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Fallout from fixing try_read_value to work with enums

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This commit is contained in:
Oliver Schneider 2018-08-01 15:29:13 +02:00
parent 551df45935
commit 2c836a7ebd
7 changed files with 35 additions and 56 deletions
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51
src/librustc_mir/interpret/const_eval.rs
View file

@ -5,7 +5,7 @@ use rustc::hir;
use rustc::mir::interpret::{ConstEvalErr, ScalarMaybeUndef};
use rustc::mir;
use rustc::ty::{self, TyCtxt, Ty, Instance};
use rustc::ty::layout::{self, LayoutOf, Primitive, TyLayout, Size};
use rustc::ty::layout::{self, LayoutOf, Primitive, TyLayout};
use rustc::ty::subst::Subst;
use rustc_data_structures::indexed_vec::IndexVec;
@ -77,7 +77,7 @@ pub fn value_to_const_value<'tcx>(
ecx: &EvalContext<'_, '_, 'tcx, CompileTimeEvaluator>,
val: Value,
layout: TyLayout<'tcx>,
) -> &'tcx ty::Const<'tcx> {
) -> EvalResult<'tcx, &'tcx ty::Const<'tcx>> {
match (val, &layout.abi) {
(Value::Scalar(ScalarMaybeUndef::Scalar(Scalar::Bits { size: 0, ..})), _) if layout.is_zst() => {},
(Value::ByRef(..), _) |
@ -85,38 +85,21 @@ pub fn value_to_const_value<'tcx>(
(Value::ScalarPair(..), &layout::Abi::ScalarPair(..)) => {},
_ => bug!("bad value/layout combo: {:#?}, {:#?}", val, layout),
}
let val = (|| {
match val {
Value::Scalar(val) => Ok(ConstValue::Scalar(val.unwrap_or_err()?)),
Value::ScalarPair(a, b) => Ok(ConstValue::ScalarPair(a.unwrap_or_err()?, b.unwrap_or_err()?)),
Value::ByRef(ptr, align) => {
let ptr = ptr.to_ptr().unwrap();
let alloc = ecx.memory.get(ptr.alloc_id)?;
assert!(alloc.align.abi() >= align.abi());
assert!(alloc.bytes.len() as u64 - ptr.offset.bytes() >= layout.size.bytes());
let mut alloc = alloc.clone();
alloc.align = align;
let alloc = ecx.tcx.intern_const_alloc(alloc);
Ok(ConstValue::ByRef(alloc, ptr.offset))
}
}
})();
match val {
Ok(val) => ty::Const::from_const_value(ecx.tcx.tcx, val, layout.ty),
Err(error) => {
let (stacktrace, span) = ecx.generate_stacktrace(None);
let err = ConstEvalErr { span, error, stacktrace };
if let Some(mut err) = err.struct_error(ecx.tcx, "failed to convert Value to ConstValue") {
err.delay_as_bug();
} else {
span_bug!(span, "failed to convert Value to ConstValue")
}
let alloc = Allocation::undef(layout.size, layout.align);
let val = match val {
Value::Scalar(val) => ConstValue::Scalar(val.unwrap_or_err()?),
Value::ScalarPair(a, b) => ConstValue::ScalarPair(a.unwrap_or_err()?, b.unwrap_or_err()?),
Value::ByRef(ptr, align) => {
let ptr = ptr.to_ptr().unwrap();
let alloc = ecx.memory.get(ptr.alloc_id)?;
assert!(alloc.align.abi() >= align.abi());
assert!(alloc.bytes.len() as u64 - ptr.offset.bytes() >= layout.size.bytes());
let mut alloc = alloc.clone();
alloc.align = align;
let alloc = ecx.tcx.intern_const_alloc(alloc);
let val = ConstValue::ByRef(alloc, Size::ZERO);
ty::Const::from_const_value(ecx.tcx.tcx, val, layout.ty)
ConstValue::ByRef(alloc, ptr.offset)
}
}
};
Ok(ty::Const::from_const_value(ecx.tcx.tcx, val, layout.ty))
}
fn eval_body_and_ecx<'a, 'mir, 'tcx>(
@ -454,7 +437,7 @@ pub fn const_val_field<'a, 'tcx>(
),
_ => {},
}
Ok(value_to_const_value(&ecx, new_value, layout))
value_to_const_value(&ecx, new_value, layout)
})();
result.map_err(|err| {
let (trace, span) = ecx.generate_stacktrace(None);
@ -555,7 +538,7 @@ pub fn const_eval_provider<'a, 'tcx>(
if tcx.is_static(def_id).is_none() && cid.promoted.is_none() {
val = ecx.try_read_by_ref(val, layout.ty)?;
}
Ok(value_to_const_value(&ecx, val, layout))
value_to_const_value(&ecx, val, layout)
}).map_err(|err| {
let (trace, span) = ecx.generate_stacktrace(None);
let err = ConstEvalErr {

2
src/test/ui/const-eval/ub-enum-ptr.rs
View file

@ -21,7 +21,7 @@ union Foo {
// A pointer is guaranteed non-null
const BAD_ENUM: Enum = unsafe { Foo { a: &1 }.b};
//~^ ERROR this constant likely exhibits undefined behavior
//~^ ERROR this constant cannot be used
fn main() {
}

7
src/test/ui/const-eval/ub-enum-ptr.stderr
View file

@ -1,11 +1,10 @@
error[E0080]: this constant likely exhibits undefined behavior
error: this constant cannot be used
--> $DIR/ub-enum-ptr.rs:23:1
|
LL | const BAD_ENUM: Enum = unsafe { Foo { a: &1 }.b};
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ type validation failed: encountered pointer at .TAG, but expected something in the range 0..=0
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ a raw memory access tried to access part of a pointer value as raw bytes
|
= note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rust compiler repository if you believe it should not be considered undefined behavior
= note: #[deny(const_err)] on by default
error: aborting due to previous error
For more information about this error, try `rustc --explain E0080`.

2
src/test/ui/const-eval/union-const-eval-field.rs
View file

@ -34,7 +34,7 @@ const fn read_field2() -> Field2 {
}
const fn read_field3() -> Field3 {
const FIELD3: Field3 = unsafe { UNION.field3 }; //~ ERROR exhibits undefined behavior
const FIELD3: Field3 = unsafe { UNION.field3 }; //~ ERROR cannot be used
FIELD3
}

9
src/test/ui/const-eval/union-const-eval-field.stderr
View file

@ -1,11 +1,10 @@
error[E0080]: this constant likely exhibits undefined behavior
error: this constant cannot be used
--> $DIR/union-const-eval-field.rs:37:5
|
LL | const FIELD3: Field3 = unsafe { UNION.field3 }; //~ ERROR exhibits undefined behavior
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ type validation failed: encountered undefined bytes
LL | const FIELD3: Field3 = unsafe { UNION.field3 }; //~ ERROR cannot be used
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ attempted to read undefined bytes
|
= note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rust compiler repository if you believe it should not be considered undefined behavior
= note: #[deny(const_err)] on by default
error: aborting due to previous error
For more information about this error, try `rustc --explain E0080`.

4
src/test/ui/const-eval/union-ice.rs
View file

@ -20,9 +20,9 @@ union DummyUnion {
const UNION: DummyUnion = DummyUnion { field1: 1065353216 };
const FIELD3: Field3 = unsafe { UNION.field3 }; //~ ERROR this constant likely exhibits undefined
const FIELD3: Field3 = unsafe { UNION.field3 }; //~ ERROR this constant cannot be used
const FIELD_PATH: Struct = Struct { //~ ERROR this constant likely exhibits undefined behavior
const FIELD_PATH: Struct = Struct { //~ ERROR this constant cannot be used
a: 42,
b: unsafe { UNION.field3 },
};

16
src/test/ui/const-eval/union-ice.stderr
View file

@ -1,21 +1,19 @@
error[E0080]: this constant likely exhibits undefined behavior
error: this constant cannot be used
--> $DIR/union-ice.rs:23:1
|
LL | const FIELD3: Field3 = unsafe { UNION.field3 }; //~ ERROR this constant likely exhibits undefined
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ type validation failed: encountered undefined bytes
LL | const FIELD3: Field3 = unsafe { UNION.field3 }; //~ ERROR this constant cannot be used
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ attempted to read undefined bytes
|
= note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rust compiler repository if you believe it should not be considered undefined behavior
= note: #[deny(const_err)] on by default
error[E0080]: this constant likely exhibits undefined behavior
error: this constant cannot be used
--> $DIR/union-ice.rs:25:1
|
LL | / const FIELD_PATH: Struct = Struct { //~ ERROR this constant likely exhibits undefined behavior
LL | / const FIELD_PATH: Struct = Struct { //~ ERROR this constant cannot be used
LL | | a: 42,
LL | | b: unsafe { UNION.field3 },
LL | | };
| |__^ type validation failed: encountered undefined bytes at .b
|
= note: The rules on what exactly is undefined behavior aren't clear, so this check might be overzealous. Please open an issue on the rust compiler repository if you believe it should not be considered undefined behavior
| |__^ attempted to read undefined bytes
error[E0080]: this constant likely exhibits undefined behavior
--> $DIR/union-ice.rs:35:1