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Disallow arm bodies on never patterns

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This commit is contained in:
Nadrieril
2023-11-27 04:08:09 +01:00
parent 06a8ed10b6
commit 70deb9a57f
8 changed files with 75 additions and 26 deletions
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21
compiler/rustc_ast_lowering/src/expr.rs
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@@ -2,7 +2,8 @@ use super::errors::{
AsyncCoroutinesNotSupported, AsyncNonMoveClosureNotSupported, AwaitOnlyInAsyncFnAndBlocks,
BaseExpressionDoubleDot, ClosureCannotBeStatic, CoroutineTooManyParameters,
FunctionalRecordUpdateDestructuringAssignment, InclusiveRangeWithNoEnd, MatchArmWithNoBody,
NeverPatternWithGuard, NotSupportedForLifetimeBinderAsyncClosure, UnderscoreExprLhsAssign,
NeverPatternWithBody, NeverPatternWithGuard, NotSupportedForLifetimeBinderAsyncClosure,
UnderscoreExprLhsAssign,
};
use super::ResolverAstLoweringExt;
use super::{ImplTraitContext, LoweringContext, ParamMode, ParenthesizedGenericArgs};
@@ -567,20 +568,24 @@ impl<'hir> LoweringContext<'_, 'hir> {
let hir_id = self.next_id();
let span = self.lower_span(arm.span);
self.lower_attrs(hir_id, &arm.attrs);
let body = if let Some(body) = &arm.body {
// FIXME(never_patterns): Disallow never pattern with a body or guard
let is_never_pattern = pat.is_never_pattern();
let body = if let Some(body) = &arm.body
&& !is_never_pattern
{
self.lower_expr(body)
} else {
if !pat.is_never_pattern() {
self.tcx
.sess
.emit_err(MatchArmWithNoBody { span, suggestion: span.shrink_to_hi() });
// Either `body.is_none()` or `is_never_pattern` here.
if !is_never_pattern {
let suggestion = span.shrink_to_hi();
self.tcx.sess.emit_err(MatchArmWithNoBody { span, suggestion });
} else if let Some(body) = &arm.body {
self.tcx.sess.emit_err(NeverPatternWithBody { span: body.span });
guard = None;
} else if let Some(g) = &arm.guard {
self.tcx.sess.emit_err(NeverPatternWithGuard { span: g.span });
guard = None;
}
// An arm without a body, meant for never patterns.
// We add a fake `loop {}` arm body so that it typecks to `!`.
// FIXME(never_patterns): Desugar into a call to `unreachable_unchecked`.
let block = self.arena.alloc(hir::Block {