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Auto merge of #32358 - Manishearth:pr-32053, r=Manishearth

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Add note if method is called on a function object

rebase of #32053
This commit is contained in:
bors 2016-03-19 21:15:23 -07:00
commit b6fcab5c7c
2 changed files with 105 additions and 51 deletions
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121
src/librustc_typeck/check/method/suggest.rs
View File

@ -25,11 +25,13 @@ use middle::subst::Substs;
use middle::traits::{Obligation, SelectionContext};
use util::nodemap::{FnvHashSet};
use syntax::ast;
use syntax::codemap::Span;
use syntax::errors::DiagnosticBuilder;
use rustc_front::print::pprust;
use rustc_front::hir;
use rustc_front::hir::Expr_;
use std::cell;
use std::cmp::Ordering;
@ -37,6 +39,42 @@ use std::cmp::Ordering;
use super::{MethodError, NoMatchData, CandidateSource, impl_item, trait_item};
use super::probe::Mode;
fn is_fn_ty<'a, 'tcx>(ty: &Ty<'tcx>, fcx: &FnCtxt<'a, 'tcx>, span: Span) -> bool {
let cx = fcx.tcx();
println!("{:?}", ty);
match ty.sty {
// Not all of these (e.g. unsafe fns) implement FnOnce
// so we look for these beforehand
ty::TyClosure(..) | ty::TyFnDef(..) | ty::TyFnPtr(_) => true,
// If it's not a simple function, look for things which implement FnOnce
_ => {
if let Ok(fn_once_trait_did) =
cx.lang_items.require(FnOnceTraitLangItem) {
let infcx = fcx.infcx();
infcx.probe(|_| {
let fn_once_substs =
Substs::new_trait(vec![infcx.next_ty_var()],
Vec::new(),
ty);
let trait_ref =
ty::TraitRef::new(fn_once_trait_did,
cx.mk_substs(fn_once_substs));
let poly_trait_ref = trait_ref.to_poly_trait_ref();
let obligation = Obligation::misc(span,
fcx.body_id,
poly_trait_ref
.to_predicate());
let mut selcx = SelectionContext::new(infcx);
return selcx.evaluate_obligation(&obligation)
})
} else {
false
}
}
}
}
pub fn report_error<'a, 'tcx>(fcx: &FnCtxt<'a, 'tcx>,
span: Span,
rcvr_ty: Ty<'tcx>,
@ -79,60 +117,41 @@ pub fn report_error<'a, 'tcx>(fcx: &FnCtxt<'a, 'tcx>,
// snippet
};
macro_rules! span_stored_function {
() => {
err.span_note(span,
&format!("use `({0}.{1})(...)` if you meant to call \
the function stored in the `{1}` field",
expr_string, item_name));
}
}
macro_rules! span_did_you_mean {
() => {
err.span_note(span, &format!("did you mean to write `{0}.{1}`?",
expr_string, item_name));
}
}
// Determine if the field can be used as a function in some way
let field_ty = field.ty(cx, substs);
match field_ty.sty {
// Not all of these (e.g. unsafe fns) implement FnOnce
// so we look for these beforehand
ty::TyClosure(..) | ty::TyFnDef(..) | ty::TyFnPtr(_) => {
span_stored_function!();
}
// If it's not a simple function, look for things which implement FnOnce
_ => {
if let Ok(fn_once_trait_did) =
cx.lang_items.require(FnOnceTraitLangItem) {
let infcx = fcx.infcx();
infcx.probe(|_| {
let fn_once_substs =
Substs::new_trait(vec![infcx.next_ty_var()],
Vec::new(),
field_ty);
let trait_ref =
ty::TraitRef::new(fn_once_trait_did,
cx.mk_substs(fn_once_substs));
let poly_trait_ref = trait_ref.to_poly_trait_ref();
let obligation = Obligation::misc(span,
fcx.body_id,
poly_trait_ref
.to_predicate());
let mut selcx = SelectionContext::new(infcx);
if is_fn_ty(&field_ty, &fcx, span) {
err.span_note(span,
&format!("use `({0}.{1})(...)` if you meant to call \
the function stored in the `{1}` field",
expr_string, item_name));
} else {
err.span_note(span, &format!("did you mean to write `{0}.{1}`?",
expr_string, item_name));
}
}
}
if selcx.evaluate_obligation(&obligation) {
span_stored_function!();
} else {
span_did_you_mean!();
}
});
} else {
span_did_you_mean!();
}
if is_fn_ty(&rcvr_ty, &fcx, span) {
macro_rules! report_function {
($span:expr, $name:expr) => {
err.fileline_note(
$span,
&format!("{} is a function, perhaps you wish to call it",
$name));
}
}
if let Some(expr) = rcvr_expr {
if let Ok (expr_string) = cx.sess.codemap().span_to_snippet(expr.span) {
report_function!(expr.span, expr_string);
err.span_suggestion(expr.span,
"try calling the base function:",
format!("{}()",
expr_string));
}
else if let Expr_::ExprPath(_, path) = expr.node.clone() {
if let Some(segment) = path.segments.last() {
report_function!(expr.span, segment.identifier.name);
}
}
}

35
src/test/compile-fail/issue-29124.rs Normal file
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@ -0,0 +1,35 @@
// Copyright 2015 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.
struct ret;
struct obj;
impl obj {
fn func() -> ret {
ret
}
}
fn func() -> ret {
ret
}
fn main() {
obj::func.x();
//~^ ERROR no method named `x` found for type `fn() -> ret {obj::func}` in the current scope
//~^^ NOTE obj::func is a function, perhaps you wish to call it
//~^^^ HELP try calling the base function:
//~| SUGGESTION obj::func().x();
func.x();
//~^ ERROR no method named `x` found for type `fn() -> ret {func}` in the current scope
//~^^ NOTE func is a function, perhaps you wish to call it
//~^^^ HELP try calling the base function:
//~| SUGGESTION func().x();
}