bjoernager/rust
bjoernager/rust
1
Fork 0
Code Issues Pull requests Activity

Rollup merge of #113925 - clubby789:const-ctor-repeat, r=estebank

Browse source 
Improve diagnostic for const ctors in array repeat expressions

Fixes #113912
This commit is contained in:
Matthias Krüger 2023-11-08 00:47:50 +01:00 • committed by GitHub
commit b724d9c90e
No known key found for this signature in database
GPG key ID: 4AEE18F83AFDEB23
7 changed files with 126 additions and 28 deletions
Download patch file Download diff file Expand all files Collapse all files

29
compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs
View file

@ -28,6 +28,7 @@ use rustc_infer::infer::error_reporting::TypeErrCtxt;
use rustc_infer::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind};
use rustc_infer::infer::{DefineOpaqueTypes, InferOk, LateBoundRegionConversionTime};
use rustc_middle::hir::map;
use rustc_middle::traits::IsConstable;
use rustc_middle::ty::error::TypeError::{self, Sorts};
use rustc_middle::ty::{
self, suggest_arbitrary_trait_bound, suggest_constraining_type_param, AdtKind, GenericArgs,
@ -2768,20 +2769,30 @@ impl<'tcx> TypeErrCtxtExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
));
}
}
ObligationCauseCode::RepeatElementCopy { is_const_fn } => {
ObligationCauseCode::RepeatElementCopy { is_constable, elt_type, elt_span, elt_stmt_span } => {
err.note(
"the `Copy` trait is required because this value will be copied for each element of the array",
);
if is_const_fn {
err.help(
"consider creating a new `const` item and initializing it with the result \
of the function call to be used in the repeat position, like \
`const VAL: Type = const_fn();` and `let x = [VAL; 42];`",
);
let value_kind = match is_constable {
IsConstable::Fn => Some("the result of the function call"),
IsConstable::Ctor => Some("the result of the constructor"),
_ => None
};
let sm = tcx.sess.source_map();
if let Some(value_kind) = value_kind &&
let Ok(snip) = sm.span_to_snippet(elt_span)
{
let help_msg = format!(
"consider creating a new `const` item and initializing it with {value_kind} \
to be used in the repeat position");
let indentation = sm.indentation_before(elt_stmt_span).unwrap_or_default();
err.multipart_suggestion(help_msg, vec![
(elt_stmt_span.shrink_to_lo(), format!("const ARRAY_REPEAT_VALUE: {elt_type} = {snip};\n{indentation}")),
(elt_span, "ARRAY_REPEAT_VALUE".to_string())
], Applicability::MachineApplicable);
}
if self.tcx.sess.is_nightly_build() && is_const_fn {
if self.tcx.sess.is_nightly_build() && matches!(is_constable, IsConstable::Fn|IsConstable::Ctor) {
err.help(
"create an inline `const` block, see RFC #2920 \
<https://github.com/rust-lang/rfcs/pull/2920> for more information",