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Rollup merge of #77093 - lcnr:const-generics-infer-warning, r=varkor

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merge `need_type_info_err(_const)`

I hoped that this would automatically solve #76737 but it doesn't quite seem like it

fixes #77092

r? @varkor
This commit is contained in:
Ralf Jung 2020-09-26 12:58:17 +02:00 • committed by GitHub
commit ac8169dc10
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15 changed files with 253 additions and 154 deletions
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275
compiler/rustc_infer/src/infer/error_reporting/need_type_info.rs
View file

@ -176,7 +176,10 @@ fn closure_return_type_suggestion(
suggestion,
Applicability::HasPlaceholders,
);
err.span_label(span, InferCtxt::missing_type_msg(&name, &descr, parent_name, parent_descr));
err.span_label(
span,
InferCtxt::cannot_infer_msg("type", &name, &descr, parent_name, parent_descr),
);
}
/// Given a closure signature, return a `String` containing a list of all its argument types.
@ -217,65 +220,151 @@ impl Into<rustc_errors::DiagnosticId> for TypeAnnotationNeeded {
}
}
/// Information about a constant or a type containing inference variables.
pub struct InferenceDiagnosticsData {
pub name: String,
pub span: Option<Span>,
pub description: Cow<'static, str>,
pub parent_name: Option<String>,
pub parent_description: Option<&'static str>,
}
impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
pub fn extract_type_name(
/// Extracts data used by diagnostic for either types or constants
/// which were stuck during inference.
pub fn extract_inference_diagnostics_data(
&self,
ty: Ty<'tcx>,
arg: GenericArg<'tcx>,
highlight: Option<ty::print::RegionHighlightMode>,
) -> (String, Option<Span>, Cow<'static, str>, Option<String>, Option<&'static str>) {
if let ty::Infer(ty::TyVar(ty_vid)) = *ty.kind() {
let mut inner = self.inner.borrow_mut();
let ty_vars = &inner.type_variables();
let var_origin = ty_vars.var_origin(ty_vid);
if let TypeVariableOriginKind::TypeParameterDefinition(name, def_id) = var_origin.kind {
let parent_def_id = def_id.and_then(|def_id| self.tcx.parent(def_id));
let (parent_name, parent_desc) = if let Some(parent_def_id) = parent_def_id {
let parent_name = self
.tcx
.def_key(parent_def_id)
.disambiguated_data
.data
.get_opt_name()
.map(|parent_symbol| parent_symbol.to_string());
) -> InferenceDiagnosticsData {
match arg.unpack() {
GenericArgKind::Type(ty) => {
if let ty::Infer(ty::TyVar(ty_vid)) = *ty.kind() {
let mut inner = self.inner.borrow_mut();
let ty_vars = &inner.type_variables();
let var_origin = ty_vars.var_origin(ty_vid);
if let TypeVariableOriginKind::TypeParameterDefinition(name, def_id) =
var_origin.kind
{
let parent_def_id = def_id.and_then(|def_id| self.tcx.parent(def_id));
let (parent_name, parent_description) =
if let Some(parent_def_id) = parent_def_id {
let parent_name = self
.tcx
.def_key(parent_def_id)
.disambiguated_data
.data
.get_opt_name()
.map(|parent_symbol| parent_symbol.to_string());
(parent_name, Some(self.tcx.def_kind(parent_def_id).descr(parent_def_id)))
} else {
(None, None)
};
(
parent_name,
Some(self.tcx.def_kind(parent_def_id).descr(parent_def_id)),
)
} else {
(None, None)
};
if name != kw::SelfUpper {
return (
name.to_string(),
Some(var_origin.span),
"type parameter".into(),
parent_name,
parent_desc,
);
if name != kw::SelfUpper {
return InferenceDiagnosticsData {
name: name.to_string(),
span: Some(var_origin.span),
description: "type parameter".into(),
parent_name,
parent_description,
};
}
}
}
let mut s = String::new();
let mut printer = ty::print::FmtPrinter::new(self.tcx, &mut s, Namespace::TypeNS);
if let Some(highlight) = highlight {
printer.region_highlight_mode = highlight;
}
let _ = ty.print(printer);
InferenceDiagnosticsData {
name: s,
span: None,
description: ty.prefix_string(),
parent_name: None,
parent_description: None,
}
}
}
GenericArgKind::Const(ct) => {
if let ty::ConstKind::Infer(InferConst::Var(vid)) = ct.val {
let origin =
self.inner.borrow_mut().const_unification_table().probe_value(vid).origin;
if let ConstVariableOriginKind::ConstParameterDefinition(name, def_id) =
origin.kind
{
let parent_def_id = self.tcx.parent(def_id);
let (parent_name, parent_description) =
if let Some(parent_def_id) = parent_def_id {
let parent_name = self
.tcx
.def_key(parent_def_id)
.disambiguated_data
.data
.get_opt_name()
.map(|parent_symbol| parent_symbol.to_string());
let mut s = String::new();
let mut printer = ty::print::FmtPrinter::new(self.tcx, &mut s, Namespace::TypeNS);
if let Some(highlight) = highlight {
printer.region_highlight_mode = highlight;
(
parent_name,
Some(self.tcx.def_kind(parent_def_id).descr(parent_def_id)),
)
} else {
(None, None)
};
return InferenceDiagnosticsData {
name: name.to_string(),
span: Some(origin.span),
description: "const parameter".into(),
parent_name,
parent_description,
};
}
debug_assert!(!origin.span.is_dummy());
let mut s = String::new();
let mut printer =
ty::print::FmtPrinter::new(self.tcx, &mut s, Namespace::ValueNS);
if let Some(highlight) = highlight {
printer.region_highlight_mode = highlight;
}
let _ = ct.print(printer);
InferenceDiagnosticsData {
name: s,
span: Some(origin.span),
description: "the constant".into(),
parent_name: None,
parent_description: None,
}
} else {
bug!("unexpect const: {:?}", ct);
}
}
GenericArgKind::Lifetime(_) => bug!("unexpected lifetime"),
}
let _ = ty.print(printer);
(s, None, ty.prefix_string(), None, None)
}
// FIXME(eddyb) generalize all of this to handle `ty::Const` inference variables as well.
pub fn need_type_info_err(
pub fn emit_inference_failure_err(
&self,
body_id: Option<hir::BodyId>,
span: Span,
ty: Ty<'tcx>,
arg: GenericArg<'tcx>,
error_code: TypeAnnotationNeeded,
) -> DiagnosticBuilder<'tcx> {
let ty = self.resolve_vars_if_possible(&ty);
let (name, name_sp, descr, parent_name, parent_descr) = self.extract_type_name(&ty, None);
let arg = self.resolve_vars_if_possible(&arg);
let arg_data = self.extract_inference_diagnostics_data(arg, None);
let kind_str = match arg.unpack() {
GenericArgKind::Type(_) => "type",
GenericArgKind::Const(_) => "the value",
GenericArgKind::Lifetime(_) => bug!("unexpected lifetime"),
};
let mut local_visitor = FindHirNodeVisitor::new(&self, ty.into(), span);
let mut local_visitor = FindHirNodeVisitor::new(&self, arg, span);
let ty_to_string = |ty: Ty<'tcx>| -> String {
let mut s = String::new();
let mut printer = ty::print::FmtPrinter::new(self.tcx, &mut s, Namespace::TypeNS);
@ -305,7 +394,7 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
}
let err_span = if let Some(pattern) = local_visitor.found_arg_pattern {
pattern.span
} else if let Some(span) = name_sp {
} else if let Some(span) = arg_data.span {
// `span` here lets us point at `sum` instead of the entire right hand side expr:
// error[E0282]: type annotations needed
// --> file2.rs:3:15
@ -352,7 +441,7 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
_ => String::new(),
};
// When `name` corresponds to a type argument, show the path of the full type we're
// When `arg_data.name` corresponds to a type argument, show the path of the full type we're
// trying to infer. In the following example, `ty_msg` contains
// " in `std::result::Result<i32, E>`":
// ```
@ -391,11 +480,11 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
&mut err,
&decl.output,
self.tcx.hir().body(body_id),
&descr,
&name,
&arg_data.description,
&arg_data.name,
&ret,
parent_name,
parent_descr,
arg_data.parent_name,
arg_data.parent_description,
);
// We don't want to give the other suggestions when the problem is the
// closure return type.
@ -409,15 +498,15 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
// nudge them in the right direction.
format!("a boxed closure type like `Box<dyn Fn({}) -> {}>`", args, ret)
}
Some(ty) if is_named_and_not_impl_trait(ty) && name == "_" => {
Some(ty) if is_named_and_not_impl_trait(ty) && arg_data.name == "_" => {
let ty = ty_to_string(ty);
format!("the explicit type `{}`, with the type parameters specified", ty)
}
Some(ty) if is_named_and_not_impl_trait(ty) && ty.to_string() != name => {
Some(ty) if is_named_and_not_impl_trait(ty) && ty.to_string() != arg_data.name => {
let ty = ty_to_string(ty);
format!(
"the explicit type `{}`, where the type parameter `{}` is specified",
ty, name,
ty, arg_data.name,
)
}
_ => "a type".to_string(),
@ -534,7 +623,7 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
// | ^^^ cannot infer type for `S`
// |
// = note: type must be known at this point
let span = name_sp.unwrap_or(err_span);
let span = arg_data.span.unwrap_or(err_span);
if !err
.span
.span_labels()
@ -545,55 +634,19 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
// Avoid multiple labels pointing at `span`.
err.span_label(
span,
InferCtxt::missing_type_msg(&name, &descr, parent_name, parent_descr),
InferCtxt::cannot_infer_msg(
kind_str,
&arg_data.name,
&arg_data.description,
arg_data.parent_name,
arg_data.parent_description,
),
);
}
err
}
// FIXME(const_generics): We should either try and merge this with `need_type_info_err`
// or improve the errors created here.
//
// Unlike for type inference variables, we don't yet store the origin of const inference variables.
// This is needed for to get a more relevant error span.
pub fn need_type_info_err_const(
&self,
body_id: Option<hir::BodyId>,
span: Span,
ct: &'tcx ty::Const<'tcx>,
error_code: TypeAnnotationNeeded,
) -> DiagnosticBuilder<'tcx> {
let mut local_visitor = FindHirNodeVisitor::new(&self, ct.into(), span);
if let Some(body_id) = body_id {
let expr = self.tcx.hir().expect_expr(body_id.hir_id);
local_visitor.visit_expr(expr);
}
let mut param_name = None;
let span = if let ty::ConstKind::Infer(InferConst::Var(vid)) = ct.val {
let origin = self.inner.borrow_mut().const_unification_table().probe_value(vid).origin;
if let ConstVariableOriginKind::ConstParameterDefinition(param) = origin.kind {
param_name = Some(param);
}
origin.span
} else {
local_visitor.target_span
};
let error_code = error_code.into();
let mut err =
self.tcx.sess.struct_span_err_with_code(span, "type annotations needed", error_code);
if let Some(param_name) = param_name {
err.note(&format!("cannot infer the value of the const parameter `{}`", param_name));
} else {
err.note("unable to infer the value of a const parameter");
}
err
}
/// If the `FnSig` for the method call can be found and type arguments are identified as
/// needed, suggest annotating the call, otherwise point out the resulting type of the call.
fn annotate_method_call(
@ -647,7 +700,7 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
ty: Ty<'tcx>,
) -> DiagnosticBuilder<'tcx> {
let ty = self.resolve_vars_if_possible(&ty);
let (name, _, descr, parent_name, parent_descr) = self.extract_type_name(&ty, None);
let data = self.extract_inference_diagnostics_data(ty.into(), None);
let mut err = struct_span_err!(
self.tcx.sess,
@ -656,18 +709,28 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
"type inside {} must be known in this context",
kind,
);
err.span_label(span, InferCtxt::missing_type_msg(&name, &descr, parent_name, parent_descr));
err.span_label(
span,
InferCtxt::cannot_infer_msg(
"type",
&data.name,
&data.description,
data.parent_name,
data.parent_description,
),
);
err
}
fn missing_type_msg(
fn cannot_infer_msg(
kind_str: &str,
type_name: &str,
descr: &str,
parent_name: Option<String>,
parent_descr: Option<&str>,
) -> Cow<'static, str> {
) -> String {
if type_name == "_" {
"cannot infer type".into()
format!("cannot infer {}", kind_str)
} else {
let parent_desc = if let Some(parent_name) = parent_name {
let parent_type_descr = if let Some(parent_descr) = parent_descr {
@ -681,7 +744,15 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
"".to_string()
};
format!("cannot infer type for {} `{}`{}", descr, type_name, parent_desc).into()
// FIXME: We really shouldn't be dealing with strings here
// but instead use a sensible enum for cases like this.
let preposition = if "the value" == kind_str { "of" } else { "for" };
// For example: "cannot infer type for type parameter `T`"
format!(
"cannot infer {} {} {} `{}`{}",
kind_str, preposition, descr, type_name, parent_desc
)
.into()
}
}
}

5
compiler/rustc_infer/src/infer/mod.rs
View file

@ -1163,7 +1163,10 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
}
GenericParamDefKind::Const { .. } => {
let origin = ConstVariableOrigin {
kind: ConstVariableOriginKind::ConstParameterDefinition(param.name),
kind: ConstVariableOriginKind::ConstParameterDefinition(
param.name,
param.def_id,
),
span,
};
let const_var_id =