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Fix diagnostics for calling indirect extern function pointer field #29827

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Merged
merged 1 commit into from
Nov 14, 2015
Merged

Fix diagnostics for calling indirect extern function pointer field #29827

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54 changes: 31 additions & 23 deletions src/librustc_typeck/check/method/suggest.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -92,31 +92,39 @@ pub fn report_error<'a, 'tcx>(fcx: &FnCtxt<'a, 'tcx>,

// Determine if the field can be used as a function in some way
let field_ty = field.ty(cx, substs);
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 selcx.evaluate_obligation(&obligation) {
span_stored_function();

match field_ty.sty {
// Not all of these (e.g. unsafe fns) implement FnOnce
// so we look for these beforehand
ty::TyClosure(..) | ty::TyBareFn(..) => 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 selcx.evaluate_obligation(&obligation) {
span_stored_function();
} else {
span_did_you_mean();
}
});
} else {
span_did_you_mean();
span_did_you_mean()
}
});
} else {
match field_ty.sty {
// fallback to matching a closure or function pointer
ty::TyClosure(..) | ty::TyBareFn(..) => span_stored_function(),
_ => span_did_you_mean(),
}
}
}
Expand Down
23 changes: 23 additions & 0 deletions src/test/compile-fail/issue-2392.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -11,6 +11,16 @@
#![feature(core)]
use std::boxed::FnBox;

struct FuncContainer {
f1: fn(data: u8),
f2: extern "C" fn(data: u8),
f3: unsafe fn(data: u8),
}

struct FuncContainerOuter {
container: Box<FuncContainer>
}

struct Obj<F> where F: FnOnce() -> u32 {
closure: F,
not_closure: usize,
Expand Down Expand Up @@ -66,3 +76,16 @@ fn main() {
check_expression().closure();//~ ERROR no method named `closure` found
//~^ NOTE use `(check_expression().closure)(...)` if you meant to call the function stored
}

impl FuncContainerOuter {
fn run(&self) {
unsafe {
(*self.container).f1(1); //~ ERROR no method named `f1` found
//~^ NOTE use `(*self.container.f1)(...)`
(*self.container).f2(1); //~ ERROR no method named `f2` found
//~^ NOTE use `(*self.container.f2)(...)`
(*self.container).f3(1); //~ ERROR no method named `f3` found
//~^ NOTE use `(*self.container.f3)(...)`
}
}
}