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use Span::find_ancestor_inside to get right span in CastCheck #95920

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merged 1 commit into from
Apr 12, 2022
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use Span::find_ancestor_inside to get right span in CastCheck #95920

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37 changes: 19 additions & 18 deletions compiler/rustc_typeck/src/check/cast.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -55,6 +55,7 @@ use rustc_trait_selection::traits::error_reporting::report_object_safety_error;
pub struct CastCheck<'tcx> {
expr: &'tcx hir::Expr<'tcx>,
expr_ty: Ty<'tcx>,
expr_span: Span,
cast_ty: Ty<'tcx>,
cast_span: Span,
span: Span,
Expand Down Expand Up @@ -207,7 +208,8 @@ impl<'a, 'tcx> CastCheck<'tcx> {
cast_span: Span,
span: Span,
) -> Result<CastCheck<'tcx>, ErrorGuaranteed> {
let check = CastCheck { expr, expr_ty, cast_ty, cast_span, span };
let expr_span = expr.span.find_ancestor_inside(span).unwrap_or(expr.span);
let check = CastCheck { expr, expr_ty, expr_span, cast_ty, cast_span, span };

// For better error messages, check for some obviously unsized
// cases now. We do a more thorough check at the end, once
Expand Down Expand Up @@ -240,15 +242,15 @@ impl<'a, 'tcx> CastCheck<'tcx> {
error_span,
format!("cannot cast `{}` as `{}`", fcx.ty_to_string(self.expr_ty), cast_ty),
);
if let Ok(snippet) = fcx.sess().source_map().span_to_snippet(self.expr.span) {
if let Ok(snippet) = fcx.sess().source_map().span_to_snippet(self.expr_span) {
err.span_suggestion(
self.expr.span,
self.expr_span,
"dereference the expression",
format!("*{}", snippet),
Applicability::MaybeIncorrect,
);
} else {
err.span_help(self.expr.span, "dereference the expression with `*`");
err.span_help(self.expr_span, "dereference the expression with `*`");
}
err.emit();
}
Expand Down Expand Up @@ -315,7 +317,7 @@ impl<'a, 'tcx> CastCheck<'tcx> {
struct_span_err!(fcx.tcx.sess, self.span, E0054, "cannot cast as `bool`");

if self.expr_ty.is_numeric() {
match fcx.tcx.sess.source_map().span_to_snippet(self.expr.span) {
match fcx.tcx.sess.source_map().span_to_snippet(self.expr_span) {
Ok(snippet) => {
err.span_suggestion(
self.span,
Expand Down Expand Up @@ -440,7 +442,7 @@ impl<'a, 'tcx> CastCheck<'tcx> {
}
if sugg_mutref {
err.span_label(self.span, "invalid cast");
err.span_note(self.expr.span, "this reference is immutable");
err.span_note(self.expr_span, "this reference is immutable");
err.span_note(self.cast_span, "trying to cast to a mutable reference type");
} else if let Some((sugg, remove_cast)) = sugg {
err.span_label(self.span, "invalid cast");
Expand All @@ -449,7 +451,7 @@ impl<'a, 'tcx> CastCheck<'tcx> {
.tcx
.sess
.source_map()
.span_to_snippet(self.expr.span)
.span_to_snippet(self.expr_span)
.map_or(false, |snip| snip.starts_with('('));

// Very crude check to see whether the expression must be wrapped
Expand All @@ -458,14 +460,14 @@ impl<'a, 'tcx> CastCheck<'tcx> {
let needs_parens =
!has_parens && matches!(self.expr.kind, hir::ExprKind::Cast(..));

let mut suggestion = vec![(self.expr.span.shrink_to_lo(), sugg)];
let mut suggestion = vec![(self.expr_span.shrink_to_lo(), sugg)];
if needs_parens {
suggestion[0].1 += "(";
suggestion.push((self.expr.span.shrink_to_hi(), ")".to_string()));
suggestion.push((self.expr_span.shrink_to_hi(), ")".to_string()));
}
if remove_cast {
suggestion.push((
self.expr.span.shrink_to_hi().to(self.cast_span),
self.expr_span.shrink_to_hi().to(self.cast_span),
String::new(),
));
}
Expand All @@ -481,7 +483,7 @@ impl<'a, 'tcx> CastCheck<'tcx> {
) {
let mut label = true;
// Check `impl From<self.expr_ty> for self.cast_ty {}` for accurate suggestion:
if let Ok(snippet) = fcx.tcx.sess.source_map().span_to_snippet(self.expr.span) {
if let Ok(snippet) = fcx.tcx.sess.source_map().span_to_snippet(self.expr_span) {
if let Some(from_trait) = fcx.tcx.get_diagnostic_item(sym::From) {
let ty = fcx.resolve_vars_if_possible(self.cast_ty);
// Erase regions to avoid panic in `prove_value` when calling
Expand Down Expand Up @@ -550,7 +552,7 @@ impl<'a, 'tcx> CastCheck<'tcx> {

if fcx.tcx.sess.is_nightly_build() {
err.span_label(
self.expr.span,
self.expr_span,
"consider casting this expression to `*const ()`, \
then using `core::ptr::from_raw_parts`",
);
Expand Down Expand Up @@ -651,7 +653,7 @@ impl<'a, 'tcx> CastCheck<'tcx> {
}
}
_ => {
err.span_help(self.expr.span, "consider using a box or reference as appropriate");
err.span_help(self.expr_span, "consider using a box or reference as appropriate");
}
}
err.emit()
Expand Down Expand Up @@ -685,7 +687,7 @@ impl<'a, 'tcx> CastCheck<'tcx> {

#[instrument(skip(fcx), level = "debug")]
pub fn check(mut self, fcx: &FnCtxt<'a, 'tcx>) {
self.expr_ty = fcx.structurally_resolved_type(self.expr.span, self.expr_ty);
self.expr_ty = fcx.structurally_resolved_type(self.expr_span, self.expr_ty);
self.cast_ty = fcx.structurally_resolved_type(self.cast_span, self.cast_ty);

debug!("check_cast({}, {:?} as {:?})", self.expr.hir_id, self.expr_ty, self.cast_ty);
Expand Down Expand Up @@ -741,7 +743,7 @@ impl<'a, 'tcx> CastCheck<'tcx> {
ty::FnDef(..) => {
// Attempt a coercion to a fn pointer type.
let f = fcx.normalize_associated_types_in(
self.expr.span,
self.expr_span,
self.expr_ty.fn_sig(fcx.tcx),
);
let res = fcx.try_coerce(
Expand Down Expand Up @@ -997,7 +999,7 @@ impl<'a, 'tcx> CastCheck<'tcx> {
));

let msg = "use `.addr()` to obtain the address of a pointer";
if let Ok(snippet) = fcx.tcx.sess.source_map().span_to_snippet(self.expr.span) {
if let Ok(snippet) = fcx.tcx.sess.source_map().span_to_snippet(self.expr_span) {
let scalar_cast = match t_c {
ty::cast::IntTy::U(ty::UintTy::Usize) => String::new(),
_ => format!(" as {}", self.cast_ty),
Expand Down Expand Up @@ -1027,13 +1029,12 @@ impl<'a, 'tcx> CastCheck<'tcx> {
self.expr.hir_id,
self.span,
|err| {

let mut err = err.build(&format!(
"strict provenance disallows casting integer `{}` to pointer `{}`",
self.expr_ty, self.cast_ty
));
let msg = "use `.with_addr()` to adjust a valid pointer in the same allocation, to this address";
if let Ok(snippet) = fcx.tcx.sess.source_map().span_to_snippet(self.expr.span) {
if let Ok(snippet) = fcx.tcx.sess.source_map().span_to_snippet(self.expr_span) {
err.span_suggestion(
self.span,
msg,
Expand Down
12 changes: 12 additions & 0 deletions src/test/ui/cast/cast-macro-lhs.rs
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Original file line number Diff line number Diff line change
@@ -0,0 +1,12 @@
// Test to make sure we suggest "consider casting" on the right span

macro_rules! foo {
() => { 0 }
}

fn main() {
let x = foo!() as *const [u8];
//~^ ERROR cannot cast `usize` to a pointer that is wide
//~| NOTE creating a `*const [u8]` requires both an address and a length
//~| NOTE consider casting this expression to `*const ()`, then using `core::ptr::from_raw_parts`
}
11 changes: 11 additions & 0 deletions src/test/ui/cast/cast-macro-lhs.stderr
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Original file line number Diff line number Diff line change
@@ -0,0 +1,11 @@
error[E0606]: cannot cast `usize` to a pointer that is wide
--> $DIR/cast-macro-lhs.rs:8:23
|
LL | let x = foo!() as *const [u8];
| ------ ^^^^^^^^^^^ creating a `*const [u8]` requires both an address and a length
| |
| consider casting this expression to `*const ()`, then using `core::ptr::from_raw_parts`

error: aborting due to previous error

For more information about this error, try `rustc --explain E0606`.