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Rollup merge of #59267 - estebank:assoc-const-as-field, r=davidtwco

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Provide suggestion when using field access instead of path

When trying to access an associated constant as if it were a field of
an instance, provide a suggestion for the correct syntax.

Fix #57316.
This commit is contained in:
Mazdak Farrokhzad 2019-03-26 09:05:43 +01:00 committed by GitHub
commit ba55822801
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GPG Key ID: 4AEE18F83AFDEB23
4 changed files with 66 additions and 55 deletions
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95
src/librustc_resolve/error_reporting.rs
View File

@ -5,7 +5,7 @@
use rustc::hir::def::{Def, CtorKind, Namespace::*};
use rustc::hir::def_id::{CRATE_DEF_INDEX, DefId};
use rustc::session::config::nightly_options;
use syntax::ast::{ExprKind};
use syntax::ast::{Expr, ExprKind};
use syntax::symbol::keywords;
use syntax_pos::Span;
@ -250,6 +250,29 @@ fn smart_resolve_context_dependent_help(
let ns = source.namespace();
let is_expected = &|def| source.is_expected(def);
let path_sep = |err: &mut DiagnosticBuilder<'_>, expr: &Expr| match expr.node {
ExprKind::Field(_, ident) => {
err.span_suggestion(
expr.span,
"use the path separator to refer to an item",
format!("{}::{}", path_str, ident),
Applicability::MaybeIncorrect,
);
true
}
ExprKind::MethodCall(ref segment, ..) => {
let span = expr.span.with_hi(segment.ident.span.hi());
err.span_suggestion(
span,
"use the path separator to refer to an item",
format!("{}::{}", path_str, segment.ident),
Applicability::MaybeIncorrect,
);
true
}
_ => false,
};
match (def, source) {
(Def::Macro(..), _) => {
err.span_suggestion(
@ -259,8 +282,7 @@ fn smart_resolve_context_dependent_help(
Applicability::MaybeIncorrect,
);
if path_str == "try" && span.rust_2015() {
err.note("if you want the `try` keyword, \
you need to be in the 2018 edition");
err.note("if you want the `try` keyword, you need to be in the 2018 edition");
}
}
(Def::TyAlias(..), PathSource::Trait(_)) => {
@ -269,25 +291,8 @@ fn smart_resolve_context_dependent_help(
err.note("did you mean to use a trait alias?");
}
}
(Def::Mod(..), PathSource::Expr(Some(parent))) => match parent.node {
ExprKind::Field(_, ident) => {
err.span_suggestion(
parent.span,
"use the path separator to refer to an item",
format!("{}::{}", path_str, ident),
Applicability::MaybeIncorrect,
);
}
ExprKind::MethodCall(ref segment, ..) => {
let span = parent.span.with_hi(segment.ident.span.hi());
err.span_suggestion(
span,
"use the path separator to refer to an item",
format!("{}::{}", path_str, segment.ident),
Applicability::MaybeIncorrect,
);
}
_ => return false,
(Def::Mod(..), PathSource::Expr(Some(parent))) => if !path_sep(err, &parent) {
return false;
},
(Def::Enum(..), PathSource::TupleStruct)
| (Def::Enum(..), PathSource::Expr(..)) => {
@ -315,8 +320,10 @@ fn smart_resolve_context_dependent_help(
= self.struct_constructors.get(&def_id).cloned() {
let accessible_ctor = self.is_accessible(ctor_vis);
if is_expected(ctor_def) && !accessible_ctor {
err.span_label(span, format!("constructor is not visible \
here due to private fields"));
err.span_label(
span,
format!("constructor is not visible here due to private fields"),
);
}
} else {
// HACK(estebank): find a better way to figure out that this was a
@ -366,28 +373,12 @@ fn smart_resolve_context_dependent_help(
}
}
match source {
PathSource::Expr(Some(parent)) => {
match parent.node {
ExprKind::MethodCall(ref path_assignment, _) => {
err.span_suggestion(
sm.start_point(parent.span)
.to(path_assignment.ident.span),
"use `::` to access an associated function",
format!("{}::{}",
path_str,
path_assignment.ident),
Applicability::MaybeIncorrect
);
},
_ => {
err.span_label(
span,
format!("did you mean `{} {{ /* fields */ }}`?",
path_str),
);
},
}
},
PathSource::Expr(Some(parent)) => if !path_sep(err, &parent) {
err.span_label(
span,
format!("did you mean `{} {{ /* fields */ }}`?", path_str),
);
}
PathSource::Expr(None) if followed_by_brace == true => {
if let Some((sp, snippet)) = closing_brace {
err.span_suggestion(
@ -399,16 +390,14 @@ fn smart_resolve_context_dependent_help(
} else {
err.span_label(
span,
format!("did you mean `({} {{ /* fields */ }})`?",
path_str),
format!("did you mean `({} {{ /* fields */ }})`?", path_str),
);
}
},
_ => {
err.span_label(
span,
format!("did you mean `{} {{ /* fields */ }}`?",
path_str),
format!("did you mean `{} {{ /* fields */ }}`?", path_str),
);
},
}
@ -417,13 +406,11 @@ fn smart_resolve_context_dependent_help(
(Def::Union(..), _) |
(Def::Variant(..), _) |
(Def::Ctor(_, _, CtorKind::Fictive), _) if ns == ValueNS => {
err.span_label(span, format!("did you mean `{} {{ /* fields */ }}`?",
path_str));
err.span_label(span, format!("did you mean `{} {{ /* fields */ }}`?", path_str));
}
(Def::SelfTy(..), _) if ns == ValueNS => {
err.span_label(span, fallback_label);
err.note("can't use `Self` as a constructor, you must use the \
implemented struct");
err.note("can't use `Self` as a constructor, you must use the implemented struct");
}
(Def::TyAlias(_), _) | (Def::AssociatedTy(..), _) if ns == ValueNS => {
err.note("can't use a type alias as a constructor");

2
src/test/ui/resolve/issue-22692.stderr
View File

@ -4,7 +4,7 @@ error[E0423]: expected value, found struct `String`
LL | let _ = String.new();
| ^^^^^^----
| |
| help: use `::` to access an associated function: `String::new`
| help: use the path separator to refer to an item: `String::new`
error: aborting due to previous error

13
src/test/ui/suggestions/assoc-const-as-field.rs Normal file
View File

@ -0,0 +1,13 @@
pub mod Mod {
pub struct Foo {}
impl Foo {
pub const BAR: usize = 42;
}
}
fn foo(_: usize) {}
fn main() {
foo(Mod::Foo.Bar);
//~^ ERROR expected value, found
}

11
src/test/ui/suggestions/assoc-const-as-field.stderr Normal file
View File

@ -0,0 +1,11 @@
error[E0423]: expected value, found struct `Mod::Foo`
--> $DIR/assoc-const-as-field.rs:11:9
|
LL | foo(Mod::Foo.Bar);
| ^^^^^^^^----
| |
| help: use the path separator to refer to an item: `Mod::Foo::Bar`
error: aborting due to previous error
For more information about this error, try `rustc --explain E0423`.