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Rollup merge of #79032 - lcnr:arg-count, r=varkor

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improve type const mismatch errors

Doesn't completely remove `check_generic_arg_count` as that would have required some more complex changes but
instead checks type and const params in only one step. Also moved the help added by `@JulianKnodt` in #75611 to `generic_arg_mismatch_err`.

r? `@varkor` cc `@petrochenkov`
This commit is contained in:
Mara Bos 2020-11-16 17:26:35 +01:00 • committed by GitHub
commit 835faa532f
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27 changed files with 211 additions and 302 deletions
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8
compiler/rustc_hir/src/hir.rs
View file

@ -282,6 +282,14 @@ impl GenericArg<'_> {
GenericArg::Const(_) => "constant",
}
}
pub fn short_descr(&self) -> &'static str {
match self {
GenericArg::Lifetime(_) => "lifetime",
GenericArg::Type(_) => "type",
GenericArg::Const(_) => "const",
}
}
}
#[derive(Debug, HashStable_Generic)]

182
compiler/rustc_typeck/src/astconv/generics.rs
View file

@ -23,6 +23,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
sess: &Session,
arg: &GenericArg<'_>,
kind: &'static str,
possible_ordering_error: bool,
help: Option<&str>,
) {
let mut err = struct_span_err!(
@ -49,8 +50,23 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
GenericArg::Const(_) => ParamKindOrd::Const { unordered },
};
if matches!(arg, GenericArg::Type(hir::Ty { kind: hir::TyKind::Path { .. }, .. }))
&& matches!(kind_ord, ParamKindOrd::Const { .. })
{
let suggestions = vec![
(arg.span().shrink_to_lo(), String::from("{ ")),
(arg.span().shrink_to_hi(), String::from(" }")),
];
err.multipart_suggestion(
"if this generic argument was intended as a const parameter, \
try surrounding it with braces:",
suggestions,
Applicability::MaybeIncorrect,
);
}
// This note is only true when generic parameters are strictly ordered by their kind.
if kind_ord.cmp(&arg_ord) != core::cmp::Ordering::Equal {
if possible_ordering_error && kind_ord.cmp(&arg_ord) != core::cmp::Ordering::Equal {
let (first, last) =
if kind_ord < arg_ord { (kind, arg.descr()) } else { (arg.descr(), kind) };
err.note(&format!("{} arguments must be provided before {} arguments", first, last));
@ -148,8 +164,8 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
// Check whether this segment takes generic arguments and the user has provided any.
let (generic_args, infer_args) = ctx.args_for_def_id(def_id);
let mut args =
generic_args.iter().flat_map(|generic_args| generic_args.args.iter()).peekable();
let args_iter = generic_args.iter().flat_map(|generic_args| generic_args.args.iter());
let mut args = args_iter.clone().peekable();
// If we encounter a type or const when we expect a lifetime, we infer the lifetimes.
// If we later encounter a lifetime, we know that the arguments were provided in the
@ -216,8 +232,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
GenericParamDefKind::Const => {
ParamKindOrd::Const {
unordered: tcx
.sess
.features_untracked()
.features()
.const_generics,
}
}
@ -237,6 +252,13 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
tcx.sess,
arg,
kind.descr(),
!args_iter.clone().is_sorted_by_key(|arg| match arg {
GenericArg::Lifetime(_) => ParamKindOrd::Lifetime,
GenericArg::Type(_) => ParamKindOrd::Type,
GenericArg::Const(_) => ParamKindOrd::Const {
unordered: tcx.features().const_generics,
},
}),
Some(&format!(
"reorder the arguments: {}: `<{}>`",
param_types_present
@ -288,7 +310,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
assert_eq!(kind, "lifetime");
let provided =
force_infer_lt.expect("lifetimes ought to have been inferred");
Self::generic_arg_mismatch_err(tcx.sess, provided, kind, None);
Self::generic_arg_mismatch_err(tcx.sess, provided, kind, false, None);
}
break;
@ -346,6 +368,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
// that lifetimes will proceed types. So it suffices to check the number of each generic
// arguments in order to validate them with respect to the generic parameters.
let param_counts = def.own_counts();
let named_type_param_count = param_counts.types - has_self as usize;
let arg_counts = args.own_counts();
let infer_lifetimes = position != GenericArgPosition::Type && arg_counts.lifetimes == 0;
@ -384,11 +407,11 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
// For kinds without defaults (e.g.., lifetimes), `required == permitted`.
// For other kinds (i.e., types), `permitted` may be greater than `required`.
if required <= provided && provided <= permitted {
return Ok(());
return true;
}
if silent {
return Err((0i32, None));
return false;
}
// Unfortunately lifetime and type parameter mismatches are typically styled
@ -404,25 +427,26 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
(required, "")
};
let (spans, label) = if required == permitted && provided > permitted {
let (spans, labels) = if provided > permitted {
// In the case when the user has provided too many arguments,
// we want to point to the unexpected arguments.
let spans: Vec<Span> = args.args[offset + permitted..offset + provided]
let (spans, labels): (Vec<Span>, Vec<String>) = args.args
[offset + permitted..offset + provided]
.iter()
.map(|arg| arg.span())
.collect();
.map(|arg| (arg.span(), format!("unexpected {} argument", arg.short_descr())))
.unzip();
unexpected_spans.extend(spans.clone());
(spans, format!("unexpected {} argument", kind))
(spans, labels)
} else {
(
vec![span],
format!(
vec![format!(
"expected {}{} {} argument{}",
quantifier,
bound,
kind,
pluralize!(bound),
),
)],
)
};
@ -434,105 +458,57 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
),
DiagnosticId::Error("E0107".into()),
);
for span in spans {
for (span, label) in spans.into_iter().zip(labels) {
err.span_label(span, label.as_str());
}
assert_ne!(bound, provided);
Err((bound as i32 - provided as i32, Some(err)))
err.emit();
false
};
let mut unexpected_spans = vec![];
let mut lifetime_count_correct = Ok(());
if !infer_lifetimes || arg_counts.lifetimes > param_counts.lifetimes {
lifetime_count_correct = check_kind_count(
"lifetime",
param_counts.lifetimes,
param_counts.lifetimes,
arg_counts.lifetimes,
0,
&mut unexpected_spans,
explicit_late_bound == ExplicitLateBound::Yes,
);
}
let lifetime_count_correct = check_kind_count(
"lifetime",
if infer_lifetimes { 0 } else { param_counts.lifetimes },
param_counts.lifetimes,
arg_counts.lifetimes,
0,
&mut unexpected_spans,
explicit_late_bound == ExplicitLateBound::Yes,
);
// FIXME(const_generics:defaults)
let mut const_count_correct = Ok(());
if !infer_args || arg_counts.consts > param_counts.consts {
const_count_correct = check_kind_count(
"const",
param_counts.consts,
param_counts.consts,
arg_counts.consts,
arg_counts.lifetimes + arg_counts.types,
&mut unexpected_spans,
false,
);
}
let kind_str = if param_counts.consts + arg_counts.consts == 0 {
"type"
} else if named_type_param_count + arg_counts.types == 0 {
"const"
} else {
"generic"
};
// Note that type errors are currently be emitted *after* const errors.
let mut type_count_correct = Ok(());
if !infer_args || arg_counts.types > param_counts.types - defaults.types - has_self as usize
{
type_count_correct = check_kind_count(
"type",
param_counts.types - defaults.types - has_self as usize,
param_counts.types - has_self as usize,
arg_counts.types,
arg_counts.lifetimes,
&mut unexpected_spans,
false,
);
}
// Emit a help message if it's possible that a type could be surrounded in braces
if let Err((c_mismatch, Some(ref mut _const_err))) = const_count_correct {
if let Err((_, Some(ref mut type_err))) = type_count_correct {
let possible_matches = args.args[arg_counts.lifetimes..]
.iter()
.filter(|arg| {
matches!(
arg,
GenericArg::Type(hir::Ty { kind: hir::TyKind::Path { .. }, .. })
)
})
.take(c_mismatch.max(0) as usize);
for arg in possible_matches {
let suggestions = vec![
(arg.span().shrink_to_lo(), String::from("{ ")),
(arg.span().shrink_to_hi(), String::from(" }")),
];
type_err.multipart_suggestion(
"If this generic argument was intended as a const parameter, \
try surrounding it with braces:",
suggestions,
Applicability::MaybeIncorrect,
);
}
}
}
let emit_correct =
|correct: Result<(), (_, Option<rustc_errors::DiagnosticBuilder<'_>>)>| match correct {
Ok(()) => Ok(()),
Err((_, None)) => Err(()),
Err((_, Some(mut err))) => {
err.emit();
Err(())
}
};
let arg_count_correct = emit_correct(lifetime_count_correct)
.and(emit_correct(const_count_correct))
.and(emit_correct(type_count_correct));
let arg_count_correct = check_kind_count(
kind_str,
if infer_args {
0
} else {
param_counts.consts + named_type_param_count - defaults.types
},
param_counts.consts + named_type_param_count,
arg_counts.consts + arg_counts.types,
arg_counts.lifetimes,
&mut unexpected_spans,
false,
);
GenericArgCountResult {
explicit_late_bound,
correct: arg_count_correct.map_err(|()| GenericArgCountMismatch {
reported: Some(ErrorReported),
invalid_args: unexpected_spans,
}),
correct: if lifetime_count_correct && arg_count_correct {
Ok(())
} else {
Err(GenericArgCountMismatch {
reported: Some(ErrorReported),
invalid_args: unexpected_spans,
})
},
}
}

1
compiler/rustc_typeck/src/lib.rs
View file

@ -61,6 +61,7 @@ This API is completely unstable and subject to change.
#![feature(box_syntax)]
#![feature(crate_visibility_modifier)]
#![feature(in_band_lifetimes)]
#![feature(is_sorted)]
#![feature(nll)]
#![feature(or_patterns)]
#![feature(try_blocks)]