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Fix range overflow checking

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This commit is contained in:
Nadrieril 2023-10-11 04:54:21 +02:00
parent 1e1174b034
commit 1baf8bf54d
9 changed files with 96 additions and 64 deletions
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2
compiler/rustc_mir_build/messages.ftl
View File

@ -173,7 +173,7 @@ mir_build_leading_irrefutable_let_patterns = leading irrefutable {$count ->
mir_build_literal_in_range_out_of_bounds =
literal out of range for `{$ty}`
.label = this value doesn't fit in `{$ty}` whose maximum value is `{$max}`
.label = this value does not fit into the type `{$ty}` whose range is `{$min}..={$max}`
mir_build_lower_range_bound_must_be_less_than_or_equal_to_upper =
lower range bound must be less than or equal to upper

1
compiler/rustc_mir_build/src/errors.rs
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@ -551,6 +551,7 @@ pub struct LiteralOutOfRange<'tcx> {
#[label]
pub span: Span,
pub ty: Ty<'tcx>,
pub min: i128,
pub max: u128,
}

94
compiler/rustc_mir_build/src/thir/pattern/mod.rs
View File

@ -20,15 +20,15 @@ use rustc_index::Idx;
use rustc_middle::mir::interpret::{
ErrorHandled, GlobalId, LitToConstError, LitToConstInput, Scalar,
};
use rustc_middle::mir::{self, Const, UserTypeProjection};
use rustc_middle::mir::{BorrowKind, Mutability};
use rustc_middle::mir::{self, BorrowKind, Const, Mutability, UserTypeProjection};
use rustc_middle::thir::{Ascription, BindingMode, FieldPat, LocalVarId, Pat, PatKind, PatRange};
use rustc_middle::ty::CanonicalUserTypeAnnotation;
use rustc_middle::ty::TypeVisitableExt;
use rustc_middle::ty::{self, AdtDef, Region, Ty, TyCtxt, UserType};
use rustc_middle::ty::{GenericArg, GenericArgsRef};
use rustc_middle::ty::layout::IntegerExt;
use rustc_middle::ty::{
self, AdtDef, CanonicalUserTypeAnnotation, GenericArg, GenericArgsRef, Region, Ty, TyCtxt,
TypeVisitableExt, UserType,
};
use rustc_span::{ErrorGuaranteed, Span, Symbol};
use rustc_target::abi::FieldIdx;
use rustc_target::abi::{FieldIdx, Integer};
use std::cmp::Ordering;
@ -111,6 +111,59 @@ impl<'a, 'tcx> PatCtxt<'a, 'tcx> {
}
}
/// Overflowing literals are linted against in a late pass. This is mostly fine, except when we
/// encounter a range pattern like `-130i8..2`: if we believe `eval_bits`, this looks like a
/// range where the endpoints are in the wrong order. To avoid a confusing error message, we
/// check for overflow then.
/// This is only called when the range is already known to be malformed.
fn error_on_literal_overflow(
&self,
expr: Option<&'tcx hir::Expr<'tcx>>,
ty: Ty<'tcx>,
) -> Result<(), ErrorGuaranteed> {
use hir::{ExprKind, UnOp};
use rustc_ast::ast::LitKind;
let Some(mut expr) = expr else {
return Ok(());
};
let span = expr.span;
// We need to inspect the original expression, because if we only inspect the output of
// `eval_bits`, an overflowed value has already been wrapped around.
// We mostly copy the logic from the `rustc_lint::OVERFLOWING_LITERALS` lint.
let mut negated = false;
if let ExprKind::Unary(UnOp::Neg, sub_expr) = expr.kind {
negated = true;
expr = sub_expr;
}
let ExprKind::Lit(lit) = expr.kind else {
return Ok(());
};
let LitKind::Int(lit_val, _) = lit.node else {
return Ok(());
};
let (min, max): (i128, u128) = match ty.kind() {
ty::Int(ity) => {
let size = Integer::from_int_ty(&self.tcx, *ity).size();
(size.signed_int_min(), size.signed_int_max() as u128)
}
ty::Uint(uty) => {
let size = Integer::from_uint_ty(&self.tcx, *uty).size();
(0, size.unsigned_int_max())
}
_ => {
return Ok(());
}
};
// Detect literal value out of range `[min, max]` inclusive, avoiding use of `-min` to
// prevent overflow/panic.
if (negated && lit_val > max + 1) || (!negated && lit_val > max) {
return Err(self.tcx.sess.emit_err(LiteralOutOfRange { span, ty, min, max }));
}
Ok(())
}
fn lower_pattern_range(
&mut self,
lo_expr: Option<&'tcx hir::Expr<'tcx>>,
@ -155,29 +208,9 @@ impl<'a, 'tcx> PatCtxt<'a, 'tcx> {
}
// `x..y` where `x >= y`, or `x..=y` where `x > y`. The range is empty => error.
_ => {
let max = || {
self.tcx
.layout_of(self.param_env.with_reveal_all_normalized(self.tcx).and(ty))
.ok()
.unwrap()
.size
.unsigned_int_max()
};
// Emit a different message if there was overflow.
if let Some(hir::Expr { kind: hir::ExprKind::Lit(lit), .. }) = lo_expr
&& let rustc_ast::ast::LitKind::Int(val, _) = lit.node
{
if lo.eval_bits(self.tcx, self.param_env) != val {
return Err(self.tcx.sess.emit_err(LiteralOutOfRange { span: lit.span, ty, max: max() }));
}
}
if let Some(hir::Expr { kind: hir::ExprKind::Lit(lit), .. }) = hi_expr
&& let rustc_ast::ast::LitKind::Int(val, _) = lit.node
{
if hi.eval_bits(self.tcx, self.param_env) != val {
return Err(self.tcx.sess.emit_err(LiteralOutOfRange { span: lit.span, ty, max: max() }));
}
}
// Emit a more appropriate message if there was overflow.
self.error_on_literal_overflow(lo_expr, ty)?;
self.error_on_literal_overflow(hi_expr, ty)?;
let e = match end {
RangeEnd::Included => {
self.tcx.sess.emit_err(LowerRangeBoundMustBeLessThanOrEqualToUpper {
@ -219,7 +252,6 @@ impl<'a, 'tcx> PatCtxt<'a, 'tcx> {
hir::PatKind::Range(ref lo_expr, ref hi_expr, end) => {
let (lo_expr, hi_expr) = (lo_expr.as_deref(), hi_expr.as_deref());
let span = lo_expr.map_or(span, |e| e.span);
// FIXME?: returning `_` can cause inaccurate "unreachable" warnings. This can be
// fixed by returning `PatKind::Const(ConstKind::Error(...))` if #115937 gets
// merged.

2
tests/ui/error-codes/E0030-teach.stderr
View File

@ -2,7 +2,7 @@ error[E0030]: lower range bound must be less than or equal to upper
--> $DIR/E0030-teach.rs:5:9
|
LL | 1000 ..= 5 => {}
| ^^^^ lower bound larger than upper bound
| ^^^^^^^^^^ lower bound larger than upper bound
|
= note: When matching against a range, the compiler verifies that the range is non-empty. Range patterns include both end-points, so this is equivalent to requiring the start of the range to be less than or equal to the end of the range.

2
tests/ui/error-codes/E0030.stderr
View File

@ -2,7 +2,7 @@ error[E0030]: lower range bound must be less than or equal to upper
--> $DIR/E0030.rs:3:9
|
LL | 1000 ..= 5 => {}
| ^^^^ lower bound larger than upper bound
| ^^^^^^^^^^ lower bound larger than upper bound
error: aborting due to previous error

6
tests/ui/match/match-range-fail-2.stderr
View File

@ -2,19 +2,19 @@ error[E0030]: lower range bound must be less than or equal to upper
--> $DIR/match-range-fail-2.rs:5:9
|
LL | 6 ..= 1 => { }
| ^ lower bound larger than upper bound
| ^^^^^^^ lower bound larger than upper bound
error[E0579]: lower range bound must be less than upper
--> $DIR/match-range-fail-2.rs:11:9
|
LL | 0 .. 0 => { }
| ^
| ^^^^^^
error[E0030]: lower range bound must be less than or equal to upper
--> $DIR/match-range-fail-2.rs:17:9
|
LL | 0xFFFF_FFFF_FFFF_FFFF ..= 1 => { }
| ^^^^^^^^^^^^^^^^^^^^^ lower bound larger than upper bound
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^ lower bound larger than upper bound
error: aborting due to 3 previous errors

9
tests/ui/match/validate-range-endpoints.rs
View File

@ -30,16 +30,15 @@ fn main() {
_ => {}
}
// FIXME: error message is confusing
match 0i8 {
0..129 => {}
//~^ ERROR lower range bound must be less than upper
//~^ ERROR literal out of range
0..=128 => {}
//~^ ERROR lower range bound must be less than or equal to upper
//~^ ERROR literal out of range
-129..0 => {}
//~^ ERROR lower range bound must be less than upper
//~^ ERROR literal out of range
-10000..=-20 => {}
//~^ ERROR lower range bound must be less than or equal to upper
//~^ ERROR literal out of range
// overflow is detected in a later pass for these
128..=0 => {}

40
tests/ui/match/validate-range-endpoints.stderr
View File

@ -2,58 +2,58 @@ error: literal out of range for `u8`
--> $DIR/validate-range-endpoints.rs:9:12
|
LL | 1..257 => {}
| ^^^ this value doesn't fit in `u8` whose maximum value is `255`
| ^^^ this value does not fit into the type `u8` whose range is `0..=255`
error: literal out of range for `u8`
--> $DIR/validate-range-endpoints.rs:11:13
|
LL | 1..=256 => {}
| ^^^ this value doesn't fit in `u8` whose maximum value is `255`
| ^^^ this value does not fit into the type `u8` whose range is `0..=255`
error[E0030]: lower range bound must be less than or equal to upper
--> $DIR/validate-range-endpoints.rs:20:9
|
LL | 1..=TOO_BIG => {}
| ^ lower bound larger than upper bound
| ^^^^^^^^^^^ lower bound larger than upper bound
error[E0030]: lower range bound must be less than or equal to upper
--> $DIR/validate-range-endpoints.rs:22:9
|
LL | 1..=const { 256 } => {}
| ^ lower bound larger than upper bound
| ^^^^^^^^^^^^^^^^^ lower bound larger than upper bound
error: literal out of range for `u64`
--> $DIR/validate-range-endpoints.rs:28:32
|
LL | 10000000000000000000..=99999999999999999999 => {}
| ^^^^^^^^^^^^^^^^^^^^ this value doesn't fit in `u64` whose maximum value is `18446744073709551615`
| ^^^^^^^^^^^^^^^^^^^^ this value does not fit into the type `u64` whose range is `0..=18446744073709551615`
error[E0579]: lower range bound must be less than upper
--> $DIR/validate-range-endpoints.rs:35:9
error: literal out of range for `i8`
--> $DIR/validate-range-endpoints.rs:34:12
|
LL | 0..129 => {}
| ^
| ^^^ this value does not fit into the type `i8` whose range is `-128..=127`
error[E0030]: lower range bound must be less than or equal to upper
--> $DIR/validate-range-endpoints.rs:37:9
error: literal out of range for `i8`
--> $DIR/validate-range-endpoints.rs:36:13
|
LL | 0..=128 => {}
| ^ lower bound larger than upper bound
| ^^^ this value does not fit into the type `i8` whose range is `-128..=127`
error[E0579]: lower range bound must be less than upper
--> $DIR/validate-range-endpoints.rs:39:9
error: literal out of range for `i8`
--> $DIR/validate-range-endpoints.rs:38:9
|
LL | -129..0 => {}
| ^^^^
| ^^^^ this value does not fit into the type `i8` whose range is `-128..=127`
error[E0030]: lower range bound must be less than or equal to upper
--> $DIR/validate-range-endpoints.rs:41:9
error: literal out of range for `i8`
--> $DIR/validate-range-endpoints.rs:40:9
|
LL | -10000..=-20 => {}
| ^^^^^^ lower bound larger than upper bound
| ^^^^^^ this value does not fit into the type `i8` whose range is `-128..=127`
error[E0004]: non-exhaustive patterns: `i8::MIN..=-17_i8` and `1_i8..=i8::MAX` not covered
--> $DIR/validate-range-endpoints.rs:52:11
--> $DIR/validate-range-endpoints.rs:51:11
|
LL | match 0i8 {
| ^^^ patterns `i8::MIN..=-17_i8` and `1_i8..=i8::MAX` not covered
@ -66,7 +66,7 @@ LL + i8::MIN..=-17_i8 | 1_i8..=i8::MAX => todo!()
|
error[E0004]: non-exhaustive patterns: `i8::MIN..=-17_i8` not covered
--> $DIR/validate-range-endpoints.rs:56:11
--> $DIR/validate-range-endpoints.rs:55:11
|
LL | match 0i8 {
| ^^^ pattern `i8::MIN..=-17_i8` not covered
@ -80,5 +80,5 @@ LL + i8::MIN..=-17_i8 => todo!()
error: aborting due to 11 previous errors
Some errors have detailed explanations: E0004, E0030, E0579.
Some errors have detailed explanations: E0004, E0030.
For more information about an error, try `rustc --explain E0004`.

4
tests/ui/range/range-pattern-out-of-bounds-issue-68972.stderr
View File

@ -2,13 +2,13 @@ error: literal out of range for `u8`
--> $DIR/range-pattern-out-of-bounds-issue-68972.rs:5:14
|
LL | 251..257 => {}
| ^^^ this value doesn't fit in `u8` whose maximum value is `255`
| ^^^ this value does not fit into the type `u8` whose range is `0..=255`
error: literal out of range for `u8`
--> $DIR/range-pattern-out-of-bounds-issue-68972.rs:7:15
|
LL | 251..=256 => {}
| ^^^ this value doesn't fit in `u8` whose maximum value is `255`
| ^^^ this value does not fit into the type `u8` whose range is `0..=255`
error: aborting due to 2 previous errors