,
+ expr: &hir::Expr,
+ checked_ty: Ty<'tcx>,
+ expected: Ty<'tcx>)
+ -> (Ty<'tcx>, Option<DiagnosticBuilder<'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 e = match self.try_coerce(expr, checked_ty, self.diverges.get(), expected) {
+ Ok(ty) => return (ty, None),
+ Err(e) => e
+ };
+
+ let cause = self.misc(expr.span);
+ let expr_ty = self.resolve_type_vars_with_obligations(checked_ty);
+ let mut err = self.report_mismatched_types(&cause, expected, expr_ty, e);
+
+ // If the expected type is an enum with any variants whose sole
+ // field is of the found type, suggest such variants. See Issue
+ // #42764.
+ if let ty::TyAdt(expected_adt, substs) = expected.sty {
+ let mut compatible_variants = vec![];
+ for variant in &expected_adt.variants {
+ if variant.fields.len() == 1 {
+ let sole_field = &variant.fields[0];
+ let sole_field_ty = sole_field.ty(self.tcx, substs);
+ if self.can_coerce(expr_ty, sole_field_ty) {
+ let mut variant_path = self.tcx.item_path_str(variant.did);
+ variant_path = variant_path.trim_left_matches("std::prelude::v1::")
+ .to_string();
+ compatible_variants.push(variant_path);
+ }
+ }
+ }
+ if !compatible_variants.is_empty() {
+ let expr_text = print::to_string(print::NO_ANN, |s| s.print_expr(expr));
+ let suggestions = compatible_variants.iter()
+ .map(|v| format!("{}({})", v, expr_text)).collect::<Vec<_>>();
+ err.span_suggestions(expr.span,
+ "try using a variant of the expected type",
+ suggestions);
+ }
+ }
+
+ if let Some(suggestion) = self.check_ref(expr,
+ checked_ty,
+ expected) {
+ err.help(&suggestion);
+ } else {
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();
+ }
}
+ (expected, Some(err))
}
fn format_method_suggestion(&self, method: &AssociatedItem) -> String {
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
+ self.tcx.fn_sig(def_id).inputs().skip_binder().len() == 1
+ }
+ _ => false,
+ }
+ }
+
+ /// This function is used to determine potential "simple" improvements or users' errors and
+ /// provide them useful help. For example:
+ ///
+ /// ```
+ /// fn some_fn(s: &str) {}
+ ///
+ /// let x = "hey!".to_owned();
+ /// some_fn(x); // error
+ /// ```
+ ///
+ /// No need to find every potential function which could make a coercion to transform a
+ /// `String` into a `&str` since a `&` would do the trick!
+ ///
+ /// In addition of this check, it also checks between references mutability state. If the
+ /// expected is mutable but the provided isn't, maybe we could just say "Hey, try with
+ /// `&mut`!".
+ fn check_ref(&self,
+ expr: &hir::Expr,
+ checked_ty: Ty<'tcx>,
+ expected: Ty<'tcx>)
+ -> Option<String> {
+ match (&expected.sty, &checked_ty.sty) {
+ (&ty::TyRef(_, exp), &ty::TyRef(_, check)) => match (&exp.ty.sty, &check.ty.sty) {
+ (&ty::TyStr, &ty::TyArray(arr, _)) |
+ (&ty::TyStr, &ty::TySlice(arr)) if arr == self.tcx.types.u8 => {
+ if let hir::ExprLit(_) = expr.node {
+ let sp = self.sess().codemap().call_span_if_macro(expr.span);
+ if let Ok(src) = self.tcx.sess.codemap().span_to_snippet(sp) {
+ return Some(format!("try `{}`", &src[1..]));
+ }
+ }
+ None
+ },
+ (&ty::TyArray(arr, _), &ty::TyStr) |
+ (&ty::TySlice(arr), &ty::TyStr) if arr == self.tcx.types.u8 => {
+ if let hir::ExprLit(_) = expr.node {
+ let sp = self.sess().codemap().call_span_if_macro(expr.span);
+ if let Ok(src) = self.tcx.sess.codemap().span_to_snippet(sp) {
+ return Some(format!("try `b{}`", src));
+ }
+ }
+ None
+ }
+ _ => None,
+ },
+ (&ty::TyRef(_, mutability), _) => {
+ // Check if it can work when put into a ref. For example:
+ //
+ // ```
+ // fn bar(x: &mut i32) {}
+ //
+ // let x = 0u32;
+ // bar(&x); // error, expected &mut
+ // ```
+ let ref_ty = match mutability.mutbl {
+ hir::Mutability::MutMutable => self.tcx.mk_mut_ref(
+ self.tcx.mk_region(ty::ReStatic),
+ checked_ty),
+ hir::Mutability::MutImmutable => self.tcx.mk_imm_ref(
+ self.tcx.mk_region(ty::ReStatic),
+ checked_ty),
+ };
+ if self.can_coerce(ref_ty, expected) {
+ // Use the callsite's span if this is a macro call. #41858
+ let sp = self.sess().codemap().call_span_if_macro(expr.span);
+ if let Ok(src) = self.tcx.sess.codemap().span_to_snippet(sp) {
+ return Some(format!("try with `{}{}`",
+ match mutability.mutbl {
+ hir::Mutability::MutMutable => "&mut ",
+ hir::Mutability::MutImmutable => "&",
+ },
+ &src));
}
- _ => false,
}
+ None
}
- _ => false,
+ (_, &ty::TyRef(_, checked)) => {
+ // We have `&T`, check if what was expected was `T`. If so,
+ // we may want to suggest adding a `*`, or removing
+ // a `&`.
+ //
+ // (But, also check check the `expn_info()` to see if this is
+ // a macro; if so, it's hard to extract the text and make a good
+ // suggestion, so don't bother.)
+ if self.infcx.can_sub(self.param_env, checked.ty, &expected).is_ok() &&
+ expr.span.ctxt().outer().expn_info().is_none() {
+ match expr.node {
+ // Maybe remove `&`?
+ hir::ExprAddrOf(_, ref expr) => {
+ if let Ok(code) = self.tcx.sess.codemap().span_to_snippet(expr.span) {
+ return Some(format!("try with `{}`", code));
+ }
+ }
+
+ // Maybe add `*`? Only if `T: Copy`.
+ _ => {
+ if !self.infcx.type_moves_by_default(self.param_env,
+ checked.ty,
+ expr.span) {
+ let sp = self.sess().codemap().call_span_if_macro(expr.span);
+ if let Ok(code) = self.tcx.sess.codemap().span_to_snippet(sp) {
+ return Some(format!("try with `*{}`", code));
+ }
+ }
+ },
+ }
+ }
+ None
+ }
+ _ => None,
}
}
}
projects / rustc.git / blobdiff