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never consider unsafe blocks unused if they would be required with unsafe_op_in_unsafe_fn

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This commit is contained in:
Ralf Jung 2022-08-02 15:47:14 -04:00
parent 4493a0f472
commit ee3fc9dff8
10 changed files with 124 additions and 631 deletions
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2
compiler/rustc_errors/src/diagnostic_builder.rs
View file

@ -566,7 +566,7 @@ impl Drop for DiagnosticBuilderInner<'_> {
),
));
handler.emit_diagnostic(&mut self.diagnostic);
panic!();
panic!("error was constructed but not emitted");
}
}
// `.emit()` was previously called, or maybe we're during `.cancel()`.

8
compiler/rustc_mir_build/src/check_unsafety.rs
View file

@ -75,10 +75,10 @@ impl<'tcx> UnsafetyVisitor<'_, 'tcx> {
match self.safety_context {
SafetyContext::BuiltinUnsafeBlock => {}
SafetyContext::UnsafeBlock { ref mut used, .. } => {
if !self.body_unsafety.is_unsafe() || !unsafe_op_in_unsafe_fn_allowed {
// Mark this block as useful
*used = true;
}
// Mark this block as useful (even inside `unsafe fn`, where it is technically
// redundant -- but we want to eventually enable `unsafe_op_in_unsafe_fn` by
// default which will require those blocks).
*used = true;
}
SafetyContext::UnsafeFn if unsafe_op_in_unsafe_fn_allowed => {}
SafetyContext::UnsafeFn => {

37
compiler/rustc_mir_transform/src/check_unsafety.rs
View file

@ -5,9 +5,9 @@ use rustc_hir::def_id::{DefId, LocalDefId};
use rustc_hir::hir_id::HirId;
use rustc_hir::intravisit;
use rustc_middle::mir::visit::{MutatingUseContext, PlaceContext, Visitor};
use rustc_middle::mir::*;
use rustc_middle::ty::query::Providers;
use rustc_middle::ty::{self, TyCtxt};
use rustc_middle::{lint, mir::*};
use rustc_session::lint::builtin::{UNSAFE_OP_IN_UNSAFE_FN, UNUSED_UNSAFE};
use rustc_session::lint::Level;
@ -259,7 +259,7 @@ impl<'tcx> UnsafetyChecker<'_, 'tcx> {
violations: impl IntoIterator<Item = &'a UnsafetyViolation>,
new_used_unsafe_blocks: impl IntoIterator<Item = (HirId, UsedUnsafeBlockData)>,
) {
use UsedUnsafeBlockData::{AllAllowedInUnsafeFn, SomeDisallowedInUnsafeFn};
use UsedUnsafeBlockData::*;
let update_entry = |this: &mut Self, hir_id, new_usage| {
match this.used_unsafe_blocks.entry(hir_id) {
@ -299,15 +299,11 @@ impl<'tcx> UnsafetyChecker<'_, 'tcx> {
}
}),
Safety::BuiltinUnsafe => {}
Safety::ExplicitUnsafe(hir_id) => violations.into_iter().for_each(|violation| {
Safety::ExplicitUnsafe(hir_id) => violations.into_iter().for_each(|_violation| {
update_entry(
self,
hir_id,
match self.tcx.lint_level_at_node(UNSAFE_OP_IN_UNSAFE_FN, violation.lint_root).0
{
Level::Allow => AllAllowedInUnsafeFn(violation.lint_root),
_ => SomeDisallowedInUnsafeFn,
},
SomeDisallowedInUnsafeFn,
)
}),
};
@ -522,6 +518,11 @@ fn unsafety_check_result<'tcx>(
}
fn report_unused_unsafe(tcx: TyCtxt<'_>, kind: UnusedUnsafe, id: HirId) {
if matches!(kind, UnusedUnsafe::InUnsafeFn(..)) {
// We do *not* warn here, these unsafe blocks are actually required when
// `unsafe_op_in_unsafe_fn` is warn or higher.
return;
}
let span = tcx.sess.source_map().guess_head_span(tcx.hir().span(id));
tcx.struct_span_lint_hir(UNUSED_UNSAFE, id, span, |lint| {
let msg = "unnecessary `unsafe` block";
@ -535,25 +536,7 @@ fn report_unused_unsafe(tcx: TyCtxt<'_>, kind: UnusedUnsafe, id: HirId) {
"because it's nested under this `unsafe` block",
);
}
UnusedUnsafe::InUnsafeFn(id, usage_lint_root) => {
db.span_label(
tcx.sess.source_map().guess_head_span(tcx.hir().span(id)),
"because it's nested under this `unsafe` fn",
)
.note(
"this `unsafe` block does contain unsafe operations, \
but those are already allowed in an `unsafe fn`",
);
let (level, source) =
tcx.lint_level_at_node(UNSAFE_OP_IN_UNSAFE_FN, usage_lint_root);
assert_eq!(level, Level::Allow);
lint::explain_lint_level_source(
UNSAFE_OP_IN_UNSAFE_FN,
Level::Allow,
source,
&mut db,
);
}
UnusedUnsafe::InUnsafeFn(_id, _usage_lint_root) => unreachable!(),
}
db.emit();