bjoernager/rust
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Point at return type when it influences non-first match arm

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When encountering code like

```rust
fn foo() -> i32 {
    match 0 {
        1 => return 0,
        2 => "",
        _ => 1,
    }
}
```

Point at the return type and not at the prior arm, as that arm has type
`!` which isn't influencing the arm corresponding to arm `2`.

Fix #78124.
This commit is contained in:
Esteban Küber 2023-08-14 18:36:03 +00:00
parent 4cea2bc339
commit 55f8c66a60
12 changed files with 129 additions and 21 deletions
Download patch file Download diff file Expand all files Collapse all files

80
compiler/rustc_infer/src/infer/error_reporting/mod.rs
View file

@ -743,6 +743,36 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
ObligationCauseCode::Pattern { origin_expr: false, span: Some(span), .. } => {
err.span_label(span, "expected due to this");
}
ObligationCauseCode::BlockTailExpression(
_,
scrut_hir_id,
hir::MatchSource::TryDesugar,
) => {
if let Some(ty::error::ExpectedFound { expected, .. }) = exp_found {
let scrut_expr = self.tcx.hir().expect_expr(scrut_hir_id);
let scrut_ty = if let hir::ExprKind::Call(_, args) = &scrut_expr.kind {
let arg_expr = args.first().expect("try desugaring call w/out arg");
self.typeck_results.as_ref().and_then(|typeck_results| {
typeck_results.expr_ty_opt(arg_expr)
})
} else {
bug!("try desugaring w/out call expr as scrutinee");
};
match scrut_ty {
Some(ty) if expected == ty => {
let source_map = self.tcx.sess.source_map();
err.span_suggestion(
source_map.end_point(cause.span()),
"try removing this `?`",
"",
Applicability::MachineApplicable,
);
}
_ => {}
}
}
},
ObligationCauseCode::MatchExpressionArm(box MatchExpressionArmCause {
arm_block_id,
arm_span,
@ -1973,7 +2003,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
trace: &TypeTrace<'tcx>,
terr: TypeError<'tcx>,
) -> Vec<TypeErrorAdditionalDiags> {
use crate::traits::ObligationCauseCode::MatchExpressionArm;
use crate::traits::ObligationCauseCode::{BlockTailExpression, MatchExpressionArm};
let mut suggestions = Vec::new();
let span = trace.cause.span();
let values = self.resolve_vars_if_possible(trace.values);
@ -1991,11 +2021,17 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
// specify a byte literal
(ty::Uint(ty::UintTy::U8), ty::Char) => {
if let Ok(code) = self.tcx.sess().source_map().span_to_snippet(span)
&& let Some(code) = code.strip_prefix('\'').and_then(|s| s.strip_suffix('\''))
&& !code.starts_with("\\u") // forbid all Unicode escapes
&& code.chars().next().is_some_and(|c| c.is_ascii()) // forbids literal Unicode characters beyond ASCII
&& let Some(code) =
code.strip_prefix('\'').and_then(|s| s.strip_suffix('\''))
// forbid all Unicode escapes
&& !code.starts_with("\\u")
// forbids literal Unicode characters beyond ASCII
&& code.chars().next().is_some_and(|c| c.is_ascii())
{
suggestions.push(TypeErrorAdditionalDiags::MeantByteLiteral { span, code: escape_literal(code) })
suggestions.push(TypeErrorAdditionalDiags::MeantByteLiteral {
span,
code: escape_literal(code),
})
}
}
// If a character was expected and the found expression is a string literal
@ -2006,7 +2042,10 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
&& let Some(code) = code.strip_prefix('"').and_then(|s| s.strip_suffix('"'))
&& code.chars().count() == 1
{
suggestions.push(TypeErrorAdditionalDiags::MeantCharLiteral { span, code: escape_literal(code) })
suggestions.push(TypeErrorAdditionalDiags::MeantCharLiteral {
span,
code: escape_literal(code),
})
}
}
// If a string was expected and the found expression is a character literal,
@ -2016,7 +2055,10 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
if let Some(code) =
code.strip_prefix('\'').and_then(|s| s.strip_suffix('\''))
{
suggestions.push(TypeErrorAdditionalDiags::MeantStrLiteral { span, code: escape_literal(code) })
suggestions.push(TypeErrorAdditionalDiags::MeantStrLiteral {
span,
code: escape_literal(code),
})
}
}
}
@ -2025,17 +2067,24 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
(ty::Bool, ty::Tuple(list)) => if list.len() == 0 {
suggestions.extend(self.suggest_let_for_letchains(&trace.cause, span));
}
(ty::Array(_, _), ty::Array(_, _)) => suggestions.extend(self.suggest_specify_actual_length(terr, trace, span)),
(ty::Array(_, _), ty::Array(_, _)) => {
suggestions.extend(self.suggest_specify_actual_length(terr, trace, span))
}
_ => {}
}
}
let code = trace.cause.code();
if let &MatchExpressionArm(box MatchExpressionArmCause { source, .. }) = code
&& let hir::MatchSource::TryDesugar = source
&& let Some((expected_ty, found_ty, _, _)) = self.values_str(trace.values)
{
suggestions.push(TypeErrorAdditionalDiags::TryCannotConvert { found: found_ty.content(), expected: expected_ty.content() });
}
if let &(MatchExpressionArm(box MatchExpressionArmCause { source, .. })
| BlockTailExpression(.., source)
) = code
&& let hir::MatchSource::TryDesugar = source
&& let Some((expected_ty, found_ty, _, _)) = self.values_str(trace.values)
{
suggestions.push(TypeErrorAdditionalDiags::TryCannotConvert {
found: found_ty.content(),
expected: expected_ty.content(),
});
}
suggestions
}
@ -2905,6 +2954,9 @@ impl<'tcx> ObligationCauseExt<'tcx> for ObligationCause<'tcx> {
CompareImplItemObligation { kind: ty::AssocKind::Const, .. } => {
ObligationCauseFailureCode::ConstCompat { span, subdiags }
}
BlockTailExpression(.., hir::MatchSource::TryDesugar) => {
ObligationCauseFailureCode::TryCompat { span, subdiags }
}
MatchExpressionArm(box MatchExpressionArmCause { source, .. }) => match source {
hir::MatchSource::TryDesugar => {
ObligationCauseFailureCode::TryCompat { span, subdiags }

2
compiler/rustc_infer/src/infer/error_reporting/nice_region_error/static_impl_trait.rs
View file

@ -146,7 +146,7 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
if let SubregionOrigin::Subtype(box TypeTrace { cause, .. }) = sub_origin {
if let ObligationCauseCode::ReturnValue(hir_id)
| ObligationCauseCode::BlockTailExpression(hir_id) = cause.code()
| ObligationCauseCode::BlockTailExpression(hir_id, ..) = cause.code()
{
let parent_id = tcx.hir().get_parent_item(*hir_id);
if let Some(fn_decl) = tcx.hir().fn_decl_by_hir_id(parent_id.into()) {